The Ecology of Riparian Habitats of the Southern California Coastal ...

Copies of this pubitcat~on may be obtained from the Publkcations Unrt, U S F~sh and Wildlde Service, 18th 

and C Streets, N W , Mall Stop 1111, Arlington Square Bullding, Washrnglon, DC 20240, or may be 

purchased from the Rlationai lechn~cai Inforn~at~on Serv~ce (NTIS), 5285 Port Royal Road, Springfield, VA 

Cover: Top left. drawing of California sycamore by W. Bailey; top right, drawing of predaceous nymph of the 

Gaiilsmia spreatfwing; photograph of the Santa Margarita River which has the least disturbed riparian habitat in Sari 

Diego County.

Bi ol ogical Report 85 (7.27) 

September 1989 

THE ECOLOGY OF RlPARlAN HABITATS OF THE SOUTHERN 

CAblFORNlA COASTAL REGION: A COMMUNITY PROFILE 

Phyll is M. Faber 

Ed Keller 

Anne Sands 

Barbara M. Massey 

212 Del Casa 

Mill Valley, CA 94941 

Project Officer 

Jay F. Watson 

U.S. Fish and Wildlife Service 

Lloyd 500 Building, Suite 1692 

500 NE Multnomah Street 

Port1 and, OR 97232 

Prepared for 

U.S. Department of the Interior 

Fish and Wildlife Service 

Research and Development 

National Wet? ands Research Center 

Washington, DC 20240

iabcr, ?.A,, C. Keller, A. Sands, and B.M. Massegc, 1989. Ihe ecology of riparian 

hab~ t ats of the Southern Cal i i'crrn~a codstal region: a comirltini Ly profile. U.S. Fish 

Wildl. Serv. Biaf. Rep. 8567.27). 

li2 pp.

PREFACE 

This description of the riparian 

community of Southern California is a part 

of a series of profiles describing the 

coastal habitats of the United States. Its 

purpose is to describe the structure and 

functioning of the riparian habitat in 

Southern Cal ifornia. Cowardin et a1 . 

(1979) classify this habitat as occurring 

in the Ca1 ifornia province, estuarine, 

riverine, and pal ustri ne systems. 

The profile brings together a wide range 

of information on the physical and biologic 

features of the riparian community in 

Southern Cal i forni a and some practical 

information on governmental jurisdictions 

and habitat restoration. Most of the 

riparian type of habitat has been lost in 

the past one hundred years from human 

activities, though determining the amount 

remaining was beyond the scope of this 

profile. Added as an appendix are sites 

within the study area where examples of 

riparian habitat remain and can be visited 

by the pub1 ic. 

Information in this profile will be 

useful to 1 and managers, resource planners, 

environmental consultants, ecology 

students, and interested citizens. The 

level of presentation, format, and style 

should make the profile useable for a 

diversity of needs from managing the land 

to preparing reports for classes or public 

presentations. 

Chapter 1 defines the concept of riparian 

and outlines the profile study area; 

Chapter 2 describes the physical setting 

and some of the geofluvial processes; 

Chapter 3 outlines the effect of water 

regime on the establ ishment and succession 

of plant communities and describes the most 

common species of riparian plants; Chapter 

4 details the fauna that is dependent upon 

and that uses the riparian habitat; Chapter 

5 summarizes some of the ecosystem processes 

and values; Chapter 6 spells out the 

myriad of governmental jurisdictions and 

relationships that affect the use of and 

the ability to conserve this habitat type; 

and Chapter 7 presents information on 

riparian habitat restoration including a 

number of case studies. 

iii

CONVERSiON TABLE 

Metric to U.S. Customary 

Multiply 

millimeters (mm) 

centimeters (cm) 

meters (ni) 

meters 

kilometers (kni) 

kilometers 

BY 

square meters (m2) 10.76 

square kilometers (krn2) 0.3561 

hectares (ha) 2.471 

l~ters (I) 

cubic meters (m3) 

cubic meters 

milligrams (rng) 

grams (g) 

kilograms (kg) 

metric tons (t) 

metric tons 

k~localories (kcal) 3 968 

Cels~us degrees (" 6) 1 8 (" C) 4 32 

70 Obtain 

inches 

inches 

feet 

fathoms 

statute miles 

nautical miles 

square feet 

square miles 

acres 

gallons 

cubic feet 

acre-feet 

ounces 

ounces 

pourlds 

pounds 

short tons 

f3rit1sh thernial units 

fnhrenhe~t degrees 

U.S. Customary lo Metric 

incties 25.40 

incfies 2.54 

feet (ft) 0.3018 

fathoms 1.829 

statute miles (mi) 1.609 

nautical miles (nmi) 1.852 

square feet ft2) 

square mfles jm?) 

acres 

gallons (gal) 

cubic feet (ft3) 

acre-feet 

ounces (oz) 26350.0 

ounces 28 35 

pounds (lb) 0.4536 

pounds 0 00045 

short tons (ton) 0.9072 

Britrsh thermal unrts (Btv) 0 2520 

Fahrenheit degrees (" F) 0 5556 (" F - 32) 

nitllimeters 

ccntrrrleters 

meters 

meters 

kilometers 

kilonietcrs 

square meters 

square kilometers 

hectares 

liters 

cubic meters 

cubic rneters 

milligranis 

grams 

kilograins 

meiric tons 

metric tons 

ktlocaiories 

Cels~trs degrees

CONTENTS 

PREFACE ........................................................................ 

CONVERSION TABLE ............................................................... 

FIGURES ........................................................................ 

TABLES ......................................................................... 

ACKNOWLEDGMENTS ................................................................ 

CHAPTER 1 . INTRODUCTION ....................................................... 

1.1 Introduction ......................................................... 

1.2 Riparian Habitat Distribution ........................................ 

1.3 Disturbance Effects .................................................. 

1.4 Classification Systems ............................................... 

1.5 Study Area ........................................................... 

iii 

i v 

viii 

i x 

xi i 

CHAPTER 2 . PHYSICAL SETTING AND PROCESSES ..................................... 5 

2.1 Introduction ......................................................... 5 

2.2 The Fluvial System ................................................... 5 

2.3 Basic Concepts ....................................................... 6 

2.3.1 Channel-Floodplain Environment ................................ 6 

2.3.2 Channel Pattern ............................................... 7 

2.3.3 Fl uvi a1 Hydro1 ogy ............................................. 7 

2.3.4 Bed Forms ....................... ........................... 8 

2.4 Thresholds in Stream and River Systems ............................... 9 

2.5 Human Interference in the Riverine Environment ....................... I I 

2.6 Southern Cal i fornia Stream-River System .............................. 11 

2.6.1 Geology and Soils ............................................. I1 

2.6.2 Cl imate, Hydrology, Sediment Production, and Fire ............. 13 

2.6.3 Channel Disturbance ........................................... 1 6 

2.7 Summary .............................................................. 18 

CHAPTER 3 . THE RIPARIAN COMMUNITY: PLANTS .............................. . 

3.1 History of Riparian Forests of Southern California ................... 

3.2 The Riparian Community ............................................. 

3.2.1 Water Regime .................................................. 

3.2.2 Community Structure ........................................... 

3.2.3 Deciduousness and Productivity ................... . ........... 

3.2.4 Regeneration .................................................. 

3.2.5 Succession .................................................... 

3.2.6 Tolerance of Flooding ......................................... 

3.3 Common Plants in Southern California" Riparian Community ............ 

3.4 Rare and Endangered Plants ........................................... 

3.5 Introduction and Distribution of Exotic Plants .......................

Southern California Riparian Habitat ................................ 

3.6.1 Channel Islands ............................................... 

3.6.2 Coastal Streams in Santa Barbara County ....................... 

3.6.3 Coastal Streams of the Santa Monica Mountains ................. 

3.6.4 Ventura and Santa Clara Riverr ..............*................. 

3.6.5 San Gabriel Mountain Range .................................... 

3.6.6 San Bernardino Mountain Drainage .............................. 

3.6.7 San Jacinto Range ............................................. 

3.6.8 Santa Ana Mountains ........................................... 

3.6.9 San Diego County Coastal Rivers ............................... 

Summary .............................................................. 

. THE RIPARIAN COMMUNITY: ANIMALS ................................... 

Insects .............................................................. 

4.1.1 Aquatic Insects .........................................+....a 

4.1.2 Terrestrial Insects ........................................... 

4.1.3 Role of Insects in Riparian Ecology ........................... 

Fish ................................................................. 

4.2.1 Native Fish ................................................... 

4.2.2 Introduced Fish ............................................... 

Amphibians and Reptiles .............................................. 

Birds ................................................................ 

4.4.1 Breeding Birds ................................................ 

4.4.2 Distribution of Breeding Birds ................................ 

4.4.3 The Breeding Season ........................................... 

4.4.4 Needs of Breeding Birds .............. ....................... 

4.4.5 Food and foraying ............................................. 

4.4.6 Bfrds as Agents of Insect Control ............................. 

4.4.7 Changes in Status ............................................. 

4.4.8 Species of Special Concern .................................... 

4.4.9 Expanding Species ............................................. 

Non Breeding Birds ................................................... 

4.5.1 Winter Bird Use ............................................... 

4.5.2 Taxonomic Aspects of the Riparian Bird Community .............. 

Mammal s .............................................................. 

4.6.1 Riparian-Associated Mammals ................................... 

4.6.2 Status of Riparian Mammals .................................... 

Sumary .............................................................. 

5 . ECOSYSTEM PROCESSES AND VALUES ..................................... 

Ecosystem Processes .................................................. 

5.1.1 Primary Productivity ......................................... 

5.1.2 Riparian Vegetation and Stream Ecosystems ..................... 

5.1.3 Role of Fire in Nutrient Cycling Between Ecosystems ........... 

Riparian Habitat Values .............................................. 

5.2.1 Water Qua1 i ty and Quantity and Stream Maintenance ............. 

5.2.2 Habitat for Wildlife ............................. .......... 

5.2.3 Availability of Water ......................................... 

5.2.4 Migratory Corridors ........................................... 

5.2.5 Riparian Habitat Dependency of Aquatic insects ................ 

5.2.6 Ripariaa Habitat Oep~ndency of Fish ........................... 

5.2.7 Riparian Habitat Dependency of Birds .......................... 

5.2.8 Habitat for Mama1 s ........................................... 

Positive Values for People ........................................... 

5.3.1 Air and Water Quality .............................. .......... .

5.3.2 Benefits to Agriculture ....................................... 94 

5.3.3 Aesthetic and Recreational Values ............................. 95 

5.4 Human Impacts Adverse to the Riparian Ecosystem ...................... 95 

5.4.1 Sensitivity to Disturbance .................................... 96 

5+4.2 Recreational Activities ....................................... 97 

5.4.3 Gravel Mining ................................................ 98 

5.4.4 Water Impoundments ............................................ 98 

5.4.5 Agriculture and Grazing ....................................... 99 

5.4.6 Urbanization and Road Building ................................ 99 

5.5 Summary .............................................................. 101 

CHAPTER 6 . GOVERNMENT JURISDICTIONS AND RELATIONSHIPS ......................... 102 

6.1 Introduction ......................................................... 102 

6.2 Federal Government ................................................... 102 

6.2.1 Federal Laws ................................................. 102 

6.2.2 Federal Programs and Agencies ................................. 103 

6.3 State of California .................................................. 104 

6.31 California Laws ............................................... 104 

6.3.2 State Regulations and Agencies ................................ 106 

6.4 Local Government ..................................................... 107 

6.4.1 Local Government Plans ........................................ 107 

6.4.2 Ordinances .................................................... 108 

6.4.3 Southern California Jurisdictional Plans ...................... 109 

6.5 Summary ............................................................ 111 

CHAPTER 7 . RIPARIAN ECOSYSTEM RESTORATION ..................................... 112 

7.1 Introduction ......................................................... 112 

7.2 Land Use and Ownership Patterns ...................................... 112 

7.3 Conflicting Objectives ............................................... 112 

7.4 Timing Conflicts in Restoration Projects ............................. 113 

7.5 Enforcement of Mitigation ............................................ 113 

7.6 Restoration Potential in Southern California ......................... 114 

7.6.1 Development of Restoration Plans .............................. 114 

7.6.2 EstablishingGoals ............................................ 114 

7.6.3 Critical Elements in a Restoration Design ..................... 115 

7.6.4 Implementation ................................................ 116 

7.6.5 Management and Maintenance .................................... 117 

7.6.6 Technical Monitoring .......................................... 117 

7.6.7 Milestones for Measuring Progress ............................. 118 

7.7 A Case Study of Riparian Revegetation ................................ 118 

7.8 Recommended References ............................................... 120 

7.9 Sources of Plants and Seeds .......................................... 121 

7.10 Summary .............................................................. 121 

REFERENCES ..................................................................... 123 

APPENDIXES ..................................................................... 139 

A . Birds that Breed in Riparian Habitat in Coastal S~uthern California ....... 139 

B . Birds that Use Riparian Habitat for Other than Breeding Purposes .......... 143 

C . Mammals Associated with Riparian Mabi t at in Coastal Southern 

California ................................................................ 145 

D . Examples of Riparian Habitat in Coastal Draining Watersheds of 

Southern California ............................................... 147

FIGURES 

Number 

1 

2 

3 

4 

5 

6 

7 

8 

9 

.... 

....... 

................................................... 

Study area showing major coastal drainages in Southern Cal ifornia 3 

The Southern California drainage area showing runoff in inches 6 

The fluvial system 6 

Ideal ired diagram showing areas of convergent and divergent fl ow ..... 8 

Pool -ri ffle morphology ............................................... 9 

Hierarchical reversal of bottom velocity in a pool -riffle sequence ... 10 

Threshold condition of slope controlling channel pattern ............. 10 

Comparison of a natural channel with an artifical channel ............ 12 

Generalized map of the Southern California drainage area showing 

the location of major active or recently active faults ............... 13 

Mean annual precipitation in inches for San Diego. Los Angeles. 

and Santa Barbara. California ........................................ 14 

Relationship between mean annual flood and recurrence 

interval s for several rivers ......................................... 14 

1 ..ass of reservoir storage in Gibraltar Lake from 1920 to 1980 ........ 18 

Past and present geographical distribution of box elder and alder .... 22 

Pine and incense cedar near edge of Mill Creek in San 

Bernardino Mountains ................................................. 22 

A1 der a1 ong seasonal ly flooded streambank. Wheeler Gorge 

Campground on Sespe Creek ............................................ 23 

View of alluvial fan plant community along San Jacinto River ......... 24 

Mil lows at Tapia County Park near Ma1 i bu ............................. 25 

Thickets of mulefat in the streambed in Piru Creek ................... 27 

White alder (Alnus rhombi fol i a) ....................... .........-... 28 

Goodding'sWillow(Sa1ixqooddin~ii) ................................. 29 

viii

Number 

2 l 

Arroyo willow (SaIix I&sjd_e&) ..................................... 30 

22 

23 

24 

2 5 

26 

Gal i forni a sycamore (PI atanus raceniosa) .............................. 31 

Boxelder (& nesundo) .............................................. 32 

Black walnut (Juslans californica) ................................... 33 

German ivy (Senecio Uanioides) along San Jose Creek in Goleta ...... 35 

A cross section of San Jose Creek in Goleta Valley ................... 41 

Corridor of riparian vegetation reveals the presence of a stream 

descending into Ventura River ........................................ 42 

Mountain dudleya (Dudleya densiflora) on rocky cliffs above stream 

in Fish and San Gabriel Canyons ...................................... 45 

Cross section of the Santa Ana River between Horeshoe Bend 

and Featherly Park ................................................... 48 

The Santa Margarita. the least disturbed river in San Diego County ... 50 

Predaceous nymph and adult of the Cal i forni a spreadwing 

(Archil estes cal ifornica) ..................................... . . 54 

Whirligig beetles (Dinetus sp.) on the surface of an eddy 

in a stream .......................................................... 56 

Lorquin's admiral (Limenitis lorauini) larva. pupa. and adult ........ 58 

Rainbow trout (Salmo sai rdneri ) from Ma1 i bu Creek 

and the San Gabriel River ............................................ 62 

Unarmored three-spine stickleback (Gastrerosterus aculeatus 

......................................................... 

wi 11 i amsoni) 63 

A mating pair of California tree frogs (m cadavarina) 

on a gravel bank ....................+eve...........-.............. 67 

Willow flycatcher (Em~idonax traillii) ........................ ...... 74 

Least Bell's vireo (Vireo be'ilii ~usillusf feeding a brown-headed 

cowbird ...................................................... . 75 

A beaver dam on the Santa Margarita River ............................ 81 

Riparian vegetation requires large amaunts of free or unbound water .. 85 

Re1 ationships between riparian vegetation and stream components ...... 86

Number 

4 4 Riparian zones along rivers and streams serve as corridors 

between habitat types .........................~~+~..~............. 98 

Riparian zones often have many edges and strata in a small area 

with habitat for a variety of wildlife ...........+..,........s.e..a.. 92 

Wilderness Gardens Preserve along the San Luis River ................. 95 

Riparian zones must be considered delicate due to restricted area, 

distinct microcl imate, vegetative structure and composition, 

and water quality and quantity ....................................... 95 

Percentage change from control in transportable sediment, detritus, 

and detrituslsediment ratio in narrow buffered and unbuffered 

streams in Northern California ...,................................... 97 

Cottonwood trees adversely affected by lowered water tables on the 

$an Jacinto River floodplain ......................................... 98 

Gravel operation on the San Luis Rey River ........................... 98 

Cement apron rep1 aces riparian understory i n Temecul a . . . . . . . . . . . . . . . . 100 

Road construction in riparian zones reduces their usefulness 

as wild1 ife habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . 100 

Public works project on a Santa Margarita River tributary ......... ... 104 

Riparian restoration in an urban area along the San Diego River ...... 117

TABLES 

Number 

f 

2 

3 

Suspended sediment yields for selected rivers .......................... 16 

Sediment yield for seven selected rivers in Southern California ........ 17 

Channel conditions and adjacent land use for selected rivers 

in Southern California ................................................. 18 

Some common species in the modern riparian forest of Southern 

California and their counterparts in the late Tertiary fossil 

record of the western United States .................................... 21 

Rare and endangered riparian plant species ............................. 34 

Common riparian plants in coastal drainages of Southern Ca1 ifornia ..... 37 

Moths (larvae) and their riparian host plants .......................... 59 

Butterfl ies (1 arvae) and their riparian host plants .................... 59 

Endangered. rare. and sensitive bird species in Southern California .... 72 

Orders of birds breeding in riparian habitat in Southern Gal ifornia .... 78 

Water temperature changes in small streams caused by riparian 

vegetation removal in relation to undisturbed conditions ............... 87 

Average percentage change in suspended sediment in the Alsea. 

Oregon. watershed several years after fogging .......................... 97 

Local tools for resource management .................................... 188

ACKNOWLEDGMENTS 

The authors of this community profile 

acknowledge the significant amount of 

information, unpublished data, and helpful 

advice that was generously provided by a 

number of people, including: Jon Atwood, 

Mi tch Beauchamp, David Bontrager, Mark 

Borchart, Bayard Brattstrom, Timothy 

Brothers, Oscar Clarke, Paul Coll ins, Robin 

Cox, Jeanine Derby, Wendy Eliot, Mike 

Evans, Jack Fancher, Wayne Ferren, Jr., Ted 

Hanes, Michael Hami 1 ton, Dean Harvey, Glen 

Holstein, Charles Hogue, Jon Keeley, Tom 

Keeney, Steve Lacey, Steve Loe, Don 

McFarl and, Rich Mi nnach, Brian Mooney, 

Chris Nagano, 

Tom Oberbauer, John Rieger, 

Jim St. Amant, Alan Schoenherr, Sam Sweet, 

Camm Swift, Tim Thomas, Steve Timbrook, 

Phil 1 Uni tt, Richard Vogl , Richard Warner, 

Cindi Weber, Howard Wier, and Richard 

Zembal . 

The draft manuscript was reviewed in its 

entirety by Chris Onuf and Michael Brody of 

the National Wetl ands Research Center in 

Slidell, Louisiana, Jay Watson of the U.S. 

Fish and Wild1 ife Service, Portland, 

Oregon, and Richard Zembal, U.S. Fish and 

Wildlife Service Wildlife Biologist in 

laguna Niguel, California. Parts of the 

rnanuscri pt were reviewed by Jon Atwood, 

Jack Fancher, Ted Hanes, Charles Hogue, 

Glen Holstein, El izabeth McCl intock, Steve 

Low, Joe McBride, A1 an Schoenherr, and Camm 

Swift. The critical comments of reviewers 

have contributed to a significantly 

improved final version of this profile. 

At the National Wetl ands Research Center, 

Beth Vairin edited the manuscript, Daisy 

Singleton prepared the camera-ready copy, 

and Sue Lauri tzen designed the 1 ayout. 

Errors and omissions are the sole 

responsibility of the authors. Ed Keller 

was primarily responsible for Chapter 2; 

Barbara Massey for Chapter 4; Anne Sands 

and Phyllis Faber, in association with 

Bruce Jones, Environmental Consultant, for 

Chapter 6; Anne Sands for Chapter 7; and 

Phyllis Faber for Chapters 1, 3, and 5, 

Appendix 0, organization, editing, and 

photographs unless otherwise noted. PI ates 

in Chapter 2 were drafted by D.G. Crouch. 

Wendy Bailey was responsible for the 

drawings in Chapter 3 and for redrawing 

several figures. Sally Porter typed much 

of the manuscript. Nora Harlow typed 

several tables and did final editing. The 

authors are grateful to each of these 

people.

1 .I INTRODUCTION photographs are necessary for this kind of 

determination. 

Annual fl oodi ng, with accompanying 

overfl ows of streams and rivers, predates 

man's presence in California. In the 200 

years since Cal ifornia's settlement by 

Europeans, almost every river in Southern 

Cal i forni a has been channel i zed or dammed 

to allow development on the floodplains. 

Only recently has there been concern about 

the loss of a highly productive and diverse 

ecosystem, capable not only of supporting 

a rich assemblage of plants and animals, 

but also of fulfilling other roles yet 

poorly understood. Perhaps as much as 95 

to 97 percent of the riparian community has 

been eliminated in floodplain areas of 

Southern Cal i forni a, yet remnants remain, 

particularly at higher elevations where 

development pressures have been less 

intense. 

This communi ty profile assembles the 

small amount of information available on 

the riparian habitat of Southern 

California, an important but neglected 

habitat type. It has not been possible to 

establish definitive values for losses of 

riparian habitat or for the extent of 

remaining riparian habitat. The earl iest 

aerial photographs of the Los Angeles 

Basin, taken in the late 1920s by 

Fairchild, show that the San Gabriel, Los 

Angeles, and Santa Ana Rivers were already 

channelized by that date. Vegetation can 

be determined on recent infrared aerial 

photographs; however, it is beyond the 

scope of this study to differentiate 

between qua1 i ty habitat with native trees 

and an undisturbed or intact understory and 

disturbed or degraded habitat with exotic 

plant or tree species and 1 ittle or no 

understory. The difference is of extreme 

importance in determining wildlife values, 

but extensive ground checks of aeri a1 

1.2 RIPARIAN HABITAT DlSTRlBUTlON 

Riparian habitat occurs a1 ong streambanks 

where soils are fertile and water is 

abundant, at least for some portion of the 

year. It often appears as a deciduous 

greenbelt along perennial and intermittent 

watercourses and their floodplains. 

The riparian comrnuni ty is a complex 

ecosystem: In the introduction to Ri~arian 

Resources of the Central Vallev 

Cal i forni a Desert (1983), Warner develops 

a rioarian alossarv based on the Latin word 

m', meaniig ban( or shore of a stream or 

river. The original meaning has been 

retained and the adjective "riparian" is 

defined as pertaining to the terrestrial or 

emergent zone (as opposed to aquatic or 

submersed zone) immediate1 Y adjacent to 

freshwater ( ~ ctionary i of Geol oaiia~ 

Terms, 

1962; Webster's Third New International 

Dictionary, 1963). Although current usage 

sometimes expands the meaning of "riparian" 

to include tidal and estuarine zones, this 

study generally adheres to the original 

usage of the term, restricting it far the 

most part to a zone adjacent to a 

freshwater stream or river, recognizing 

that wildlife usage of habitat areas 

transcends technical definitions of habitat 

types. 

Amphibians, reptiles, birds, and mamals 

a1 1 move back and forth across the riparian 

zone from streams into adjacent wetland and 

up1 and areas. Primary and secondary 

production derived from up1 and and riparian 

comrnunf t ies goes into stream and rivers, 

nsuri shing aquatic organisms that in turn 

support riparian organisms, In other

words, the riparian cornunity is 

interdependent with adjacent aquatic and 

up1 and communi ties. Two riparian birds, 

the dipper and the kingfisher, provide 

examples. The dipper feeds on aquatic 

stages of insects (dragonfl ies, 

damselflies, midges, caddisflies, etc.) 

that are nourished and protected by 

riparian vegetation; the kingfisher 

inhabits the riparian community but feeds 

on fish in an aquatic community that, in 

turn, feed on terrestrial insects from the 

adjacent riparian community. 

Warner defines the adjective "riparian" 

as "pertaining to the banks and other 

adjacent terrestrial (as opposed to 

aquat tc) environs af freshwater bodies, 

watercourses, and the surface-emergent 

aquifers (springs, seeps, oases) whose 

transported waters provide soil moisture 

significantly in excess of that otherwise 

available through local precipitation." An 

upland community, as opposed to a riparian 

community, is then defined as one above a 

floodplain in a zone far enough above or 

away from the transported waters of 

freshwater bodies, watercourses, and 

surface-emergent aquifers to be ent ireIy or 

largely dependent upon local precipitation 

for its water supply. 

Riparian habitat is usually seen a5 an 

ecotone, a transitional community between 

an aquatic and an upland communit.y, 

Immediately adjacent to the watercourse, in 

contrast with those of the adjdcent upland 

tommun 1 ty, plants are tall er, have 1 arger 

leaves, and are often deciduous. As a 

result of its dependence on a supplemental 

water source, the ripdrian commux~ity is 

intimately tied to the meanderings of 

itream dnd river watercourses. As a 

funrtion~ng ecosystem, it is open and has 

high energy, nutrient, and biotic 

interchanges with aquatic systems on the 

lrrncr margin and upland terrestrial systems 

on the outer margin. The boundary between 

upland and riparian camrnuniLies shifts in 

years of high or low rainfall as flooding, 

sedimentat~an, and water table levels vary. 

Warner (1983) claims that riparian 

conditions exist to approximately the 100- 

year flood zone, Where streams are 

intermittent to ephemeral , the up1 and 

boundary is increasingly difficult to 

discern. The presence or absence of 

certain plants or their overall size 

relative to those in an upland setting 

becomes the easiest determining factor. 

A riparian zone provides a classic case 

of the ecological principle of "edge" 

effect. Both density and diversity of 

species tend to be higher at the land/water 

ecotone than in adjacent upland 

communities. Many animals move from one 

community to another to forage, rest, or 

build nests. Large animals require access 

to streams for survival. In addition, a 

contiguous riparian strip provides a 

natural highway along which animals can 

move safely from one place to another. 

Increasingly, riparian corridors are valued 

by urban dwellers in that they provide a 

welcome relief from urban industrial and 

agricultural development. The soi 1 and 

vegetation a1 so provide a natural f i1 tering 

system for removing air pollutants, a 

subject of increasing importance, 

particularly in the densely populated urban 

centers of Southern Cal i fornia. 

1.3 DISTORBANCE EFFECTS 

Disturbances of the riparian ecosystem 

are sometimes reversible. Irreversible 

a1 terations of the riparian ecosystem 

result from the diversion or loss of transported 

water ta the system through diking, 

damming, channel ization, levee building, or 

road construction. Clearing for crops, 

grazing, or golf courses is potentially 

reversible as long as the water supply 

remains unaltered. The cumulative effects 

of land clearing f agricul tural and 

urbanizing), earth moving (water diversion 

and sedimentation), and pollutants 

(pesticides, herbicides, organic chemical s) 

all result in a less vigorous and 

deteriorating ecosystem with reduced 

functions and a1 tered plant and animal 

populations. 

1.4 CLASSIFICATION SYSTEMS 

In the U.S. 

Fish and Wildlife Service's 

(USFWS) C'lassification a Wetlands & 

Deepwater Habitats 01 United States, by 

Cowardin et al. (1977)Tbitats are 

c1 ass! f ied according to hydrologic and 

geomorphic factors to which vegetation 

types are related. Using this system, 

riparian habitat can be found in the

estuarine, riverine, and palustrine 

categories, This community profile of 

riparian habitat in Southern Cal ifornia 

includes segments of the palustrine system, 

defined as nontidal wet1 ands dominated by 

trees, shrubs, persistent emergents, 

emergent mosses or lichens, and all such 

wetlands that occur in tidal areas where 

salinity due to ocean-derived salts is 

below 0.5 parts per thousand. The USFWS 

classification system is not entirely 

satisfactory for defining "riparian" as it 

does not appear to take into account the 

effect of high water tables in floodplain 

areas that significantly determine the 

assemblage of plants in riparian habitat. 

An example of the use of this 

classification system can be found in 

Appendix 1 of Onuf (1983). 

The California Natural Diversity Base, in 

a modified version (1983) of an Outline of 

Cal ifornia Natural Communities by Cheatham 

and Hal ler (1975), recognizes riparian 

habitats as a major category, with 

divisions and subdivisions based on 

geographic and vegetational differences. 

The categories applicable to the riparian 

habitat of Southern California are 

Bottomland Forest and Savanna 

Ci smontane Bottoml and Forest 

Coast Live Oak Bottoml and Forest 

Arroyo Mi 1 low Bottoml and Forest 

Black Cottonwood Bottoml and Forest 

Riparian Forest 

Cismontane Riparian Forest 

Southern Ripari at) Forest 

A1 1 uvi a1 Wood1 and 

Sycamore Woodl and 

A1 1 uvial and Riparian Scrub 

Willow Scrub 

Ci smontane Wi 11 ow Scrub 

Mule Fat Scrub 

1.5 STUDY AREA 

Southern California, as defined in this 

community profile, covers the cismontane or 

coastal area between the Coast Range 

Mountains and the sea as shown in Figure 1. 

The study area is bounded on the north by 

Point Conception in Santa Barbara County 

Boundary of Southern 

I 

- 

Santa Barbara 

Coastal Streams 

2 Ventura 

3 Santa Clara 

4 Los Angeles 

5 San Gabriel 

6 Santa Ana - 

@ SB-Sanfa Borbara 

7 Santa Margartfa 

s V-Ventura 

8 San Luis Rey 

9 San Diego 

i 0 Tljuana 

SD-San Diego 

Figure 1. 

Study area showing major coastal drainages in Southern Caiilarilia.

and extends eastward along the crest of the 

Santa Ynez Mountains in the Transverse 

Range, along coastal -draining portions of 

the San Rafael Mountains drained by the 

Ventura and Santa Clara Rivers, across the 

San Gabriel and $an Bernardino Mountains, 

both drained to the west by major rivers, 

the Los Angeles, §an Gabriel, and Santa 

Ana, all crossing the vast Los Angeles 

floodplain. The study area then continues 

southeast Lo the Mexican border in the 

cismontane area From the crest of the San 

Jacinto and Santa Ana Mountains and the 

Coast Range in Orange and San Diego 

Counties ts the Pacific Ocean. The Santa 

Monica Mountains are included within this 

region, and brief mention is given to the 

Channel Islands, considered to be a 

westward extension of the Santa Monica 

Mountains.

CHAPTER 2. 

PHYSICAL SETTING AND PROCESSES 

2.1 INTRODUCTION 

Human use and interest in the riverine 

envi ronment of Southern Cal i forni a extends 

back more than one hundred years. 

Particularly in the last eighty years, 

rapid and extensive urbanization has 

significantly a1 tered the Southern 

Cal i forni a envi ronment , and streams and 

rivers have been extensively modified for 

the purposes of flood control and water 

supply. The Los Angeles River, which 

flooded during the storms of 1938 that 

killed 87 people while inflicting $78 

mi 11 ion in damage, has been so a1 tered as 

to scarcely resemble its natural conditions. 

For its size, the Los Angeles River 

may be the most extensively controlled 

river in the world. There are 290 check 

dams, 75 debris dams, 8 control and storage 

reservoirs, and 2 1 arge flood-control 

basins in the 2,155 square kilometer 

drainage basin of the Los Angeles River 

(Brownlie and Taylor, 1981), and nearly 90 

percent of the banks have been straightened 

and/or 1 ined with concrete. 

The total drainage area of streams and 

rivers in Southern Cal ifornia exceeds 

32,000 square kilometers, of which about 53 

percent is controlled by dams and reservoirs 

(Brown1 ie and Taylor, 1981). Figure 

2 shows the Southern California drainage 

area and lists some of the major rivers. 

Although we can sometimes control a river 

by constructing massive dams and channel 

works to dissipate the disastrous effects 

of floods and droughts, we still know too 

little about the processes by which natural 

river systems are formed and maintained. 

Only recently have we recognized that 

physical diversity in the natural system is 

necessary to maintain biological 

productivity and diversity, and that past 

modification of the riverine environment 

for human purposes has caused deterioration 

of riverine ecosystems. 

In this chapter we present fundamental 

concepts necessary for understanding the 

fluvial system and discuss the nature and 

extent of human modification of the 

Southern California riverine environment. 

2.2 THE FLUVIAL SYSTEM 

The fluvial or river system may be 

discussed in terms of three major zones: 

(1) the erosion zone, where much of the 

sediment i s produced in the headward 

portions of a drainage system; (2) the zone 

of storage and transport of sediment in the 

downstream or middle portion of the 

drainage system; and (3) the zone of 

deposition of sediment, which is usually a 

lake or ocean, as shown in Figure 3 

(Schumm, 1972). A1 though this idealized 

system is useful in understanding general 

concepts about stream and river processes, 

there are many exceptions. Some exceptions 

are particularly common in Southern 

Gal ifornia because of the wide variation in 

physical conditions from the mountains to 

the sea. 

The natural riverine environment a1 so can 

be viewed as a system composed of three 

interrelated parts: the fluid or water; 

the main channel and floodplain; and the 

network of channels that makes up the 

drainage basin. As the system evolves and 

changes, all three parts will mutually 

adjust and influence the others. Adjustment 

involves a mu1 ti tude of interactions 

that tend to maintain a delicate balance 

within the system. In most streams and 

rivers, that balance is a quasi -equil i briurn 

(Leopold and Maddock, 1953) or dynamic

Sonta Barbara 

SAN DIEGO R. 

KILOMETERS 

Figure 2. The Southern California drainage area showing annual runoff in inches (after California Water 

Atlas, 1979). 

. . . equilibrium (Hack, 1960). In order to 

understand the quasi -equil i brium or dynamic 

equil ibrium, we must recognize that (1) 

the stream and river channels and adjacent 

floodplain comprise an erosional , transportational 

, and depositional environment 

in which form and process evolve in 

harmony; (2) significant changes in the 

storoge 

of sediment 

fluvial system often occur when a threshold 

has been crossed; and (3) human interference 

with the fluvial system generally 

reduces the physical variabil i ty of the 

channelandfloodplain,resultinginaloss 

of hydrologic variabil ity and biological 

productivity. 

2.3 BASIC CONCEPTS 

2.3.1 Channel -Fl ood~l ain Environment 

Figure 3. The fluvial system (modified after The stream or river channel and adjacent 

Schumm, 1978), 

fl oodpl ain are part of a unique environment

characterized by erosional, transportational 

, and depositional processes in the 

fluvial system. The floodplain, a part of 

the natural fluvial system, is produced by 

depositional processes during flows of 

moderate magnitude and frequency. 

Formation and maintenance of the floodplain 

involves two main processes: (1) 

overbank flow and resultant vertical accretion 

of fine sediment; and (2) lateral 

migration of the stream channel with deposition 

and floodplain construction on the 

inside of bends. Which of these two processes 

dominates the formation and maintenance 

of a parti cul ar f7 oodpl ai n depends 

upon local conditions. In general, however, 

in highly meandering streams the rate 

of lateral migration may greatly exceed 

that of vertical accretion. In streams 

with stable meanders and 1 ittle migration 

from side to side, vertical accretion may 

be the dominant process in the formation of 

the floodplain. In the steeper headwater 

portions of streams, floodplains may be 

1 acking or poorly developed. 

Under natural conditions a stream or 

river usually has sufficient discharge to 

emerge from its bank and flood adjacent 

areas on the average of once every year or 

two. Overbank flow often supplies water to 

adjacent low1 ands on the floodplain, which 

serve as storage sites for ground water 

later released slowly to the stream during 

drier portions of the year. People living 

near rivers must recognize that overbank 

flows (floods) are a natural process of the 

fl uvial system. To maintain the integrity 

of the fluvial system, the stream or river 

channel and adjacent floodplain must be 

considered a complementary system that has 

evolved in harmony over a period of years. 

Modification of the environment to reduce 

overbank flooding wi 11 reduce hydrologic 

vari abil i ty and degrade the riverine 

environment. In recent years there has 

been a move away from absolute control of 

the river system to floodplain management, 

which involves zoning of the floodplain to 

reduce damage from the natural process of 

flooding. 

channel pattern. Natural streams fall into 

two major types of channel patterns: (1) 

braided channels, characterized by an 

abundance of mid-channel islands or bars 

that continually divide and reunite the 

channel ; and (2) channels that are not 

braided. Straight channels are rare in 

nature and are generally associated with 

geologic or structural control. Therefore, 

most non-braided channels are characterized 

by numerous bends and may be described as 

sinuous. A particular type of sinuous 

stream, characterized by very regular 

bends, is labeled a meandering stream. In 

the headward portion of streams, where the 

gradient is steep and controlled by the 

geology, channel patterns are difficult to 

distinguish, but generally are straight to 

sinuous and confined to a steep, V-shaped 

valley. After emerging from a mountain 

front, streams may flow across an alluvial 

plain and be either braided or meandering, 

depending upon the slope of the channel, 

the sediment load carried, and the 

hydrologic conditions. Streams with a high 

load of coarse sediment (gravel) and steep 

slope favor the braided pattern, whereas 

those with a lesser slope and gravel load 

are more likely to be sinuous. Streams 

emerging from a mountain front will often 

wander back and forth across the alluvial 

plain, producing a system of coalescing 

alluvial fans. In other cases, streams may 

cut across alluvial fans or plains and 

deposit their load directly in a lake or 

ocean without long-term storage of the 

sediment on alluvial plains. 

2.3.3 F1 uvi a1 Hvdrol oqy 

in most stream and river channels, the 

characteristic forms are produced by 

highmagnitude flows (floods) and may be 

modified or slightly changed only during 

lowflow periods. The principles af 

conventional hydro1 ogy apply during the 

low-flow period when the stream is 

essentially a rigid container for the fluid 

phase with l i ttle or no sediment transport. 

At high flow, when sediment is being 

eroded, transported, and deposi led, 

convent1 onal hydrol ogy is no 1 anger 

auof icable because of the many variables 

(tbl iavsky, 1966; Haddock, 1969). Thus it 

2.3.2 Channel Pattern is necessary Lo distinguish fluvial 

hydro1 ogy from more conventional hydrol ogy 

The pattern of a stream or river channel in order to understand the natural fluvial 

as viewed from the air is called the system and riverine environment.

Three important principies of fluvial associated with deposition and the 

hydrology are (I) in no part of the natural formation of bars or riffles. 

channel are contiguous stream1 ines 

(hypothetical lines that represent the 

direction of flow) parallel to one another 2.3.4 Bed Forms 

or oarallel to the banks of the channel ; 

(2) the greater the curvature of the 

A bed form is any irregularity produced 

channel, the deeper the scour is l i kely to 

on the bed of a stream or river by the 

be; and (3) during high (bankful) flow 

interactions between flowing water and 

events, scour is associated with horizontal 

moving sediment (Simons and Richardson, 

convergence or narrowing of streamflow and 

deposition with horizontal divergence or 

widening of streamfl ow (Lel iavsky, 1966). 

The third principle, illustrated in Figure 

4, is known as the convergence-di vergence 

criterion. It suggests that, in general, 

areas that converge during high-fl ow events 

will scour to form pools, while areas that 

diverge during high-flow events tend to be 

-D+ 

c - D -----' 

- 

C CONVERGENT FLOW 

D DIVERGENT FLOW 

E -- 3' CROSS SECTION LINE 

p 

1966). In most stream and river systems, 

two main types of bed forms may be present: 

(1) pools, riffles, point bars, and other 

bars that give the stream its basic morphology 

and generally are 1 arge enough to 

be measured in channel widths; and (2) 

ripples, dunes, and antidunes, which are 

primarily controlled by the hydrologic 

phase of the fluvial system and may not be 

a significant part of the basic - channel 

morphology (Kel ler and Me1 horn, 1973). 

Pools, riffles, and point bars are best 

developed in a1 1 uvi a1 meandering streams 

with a gravel bed, whereas mid-channel bars 

and side-channel bars are probably best 

developed in braided channel systems. If 

there is an appreciable amount of finer 

bed-load material (sand), then ripples and 

dunes are more likely to be present, which 

at low flow may migrate through the channel 

system, partially masking more stable bed 

forms, such as pools, riffles, and point 

bars. 

Pools, riffles, point bars, and midchannel 

bars may be identified by basic 

morphology (Kell er, 1971). Pools are 

topographic low areas (deeps) produced by 

scour (convergent flow) during high 

channel -forming events. Riffles are 

topographic high areas (shallows) produced 

by deposi t ional processes (di vergent fl ow) 

during high channel-forming events. Point 

bars are depositional forms located on the 

inside of meander bends. The pool and 

point bar together produce an asymmetric 

cross-channel profile, whereas the riffle 

ox often forms a more symmetric cross-channel 

profile (Figure 5). Other mid-channel and 

side-channel bars are formed by deposi - 

POINT BAR tional processes during high channel - 

forming events. The best developed 

WATER SURFACE 

mid-bars and islands are associated with 

braided channels characterized by steep 

channel gradient and abundance of bed- 

Figure 4. Idealized diagram showing areas of load material being transported and 

convergent and divergent flow. deposited .

sensory stimul i and physical and biological 

contrasts, such as shallow, bubbling water 

on riffles versus the slower water in 

pools, shaded versus sunl it water, and the 

different spectra of organisms that prefer 

one or the other. 

I I I I 

I 

I 

I 

bed droiiie i ! 

I ! ' 

(R; ~honnil 

A 

(C) Cross-sections 

Riffle 

-bonk erosion c-oss-section 

-.. tholweg 

riffle area 

R 

P pool area (crossing) 

fipoint bar 

Figure 5. Pool-riffle morphology. 

Pools and riff1 es are particularly 

significant bed forms in the riverine 

environment. At low flow, pools are 

characterized by slow, deep waters while 

riffles are characterized by fast, shallow 

waters. This hydrologic diversity meets 

feeding, breeding, and cover requirements 

for a wide variety of riverine organisms. 

At high flow, boulders in riffles may 

provide shelter for organisms that would be 

damaged by excessive water velocity in the 

stream channel. Pools and riffles sort 

stream gravels so that finer materials are 

found in pools and coarser materials in 

riffles; this sorting allows a wider 

variety of fish and aquatic insects to use 

the bottom of the stream channel for 

breeding, resting, and feeding. They a1 so 

promote the development of a diversity of 

streambank vegetation. Tree-shaded pool s 

and more sunl it riffles provide a diversity 

of cover and food for riparian srgani sms. 

Pools and riffles provide a diversity of 

Many stream and river channels are 

characterized by regul arly spaced pool s and 

riffles. In these channels, pools tend to 

remain in approximately the same f ocation 

over a period of years, and such channels 

may be considered morphologically stable. 

In alluvial stream and river channels, as 

well as some bedrock channels, pools are 

most commonly spaced at about five to seven 

times the channel width. Riffles are found 

between pools and thus have a similar 

spacing. Adjacent pools and riffles form 

pool -ri ffl e sequences, and many streams 

consist of a channel morphology dominated 

by regularly recurring pool -riffle 

sequences. We1 1 -developed pool -riffle 

sequences are most commonly found in 

gravel -bed alluvial streams with a channel 

slope less than 0.01 (1 m drop per 100 m 

horizontal), but may also be found in 

bedrock channels and steep mountain 

streams. For the latter, pools are often 

associated with large amounts of organic 

debris or large in-stream boulders. In 

such streams there may not be a regularly 

spaced pool-riffle sequence because the 

spacing of pools is controlled by the 

organic debris or boulders. Most of the 

pools in the steep bedrock portions of 

streams in Southern California are of this 

type. 

2.4 THRESHOLDS IN STREAM AND RIVER 

SYSTEMS 

Many hydrol ogic and morphol ogi c changes 

that take place in streams and rivers are 

in response to exceeded thresholds. In 

general, when a threshold is crossed, a 

change in process (for example, erosion to 

deposition) occurs. One of the betterknown 

hydrol ogic thresholds in stream and 

river systems is that defined as the 

velocity necessary to initiate bed-load 

motion along the bottom of the stream or 

river channel. This threshold results from 

a positive feedback mechanism, since 

initiation of movement of bed-load 

particles facilitates movement of other 

particles. Another we1 f -known hydrologic

threshold occurs when the Froude number 

exceeds 1 (the Froude number is defined as 

the ratio of the inertial force to the 

gravity force of flowing water). When the 

Froude number is less than 1, flow is 

labeled tranquil, and there is a 

characteristic set of bed forms such as 

ripples and dunes. If the Froude number 

exceeds 1, then a threshold is crossed and 

the bed forms change to plain beds or 

antidunes, 

Streams and ri vers with we1 1 -devel oped 

pool -riff1 e sequences produce another type 

of hydrologic threshold that helps form and 

maintain these bed forms. Pools at low 

flow are characterized by deep, slow-moving 

water compared to riffles, where the flow 

is faster and shallow. However, at high 

flow, the opposite may be true; pools may 

have a higher velocity or flow of water 

than adjacent riffles. This process of 

hierarchical change of velocities in pool s 

and riffles is described in Keller's (1971) 

hypothesis of velocity reversal and is 

shown in a generalized form in Figure 6. 

As discharge increases over the pool-riffle 

sequence, the initial velocity in the 

riffle exceeds that of the pool. However, 

with t ncreasing streamflow to near bankful , 

a threshold is eventually crossed beyond 

which the velocity of water in the pool may 

exceed that on the riffle. The concept of 

velocity reversal is important in 

explaining why pools tend to scour at high 

flow and fill at low flow, whereas riffles 

fill at high flow and scour at low flow. 

The scour-fill pattern associated with 

velocity reversal is a hydrologic threshold 

characterized by negative feedback that 

allows pools and riffles to be maintained 

over a number of flows and years. The 

occurrence of velocity reversal or shearstress 

reversal has a1 so been documented by 

Andrews (1979) and bi sl e (1979). However, 

the reversal apparently does not occur in 

a l pool -ri ffl e sequences, In some 

channels there is simply a convergence of 

velocities over the pool and riffle with 

increasing discharge. The effect of this 

is similar to that of reversal in that it 

will allow pools to scour. 

Several thresholds also tend to control 

the morphology and channel pattern of a 

stream or river. Perhaps the best known of 

these are the threshold values of channel 

slope, which tend to control channel 

pattern (Figure 7). The major conclusion 

that may be drawn regarding these thresholds 

is that a change in channel pattern, 

rather than being continuous, tends to 

occur quickly as threshold slopes are 

exceeded (Schumm and Kahn, 1972). Foll owing 

the change, feedback mechanisms tend to 

be negative or self-enhancing to maintain 

a quasi-equilibrium or dynamic equilibrium 

in the stream or river system. 

As a final example of thresholds in the 

ri verine system, consider the processes of 

lateral migration of a meandering channel 

in cohesive alluvial bank materials. Most 

lateral migration may occur by bank caving 

4 21 

Relativeiy Low 

------- ;:;S;i;R;E " 

- Relativeiy Htgh 

Figure 6. HierarchicaI reversal of bottom velocity in 

a pool-riffle sequence. Data from Dry Creek near 

Winters, California (Keller, 4984). 

figure 7. Threshold condition of slope controlling 

channel pattern (after Schurnm and Khan, 1972).

or slumping following a high-flow event. 

Water during high flow is stored in the 

channel bank materials, and, following 

rapid drawdown of water during flood 

recession, thi s water is 1 eft unsupported 

and the shear strength of the bank materials 

is lowered. Often the drawdown is 

rapid enough that the shear strength of the 

materials falls below a critical threshold 

of stability and failure occurs. This 

particular threshold is a negative-feedback 

mechanism in the adjustment of channel 

slope that allows the stream or river to 

migrate laterally while maintaining a 

constant channel morphology . 

Changes in sediment transport, bed form, 

and channel pattern may take place abruptly 

when a threshold is exceeded. Furthermore, 

changes that take place may be characterized 

by positive feedback, which tends 

toward a disequilibrium in the fluvial 

system or, more commonly, negative feedback, 

which tends to maintain the dynamic 

or quasi-equilibrium in fluvial systems. 

2.5 HUMAN INTERFERENCE IN THE RlVERlNE 

ENVIRONMENT 

Human use of the riverine environment has 

included a variety of land-use changes to 

control the flow of water and sediment. 

Two of the more important alterations are 

channel ization and the construction of dams 

and reservoirs. Channel ization, whether 

called channel works or channel improvement, 

is a controversi a1 practice because 

of the potentially adverse effects on the 

system ecosystem. Loss of fish and wildlife 

habitat to channelization is well 

documented in many instances. Many channel 

ization projects control floods and bank 

erosion and improve navigation, but we are 

not always able to predict which projects 

are likely to cause unacceptable ecological 

damage. In general, channel ization projects 

reduce the hydrologic and physical 

variability of streams and rivers, and the 

variability of biological communities as 

well. Figure 8 contrasts some of the 

differences between a natural channel and 

an artificial channel. Channelized streams 

are usually straighter, with poorly sorted 

stream gravels and less variability in 

depth and velocity of flow during low-fl ow 

periods. During high flow or floods, 

channel ized streams have less variation in 

flow velocity and consequently 1 ess she1 ter 

for aquatic organisms. Channel ization 

generally also reduces the aesthetic appeal 

of streams by reducing physical, biological, 

and visual diversity of the riverine 

environment . 

Channel ization is not necessarily 

undesirable, but channel s must be carefully 

designed so that environmental degradation 

is minimized. This is best accomplished by 

designing channel s to provide for physical 

and hydrologic variabil i ty similar to that 

found in natural channels (Keller, 1976). 

In other words, we must design with nature 

to minimize environmental degradation 

associated with channel ization. 

Construction of dams and reservoirs also 

may disrupt the riverine ecosystem. Reservoirs 

tend to trap sediment, and downstream 

from a reservoir the stream or river bed 

may become armored with a layer of coarse 

bed material as fine materials are removed 

from the system. Unless sediment is added 

below via tributaries, there will be an 

impoverishment of finer bed materials 

downstream from dams and a reduction in 

physical vari abil i ty. Upstream from dams 

and reservoirs, deposition will occur as a 

flowing-water environment is replaced by a 

still-water environment. Construction of 

dams on rivers also blocks sediment that 

would otherwise reach the coastal environment, 

and beaches may be deprived of their 

natural supply of sediment. Dams and 

reservoirs also tend to reduce flow variability 

as flooding is reduced and the lowflow 

discharge becomes more constant. Such 

hydro1 ogic changes reduce physical vari - 

abil i ty in the riverine ecosystem, which in 

turn reduces the diversity of the biological 

community. 

2.6 SOUTHERN CALIFORNIA STREAM-RIVER 

SYSTEM 

2.6.1 Geolosv and Soilq 

The coastal drainage area falls within 

two major geologic provinces in Southern 

California: The Transverse Ranges and the 

Peninsular Ranges, as shown in Figure 9. 

Also shown in this figure are the numerous 

active faults found within the Southern 

Cal i fornia drainage area, including the San 

Andreas fault. Rock types within the

NATURAL CHANNEL 

ARIlFiClAL CHANNEL 

SUITABLE WATER TEMPERATURES: 

INCREASED WATER TEMPERATURES: 

AMOUATE SHADING; GOOD CWER FOR FISH 

NO SHADING* NO COVER FOR FISH LIFE. 

LIFE; MINIMAL VARIATION IN TEMPERATURES; RAPID OAILY'AND SEASONAL FLUCTUATI~)NS 

ABUNDANT LEAF MATERIAL INPUT. IN TEMPERATURES; REDUCED LEAF MATERIAL 

INPUT. 

/ / POOL-RIFFLE SEQUENCE . -\ 

kt 

ooru gravef 

SORTED GRAVELS PROVIDE MVERSlFlED HABITATS 

FOR MANY STREAM ORGANISMS. 

MOSTLY RIFFLE \\ 

UNSORTED GRAVELS : 

\: 

-. :\ 

REWCTION IN HABITATS; FEW ORGANISMS 

HIGH FLOW 

POOL ENVIRONMENT 

HIGH FLOW 

DIVERSITY ff WATER VELOCITIES: 

HIW IN POOLS LOWER IN RIFFLES. RESTING AREAS 

ABUNMNT BE~EATH UIDERCUT BANKS OR BEHIND 

LARGE ROCKS, *to. 

YE"," 

~$EH~~U~~$E,"I~Ev~~,"C~~~H$~~,"~. 

OR NO RESTING PLACES. 

WFICIEN? WATER DEPTH TO SUPPORT FlSH AND 

OTHER AWATIC LFE DWIlNG DRY SEASON. 

INSUFFICIENT DEPTH OF FLOW WRING OW 

SEASONS TO SUPPORT DIVERSITY OF FlSH 

AN0 AQUATIC LIFE. FEW IF ANY POOLS 

(ALL RIFFLE). 

Figure 8. Comparison of a natural channel with an artificial channel 

(modified after Corning, 1975). 

Transverse and Peninsular Ranges vary from 

young sedimentary rocks to older igneous 

and metamorphic rocks. However, in many 

instances the rocks are intensely sheared 

and a1 tered by ongoing mountain-building. 

Rates of uplift and subsidence vary from 

less than 1 m a year to several millimeters 

a year, and horizontal motion along the San 

Andreas and re1 ated faults is several 

centimeters a year. The rate of uplift or 

horizontal motion along faults in the 

Southern Ca1 ifornia area is highly variable 

and si te-specific, but the greatest rates 

of vertical uplift are in the western 

Transverse Ranges from the Ventura area 

south to Los Angeles. lesser rates of 

up1 ift are found south of Los Angeles to 

San Diego. In the Transverse Ranges, rates 

of uplift are several times the rate of 

denudation, producing steep mountain 

topography that rises to elevations in 

excess of 3,000 m. Along the coast south 

of Los Angeles to San Diego, where rates of 

uplift are apparently less than in the 

Transverse Ranges, the topography i s more 

subdued and often characterized by flattopped 

mesas. 

The geology, and particularly the active 

mountain-building, of Southern Cal ifornia 

has a tremendous impact on land forms, 

streams, and rivers of the area. Hany 

streams and rivers flow along active faults 

for at least part of their length, and

Figure 9. Generalized map of the Southern California drainage area showing the location 

of major active or recently active faults. 

stream gradients, and thus sediment 

delivery and rate of runoff, are affected 

by geologic processes. In particular, the 

combination of weak crushed rocks and 

occasionally intense seasonal precipitation 

leads to periodic high rates of sediment 

production. 

Soils in the Southern Cal ifornia drainage 

area are variable and dependent upon rock 

type, tectonic activity, topography, and 

climatic conditions, as well as time. In 

general, soils on floodplains and low river 

terraces are youthful and poorly developed, 

whereas better developed soi 1 s are found on 

older upland surfaces. Because rates of 

denudation are high in the Transverse 

Ranges where uplift rates are high, preservation 

of land forms and soils older than 

a few hundred thousand years is uncommon. 

On the other hand, in areas where up1 ift 

rates are low, residual soils on bedrock 

and soils on alluvial surfaces may be considerably 

01 der. Older soi 1 s are generally 

recognized by thicker profiles and "5" soil 

horizons with redder colors and higher clay 

content. 

2.6.2 Climate, Hvdrolosv, Sediment 

Production, and Fire 

The climate of the Southern Cal ifornia 

drainage area is Mediterranean, 

characterized by periodic rainfall between 

the months of November and March. It is 

not unusual for most precipitation to fall 

in a few storms. During cool winter 

months, most precipitation results from 

unstable polar air masses that move into 

the area from the north Pacific. During 

fall and winter, tropical disturbances from 

the south occasional ly produce intense 

precipitation; rainfall intensities of 2.6 

cm in 1 minute, 29.2 cm in 2 hours, and

CiMVLATiVE P€.QCEWT DEPARTURC: FROM AVERAGE 

u a w 

w1.c 

r+* m 

m n w 

1cca 

r+ 1 

3Z: 

vr *-+a a 

u 5 w o -4- 

w m r+c V) 

0 PJrtc, 

-3- 5- 

w 

7% 3 

-n' " g$ 

sm4.3u, 

3 1 3 

zZ-3 

m 

g-WU P) 

3 ,cog ;: 

g 5 - . 3 . ~ 

=i *dLI- 

w 

-. g-?. 7 

W g V) rto 

1 r+w3 

s %rt 

Z=W LI1-r.d 

W 3 -0 5 

--.am a m 

DISCHA9GE. RATIO TO MEAN ANNUAL FLOOD IRI 2 33) 

0 - N w o m m 5 

N W D m m E 

o o o ooo 

0 0 0 0 0 0 0 0 0 0 0 0 

I I I i iem 

V) w 4. OU 

TS J W "I 

O e -.m* 

V)d.nV) 

,+ -0 -a- 

-3 0y.w 

: 

m -3 

3 &.W 

g g W " " 7 

3 2.V) Q) +@ 

p, ag5 

gg 2 J i-4. 

%a=,. 0 

-2 %; 

*5.2% 

=em 3 m 

m 5 - 5 w r 

-5 s g 

mw 

g gg-. 2; 

g2 art 3 

3' rtmJ< 

r[) , V) =-"@ 

0 Zt+? 

3- 4. 

oTgp" 0. 

2 d. CT 

0 w-.. 

4.S" "2 3: 

225E r+rt 

1 -3IY2Y-- 

=I mccm 

d=r3 

m -5 -1. 

eJrm-5s2J

Dd.0 r+ 

x3--ha 

w V) 7 

3 4. 4. 

ua mv, 

--'I3 t.q TU =T 

m ". 

* *22m

Table 1. Suspended sediment yields for selected rivers (sfata from Kelsay, 

1977; Brownlie and Taylor, 1981). 

Drain e area 

Yield 

Drainage basin (km t Itons/h /yr) 

3? 

Southern Cal i forni a 

Ventura River 585 

Santa Clara River 4,219 

San Diego River 1,119 

Northern Cal i forni a 

Eel River 7,778 

Van Duzen River 570 

Redwood Creek 720 

Other in U.S.A. 

Schuyl ki 11 River, Pa. 4,902 

Delaware River, N.J. 17,560 

Rio Grande River, N.M. 67,153 

Mississippi River, La. 3,220,665 

a~ontroll ed. 

hatural . 

Some studies have suggested that after a 

fire, sediment yields increase only about 

10 percent; other studies have shown that 

sediment yields may be increased many 

times. Certainly the effects are most 

pronounced in the first few years 

immediately following a fire, particularly 

if they are wet years, and impacts decrease 

as vegetation becomes reestabl i shed. Fire 

is a frequent occurrence, particularly in 

the up1 and drainage basins throughout 

Southern Gal iforni a, and study of its 

effects, particularly on riparian vegetation 

and aquatic communities, should be 

expanded. 

Possible effects of fire on sediment 

production are illustrated in Figure 12, 

which shows the change in sediment storage 

in Gibraltar Lake, Santa Barbara's primary 

reservoir, from 1920 to 1980. The graph 

suggests that if the height of the dam had 

not been raised in 1949, the lake would now 

be completely filled with sediment. Fire 

occurrences are shown on the graph. Steep 

portions of the curve reflect times when 

sediment was being delivered at an 

accelerated rate and are closely correlated 

to fires in the drainage basin. For 

example, the 1964 Coyote Creek fire, which 

burned 40,000 acres (16,188 ha) in the 

Gibraltar watershed, was associatgd rith 

loss of 4,521 acre-feet (5.57 x 10 m ) of 

storage in Gibraltar Lake over the fiveyear 

period immediately following the burn. 

The fire affected 28.5 percent of the 

Gi bra1 tar watershed, and the data suggest 

that a similar fire might fill the 

reservoir with sediment, producing a loss 

of water supply to the city of Santa 

Barbara. 

2.6.3 Channel Disturbance 

It is difficult to assess the impact of 

human use on the streams and rivers of 

Southern Cal i forni a because of the 1 arge 

number of potential disturbances, including 

channel ization, construction of dams and 

reservoirs, mining of the streambed for 

sand and gravel, land-use changes, and 

recreational use. A quantitative 

assessment of the overall impact on the 

Southern Cal i forni a drainage area is beyond 

the scope of this chapter. However, to 

approximate the effects of human use and 

interest on the riparian environment, a 

prel imi nary inventory has been made of 

channel conditr'on and adjacent land use 

along the main channels and major 

tributaries of seven drainage systems in 

Southern Cal ifornia: Ventura, Santa Clara,

'A- 

w s 

w 0 

nc, 

UP-

1:130,600) with a l imited field check. 

Data from this survey are shown on Table 3. 

Figure 12. Loss of reservoir storage in Gibraltar 

Lake from 1920-1980 (data from City of Santa 

Barbara, 1981 ). 

The river systems studied differ considerably 

in channel condition and adjacent 

I and use. For example, 82 percent of 

the channel in the Los Angeles River basin 

is 1 ined with concrete, compared with only 

2 percent or less in the Ventura, San Luis 

Rey, and San Diego Rivers. Probably the 

most encouraging aspect of the data is that 

along the Ventura, Santa Clara, San 

Gabriel, Santa Ana, San Luis Rey, and San 

Diego Rivers there is still an appreciable 

amount of riverbed and banks that are natural 

in appearance and some have a significant 

amount of riparian vegetation. This 

suggests that in some areas there remains 

a potential for conservation or enhancement 

of riparian habitat for fish and wildlife. 

2.7 SUMMARY 

Los Angeles, San Gabriel , Santa Ana, San 

Luis Rey, and San Diego Rivers. In all, Of the total drainage area of Southern 

over 2,000 km of stream channels were California, 53 percent, more than 32,000 

inventoried from aerial photography (scale km2, is control 1 ed by dams and reservoirs. 

Table 3. Channel conditions and adjacent land use for selected rivers in Southern California. Data from 

1:130,OOO scale aerial photographs (1979 or 1983) collected by Cindy Hovind with supervision by the author. 

Characteristic 

San 

Santa Los San Santa Luis San 

Ventura Clara Angeles Gabriel Ana Rey Diego 

Length of rivers observed (km)" 144 515 378 170 448 227 227 

Channel conditions 

Natural 70% 59% 12% 42% 36% 60% 69% 

straightenedb 27% 35% 6% 4% 35% 39% 30% 

Concrete l inedC 2% 6% 83% 55% 29% 0% I% 

Riparian vegetationd 100% 60% 17% 4 7% 46% 100% 96% 

Land use adjacent to channele 

Eaatural 55% 67% 14% 4 5% 44% 65% 68% 

Urban 22% 16% 85% 55% 40% 9% 34% 

Agricu? ture 24% 26% 1% 0% 19% 28% 4% 

aTotal length of main channel and major tributaries inventoried. 

'A1 tered but not concrete-l i ned. 

"Channels with concrete banks with or without a concrete bed. 

d 

Trees, bushes, and brush within or on the banks of river channels, whether native or 

introduced. 

ePercentages do not total 100% because of different land uses on opposite sides of 

channel.

The stream or river channel and adjacent 

floodplain are characterized by processes 

of erosion, transport, and deposition. 

Hydro1 egic and morphological changes in 

streams and rivers occur in response to 

thresholds that are exceeded, and often 

these changes take place abruptly. 

Channel inat ion projects reduce the 

hydrologic and physical variabil i ty of 

streams and rivers, and thus the diversity 

of biological comuni ties as we1 l . Because 

of the extreme variability in precipitation 

and runoff, flows of water in streams and 

rivers tend to be extreme with large flows 

as flash floods related to storms. 

Suspended sediment yields are high, though 

not as high as in Northern California, and 

are often associated with fire.

CHAPTER 3. 

THE RIPARIAN CQMMUNiTY: PLANTS 

3.1 HISTORY OF RIPARIAN FORESTS OF 

SOUTHERN CALIFORNIA 

According to Axel rod (Robichdux, 19771, 

who has considered the evidence from 

numerous fossil floras now known in the 

western United States, modern plant commun~ties 

of California are composed of 

assemblages of taxa derived from diverse 

floristic sources. Axelrod (1950, 1967) 

has examined species composition (individual 

lineages and communities) in the 

context of former topographic, climatic, 

dnd vegetational settings, concluding that 

in today's riparian cornmuni ty of Southern 

td 1 i fornia there are representatives from 

both d southern madro-tertiary xeric elemtwt 

and frorn a northern arcto-tert i ary 

mesic element. The southern element 

inrlutles &rbgtts, &Jt-tsta~hjJ-gs, Ceanothc~.,, 

C(y-coc,w&us, fitpreyus, Qiierci~s, and 

U~nbtll l ul nri a, whclrchas the northern element 

3.2.1 Water Rue 

includes species in such genera as Ax, Riparian vegetation is directly related 

A 1 1 , C-s-tq~~gsi 5, :ra~&g, Pi=$, to the physiography and hydrology of stream 

Q\~f:-rcl?_s, and $~ao3. Modern communities systems, including factors relating to 

dr*~l ~mi)overished representatives of richer, watershed dimension (size, elevation, slope 

mortl gcneral ized ancestral communi t ies. exposure, stream gradient, etc.) . Where 

ldxa were gradually el iminatcd from Cal i- slopes are steep, swift water scours the 

fornid during the late Tertiary period in streambed down to bedrock. Major storms 

re5ponse to a gcneral trend toward a tear out large stands of vegetation and 

cooler, drier climate and a shift in the frequent1 y a1 ter stream courses. Where 

s~~~sondl distrr but ion of precipitation. gradients are shallow, alluvium is 

Suartl of the species rn the motlorn riparian deposited, providing sites for plants to 

rcirntnun~ ty are assod~ated, as ancestral become established. General floristic 

forms, In fossil cumrn~inities tt~roughout patterns in riparian habitat remain in a 

most of Caf ifarnia's late Tertiary and perpetual state of succession, folf owing 

Uuatcrnary h~stary, covering a time span of changes in land forms and water regimes. 

20 nii 11 ion years. 

Mob~chaux (1977) compared present and 

past distributions of some dominant woody 

species in the ripat idn coniniiitlity (Tabje 

4)" One example is provided in Figure 13. 

As the c l imabe beearne cooler and drier with 

more dr stinct seasons, certain species, 

such as boxelder (m nequndo var. 

cal i forni cus) and val ley oak (Quercus 

lobata), were eliminated from the northern 

part of their ranges and became restricted 

to California. Other species, such as 

yellow wil low ($11 ix 1 asiandra) , remained 

in the north but gradually were confined to 

the mild coastal strip where the effects of 

changing climate were smallest. Still 

other species, such as white alder (Alnus 

rhombi fol iaj , apparently were able to 

survive in unmodified Form in the northern 

interior regions. Robichaux speculates 

that when an association of species in a 

fossil flora resembles those in a modern 

community, the community was formed in the 

ancient landscape with habitat requirements 

simi lar to those of its modern counterpart. 

3.2 THE RIPARIAN COMMUNITY 

a. Perennial streams form in the higher 

mountain ranges from springs, coalesce into 

large streams, and finally f1 ow out of the 

miitintaii-is onto the floodplain as sizable 

rivers. Above 7,000 ft, associated 

riparian vegetation consists almost 

entirely of shrubby montane species of

Table 4. Some corntnon species in the modern riparian forest of Southern 

Caljlornla and their counterparts In the late Tertiary fossli record of the 

Western United States (adapted from Roblchaux, 1977). 

Modern speciesa 

Acer nequndo 

- Alnus ----- rhombifol ia 

-- Cornus cal ifornica 

Fraxinus latifol ia 

Juul an$ cal ifornica 

Pl atanus racemosa 

Po~ulus fremonti i 

Quercus lobata 

Sal ix lasiandre 

Salix lasioleosi% 

Sal ix laevisata 

Salix gooddinsii 

Sal ix hindsiana 

Joxi codendron di versi 1- 

_ 

fossil speciesb 

A. minor 

-%. holl andiana, 4. merriami 

- C. ovalis 

F. coul teri, E. caudata 

j. pseudomoraha 

- P. paucidentatg 

P. prefremonti i 

- 

p. prel obata, Q. morasensi s 

S . hesoeri a 

- S. wildcatensis 

S. laevisatoides 

S. truckeana 

- S endenens i s 

T . franci scan 

- 

"Nomenclature foll ows Munz, 1953. 

b~eaf and seed impressions of the fossil species are 

generally indistinguishable from those of their modern 

counterparts. A different name is assigned to the fossil 

taxon to avoid the difficulties of equating modern and 

fossil species. 

willow (Salix spp.). Jeffrey pine (Pinus spp. ) , elderberry (Sambucus mexicanaf , and 

jeffreyi) and incense cedar (Calocedrus wild grape (Vitis sirdiana). In areas 

decurrens) often grow near the edges of where there is a well-developed canopy, 

streams (Figure 14). Below 7,000 ft, white perennial water flow, and rocky or cobbly 

alder and willow commonly occur along substrate, only scattered, nonpersistent 

seasonal l y f1 ooded streambanks between 1 ow- vegetation grows (Ferren, 1983). Underwater 

and maximum flood levels, often in story plant diversity increases signi - 

dense stands of young trees (Figure 15). ficantly near low-energy portions of the 

Cottonwood (Po~ul us spp. ) and sometimes stream, particularly where silt accumulates 

sycamore (Platanus racemosa) grow in the and there is greater sunlight penetration 

seasonally flooded habitat but more between older and taller trees. 

commonly on banks, crests of banks, and 

terraces along the .stream above the zone of 

b. 

seasonal inundation but in an area where 

Hybrid streams, characterized by 

the water table remains close to the 

perenni a1 or year-round aboveground f? ows 

surface and where roots are probably 

in some years and intermittent flows in 

in 

saturated soil (Ferren, 1984). Sycamore, 

others, often form in mountains at lower 

coast 1 ive oak (Quercus aqrifol ia) , and 

elevations or on smaller watersheds. In 

these streams alder drops out; wfllow, 

California bay (Umbel1 ~1aria cal ifornica) 

grow to very large sizes on first, second, 

cottonwood, sycamore, and coast live oak 

remain as dominant species, the latter two 

and third terraces above the streambed. 

often attaint ng large sires from subsurface 

Here, where sufficient 1 ight penetrates for 

shrub and herb develoflment, can be found 

water suppl ies. 

the richest assemblages of understory 

riparian species, incf uding mu1 e fat c. Intermittent streams flow for at 

(Baccharis qlutinosa), dogwood (Carfius least part of the year aboveground. In 

21

Box older (Acernesurni) \. * " -- - . - 

Figure 14. Plne and incense cedar grow near the 

edge of Mill Creek at 5,900 ft In the San Bernardino 

Mountains, 

these streambeds soils are kept moist, not 

saturated, by winter rains and subsurface 

water levels and are often sheltered by 

north-facing slopes or adjoining bluffs to 

the south, and willow and cottonwood drop 

out. Typically, sycamore moves down into 

the streambed, along with coast live oak 

and California bay, sustained by subsurface 

water sources (Ferren, 1983). 

The diversity of emergent herbaceous 

plants increases significantly in inter- 

_..- mi ttent streams with exposed sand and 

Afder (Alnus rhombifolia) gravel substrates that receive direct 

sun1 ight through an open or non-existent 

Mictcene floras = A Pbistocene floras = X riparian canopy (Ferren, 1983). 

Pliocene floras = @ Presem distr~bulions = 0 

d- F~hemeral streams flow in years of 

heavy rainfall, particularly during 1 arge 

Figure 13. Past and present geographical distribu- storms. Coast l ive oak, typically of 

tions of box elder and alder (from Rsbictraux, 1977). small er stature, remains the dominant 

22

Figure 15. Wheeler Gorge Campground on Sespe Creek. Alder, the most reliable riparian indicator species, 

grows along seasonally flooded streambanks between low-water and maximum flood levels. 

species in a habitat with less certain and 

less abundant water supply. This habitat 

often appears as a continuum or ecotone 

with vegetation on north-facing slopes, as 

can be seen in the Santa Monica Mountains 

where Caf i forni a walnut (Jusl ans 

californica) grows in streambeds and up 

onto north-facing slopes. 

e. Floodolains and alluvial fans of a 

number of watercourses flowing out of the 

San Gabriel, San Bernardino, and San 

Jacinto Mountains support a distinctive 

plant community, structurally and 

floristically diverse, consisting of an 

unusually l arge proportion of arborescent 

evergreen shrubs and a rich assemblage of 

subshrubs, as shown in Figure 16 (Smith, 

1980). 

3.2.2 Community Structure 

Structure and composition of riparian 

forests are directly related to factors 

such as water regime, frequency of disturbance, 

air temperature, root-zone 

aeration, depth of ground water, width and 

elevation of the floodplain, and the stand 

age of trees. The community can be divided 

into three zones: an active zone closest 

to the stream that is most subject to disturbance 

from winter storm damage and is 

characterized by willow and alder; a border 

zone that is less subject to disruption but 

has a re1 iable water supply and is characterized 

by larger trees of willow, 

cottonwood, sycamore, and a we1 l devef oped 

unde~story wi th considerable plant diversity; 

and an outer zone on higher terraces

Flgirre 16. Vicw of an alfuvfal fan plant community, a distinctive community of shrubs and subshrubs that 

or-rcc covered much of the LOS Angeles Basin. Thls remnant Is along the San Jacinto River at 2,500 ft. 

thdt at-e only occasionally subjected to 

flooding but where trees, part icuf arly 

sycdalores and oaks, take advantage of the 

highor water tables found adjacent to 

uivcvs and streams and grow to very large 

sires. 

Availability of water, frequently in 

~vmbinativn with deep soils, increases 

plant biomass production and provides a 

suitable site for plants that are limited 

in adjacent up1 and cornmuni ties by inade- 

quate water and shallow soils (Minore, 

197Q). Riparian communities, particularly 

In the border zone, often exhibit 

considerable diversity in plant species. 

lhis is especially true for those adapted 

ta wet or moist conditions (lrlaxinrov, 19'31; 

Campbe; 1 and Green, 1968; ifortone, 1972) . 

Ihese pl ants general 7y are characterized by 

large, soft leaves; examples are wild grape 

and elderberry. Little emphasis has been 

placed on the understory in this community 

profile, but it should be pointed out that 

it plays a major role in the riparian 

community. Many fauna, birds, and insects 

are closely associated with and dependent 

an the dense, lush foliage and its 

associated microclimate. 

Riparian zones usually have a high rate 

of recovery and develop a range of 

successional vegetation where the habitat 

is protected or appropriately managed. 

from information on riparian forests of the 

Sacramento River that is pertinent to the 

riparian forests of Southern Cal ifornia, 

Strahan 11981) observed that cottonwood and 

willow are the classic pioneer species of 

riparian forests. Seeds of both specjes 

initfafly become established almost 

exclusively on recent1 y deposited exposed 

a1 luvium. These trees predominate in young 

stands on low terraces near the river.

More mesic species, such as boxelder and 

black walnut, enter cottonwood/wil low 

stands over time and predominate in stands 

away from the river. Oak and sycamore are 

found in old stands on high terraces and 

along banks high above the river. Species 

diversity increases as stands age, reaches 

a maximum in stands with mixtures of 

pioneer and 1 ater successional species, and 

may decline slightly in oldest stands 

(Figure 17). 

It has been shown that when disturbance 

is high, willow dominance shifts to sandbar 

willow (Sal ix hindsiana) and, when somewhat 

less severe, to Goodding's willow (Salix 

goodi nqi i ) . Cool growing seasons favor 

bl ack cottonwood, whereas turbulent, we1 l- 

aerated water close to the surface allows 

white alder to become dominant. When water 

tables are deep, sycamore is the usual 

dominant species where aeration of the soi l 

is high, and valley oak is dominant where 

aeration is low (Holstein, 1981). 

From a study of four coastal streams in 

Santa Barbara County, Ferren (1983) 

reported that white alder and willow 

usually grow in seasonally flooded habitats 

between low water and seasonal maximum 

flood levels as determined by a line of 

debris along the streambank. Sycamore, 

black cottonwood, coast 1 ive oak, toyon 

(Heteromeles arbutifol ia), Gal ifornia bay, 

l aurel sumac (b 1 auri na) , and elderberry 

usually grow on banks, crests of banks, and 

terraces along streams above the zone of 

seasonal inundation, where the water table 

remains close to the surface and where the 

roots are probably in saturated soil. The 

latter three species also continue up the 

ravine slopes and are found in southern 

coastal oak woodland or coast live oak 

forest communities. As a part of the 

riparian community, they are not dependent 

on the additional water source, but are 

to1 erant of occasional flooding and 

saturated soi 1 s. 

In a study of plant distribution 

gradients from streamside riparian to 

adjoining upland habitats on the west fork 

of the San Gabriel River, Brothers (in 

press) found that of the vegetation in a 

riparian zone, a few species were riparian 

and a much larger number were from adjacent 

Figure 17. Tapia County Park near Malibu. Willows are pioneer pliants that predominate on iow terraces near 

the stream, while cottonwood and sycamore predominate on higher terraces.

nonriparian areas integrading into the 

riparian zone. He found considerable 

variation in species composition between 

north- and south-facing slopes and between 

small and larger basins, indicating the 

importance of moisture availabil i ty. 

Syvertsen (1974) studied moisture stress 

(stem water potential) in coast live oak 

during a dry year and found it to vary with 

slope position. All species studied showed 

lower stress at the bottom of the slope. 

Stand density influences moisture stress 

where total water supply is limited, so 

that stands with widely spaced trees suffer 

less moisture stress in dry seasons than do 

trees in dense stands (Rundel, 1980). 

California walnut and toyon both had lower 

stress in open south-facing plots than in 

the denser north-sl ope stands (Syvertsen, 

1974). 

3.2.3 Deciduousness and Productivity 

The presence of winter-deciduous vegetation 

in the riparian communities of 

California is an anomaly in a state known 

For its Mediterranean-type climate and 

sclerophyl lous evergreen vegetation 

(Holstein, 1981). Oeciduousness Is promoted 

whenever a long, productive growing 

season is paired with minimally productive 

but not necessarily stressful cool or cold 

season. Trees with rich stores of food can 

afford the energy cost of producing a new 

crop of leaves each year. The productivity 

potential in Ca? ifornia, frequently unfulfilled 

because of summer drought, is 

realized in the riparian vegetation that 

l ines perenni a1 streams. These streams 

carry the part of the winter water surplus 

that is slowly released from deep aquifers 

and me1 ting mountain snow, making it avail - 

able to lowland riparian vegetation in summer 

when little water is available from 

local c? imate. The greater productivity 

and biomass of this vegetation is particularly 

obvious when contrasted with that of 

nearby communities that lack imported water 

(Holstein, 1981). 

Riparian systems serve as seed sources 

for downstream ecosystems. Seeds are 

transported within the riparian system from 

one point in a stream to a downstream 

location or are carried into the riparian 

system from adjacent ecosystems by winter 

runoff and are deposi ted by fl ood waters. 

Seasonal variation of fl ow regimes 

greatly i nfl uences establ l shment and 

survival of pioneer species, cottonwood and 

willow, on gravel bars. According to 

Strahan (19811, establishment and survival 

of riparian species are related not only to 

the physical characteristics of landforms 

but to a sequence of fluvial events. 

During the winter, streamflows must remove 

humus and freshly fallen leaf litter from 

the surface so seeds land on mineral soil. 

A receding water level in late spring and 

early summer must coincjde with cottonwood 

and wi 1 low seed dispersal . Wi 11 ows are 

more commonly found on finer textured 

deposits, while cottonwoods develop on the 

more coarsely textured deposits. Gotton- 

wood seeds require a moist surface for 

germination. Fresh seeds germinate more 

rapidly than old seeds and, in studies in 

Arizona, Fremont cottonwood seeds remained 

viable for only five weeks under natural 

conditions (Fenner et a1 . , 1984). 

Rapid root growth rates are essential for 

cottonwood seedlings because the moist 

a?luvium deposited in the spring dries 

rapidly with the onset of high summer 

temperatures. The decl ining water table 

also promotes root growth to greater 

depths. Before further flooding, seedl ings 

must achieve sufficient size to withstand 

mechanical injury. The subsurface of bars 

must remain moist throughout the summer in 

order for seedlings to withstand late 

summer drought. While initial seed? ing 

density is usually very high, winter floods 

and summer drought account for significant 

seed1 i ng mortal i ty (McBridge and Strahan, 

1984). 

Within the mature riparian forest the 

link between regeneration and flow regime 

is not as direct. Floods may remove or 

bury in silt seed1 ings establ ished for one 

or more seasons. Boxelder, black walnut, 

and oak seeds all germinate through litter 

and under the shade of established 

cottonwood and wi'i low forests (Strahan, 

1981).

3.2.5 Succession 

Riparian pa ant communities undergo a 

natural and predictable sequence of 

revegetation after destruction by flooding. 

Such succession may take 50 to 75 or more 

years to complete, starting from bare sand 

and culminating in a mature riparian forest 

or woodland community on the floodplain 

extending varying distances from the stream 

channel, depending on 1 and contours (Smith, 

1979). In contrast to the mature forest or 

woodland farthest from the watercourse, 

which requires years to mature, immature 

expressions of the riparian communi ty 

develop rapidly, forming gravel -bar 

thickets and open flood-plain vegetation. 

Often this active zone will consist solely 

of widely scattered herbs or of immature 

willow (Figure 18). According to Smith 

(1979), those mixed stands of willow and 

cottonwood that typical ly develop on middl e 

terraces of streams may be the oldest 

stands of trees along the Santa Clara 

River. These areas are not subject to 

flooding and erosion as often as lower 

levels, and thus the vegetation can achieve 

a more advanced stage of succession than on 

f1 oodpl ai ns and gravel bars. Large 

sycamore and cottonwood, found on middle 

terraces, and oak trees, found on the upper 

terraces of floodplains and in canyons, are 

rarely subjected to floods and grow to very 

large sizes (Phillips, 1963); however, too 

often many are cut down to provide 

agricultural lands. It is the middle and 

outer zones of the riparian community that 

are the most depleted. 

3.2.6 To1 erance of Flooding 

Teskey and Hinkely (1980) and Walters et 

a1 . (1980) have reviewed the 1 i terature on 

long- and short-term responses of plants to 

Figure 18. Thickets of mulefat become established between floods sr graver bars as seen along Piru Creek at 

4,600 ff elevation.

flooding. The major effect of flooding or 

of saturated soils is to create an anaerobic 

environment surrounding the root 

system as water replaces air spaces in the 

substrate. The anaerobic environment 

(oxygen/CO, 1 eve1 s and i on-exchange 

reactions) interferes with normal root 

metabolism, resulting in plant stresses 

that affect physiological activities such 

as water and nutrient uptake, xylem and 

phloem transport, photosynthesis, and 

transpiration. A root system formed under 

aerobic condi tians becomes dormant or 

begins to die inmediately after flooding, 

A plant's tolerance of lengthy periods of 

flooding is dictated by its ability to grow 

adventitious roots and new secondary roots 

under low-oxygen conditions. A floodtolerant 

species can maintain a root system 

developed under aerobic conditions in a 

partially anaerobic rhizosphere while 

producing new secondary or adventitious 

roots. Intolerant species not only suffer 

normal root system loss but are unable to 

produce advent1 tious roots (Hosner, 1958, 

1960) . 

Sycamore, cottonwood, and willow are a1 1 

considered flood-tolerant, whereas big-leaf 

maple, California bay, and coast 1 ive oak 

are a1 1 cons4dered intermediately tolerant, Figure 19. White alder (W r m . Drawing 

that is, able to withstand 1 to 3 months of by W. Bailey. 

flooding during the growing season (Marri s 

et a1 ., 1979). Alternating periods of 

watershed runoff, resulting in flooding of 

the riparian ecosystem, followed by periods 

of summer drought, appear to be essential 

on the Mentone fork of the Santa Ana River 

(T.L. Hanes, California State University, 

for preserving the diversity of riparian 

vegetat ian (Onuf, 1983) . 

Fullerton; pers. corn.). Alder is an early 

pioneer following major storm scouring, 

which significantly alters streambeds, and 

3.3 

reestablishes quickly by vegetative growth 

COMMON PLANTS IN SOUTHERN from existlng root systems and by seed. 

CALIFORNIA'S RIPARIAN COMMUNITY Trees grow rapidly, showing a maximum 

growth in diameter of 3.84 cm a year (Long, 

White alder ( ), ranging 1982). White alder grows from 30 to 100 ft 

from Southern California north to British tall, with a thin, open crown and a 

Columbia, is a rtparian deciduous tree straight, slender trunk 1-3.5 ft in 

(Figure 19). In coastal or cismontane diameter. Trees are monoecious, producing 

Southern California, it is restricted to male and female catkins on a single tree 

permanent streams and thus is a more and seeds in cone-1 i ke structures that form 

re1 Sable indicator of the presence of water in greater abundance in full sun1 ight than 

than el ther sycamore or cottonwood (Jepson, in partial shade. Reproductive success is 

1923). At 6,500 ft and below, alder forms best in moist or wet sand, gravel, or humus 

dense groves at the heads of mountain soil, where seed1 ings grow rapidly and form 

streams and intergrades with cottonwood and open stands on stream borders (Sudworth, 

willow at lower elevations. It descends to 1967). The ecological factor that most 

the mauths of canyons only where cold air 

and abundant water pemit, as, for example, 

controls the distribution of white alder 

seems to be the need for consistent 

28

saturation of its root zone by cool, wellaerated 

water. 

Willows (Sal ix spp. ) are fast-growing 

deciduous trees that are faithful indicators 

of riparian habitat. The genus name 

is derived from the Celtic &, near, and 

u, water, in reference to its place of 

growth, or from the Latin word for willow. 

Willows spread vegetative1 y from root 

sprouts into large stands, often forming 

the dominant overstory, usually with a deep 

litter layer or herbaceous understory. 

Trees are of one sex only, and a stand will 

often be all male or all female, with 

female stands usually outnumbering male 

stands. Flowers are both insect- and windpollinated 

and develop in catkins from 

which numerous seeds, winged with silky 

down, are produced and dispersed by wind. 

Red willow (Salix laeviaata) grows at 

elevations up to 4,000 ft, often with 

ye1 1 ow wi 1 low, along fast-flowing perenni a1 

streams in cismontane Southern California 

and on Catalina Island. Trees are of 

medium size, 20-40 ft tall, and can be 

recognized by their dark, rough trunk bark 

and reddish bark on young branchlets 

(McMinn and Maino, 1967). 

Ye1 1 ow wi 11 ow (Sal i x 1 asi andra) extends 

into cismontane Southern Cal ifornia to 

elevations of 8,000 ft and onto Santa Cruz 

Is1 and, where it grows a1 ong streambanks 

and in perennially wet places. While there 

is considerabl e habitat over1 ap between 

yellow and red willow, the former may have 

less tolerance for habitats along 

intermittent streams than red willow and 

thus need more permanent water. According 

to G. Holstein (University of California, 

Davis; pers. comm.), this observation needs 

verification. At lower elevations, yellow 

willow grows into medium-sized trees 15-45 

ft tall and at higher elevations into 

shrub-1 i ke forms. It is easily recognized 

by the yellow color of its 1-year-old 

branchlets, its gl andul ar-warty petioles, 

and its long, tapering leaves. 

Goodding's willow (Sal ix qooddinai i var. 

variabilis) is found along streambanks and 

in wet places in drier habitat areas in 

cismontane Southern Ca1 ifornia to 

elevations of 1,500 ft, where it grows into 

trees 20-60 ft tall. Its distribution, 

limited to the riparian zones of the 

Central Valley, Southern California, and 

the deserts of the Southwest suggests a 

need for a long, hot growing season and 

abundant ground water (Holstein, 1984) 

(Figure 20). 

Arroyo willow (Salix lasiole~is) is also 

called white willow because of the smooth, 

ash-gray bark of young trees and branches 

of older trees. It is widely distributed 

in cismontane Southern Cal ifornia. Along 

perennial streams at low elevations, down 

to 100 ft, it grows into small trees 15-25 

ft tall. At elevations up to 2,500 ft and 

along intermittent watercourses where there 

are moist benches, depressions, and gentle 

slopes with damp humus and rocky or 

gravelly soil, it assumes a spreading, 

shrubby form. In addition to its ash-gray 

bark, arroyo willow can be identified by 

its 1 eaves, which are dark ye1 1 ow-green and 

glabrous on the upper surface and exchange 

Figure 20. Goodding's willow (W 1. 

Drawing by W. Baiky.

eactions, interferes with normal silvery, 

often silky, in appearance on the lower 

surface (Figure 21). 

Sandbar willow (Sal ix hindsiana) is very 

common along sandbars and riverbeds, particularly 

near the coast, but it is found 

up to 3,000 ft in cismontane California. 

Sandbar willow grows as a tree, up to 20 ft 

tall, or as a shrub; it can be distinguished 

by its gray, furrowed bark and 

gray, sil ky-haired leaves with exceptionally 

short petioles (Peattie, 1953). 

mountains and the sea. Disjunct populations 

grow on Santa Cruz and Santa Catalina 

islands (Griffin and Critchfield, 1976). 

Fremont cottonwood is confined to a1 1 uvial 

stream bottoms and their borders in moist, 

sandy, and humusy soils or moist, gravelly 

ones, rarely growing in dry foothills 

except along perenni a1 streams. Growing 

from 50 to 100 ft tall, with a diameter of 

1.5-4 ft, this tree will occasionally 

become establ i shed along intermittent 

streams where it rarely survives to a 

mature age (Peattie, 1953). 

Fremont cottonwood (Popul us fremont i i ) is Fremont cottonwood (Figure 22) is a 

scattered throughout Southern Cal iforni a short-l ived, fast-growing, deciduous tree 

along streams and on lowlands between the that grows in strips along streambanks, in 

small pure stands, or scattered in mixtures 

of willow. It occasionally grows with 

California sycamore and, at higher el evations, 

with white alder. It revegetates 

from root shoots or by seed. Flowers 

appear before leaves in the spring, are 

pollinated by wind, and grow in long 

catkins with the sexes on separate trees. 

. Innumerable minute, short-1 ived, cottony 

I *j 

, 

Figure 21, Arroyo willaw (Sal& . Drawing Figure 22. Fremont cottonwood (Populu~ 

by W. Bailey. 

fremontil). Drawing by W. Bailey. 

30

seeds are effectively disseminated by wind. 

These have a high rate of germination, but 

a transient vitality (Fenner, 19634; 

Sudworth, 1967). 

B1 ack cottonwood (Po~ul 

b 

grows at higher elevations than Fremrorat 

cottonwood and along the coast, H n 

ci smontane Southern Cal i forni a the ranges 

general ly over1 ap. There are d i sjunct 

populations on Santa Cruz, Santa Catal ina, 

and Santa Rosa Islands (Sudworth, 1967; 

Griffin and Critchfield, 1976). Beyond 

elevational distribution, the two species 

differ in size and in leaf shape and color. 

Black cottonwood is the tallest species of 

poplar, growing 80-125 ft high at lower 

elevations and smaller at higher elevations, 

where it grows with white alder, 

incense cedar, and occasionally big-cone 

Douglas fir. Seedlings survive well on 

moist, bare humus or sandy solls and are 

often abundant on wet gravel bars. 

us 

California sycamore (Pl atanus 1 //' 

is abundant at elevations below t $/f 

throughout ci smontane Southern Cal i forn 4 a 

along streams and near springs, on alluvial 

benches or in moist gull ies where water Figure 23. California sycamore ( 

from streams or ground-water suppi ies are Drawing by W. Bailey. 

either perennial or intermittent (Sudworth, 

1967). Every 1 ikely canyon and creek 

bottom has sycamore trees (Figure 23). 

They grow in small groups in pure stands ar sycamores still stands on Milpas Street in 

mixed with white alder, big-leaf maple, Santa Barbara, a quarter mile from the 

Gal ifornia walnut, and occasionally willow, beach. A lantern was once hung in the 

with a coastal sage-scrub or herbaceous upper branches on stormy nights to guide 

understory. When growing close to a stream boats along the coast before the harbor was 

where soils regularly shift from periodic built (Peattie, 1953). 

flooding, sycamores may exhibit extensive 

leaning, sprawl ing, or Fork-shaped growth. Boxel der (w var. 

Trees growing farther from the streambank -1, another deciduous riparian tree, is 

grow upright, 40-90 ft tall, with thick, limited in coastal Southern California to 

barrel-shaped trunks supporting massive the Santa Ynez Mountains in Santa Barbara 

crowns of wide-spreading 1 imbs ' Caf i forni a County, below Fort Tejon and Canada de las 

sycamore is a tenacious tree, repeatedly Uvas in the Tehachapi Mountains, and in 

repairing damage to its crown and limbs by elevated canyons on the western slopes of 

vigorous sprouts and growth of wood. It is the San Bernardlno and San Jacinto mouna 

deciduous tree with broad leaves, 5- 11 tains. Trees are few and widely scattered 

inches long and wide, for which the genus with wide gaps in distribution along 

is named (the Greek word platys means borders of perennial streams, bottoms of 

broad). It has tiny unisexual wind- moist canyons, and gulches. Cal-iforlria 

pollinated flowers borne in ball -1 ike boxelder is found in strips and patches of 

c'ttisters ari the same tree. The large, pure growth, but camonly grows with white 

bristly, globular frujt breaks up at alder, sycamore, and willow, It is a 

maturity, releasing the numerous small short, stacky tree, growing 20-50 ft tall 

nutlets that are disseminated by drifting and is moderately tolerant of shading, 

an the wind in fall. One of the lawest especially in its early ilfe. It is 

31

dioecious with male flowers in short 

clusters and females hanging in racemes on 

separate trees (Jepson, 1923). Female 

flowers are wind-pol 1 inated and produce 

finely pubescent samaras with wings that 

are on1 y sl ightl y divergent (Figure 24). 

Big-leaf maple (m macro~hvllum) is 

almost entirely restricted to the riparian 

zone in Southern Cal ifornia, scattered 

along banks or benches of perennial streams 

and on spring-rich mountain sides in moist 

canyons. This handsome, broad-crowned tree 

can grow to 80 ft tall. Big-leaf maple 

endures shading well during early 1 ife, but 

grows best and produces the most seed in 

open woods with good iight from above. 

Flowers are of two kinds, perfect (with 

stamens and pistils) and staminate, and are 

found together in the same hanging raceme 

on the same tree (Jepson, 1936). Fruits 

are winged samaras that, when dry, disperse 

by floating on the wind (Figure 25). 

Cal ifornia black walnut (Jug1 an$ caf i - 

fgrnicq) is a deciduous, sometimes-riparian 

- 

Figure 25. Big-leaf maple (Am1 mac;laPb~!!~). 

~riwin~ by W. Bailey. 

L e 

tree native to southeastern Santa Barbara 

County. It is locally common below elevations 

of 2,500 ft from the Santa Ynez 

Mountains southeastward to the Santa Ana 

Mountains in the watersheds of the Santa 

Ynez, Ventura, Matili ja, Piru-Sespe, and 

Newhall Rivers. It is also found in the 

Santa Monica Mountains and on south 

slopes of the San Gabriel Mountains; on 

south and west slopes of the San Bernardino 

Mountains up to elevations of 3,000 ft; in 

i I Waterman Canyon up to elevations of 2,900 

ft; and on low slopes of the Santa Ana 

Mountains, its southern limit. A specimen 

found growing on Cuyamaca Peak in San Diego 

County is probably not indigenous (Griffin 

and Critchfield, 1976). A colony of 

Cal i fornia walnut growing an Jal ama Creek 

in western Santa Barbara County is considered 

to be a natural disjunct locality 

(Griffin and Cri tchfield, 1976). The habi - 

tat of the California walnut is similar to 

that of the California sycamare, namely, 

1. * the margi ns of perenni a1 and intermittent 

streams, usually in moist, gravelly or 

Figure 24. Boxelder (4a.r tl~:wn_d.p). Drawing by W. sandy sol 1 , and sometimes in dry situations 

Bailey. where it is sustained by ground-water

suppl 1 es (Sudworth, 1967). However, it 

differs from sycamore in that extensive 

stands are found on foothill slopes not 

associated with riparian habitats. 

Jepson regarded the Cal i forni a walnut in 

Northern Cal ifornia to be a shrub architectural 

ly, though often of "elephantine 

proportions," since stems from the base 

give the appearance of several trunks 

curving up and then dropping down nearly to 

the ground. This creates a handsome crown, 

12-20 ft high. Small clusters of inconspicuous 

female flowers are wind-pol 1 inated 

from male catkins found on the same tree. 

Fruits develop into nuts that are small but 

exceptionally hard (Figure 26). 

3.4 RARE AND ENDANGERED PLANTS 

There are few rare and endangered plants 

in the riparian community. Rather, the 

entire community type is endangered by a 

variety of man's activities, principally 

agriculture, dam and watershed a1 terations, 

road construction, and residenti a1 and 

Figure 26. California black walnut ( J ! S 

caiifornica). Drawing by W. Bailey. 

commerci a1 development . Table 5 shows 

plants on the California Native Plant 

Society's List Ib, Rare and Endangered 

Plants in California (Smith, 1984), that 

are found in the riparian communities of 

the study area. Many of these are endemic 

to small areas and are threatened by human 

activities. 

3.5 lNTRODUCTlON AND DISTRIBUTION OF 

EXOTIC PLANTS 

Purposeful introduction of exotic plants 

into Cal ifornia began in 1769 when Father 

Junipero Serra establ i shed the first 

European settlement at San Diego. According 

to Frenkel (1970), at least 16 species 

of exotic plants were established in 

California during the period of Spanish 

colonization from 1769-1824; 63 more 

species were established during Mexican 

occupation from 1825-1848; and 55 during 

American pioneer settlement from 1849-1860. 

By 1968 Munz and Keck listed a total of 975 

exotic plants, most introduced acci - 

dentally. New weeds are being established 

in Cal i fornia continuously ; some spread 

aggressively, while others do not. Some 

species persist only where irrigation 

provides needed summer moisture; others 

become truly naturalized and grow along 

with or in competition with native species. 

There are numerous introduced species in 

the riparian plant community of Southern 

Cal i forni a. Zembal (1984a) 1 i sts 99 

introduced vascular species in a checklist 

for Prado Basin, Santa Ana River Canyon, 

and environs, 31.8 percent of the total 

species found, and 144 introduced vascular 

species, or 27.6 percent of the total 

species found, for the Santa Margarita 

River watershed. 

Three introduced species in the riparian 

pl ant comrnuni ty of Southern Cal ifornia 

deserve special mention, as they may 

eliminate native species of plants and 

significantly change the character of 

habitat for wildlife: salt cedar or 

tamari sk (Tamarix spp. ) , German ivy 

(Senecio mi kanioides) , and giant reed grass 

or cane (Arundo donax). 

Salt cedar (Tamarix ramosissirna), a 

summer-fl oweri ng small tree native from 

eastern Europe to central Asia, was 

introduced into the United States for

Table 5. Rare and endangered riparian plant species. 

P 

. - - -- -- 

Plant name Location Statusa 

Delohinium hes~eri um Cuyamaca Lake CDFG rare 

ssp. cuvamacae 

CNPS rare and endangered 

(Cuyamaca 1 arkspur) 

Downinqia concolor var. 

brevo i r 

(Cuyumaca Lake downingia) 

Dudleva densi flora 

(Santa Gabriel Mts. dudl eya) 

Dudleva mu1 ticaul is 

(many -stemmed dudl eya) 

Sriastrum $ens1 fol ium 

ssp. sanctorum 

(Santa Ana River woolly-star) 

Limnanthes graciliz var. 

parishi i 

(Parish's meadowfoam) 

Mahonb 

(Nevis9s barberry) 

Monardell a 1 inoides spp. 

---- vimineq 

(San Diego Co. monardella) 

Cuyamaca Lake 

San Gabriel Mts 

L.A., Orange, Riv., 

San Bern., San 

Diego Counties 

San Bern. Co. 

San Diego Co. 

L.A., Riv., San 

Bern., San Diego 

counties 

San Diego Co. 

CDFG endangered 





CDFG endangered 




Sidalcea pedata 

(bird-footed checker 

ma1 low) 

San Bern. Co 

State & Federal endangered 


'CDFG 

= California Department of Fish and Game; CNPS = California Native Plant Society. 

ornamental purposes in the early 1800s and 

today is the dominant species in many 

vipari an plant conimuni ties (Robinson, 

1965). Tt was already well adapted to 

southwestern riparian systems, particularly 

those in the desert. Salt cedar is found 

along many small stream channels in San 

Diego County, with a particularly 1 arge 

stand, almost 100 percent cover, in the San 

Diego River in Lakeside near the high 

school. It invades rapidly after fl soding 

on newly deposited alluvial soils, driving 

out native willow and cottonwood, 

particularly when soils dry rapidly after 

flooding. According to Brothers (1981), 

salt cedar is better able than the native 

flora to colonize a habitat created by 

alteration of the natural runoff regime. 

It prefers alkaline soils and is quite 

salt -to1 erant . GI ands for excreting salt, 

located on its leaves, enable salt cedar to 

invade saline soils, The presence of salt

cedar promotes salt accumulation on the 

soil surface that deters germination and 

growth of native species. Salt cedar 

matures rapidly and begins producing 1 arge 

numbers of small wind- and water-borne 

seeds within a year. Its success may be 

attri butable to its pro1 onged annual seed 

production and lower moisture requirement 

compared with native riparian vegetation 

(Horton, 1972). Salt cedar grows in dense 

stands and is deciduous. After 15-20 years 

of growth of stands, fire becomes a real 

hazard. After a fire, trees sprout from 

root crowns within a few days. Salt cedar 

withstands flooding by developing adventitious 

roots. Anderson and Ohmart (1977) 

cite records of rapid invasion by salt 

cedar in the southwest, where it has become 

the dominant community type. 

German ivy (Senecio mikanioides) is a 

perennial vine that was first recorded in 

California in 1890. It is found as an 

introduced exotic from north of San 

Francisco Bay south to the Los Angeles 

basin, with on1 y isolated patches occurring 

farther south at Chula Vista and along 

creeks in San Diego and Escondido. Heavy 

infestations grow along coastal streams in 

Santa Barbara county, particularly in 

disturbed residential areas. Its slender 

twining stems reach out and blanket nearby 

understory vegetation, which eventually 

dies out (Figure 27). Invasion by German 

ivy creates a significant habitat change 

for wild1 ife. 

Giant reed or cane (Arundo donax) is a 

tall perennial grass, 20-23 ft tall, with 

broad bl ades and 1 arge, p1 ume-1 i ke 

i nfl orescences . Introduced from Europe, it 

is now widely distributed in moist places 

in desert and ci smontane Gal ifornia and has 

displaced extensive amounts of nati we 

vegetation along streams and waterways, 

particularly at elevations below 1,000 ft. 

Figure 27. German Ivy ( 

), an exotic weed that blankets asad eveMual!y kills native 

vegetation, is shown growing along San Jose Creek in Goleta.

It grows into dense, impenetrable thickets 

along stream margins or on islands. Bird 

inventories conducted a1 ong the San Diego 

River indicate that it has little habitat 

value and is apparently not used, even by 

reed-loving birds. Residents at Fall brook 

in San Diego County unsuccessful 1 y tried to 

el iminate giant reed on one stretch of the 

Santa blargarita River by manual and 

chemical means. 

3.6 SOUTHERN CALIFORNIA RIPARIAN HABITAT 

Because the geographic area of this 

community profile is so large, with 

considerable variation in cl imate and 

topography, the riparian community contains 

distinctive variations. Weather and 

temperature patterns are considerably 

moderated by cooling winds and fog from the 

Pacific Ocean along the short coastal 

streams of Santa Barbara County and the 

Channel Islands and along ocean-facing 

streams of the Santa Monica Mountains in 

Los Angeles County and the Santa Ana 

Mountains of Orange County. This coastal 

influence is diminished in the watersheds 

of streams and rivers that flow longer 

distances from mountain ranges further 

inland, notably from the San Gabriel and 

San Bernardino Mountains, and to a lesser 

degree from the Coast Range Mountains in 

San Diego County. The size of watersheds 

varies from small acreages along the Santa 

Barbara coast to very large acreages in the 

San Bernardino Mountains. The vegetation 

was mapped by Weislander (1929) between 

1929 and 1935. 

The following section high1 ights 

similarities and differences in riparian 

vegetation from locations within the study 

area for which information is available. 

The small number of rare and endangered 

plants growing in the riparian community 

are listed. Species information is 1 imited 

to areas where floristic studies have been 

undertaken; thus the level and qua1 ity of 

information varies and geographic coverage 

is uneven, Information about willow 

distribution is included where avail able. 

Di stri botional patterns of will ow species 

have not been studied; however, more 

information on factors affecting these 

patterns would provide useful information 

for successful restoration efforts. Table 

6 provides information on the distribution 

and abundance of common rjparian trees and 

shrubs in the study area. Appendix D 

provides examples of riparian habitat in 

coastal -draining watersheds in the study 

area where there is access, 

3.6.1 Channel Islands 

The geographic extent of riparian 

vegetation on the Channel Is1 ands reflects 

climatic, size, and elevational differences 

among islands. Of the eight off-shore 

islands forming the Channel Is1 ands, only 

three of the largest, Santa Cruz, Santa 

Rosa, and Santa Catal ina (all between 100 

and 150 mi2 with elevations under 2,400 ft) 

support riparian communities, and these are 

depauperate, dominated by a few species of 

cottonwood and willow (Philbrick and 

Hal 1 er, 1977). 

Thorne (1967) noted the presence of both 

black and Fremont's cottonwood, red and 

arroyo willow, and elderberry in the 

riparian communi ties of Middle Ranch and 

Cottonwood Canyons on Santa Catal ina 

Island. Similar riparian assemblages occur 

on Santa Cruz Island, including a half 

dozen small to medium-sized stands of bigleaf 

maple (m rnacro~hvll um) occurring at 

low elevations on the north side of the 

island (Philbrick and Hal ler, 1977). 

Cal i forni a bay and sycamore, both common 

species in the Santa Barbara riparian 

assemblage, are missing from the native 

flora of the islands (Timbrook, Santa 

Barbara Botanic Garden, Santa Barbara; 

pers. comm. 1984). Minnich (1980) reports 

that a few sycamores were introduced to 

Santa Cruz and Santa Catalina Islands in 

the early 20th century. Fossil seeds of 

California wax myrtle (Myrica cal ifornica) 

have been reported on Santa Cruz along 

Willow Creek, indicating wetter conditions 

in the past (Chaney and Mason, 1930). 

About 20 groves of Fremont cottonwood occur 

on Santa Cruz Island, some forming long 

gallery forests along streams; willow forms 

impenetrable stands where there is 

permanent water. Mu1 efat commonly occurs 

a1 ong ephemeral stream washes, particularly 

where there has Seen severe erosion 

(Minnich, 1980). There are no rare or 

endangered pl ants reported in the ri pari an 

community of the Channel Islands.

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3.6.2 Coastal Streams in Santa Barbara 

County 

Coastal streams in Santa Barbara County 

drain the southern slope of the Santa Ynez 

Mountains in the Transverse Range and flow 

into the Pacific Ocean within a few miles 

of their origin. These mountains rise to 

elevations of around 4,500 ft, so several 

thousand ft can separate the upper limits 

of a stream watershed and sea level. 

Nearly continuous winds and south-facing 

slopes combine to create xeric soil 

conditions, which are somewhat modified by 

moist coastal fog (Fletcher, 1983). 

Ho71 ister Ranch, covering the most 

western portion of the study area, extends 

8.5 mi eastward from Point Conception to 

Gaviota, 25 mi west of Santa Barbara, and 

from the mean high-tide line to the crest 

of the Santa Ynez Mountains. A flora of 

this ranch lists scrub/shrub wetlands on 

saturated, seasonally or temporari ly 

flooded soi 1 s a1 ong streambanks of upper 

canyons, seeps, and some lower canyons. 

Arroyo willow is the dominant plant species. 

Forested wetlands are found along 

streambanks and seeps on north-facing 

slopes in Alegria, Quarta, and Santa Anita 

Canycns, with sycamore, bl ack cottonwood, 

coast live oak, red willow, yellow willow, 

and arroyo willow all listed as dominant 

types (Fletcher, 1983). Extensive grazing, 

fi re-prevention practices, and clearing for 

avocado groves have degraded or eliminated 

much of the riparian habitat on the ranch 

(Fletcher, 1983). 

Four coastal streams that drain the 

southern slope of the Santa Yner Mountains 

in the Goleta Valley watershed in Santa 

Barbara County were studied before a U.S. 

Army Corps of Engineers flood-control project 

was started (Ferren, 1984). Upstream 

acreages adjacent to these streams are 

1 argely planted in avocados, whereas land 

adjacent to downstream acreages is residential 

and commercial/industrid . San 

Jose Greek supports the most diverse 

assemblage of riparian vegetation of any of 

the four creeks studied (Figure 28). 

Dominant trees and shrubs include white 

alder, western sycamore, bl ack cottonwood, 

red willow, yellow willow, arroyo willow, 

and Cal ifornia bay. Cal ifarnia 1 ive oak is 

common along upper streambanks and extends 

into upland communities. Arroyo willow is 

the most comon tree or shrub, particularly 

toward the floodplain; toyon is found 

occasionally in the streambank community, 

whereas big-leaf maple is rare throughout 

the Santa Barbara coastal -stream study 

area. Yellow willow, rare at low 

elevations and increasing in frequency 

upstream, dominates a narrow 1 ow-el evation 

floodplain. Seedlings of white alder and 

black cottonwood appear scattered through 

the understory, suggesting that, if left 

undisturbed, the existing dominance of 

yellow willow may be altered in the future 

(Ferren, 1983). 

Dominants of the shrubby understory 

include virgin's bower (Clematis 

l iausticifol la), red osier dogwood (Cornus 

stolonifera), a scrub form of black 

cottonwood, coffeeberry (Rhamnus 

cal ifornica) , Cal i forni a blackberry (Rubus 

ursinus), arroyo willow, and poison oak. 

Habitat preferences are observed among 

these shrubs, For example, dogwood is 

restricted to seasonally flooded areas, 

arroyo willow and black cottonwood grow as 

scrub vegetation in streambeds or along low 

banks, and blackberry and poison oak 

usually grow on banks, slopes, and terraces 

(Ferren, 1983). There are no rare or 

endangered plants reported for the riparian 

community of coastal Santa Barbara County. 

3.6.3 Coastal Streams of the Santa Monica 

Mountains 

The Santa Monica Mountains extend eastwest 

for 47 mi from Griffith Park in Los 

Angeles to Point Mugu and from the Pacific 

Ocean on the south approximately 7 mi north 

to the San Fernando and Simi valleys. The 

mountain range is young geological ly with 

highest elevations of about 2,800 ft. 

Slopes are steep (80 percent are in excess 

of 25 percent gradient) and there are 49 

short coastal streams that are all highly 

erosive. In addition, the area is 

particularly subject to major wildfires 

fueled by the Santa Ana winds, a seasonal 

weather phenomenon of Southern California, 

and by a combination of steep slopes and 

highly combustible vegetation (U.S. 

National Park Service, 1383). The southern 

half of the mountain range is now included 

within the boundary of the Santa Monica 

Mountains National Recreation Area, and 

acquisitions are being added by State, 

Federal, and private agencies. Some

iparian vegetation occurs a1 ong many 

canyon bottoms, but riparian habitat is 

specifically noted in the National Park 

Service Plan (1983) for the following 

canyons: Corral, Trancas, Tuna, Pera, and 

Solstice. 

White alder is infrequent, found only in 

the lower parts of steep canyons along 

perennial streams. Arroyo willow is 

abundant and is the dominant riparian 

species, particularly in flood-p1 ain areas. 

Red willow is common throughout the 

riparian corridors at higher elevations 

where it is less susceptible to flooding 

(Thomas, 1984). Sandbar wi 1 low (Sal i x 

hindsiana) is not found within the National 

Recreation Area, but is present at low 

elevations along the north side of the 

range al~ng riverbeds and to the west 

bordering salt marshes. Goodding's and 

yellow willow are not found in the Santa 

Monica Mountains (Raven and Thompson, 

1966). Big-leaf maple i s found only in 

north slopes near springs on ridges at 

2,000 ft or higher where water collects and 

cold air flows down canyons. The Santa 

Monica Mountains are the center of 

distribution for California walnut, which 

grows on mofst riparian terraces and onto 

north-facing slopes (Thomas, 1984; Minnich, 

1980). Flowering ash (Fraxinus dipeta1 a) 

and E. velutina var. coriacea are both 

found only on the inland side of the high 

central and western portion of this range. 

No rare or endangered plants are reported 

in the siparlan community of the Santa 

Monica Mountains, 

3.6.4 Ventura and Santa Clara Rivers 

Both the Ventura and Santa Clara Rivers 

drain parts of the Los Padres National 

Forest in the Transverse Range where a 

number of peaks exceed elevations of 5,000 

ft. Upper reaches of the Ventura River, 

such as Matilija Creek, drain canyons of 

Old Man Mountain and Nordhoff Ridge and are 

relatively undisturbed, but when these 

creeks descend into the valley they form a 

wash at about 1,000 ft (Figure 29). Orange 

and walnut groves are planted right up to 

the edges of the wash. Willow, eucalyptus, 

and cane grow in scattered places along the 

Figure 29. Marrow corridor sf riparian vegetation revesals the presence of a Stream descending into the 

Ventura River.

wash and occasionally along the edge of the 

river, which is channelized closer to the 

ocean. 

The Santa Clara River is a long river 

flowing east-west. It is fed by several 

streams flowing south out of the San Rafael 

Mountains in the Transverse Range in 

Ventura and Los Angeles Counties. A 

comparison of aerial photographs of the 

lower Santa Clara River from 1927, 1941, 

1969, and 1979 shows that much of the 

middle- and upper-terrace zones had a1 ready 

been converted to agriculture by 1927 

(Fairchild Aerial Photograph Collection, 

Whittier College). The distribution and 

gross extent of riparian woodlands, the 

characteristic vegetation of higher 

terraces, have not diminished markedly over 

the last 50 years; however, in recent 

years, activities such as off-road vehicle 

traffic, mining, natural flooding, and 

urban development have resulted in thinning 

and fragmentation of these woodlands. The 

disturbed nature of the vegetation at the 

mouth of Santa Paula Creek exemplifies such 

damage. The major difference in the nature 

of the river vegetation between 1927 and 

today, as reflected in the photographs, is 

the current absence of riparian thickets on 

the flood-pl ain and low gravel bars in many 

places. Past photographs show that such 

thickets were once characteristic of the 

entire riverbed. At present, gravel -bar 

vegetation is extremely sparse or 1 acking, 

especially in the vicinity of mining 

operations, due in part to natural scouring 

and in part to lowered water tables caused 

by gravel in mining. 

Mature, undisturbed riparian wood1 ands 

are located on terraces above the riverbed 

and are most frequent downstream from the 

Highway 101 bridge and upstream from Santa 

Paula Creek, with a few scattered patches 

between. Poorly developed riparian 

vegetation occurs on recently flooded 

gravel bars, along the main channel 

throughout the length of the river, and on 

terraces in the vicinity of gravel 

extraction operations. Mature, undisturbed 

riparian woodlands are located 10-12 ft 

above the river bed and are structurally 

diverse (Smith, 1979). Tree strata, 30- 

60 ft high, consist of arroyo willow, red 

wi 11 ow, bl ack cottonwood, and occasional 

Fremont cottonwood. Thickets of giant 

reed, mulefat, and young willows grow 

beneath this dense tree canopy, and a 

diverse understory of native vines such as 

poi son oak, b1 ackberry, and herbs develops. 

An ecologically important type of riparian 

vegetation grows around undisturbed 

siltation ponds and natural depressions 

along the Santa Clara River banks (Smith, 

1979). Standing water in these areas 

allows the development of a freshwater 

marsh containing plants such as cattail 

(Tv~ha spp. ), bulrush (Scir~us robustus), 

sedge (Carex spp. ), rush (Juncus spp.), and 

numerous aquatic species that provide 

important habitat and food for waterfowl. 

Numerous creeks drain vast areas of the 

Transverse Range to the north, much of 

which is included in the Los Padres 

National Forest. Santa Paula Creek, a 

short system, is unaffected at its upper 

reaches, but the riparian vegetation 

located at its confluence with the Santa 

Clara River is arrested at an immature 

state from past gravel -mining operations, 

which lowers water tables, and by natural 

flooding. Habitat here is sparse and 

disturbed (Smith, 1979). Sespe Creek, the 

longest of the tributary creeks and 

undammed to date, flows from east to west 

from a point near the border between Santa 

Barbara and Ventura Counties through the 

Los Padres Forest Condor Refuge, where it 

turns south and joins the Santa Clara 

River. Riparian habitat is reduced by the 

frequency and severity of floods and by 

cattle grazing. Piru Creek drains a vast 

area to the north in the Los Padres 

National Forest. It is damd at Santa 

Fel icia, creating Lake Piru. Mature 

riparian habitat a1 ong both creeks and 

their tributaries is disturbed, principally 

by extensive grazing. No studies have been 

made of species compositjon in these vast 

areas, and no rare or endangered plants are 

reported for riparian habitat. 

3.6.5 $an Gabriel Mountain Ranae 

The San Gabriel Mountains, part of the 

larger Transverse Range, extend from the 

Ridge Route of 1-5 and Soledad Canyon 

(California Route 14) on the west to Cajon 

Pass (Interstate 15) on the east and 

occupies the northern fourth of Los Angeles 

County and a small portion of southwestern 

San Bernardino County. Most of this range, 

which has an east-west orientation, is

within the Angeles National Forest; the 

extreme eastern part is within the San 

Bernardino National Forest. Elevations in 

the San Gabriel Mountains are high, 800- 

10,000 ft, and watersheds are drained on 

the coastal side, forming three major 

rivers: to the west, Tujunga Creek and its 

tributaries form the Los Angeles River; in 

the central portion of the mountain, San 

Gabriel Creek and its tributaries form the 

San Gabriel River; and to the east Lytle 

Creek in San Bernardino County joins 

drainages from the San Bernardino Mountains 

to form the Santa Ana River. Each of these 

rivers flow many mi 1 es across the broad and 

highly urbanized Los Angeles floodplain 

before emptying into the Pacific Ocean. 

According to photographs in the Fairchild 

Aerial Photo Collection, Whittier College, 

all three rivers were channelized before 

1927. 

Riparian wood1 ands are severely 

restricted by the availability of water 

from perennial streams or subsurface 

moisture in the semiarid climate of the San 

Gabriel Mountains and stand out in sharp 

re1 ief against adjacent low-growing scrub 

and shrub lands. At elevations of 2,000- 

5,000 ft, the riparian community contains 

elements of a mjxed evergreen forest found 

in the Coast Ranges, particularly in cold 

canyons (Hanes, 1976). 

Dominant species 

include shrubby forms of Sal ix, big-1 eaf 

maple, Ca1 ifornia bay, black cottonwood, 

canyon 1 ive oak (Ouercus chrvsol eai s) , and 

big-cone Doug1 as fir (Pseudotsuua 

macrocarpa) . At middle elevations, streams 

are domjnated by white alder, and at low 

elevations on riparian terraces by arroyo 

wil law, mulefat, Fremont cottonwood, and 

western sycamore (Hanes, 1976). Mistletoe 

(Phoradendron tomentosum subsp. 

macro~hvl 1 urn) is a common hemi parasi te on 

dominant tree species. Coast live oak 

grows on upper riparian terraces, 

particularly north-facing ones, some 

distance from perenni a1 water supplies. 

As creeks emerge from the San Gabriel 

Mountains onto gravelly a1 1 uvial 

floodplains, there are remnants of a vast 

a1 luvial scrub habitat that once covered 

much of the Los Angeles Basin, part.icularly 

on higher terraces less subject to severe 

scouring in major storms (T,L. Hanes, pers. 

corn.). Most of the streams draining 

directly onto this floodplain are now 

damned. Aerial photographs of the flood 

basin reflect the presence of three 

physiographic zones of different ages that 

support distinct types of vegetation: a 

wash, a terrace above the wash, and a 

higher alluvial terrace (R. L. Smith, 1980). 

The youngest zone, the wash, supports 

scattered, short-statured pioneer species 

and contains islands or remnants of a 

higher alluvial terrace, most of which has 

been destroyed by erosion during past 

floods, These older islands now support 

1 arge shrub populations. The terrace 

immediately above a wash supports a uniform 

and dense scrub vegetation dominated by 

buckwheat (Eriosonum fascicul atum). The 

highest zone of the floodplain, mature 

a1 1 uvi a1 terraces, and the uneroded 

a1 1 uvial islands support a combination of 

shrubs and subshrubs that distinguishes the 

fan and floodplain vegetation by its rich 

diversity (Srni th, 1980). Laurel sumac 

(b 1 aurina) , lemonadeberry (B. 

inteqrifol ia) , Leaidosoartum sauamatum, 

Cal i forni a buckwheat (Erioaonum 

fasciculatum), California juniper 

(Juniaerus cal i fornica) , and prickly pear 

(O~untia spp.) are the dominant species. 

Mature stands are diverse and appear to 

represent a climax vegetation that develops 

after severe periodic flooding. R.L. Smith 

(1980) regards this plant assemblage as a 

specialized form of coastal sage scrub. 

Leaidos~artum sauamatum is the one species 

of this plant assembl age that is restricted 

to alluvial substrates and is thus confined 

to drainages. On the other hand, Juniaerus 

cal i fornica is unusual on the floodplain, 

growing more typical ly on desert slopes 

(Munz, 1974). Smith suggests that major 

drainages such as the San Gabriel River act 

as corridors for dispersal of juniper seed 

from dry interior mountain slopes. 

Dominance of lemonadeberry, primarily a 

coastal species, is unusual this far 

inland. 

With the exception of a remnant of 

riparian woodland habitat heavily invaded 

by exotic plants at Whittier Narrows County 

Nature Center, nothing remains of a onceextensive 

willow forest that folloraed the 

San Gabriel River across its f'loodplain. 

Intermittent immature stands of willow and 

mulefat now grow in wash areas on upper 

parts of the river.

Canyon Road near Yorba Linda to the ocean The U.S. Forest Service (USES) has mapped 

in work that was carried out largely before the vegetation of order IIH streams in the 

1927 (Fairchi ld Photo COT 1 ection) . Prado San Bernardino National Forest (USFS 1984). 

Dam was built at the head of Santa Ana The most widespread and best adapted 

Canyon in 1941. 

riparian tree

subjected to less intense erosional 

di sturbance. 

More rare riparian pl ants i nci ude dogwood 

(Cornus mttal7 i i) , which occurs along 

watercourses and on shaded slopes near Lake 

Arrowhead and bake Gregory. A few 

populations of boxefder grow on northfacing 

canyons on Mill Creek Ridge and Oak 

Glen. Mountain maple (a qlabrum) has 

been reported on the north face of 

Sugar1 oaf Mountain near 10,000 ft elevation 

(Minnich, 1976). Grinnell (1908) reported 

that nettle (Urtica holsericea), which grew 

5 to 6 ft tall, was abundant along streams 

wherever shaded by alder canopy and that 

clematis (Clematis l iqusticifol ia) grew at 

elevations of up to 5,500 ft. 

The riparian woodland in the Prado Basin 

is the largest in Southern California. A 

USFWS study (Zembal, 1984a) of this basin, 

the Santa Ana River Canyon, and environs 

points out that a small number of species 

accounts for much of the plant cover. A 

total of 99 species were identified in 

floodplain and riparian habitats. 

Approximately one-third of the plants in 

the study were identified as introduced or 

non-native species. 

Two small and widely separated 

populations of the rare many-stemmed 1 iveforever 

(Dudleva mu1 ticaulus) (CNPS List 

Ib, 3. Smith and York, 19841, growing on 

nearly vertical rock or dirt walls in the 

river canyon are threatened by devef opment. 

Santa Ana River eri astrum (Eriastrum 

densi fol i um) , thought to have been 

extirpated, was found in a nearby canyon 

(Lathrop and Thorne, 1978). Recently a few 

stands were located in the northern 

portions of the plant's historic range 

growing above main watercourses where 

flooding and scouring have been infrequent 

enough to a17ow open shrublands to persist 

in the floodplain. Zembal and Kramer 

(1984) estimate that suitable habitat for 

the plant has been reduced by 90 percent. 

Both species are proposed for Federal 

listing under the Endangered Species Act. 

Black willow is very common along the 

Santa Ana watercourse and throughout the 

basin; sandbar willow is common along 

watercourses growing in scattered dense 

stands; and arroyo willow is found 

occasionally along some basin watercourses 

and commonly along others. Red willow and 

black coltonwoad are uncomon along the 

Santa Ana River Canyon, and Fremont 

cottonwood and sycamore are uncomon but 

focally conspicuous a? ong the outer fringes 

and higher ground of the watercourses, 

often growing in groves of several to 

several dozen trees. Flowering ash is 

uncommonly found in the undergrowth, and 

Cal ifornia walnut is present but uncommon 

in the bordering shrubland (Zembal , 1984b), 

Below Prado Dam, built in 1941, remnants 

of perennial stream riparian vegetation 

remain, particul arly in Featherly County 

Park, situated on an alluvial plan (Marsh 

and Abbott, 1972). Alonq this portion of 

the river el bational- gradients are 

reduced, resulting in ponding and the 

development of a sizable instream flora, 

including bur-marigold (Bidens 1 aevi sj , 

watercress (Rori~~a nasturtium-aauaticum), 

cattail (Tv~ha spp.), and bulrush (Scir~us 

spp. ) . Cottonwood, wi 1 low, and mulefat 

dominate a dense greenbelt of trees and 

shrubs lining the river margin. Older 

trees are commonly festooned with wild 

grape, which creates shade for a rich 

understory of herbaceous annual and 

biennial species. Sycamore and coast l ive 

oak grow to 1 arge sires on upper terraces, 

supported by a high water table. 

Marsh and Abbott (1972) list 367 species 

of plants in a study covering 31 mi of the 

lower Santa Ana River from Prado Dam to the 

river mouth. These plants belong to 252 

genera and represent 72 families. Of the 

total number of species, 229 are native and 

138 are exotic. There are 62 species in 

the sunflower family and 11 species each of 

sedges and buckwheat. In transects across 

the river in the Horseshoe Bend/Featherly 

Park area 250 plant species were 

identified, many of which are listed in 

Howell (1929) and many introduced since 

then (Marsh, 1972). Figure 31 shows a 

cross section of the Santa Ana River 

between Horseshoe Bend and Featherly Park. 

3.6.7 San Sacinto Ranqe 

The San Jacints Range, approximately 40 

mi long and 15 mi wide, is separated from

I I I I I 

Left Unrik (North) Former R~ver Co~lrse 

R~ght Bank 

(South) 

Figure 31. Cross section of the Santa Ana River between Horseshoe Bend and Featherly Park (adapted from 

Marsh, 1972). 

the San Bernardino Range by the trough-like 

San Gorgonio Pass, through which runs the 

San Andreas fault. At 10,831 ft, San 

Jacinto Peak is the second highest in 

Southern Cal i fornia. The range, forming 

the beginning of the Peninsular Ranges, 

runs southeast, on the east rising 

precipitously from the Col orado Desert in 

the upper Coachella Valley and on the west 

from a series of foothills, low ranges, 

so% i tary peaks, and occasional val 1 eys. On 

the south, the San Jacinto Mountains grade 

into the Santa Rosa Plateau and Mountain 

Range. The entire range is within 

Riverside County, and most is within the 

San Bernardino National Forest with 

ownership shared by the USFS, the State, 

various Indian tribes, and some private 

inhofdings. 

The most extensive drainage is toward the 

west in the north fork of the San Jacinto 

River and its tributaries, many of which 

are perennial streams. Flooding is common 

in years of heavy rainfall because of the 

large quantities of water carried in winter 

and spring. The most extensive riparian 

community occurs on the moist western 

slopes, particularly an the fairly level 

benches at middle elevations. Stands of 

white alder frequently line fast-flowing 

perenni a1 streams. Ye1 1 ow will ow grows 

intermittently a1 ong stream courses 

throughout the higher mountain drainages. 

At higher elevations dense assemblages of 

herbaceous perenni a1 s surround wet springs, 

with plants such as Senecio triansularis 

and several species of Eoilobium 

predominating . Twaybl ade (Listera

convallarioides), a rare plant for this 

area, grows at about 8,000 ft near the 

north fork of the San Jacinto River 

(Hamilton, 1983). Below 8,000 ft, arroyo 

willow grows along streams in the wider 

canyons in patches where small benches slow 

the water flow. The riparian understory is 

sparse, with western azal ea (Rhododendron 

occidentale) , elderberry, and Ri bes spp. 

growing occasionally. Below Lake Hemet to 

the Cranston Ranger Station, riparian 

habitat is relatively pristine. Elements 

of the Sonoran Desert flora merge into the 

riparian plant assembl age at lower 

elevations with O~untia spp. growing 

commonly, Yucca whioolei and Aqave spp. 

less frequently (Hamil ton, 1983). Willows 

become lush as creeks merge and flow out 

onto the wide a1 luvi a1 floodplain. 

Remnants of alluvia1 scrub habitat can be 

seen on higher terraces. Below the ranger 

station there is frequent disturbance and 

only a patchy canopy of cottonwood and 

sycamore remains. Occasional 1 arge and 

usually old specimens of these trees remain 

on an increasingly urbanized floodplain. 

3.6.8 Santa Ana Mountains 

The Santa Ana Mountains parallel the 

southeastern trend of the Southern 

California coast1 ine; they are approximately 

40 mi long, vary in width from 4 to 

13 mi, and are located 20-25 mi inland from 

the ocean. This narrow and precipitous 

range has an average height of 3,500 ft and 

several peaks with elevations exceeding 

5,000 ft. Most of the range straddling 

Orange and Riverside Counties is in public 

ownership in the Cleveland National Forest, 

with private holdings for homes and cabins 

in Silverado and Trabuco Canyons and cattle 

ranching in the western foothills and Black 

Star Canyon. 

Santiago and Trabuco Creeks are the main 

streams draining the mountains to the west. 

In 1951 Pequegnat referred to these streams 

as perennial, whereas in 1976 Vogl 

described them as intermittent. Short 

ephemeral streams feed into the larger 

streams and drain the eastern side (Vogl, 

1976). Larger stream drainages are lined 

with occasional stands of white alder and 

an abundance of willow and Fremont's 

cottonwood (Vogl , 1976). Black cottonwood 

is less common but occurs throughout the 

range (Lathrop and Thorne, 1978). Poison 

oak and wild grape often grow in willow and 

mulefat thickets. Clematis liqusticifolia 

is found infrequently cl imbing over shrubs. 

With an increase in altitude, alder is 

rep1 aced by big-leaf maple, and lowland 

will ow by arroyo willow (Pequegnat, 1951). 

Smaller streams are flanked with coast 

1 ive oak and Cal ifornia bay; flowering ash 

is scattered throughout. Canyon oak 

(Ouercus chrvsole~is) and 

interior 1 ive 

oak (9. wisl izenii) are present at 

higher elevations and at heads of canyons, 

where they often form pure stands of a 

single species. Dense stands of canyon 

oak have stabilized some of the steepest 

parts of Modjeska and Santiago Peaks (Vogl , 

1976). Gal ifornia walnut is found 

infrequently in the riparian woodlands, 

mainly in Hagador, Santa Ana, and lower 

San Juan Canyons (Lathrop and Thorne, 

1978). 

3.6.9 San Dieso County Coastal Rivers 

The coastal ~rovince of San Diego County 

has a series of wide marine terraces, known 

as mesas, which range from elevations of 

50-60 ft at the coast to 800-1,200 ft 

inland. These mesas are dissected by a 

number of east-west-fl owing streams and 

rivers that arise in the mountains to the 

east (6,500 ft at their highest point). 

The climate in San Diego County is semiarid 

with a concentration of rainfall in a few 

major storms, causing soil erosion and 

loss. All of the major rivers in $an Diego 

County are dammed somewhere along their 

course before they reach the floodplain, 

which results in greater control of storm 

water flows but also in the retention of 

soils behind the dams and in a1 terations in 

the riparian county. 

The riparian community of San Diego 

County was once abundant along water 

courses flowing out of the mountains before 

cutting across broad mesas towards the 

Pacific Ocean. Today, however, there is 

I i ttle contiguous riparian habitat, 

particularly in the southern part of the 

county where urbanization pressures have 

been greatest.

The Santa Margarita is the least 

disturbed river in San Diego County. Its 

watershed is about 60 mi long ?and eqcompasses 

an area of about 740 mi extending 

inland nearly to the San Jacinto Mountains 

(Zembal, 1984b). The headwaters of its 

tributaries are at low elevations and some 

are long distances from the coast. Tributaries 

of the Santa Margarita River are 

perennial or intermittent. The river 

slopes gradually toward the coast and 

during most of the year is shallow with a 

flat, sandy bottom (Figure 32). Deeper 

water in the form of oxbows, small pools, 

or ponds occurs along lower portions of the 

river where the floodplain is broad. The 

upper reach of the river is rockstrewn with 

limited riffles, a few boulder deposits, 

and deeper holes. 

In a USFWS study of a proposed Santa 

Margari ta Bureau of Recl amation dam 

project, Zernbal (398451 describes arroyo 

willow as the mast abundant and widespread 

species. Mild grape and poison oak contribute 

to the canopy of Fremont cottonwood, 

western sycamore, and coast 1 ive oak. 

Tree densities are highest in young or 

short willow woodland (about 16 ft tall). 

Stands forming between sandbars, adjacent 

to water channels, and in older woodlands 

usually consist of sandbar or arroyo willow. 

Over 100 species make up the low 

groundcover; however, mu1 efat , mugwort 

(Artemi si a douslasiana), willow sprouts, 

Doug1 as mulefat (Baccharis doucal asi i), 

poison oak, wild grape, wild blackberry 

(Rubus ursi nus), sweet clover (Me1 i 1 otus 

sp,), scouring rush (Esuisetum sp.), stinging 

nettle (Urtica holosericea), and nut 

grass (Cvperus sp.) are the most common. 

One rare and endangered plant, sticky 

dudleya (Dudleva viscida, CNPS List lb, J. 

Smith and York, 19841, and one plant of 

l imited distribution, San Miguel potmint 

Figure 32. The Santa Mergarita, the !east itdisturbed river in Saki Diego County, Is shallow with a fiat sandy 

bottom.

(SatureSia chandleri, CNPS List 4, J, Smith 

and York, 1984) grow on vertical canyon 

walls above tributaries of the Santa 

Margari ta Ri ver . 

The San Luis Rey River is considered to 

be one of the least modified and easily 

restorable rivers in urbanized Southern 

California, despite the extensive conversion 

of floodplain riparian habitat to 

agricultural and other uses (U.S. Army 

Corps of Engineers, (yrps) 1981). Its 

watershed covers 565 mi . The river originates 

in the foothills around slopes of 

Mount Palomar (elevation 6,138 ft) clothed 

with ponderosa pine and covered with snow 

in winter. It flows south, then northwesterly 

through coastal sage scrub and 

chaparral communities before emptying into 

Lake Henshaw, a reservoir within the Cleveland 

National Forest. Lake Henshaw controls 

about one-third of the San Luis Rey 

River watershed. West of Lake Henshaw, the 

San Luis Rey River flows through coastal 

oak woodl ands, chaparral , and coastal sage 

scrub canyons as it passes through the 

three Indian reservations of Pal a, Rincon, 

and La Jol 1 a. These native communities are 

gradually being replaced by citrus and 

avocado orchards, cattle and horse ranches, 

go1 f courses, and resort condominiums. 

Flow is irregular in this section of the 

river, varying with the amount of water 

released at the dams upstream. Farther 

west and downstream much of the natural San 

Luis Rey River floodplain has already been 

turned into truck farms, wheat and barley 

fields, high-and medium-density residential 

areas, commerci a1 zones, and industri a1 

parks. Sand-mining operations are frequent 

along the lower reaches of the river. 

Before emptying into the Pacific ocean at 

the city of Oceanside, the San Luis Rey 

River flows through subcl imax riverine 

riparian and wooded riparian habitats and 

a series of fresh to brackish water marshes 

with a saltwater lagoon at the mouth. The 

mouth of the river at Oceanside was 

converted into a marina in the early 1960s- 

Its adjacent wet1 ands were filled for 

resort and condomi ni um development and 

highway construction. 

Detailed floristic studies have not been 

carried out along the San Luis Rey River; 

however, most of the remnants have been 

disturbed, and native vegetation has been 

replaced by non-native plants such as tree 

tobacco, giant reed, and brome grasses. 

Freshwater marsh and understory riparian 

vegetation includes cattail (fi~ha sp. ), 

bulrush (Scir~us ssp.), wild celery (A~ium 

spp. ) , mul efat, elderberry, poison hemlock 

(Coni um maculatum) , and wild grape. Numerous 

sycamores, estimated to be 50-100 years 

old, grow beside the river in the floodplain 

along with associated willow. The 

San Luis Rey is the southern limit for 

black cottonwood. An assortment of understory 

plant assemblages are found, ranging 

from those associated with freshwater 

marshes that develop in old oxbow formations 

to weedy exotics associated with 

human - a1 tered environments. The rare and 

endangered st icky dud1 eya (Dud7 e ~ vi a scida) 

grows in several locations in the narrows 

where there are vertical cliff walls near 

perennial creeks. 

The rivers in San Diego County south of 

the §an Luis River have been severely 

disturbed or degraded so that only remnants 

of riparian habitat remain on the 

floodplain, often between a road and a 

streambed. Some of the better remnant 

sites are listed in Appendix D. Over the 

past 50 years disturbances have been from 

agriculture and sand mining, and in the 

past 20 years, from rapid urbanization. 

White alder is found only above 4,000 ft 

along mountain streams, where it is the 

most re1 i abl e indicator of water. Western 

azalea (Rhododendron occidentale) occasionally 

grows above 3,000 ft. Mountain 

dogwood (Cornus nuttallii) is found on 

shaded slopes or along streams on Palomar 

and Cuyamaca mountains (Higgins, 1949). 

Boxelder was reported by Higgins in 1949 an 

the La Posta Indian Reservation and in 

Doane Valley on Palomar Mountain. 

Red willow is the most common willow in 

San Diego County, where it is found growing 

along streams from the coast into the mountains. 

Arroyo willow is found in a shrubby 

form, sometimes as a small tree, from Point 

Loma east to the Cuyamaca Mountains. Ye1 - 

low willow or lance-'leaf Pacific willow 

(Saf i x 1 asi andra var. 1 anci fol ia) is uncommon, 

growing only as a shrub along San 

Mateo Creek, in Murphy Canyon, and on Hot 

Springs Mountain. Goodding" wwil low grows 

fairly comoniy along streams in Moosa 

Canyon, San Pasquaf , and Lakeside. 

Graybark willow (Sal ix hindsiana var.

leucodendroides) grows as a shrub in or 

cf ose to coastal streams. 

Common trees of San Diego County along 

streambeds or on floodplains include Fremont 

cottonwood, Cal i forn i a sycamore, and 

coast live oak, which grows to very large 

size on the moisture-rich floodplain. 

Elderberry, usually a shrub but sometimes 

a small tree, is common along streams 

throughout the county up into the mountains. 

California walnut is rare, with a 

specimen reported by tliggins (1949) in 

Del uz. California bay is not found on the 

coastal side of San Diego County, but only 

in relictual stands on the eastern desert 

slope. Flowering ash, not known in the 

county prior to 1950, is now reported to 

grow in Sloan Canyon. Lvthrum californicum, 

unconinlon in San Di ego County, 

grows in the Otay River Va?+iey. 

A rare plant, San Diego monardelfa 

(Mgnardell a 1 ino ides subsp. viminea, CNPS 

List lb, Smith, 19841, occurs in larger 

canyons along ephemeral streams that support 

a flood-disturbance type of vegetation. 

According to a study for the 

California Department of Transportation 

(CALTRANS) by Scheid (1985), small popuf a- 

Lions can be found growing on coarse, 

rocky, sandy alluvium on floodplains, on 

benches cut from the banks of channels, on 

stabilized sandbars, along the banks of 

channels and drainages, and even in streambeds 

in sonie locations. Though occurring 

in several physical settings, the locations 

are all similar in soils and associated 

pegetatian and in the processes leading to 

the physical developlnent of the sites 

within the stream system. 

Because of extensive disruption along 

rivers and streams, exotic species are now 

a major coniponent of San Diego County's 

ripariara habitat. Salt cedar arid giant 

reed thrive and aggressively rep1 ace native 

riparid0 species In river courses below 

S,OOi) ft. 

Examples are widespread, but a 

particul arty large invasion of salt cedar 

can be seen along the San Diego River near 

takesidc and of giant reed, off Mission 

Gorge Road and the Father Serra Trial Woad. 

Efforts in Fallbrook to eliminate giant 

reed by manual or cheniical means have been 

marginally successful. Castor bean 

(Ricinus communis) , though prevalent, does 

not have a perennial root as do salt cedar 

and giant reed, and thus has not become a 

dominant pl ant ; however, where a1 I uvi um has 

been removed and poorer soils remain, huge 

thickets of castor bean become establ ished, 

excluding light and precluding the establishment 

of native species. German ivy is 

a 'less serious pest in San Diego County 

than farther north in Santa Barbara County 

but is well established in the side creeks 

near Chul a Vista. Ludwiqia urusuayensis 

has become a dominant water-covering 

aquatic weed that creeps up and covers 

streambanks , 

3.7 SUMMARY 

The modern riparian plant community of 

Southern California is derived from a 

southern madro-terti ary xeric element and 

a northern arcto-tertiary mesic element. 

Species distribution in this flood-prone 

habitat is closely tied to the water regime 

of streams, not only for water supply in a 

seasonally dry landscape but for a series 

of events important in plant establishment 

and succession. Common trees include white 

alder (a riparian indicator species), 

wit 1 ow, cottonwood, and sycamore. The zone 

closest to the water is most frequently 

disturbed by storms and is dominated by 

alder and willow, while cottonwood, 

sycamore, and oak grow to larye sizes on 

terraces above the river. This part of the 

riparian community is the most depleted. 

Species composition varies somewhat from 

north to south, coastal to inland, and low 

to high elevational gradients. There are 

only a few rare or endangered plants 

associated with riparian habitat, but the 

riparian community itself is an endangered 

community due to the activities of man, In 

addi tion, several invasive exotic species 

are reducing the extent and quality of the 

small amount of remaining riparian habitat.

CHAPTER 4. 

THE RIPARIAN COMMUNITY: ANIMALS 

California's insect fauna is so huge, 

with an estimated 27,000-28,000 species, 

that there is no State list (Powell and 

Hogue, 1979). In the Los Angeles basin, 

there are somewhere between 3,000 and 4,000 

species (Hogue, 1974). For comparison, the 

State has about 500 species of birds 

(Small, 19741, the 1 argest vertebrate 

cl ass. 

The literature on insects is vast, but 

much of it is taxonomic; new species 

continue to be described and families 

revised. The riparian insect fauna as a 

group has not been dealt with 

comprehensively, and only rarely has a 

scientific paper on the fauna of a Southern 

California area included insects. One 

exception was Ingles (1929), who examined 

the fauna, including insects, of the upper 

Santa Ana River wash in Los Angeles County 

at a time when conditions were quite 

natural along that part of the river. His 

data were qualitative; he was more 

interested in distribution than abundance. 

He defined four plant associations, one of 

which was riparian (will ow/cottonwood) , and 

his fist of riparian insects included 

species from 8 orders: Orthoptera (8 

species); Ephemeroptera (1); Odonata (10); 

Hemiptera (3); Coleoptera (38); Lepidoptera 

(23); Diptera (24); and Hymenoptera (8). 

He considered his findings an affirmation 

of common know1 edge concerning the animals 

of the wash; it is now of historical value 

as an illustration of what the insect faun5 

of a lowland river used to be in Southern 

Ca1 ifornia. 

Recently, lists sf insects have been 

i nc? uded in some environmental impact 

reports, along with a discussjon of the 

impact of a proposed project on the fauna. 

These documents are not readily obtainable, 

and only one has been cited--a study of the 

Santa Barbara coastal creeks (Onuf, 1983) . 

Insects occupy all types of riparian 

space and include soil dwellers, plant 

borers, leaf users, and water dwellers. 

Aquatic insects apparently are adapted only 

secondarily to life in the water; their 

ancestral origins are thought to be 

terrestrial (Usinger, 1956). Many insects 

are, however, aquatic, and in discussing 

riparian insects it is convenient to treat 

aquatic and terrestri a1 forms separately. 

4.1.1 Aauatic Insects 

Many riparian insects are aquatic in the 

nymphal or larval state and as adults are 

terrestrial or aerial. Adults of these 

species (e.g., dragonflies, stoneflies, 

dobsonflies, mosquitoes, and midges) stay 

close to the water in which they will lay 

their eggs. Several orders, notably the 

true bugs and beetles, are aquatic as 

adults as well, but whereas larvae and 

nymphs are adapted to obtaining oxygen 

under water through gills, spiracles, or by 

cutaneous respiration, adults must breathe 

air. Ingenious methods, such as carrying 

an air bubble, have evolved for maintaining 

an air supply under water (Usinger, 1956). 

Aquatic nymphs and larvae are often 

predaceous and are in turn prey for fish. 

The immature stages usually are 

substantially different from the adult 

forms, and many have not yet been 

identified. Invaluable source books on 

this subject are Usinger (1956) and Merritt 

and K.W. Cummins (1978). 

The fol lowing brief account high1 ights 

some of the more important groups

associated with riparian habitat in 

Southern Cal i fornia. 

a. Mayfl ies (Ephemeroptera). The nymphs, 

called the "cattle" of the aquatic 

environment for their role in transforming 

plant into animal tissue (Day, 

1956), require weeks or months to 

develop, Aerial adults live only a 

few days (Edmunds et al., 1976). The 

nymphs are a major food source for 

fish, dragonfl ies, and birds (Day, 

1956). There are about 170 species in 

Cali forni a; Powel 1 and Hogue (1979) 

list three genera that are common in 

Southern California's coastal streams 

and 1 akes: bl ue-winged duns 

(E~hemerella), flat-nymphed mayfl ies 

(E~eorus), and stil t-legged flies 

(Call i baeti s) . One species of 

Callibaetes, 5;. pacificus, is ubiquitous 

in still-water ponds and is an 

important food ssurce. Mayfl ies are 

an excel lent indication of environmental 

quality and have been used by 

the U. S. Environmental Protection 

Agency for this purpose (C. Nagano, 

Natural History Museum, Los Angeles 

County; pers. corn.). Figure 33. A predaceous nymph and adult of the 

California spreadwing, a dalnselfly common in 

freshwater bogs. Photo courtesy of Charles l-iogue. 

b. Damsel fl ies and dragonfl i es (Odonata) . 

The nymphs (also called naiads) are 

Dredaceous water dwellers, eatins 

immature insects, crustaceans; 

source for trout (Jewett, 1956). Wintadpoles, 

fish, and young sal amanders 

ter stonefl ies (F. Capni idae) mature 

(Essig, 1926). They do not usually 

early in the year and are a food 

chase their prey but lie in wait for 

source when other insects are unavail - 

it (Needham and Westfall, 1955). They 

able (Powel 1 and Hogue, 1979). There 

serve as food for fish, birds, and 

are about 100 species of stonefl ies in 

frogs (Smith and Pri tchard, 1956). 

California, with at least 3 important 

Adults feed on mosquitoes and gnats 

genera in Southern California: 

(Powel 1 and Hogue, 1979). Widespread 

Nemoura, Pteronarcys, and Acroneuria. 

wherever there is permanent, clean 

freshwater, the adults are handsome d. 

Crickets (Orthoptera). Orthopterans 

insects, interesting to watch and much 

are not usually associated with water, 

valued by collectors (Figure 33). 

but the pygmy mole crickets (Tri- 

There are about 100 species of this 

dactyl us spp.) are an exception. They 

order in California (Powell and Hogue, 

are fossorial , burrowing in loose soil 

1979). The commonest dragonfl ies are 

bordering water, and swim well (La 

those in the Libellulidae or skimmer 

Rivers, 1956). Their role in riparian 

family; the cornonest damsel flies are 

ecology has not been we1 1 researched. 

the bluets (F. Coenagrionidae) . 

e. True bugs (Hemipteraj . Water bugs 

c. Stonefl ies (Plecsptera) . Stonefly generally overwinter as adults and lay 

nymphs require moving water and are eggs in the spring. The nymphs hatch 

associated mostly with mountain and develop in summer, become adults 

streams, where they are a major food in late summer, and continue the

annual cycle (Usinger, 1956). In many 

families a1 1 stages are aquatic; a few 

have fossorial adults, Most water 

bugs can fly buhre more at home in 

water, 

There are several families in Southern 

Caf i forni a. The water boatmen (Cori - 

xidae) feed on algae, diatoms, rotifers, 

and mosquito larvae and are 

themselves preferred food for many 

fish (Usinger, X956), Backswimmers 

(Notonectidae) swim upside down and 

prey on mosquitoes and snlall fish. 

They can inflict a painful bite 

(Usi nger, 1956). Water striders 

(Gerridae) prey on organisms that fall 

into the water. The most common species 

in Southern California is Gerris 

remisis (Powell and Hogue, 1979). 

Giant water boatmen (Belostomatidae) 

occur in streams and ponds and hunt 

from under water. Amons the larqest 

insects, they prey on other insects, 

tadpoles, fish, and even snakes. 

Females of some genera lay eggs on the 

back of the male, where they are 

carried until they hatch (Usinger, 

1956). One species, the electric 

1 ight bug (Lethocerus americanus), may 

no longer exist in Southern California; 

it was dependent on freshwater 

ponds. Common species in Southern 

Cal ifornia are the toe biters (Abedus 

indentatus) and Belastoma flumineum. 

All giant water boatmen can inflict a 

painful bite. The creeping waterbugs 

(Naucoridae) are inhabitants of slow 

streams with pebbly bottoms. They are 

highly predaceous -and eat water boatmen, 

mosquito larvae, and mollusks. 

They also can inflict a painful bite. 

The common Southern Gal ifornia species 

is Ambrvsus occidental r's (Powell and 

Hogue, 1979). 

f. Dobsonff ies (Neuroptera) . Adults 

deposit egg masses on objects overhanging 

water, The larvae are fully 

aquatic, have powerful mandibles, and 

are high1 y predace3us. Nature 1 arvae 

burrow into banks above water and 

pupate (Powell and Hogue, 1979). 

Neohermes f i 1 i corn! s l arvae are 

izparlant fish food, 

g. Caddisfl ies (Vrichoptera) . The 

aquatic larvae of many species form 

cases of silk with pebbles and plant 

fragments attached, are stationary, 

and feed on plants. They are food for 

fish and have often been used as bait. 

There are about 300 species in 14 

families in California (Powell and 

Hogue, 1979). The family Limnephi1 

idae dominates Gal i fornia's 

Tricopterans, with more than 40 

species described. The genus Limneghilus 

is widespread in the foothills 

and mountains and is a major food for 

trout (C. Hogue, pers. corn.). 

h. Moths (Lepidoptera) . Only a few moths 

have adapted to aquatic habitat, 

mostly in the subfamily Nymphul ini . 

In one genus, Parar~vractis, all 

stages except adults are aquatic. The 

1 arvae are rock-dwell ers and construct 

silken tents from which they feed on 

algae and diatoms (Lange, 1956). 

Beet1 es (Col eoptera) Water beetl es, 

1 ike the water bugs, include partially 

and fully aquatic species. Adults as 

well as eggs and larvae or nymphs are 

often aquatic; only the pupal stage is 

terrestrial. Adults carry their air 

supply with them in the form of a 

bubble or a sheet of air held by fine 

hairs (Leech and Chandler, 1956). The 

l arvae are general ly predaceous, as 

are many adults (with some exceptions, 

such as scavenger beetles). Many 

fami 1 ies are represented in Southern 

California. A few of the more common 

ones are l i sted be1 ow. 

(1) Predaceous diving beetl es 

(Dyti scidae) . Common from sea 

level to 4,000 m in many 

freshwater situations; the larvae 

are predaceous and cannibal 4 st ic, 

feeding on larvae and adults of 

other insects, worms, 1 eeches, 

snails, tadpoles, and small fish, 

Adults are prey for a1 1 classes of 

vertebrates; among birds, they are 

particul arly sought by ducks and 

waders (Leech and Chandler, 1956), 

(2) Whirligig beetles (Eyrinidae). 

These beetles can dive and fly but 

are most at home on the surface of 

the water, which is their foraging 

niche (Figure 34). Found tn a

the early stages. The adults are 

aerial or terrestrial. Dipterans perform 

many ecological functions; they 

prey on other invertebrates, serve as 

food for birds, amphibians, and fish, 

and are useful indicators of environmental 

quality. The biting habit of 

some flier is highly irritating to 

humans, and several species transmit 

serious mammal i an diseases. 

Figure 34. Whirligig beetles (Dineutu~ sp.) on the 

surface of an eddy in a stream. Photo courtesy of 

Charles Hogue. 

(1) Net-winged midges (Blephariceri - 

dae). Larvae are found in swiftwater 

streams from 40 to 4,000 m. 

They are vegetarian and, as they 

are sensitive to pollution, are 

indicators of the health of the 

stream. One species, Aqathon 

comstocki, is an important food of 

the dipper (Cincl us mexicanus). 

This family is under study in the 

San Gabriel Mountains. 

variety of freshwater habitats, 

the larvae are predaceous and 

cannibal i stic (Leech and Chandler, 

1956) . 

(3) Water scavenger beet1 es (Hydrophi1 

idae). Most species of water 

beetles are in this family. They 

are generally vegetarian and move 

more slowly than the predaceous 

beetles. Both adults and larvae 

are an important food source for 

fish and aquatic birds (Leech and 

Chandler, 1956). 

(4) Water pennies (Psephenidae). The 

larvae are round and flat, with 

the body margins expanded to cover 

the head and legs (Powell and 

Hogue, 1979). They cling to the 

surfaces of rocks like limpets. 

Adults are terrestrial and are not 

easily seen. klater pennies are 

found throughout California in 

clear, fast streams, usually below 

1,600 m (Leech and Chandler, 4. 

1956). 

(2) Craneflies (Tipulidae). One 

species, the giant cranefly 

(Holorusia rubiqi nosa) , has a 

huge, semiaquatic larva that is a 

major food source for birds. 

(3) Mosquitoes (Cucul idae) . Both 

larvae and pupae are aquatic 

(Wirth and Stone, 1956) and 

generally vegetarian (Essig, 

1926). They are ubiquitous in 

ponds and many stillwater situations, 

as we17 as in streams. 

(4) Midges (Chironomidae). Midges in 

all stages of metamorphosis are a 

prime source of food for fish 

(Wirth and Stone. 1956). Larval 

feeding habitats vary; some are 

predaceous, while others feed on 

detritus. There are about 200 

species in California (Powell and 

Hogue, 1979) and, in the familiar 

swarms that occur in spring and 

summer, the number of individuals 

can be astronomical. Chironomids 

have been used as indicators of 

environmental qua1 i ty . 

1.2 Terrestrial Insects 

Terrestrial insects range from tiny 

FS ies, gnats, midges, mosquitoes primitive wingless soil -reducing spring- 

(Diptera). Approximately half of this tails to large highly evolved flying social 

large and diverse order are aquatic in ants. There are probably more species of

eetles than any other order ;n terrestrial 

riparian habitat, which is not surprising 

since Coleoptera is the largest order in 

the animal ki ngdom (Powel 1 and Hogue, 

1979) . 

Certain plants host an astonishing 

variety of insects, both larvae and adults. 

Some of these host/insect re1 at ionships are 

noted below; more complete listings are 

found in indexes of host plants in Essig 

(19261, Tietz (1972), and Emmel and Emmel 

(1973). The more important orders are 

brief1 y described be1 ow. 

a. Springtail s, etc. (Protura, Diplura, 

Col lembol a). These primitive insects 

are almost microscopic. They do not 

undergo metamorphosis; many lack eyes 

and antennae. They are vegetarian and 

their habitat is moist soil, leaf 

litter, and rotting wood. There are 

only a few species of Proturans and 

Diplurans in Cal ifornia, but about 150 

Col 1 embol a ( Powel 1 and Hogue, 1979). 

They are not well studied, but are 

known to be important soil reducers. 

b. Bird l ice (Ma11 ophaga) . These ectoparasites 

feed on hair, feathers, and 

dried blood around wounds on the host. 

They can cause great discomfort and 

even death if the infestation is 

severe. Eggs are deposited on the 

host. Many riparian bird species are 

afflicted by Mallophagans. A list of 

host species is given by Emerson 

(1964). 

c. True bugs (Hemiptera). Three species 

in different famil i es are common plant 

bugs in riparian habitat: western 

boxelder bug (Leptocori s rubrol inea- 

- tus) feeds on the foliage of boxelder 

and maple (Powell and Hogue, 1979); 

giant willow aphid (Tuber01 achnus 

saliqnus) feeds in large, compact 

colonies on the trunks and branches of 

willows (Essig, 1926); and the oak 

treehopper ( Platycot is vi ttata) 

inserts its eggs in twigs on oaks 

throughout Cal i forni a and occasionally 

on other broadleaved trees (Essig, 

1926). 

d. fl ies, gnats, midges, mosqui toes 

(Diptera) . As noted previously, about 

ha1 f the Dipterans have aquatic 

larvae, and adults usually stay close 

to water. Some, such as mosquitoes, 

horsefl i es, and deerfl i es, are severe 

nu1 sances to humans. Several fami 1 ies 

with aquatic larvae whose adults play 

important roles in riparian 

terrestrial ecology are: 

(I) Moth ff ies (Psyrhodidae). The 

lance-winged moth fly, Maruina 

lanceolata, is cornon along 

streams, crawl ing on boulders and 

feeding on diatomaceous and algal 

films on the substrate (Powell and 

Hogue, 1979). 

f 2) Mosquitoes (Cucul idae) . This is 

probably the most thoroughly 

studied family of Di ptera because 

of the diseases transmitted by 

mosquitoes and their general rof e 

as nuisances. Only the females 

bite. There are 47 known species 

in California (Powell and Hogue, 

1979). 

(3) Horse flies, deer flies (Tabanidae). 

There are about 75 species 

in California (Powell and Hogue, 

1979). Most are strong fl iers and 

the females are wicked biters; the 

males are mostly nectar sippers 

(Cole, 1969). Some species are 

suspected of transmitting 

diseases, including tularemia and 

anthrax. The common horse fly in 

Ca1 iforni a is Tabanus ~unctifer; 

the females feed on the blood of 

1 arge mammals but rarely bite man 

(Powel 1 and Hogue, 1979). 

Other Dipterans are riparian without 

being aquatic. Many are associated 

with damp soil and riparian trees such 

as willows and oaks. Eggs are laid in 

moist soil, leaf mold, or under bark, 

and the larvae are general iy 

vegetarian. Some examples are: 

(4) Cranefl ies (Tipul idae) . The 

common craneflies of the genus 

I are active in mo-irt 

wood1 ands and are nectar-feeders, 

The larvae are found in rich, damp 

soil and feed on roots and 

decaying vegetation (Cole, 1969).

(5) March flies (Bibionidae). Larvae 

feed on plant roots and decaying 

vegetation; adults swarm in the 

spring. The adults have an 

affinity for blossoms and may be 

of value as pollinators (Cole, 

1969). 

(6) Pomace fl ies (Drosophil idae) . The 

trail gnat (Amiota ~icta) is a 

small and extremely irritating 

pest to hikers. Adults are found 

near streams and are attracted to 

human eyes. Larvae are unknown 

(Powell and Hogue, 1979). 

e. Moths, butterflies (Lepidoptera). The 

eqqs are laid on or near food, and the 

larvae are largely vegetarian, feeding 

on a wide variety of hosts (Tietz, 

1962). Mature moths and butterflies 

are generally nectar-feeders and are 

prime pollinators for many flowering 

plants. Moths are generally noc- b 

turnal, while butterflies are active 

during the day (Powell and Hogue, 

1979). The 1 arvae are seldom damaging 

to their hosts; the list of caterpillars 

that feed on riparian trees 

and shrubs in Southern California is 

long and includes species from many 

families (Figure 35). Table 7 lists 

characteristic riparian moths and 

their host plants. The host tree 

harbors the larval stage unless otherwise 

noted. Table 8 lists riparian 

butterflies (larvae) and their host 

pl ants. 

Beetles (Coleoptera) . Terrestrial 

riparian beetl es incl ude ground 

dwell ers (Cicindel idae, Carabidae) , 

borers (Cerambycidae, Curcul ionidae) , 

leaf miners (Chrysomel idae), predators 

on other insects (F. Coccinell idae) , 

and many more. Only the briefest 

coverage is possible here. 

(1) Tiger beetles (Cicindel idae) . The 

fast-moving adults inhabit sandy 

or gravelly shores of lakes and 

streams (Essig, 1926). Larvae 

live in burrows in the same 

habitat (Powell and Hogue, 1979). 

The Oregon tiger beetle, Cicindel a 

oreqona, is a common Southern 

California species (Powel 1 and 

Hogue, 1979)- The greenest tiger 

Figure 35. Lorquin's admiral (u brauini) 

larva, pupa, and adult. The larvae feed on willows 

and cottonwoods. Photo courtesy of Charles Hogue. 

beetle, - C. tranauebarica 

viridissima, is being considered 

for 1 isting as an endangered 

species (Zembal , 1984a). It 

inhibits the Santa Ana River 

drainage (C. Nagano, pers. comm). 

(2) Predaceous ground beetl es (Carabi - 

dae) . The eggs of these beetles 

are usually laid on the ground. 

Both 1 arvae and adults are active 

predators, the adults mastly at 

night (Essig, 1926). This is a 

huge and diverse family with 800 

species in California. Tule 

beetles (Auonum spp.) are common

fable 7. Wflotfi~ (lawae) and their riparian host plants (from Powell and Hogue, 1979). 

Common name Scientific name Host tree 

Locust cl earwi ng 

Carpetworm 

Cal i forni a oak moth 

W i 11 ow nestmaker 

Annaphi 1 a 

Yellow-spotted 

tiger moth 

Nevada buck moth 

Eyed sphinx 

Paranthrene robini ae 

- P r i o n ~ ~ robiniae y ~ t ~ ~ 

Phrvsanidia cal ifornica 

Icthvura aoi cal is 

Anna~hila spp. 

Hal isidota maculata 

Hemi 1 euca nevadensi s 

Smeri nthus cerisvi 

Willow, sycamore, cottonwood 

Alder, cottonwood, 1 ive oak, 

map1 e 

Live oak 

Willow 

Willow (adults) 

Wil 1 ow, other broad-leaved 

trees 

Willow 

Willow 

Table 8. Butterflies (larvae) and their riparian host plants (from Emrnel and Ernrnel, 1973). 

Common name Scientific name Host plant or tree 

Western tiger 

swallowtail 

Lorqui n' s admiral 

Satyr angl ewi ng 

California sister 

Mourning cloak 

Sylvan hai rstreak 

Pa~i 1 i o rutul us 

Limentis lorquini 

Polyqoni a satyrus 

Adel a ha bredowi 

Nvmohal is anti o ~ a 

Satvrium svlvinus 

Sycamore, wi 11 ow 

Willow 

Creek nettle 

Urt ica hol osericea 

Live oak 

Willow, alder, cottonwood 

1 anceol at4

in marshy places in Southern 

California; the bombardier beetle, 

Brachinus tscherni khi, inhabits 

rocky margins of lakes and streams 

(Powell and Hogue, 1979), as do 

the fa1 se bombardiers, Chl aenius 

spp. (Hogue, 1974). 

(3) Ladybirds (Coccinell idae) . Both 

larvae and adults of most species 

eat aphids and other scale insects 

and are considered benef ici a1 

(Essig, 1926). The convergent 

l adybird beetle, Hi opodamia 

converaens, is a common species in 

Southern Cal i forni a; great masses 

of these beetles hibernate in 

coastal canyons, then migrate 

downstream to the valleys in early 

spring to feed on aphids (Powell 

and Hogue, 1979). 

(4) Longhorn beetles (Cerambycidae). 

Larvae bore into wood of dead and 

dying trees, and into the roots of 

living trees and shrubs. Adults 

commonly visit flowers (Essig, 

1926). The branded alder borer, 

Rosa1 ia funebris, attacks alder 

and California laurel ; the 

California prionus, Prionus 

cal ifornica, bores into oaks 

(Powell and Hogue, 1979). 

(5) Weevil s (Curcul ionidae) . Both 

larvae and adults are vegetarian 

and are extremely destructive to 

their hosts. Females bore into 

tree trunks, twigs, and flowers to 

lay eggs, and the larvae hatch in 

their food supply. This huge 

family has more than 1,000 species 

in Cal ifornia, attacking many 

plants (Powell and Hogue, 1979). 

In riparian habitat the rose 

curcul io, Rhvnchi tes bicolor, 

commonly infests wild roses and 

blackberries along streams. 

(6) Leaf beet1 es (Chrysomel idae) . 

Both adults and larvae feed on 

leaves and are very destructive to 

their hosts. In riparian habitat 

there are numerous species; some 

general ists, others specialists. 

Members of at least four genera 

(m, Di sonvcha, Gal erncel l a, 

Pachvbrachvs) feed primarily on 

willow 1 eaves; several species 

of Lina have a predel Sction far 

riparian trees, including 

cottonwood, willow, and aspen 

(Essig , 1926). 

f. Ants, wasps, bees (Hymenoptera). 

These highly evolved, often social 

insects are not particularly 

associated with riparian habitat, but 

there are some exceptions. 

(1) Sawflies (Tenthredinidae). Females 

usually cut slits in young 

shoots or leaves and insert their 

eggs; the larvae feed on the 

leaves. In Southern Cal ifornia 

the green willow sawflies, 

Rhoso~aster spp. , are common 

(Powell and Hogue, 1979). Some 

sawflies cause galls, e.g., the 

willow leafgall sawfly, Euura 

pacifica. Larvae of this species 

are parasitized by a braconid wasp 

(Essig, 1926). 

(2) Gall wasps (Cynipidae). The large 

fami 1 iar oak gall is caused by the 

California oak gall wasp, Andricus 

californicus, which is in turn 

parasitized by the oak gall 

chalcid, Torvmus cal ifornicus 

(Powel 1 and Hogue, 1979). 

4.1.3 Role of Insects in Rioarian Ecolosy 

Ecologically, riparian insects are prey, 

predators, pal 1 inators, water purifiers, 

grazers, soi 1 reducers, mosqui to-control 

agents, and more. As a source of food for 

other animals their importance cannot be 

overstated; they feed all classes of vertebrates, 

as we11 as other insects. Birds in 

particular depend on them; the great blooms 

of insects in late spring and summer 

provide food for the migrants that come to 

breed (Pequegnat, 1951), and resident birds 

use this supplemental food source to raise 

their young (Rosenberg et a7. 1982). As 

predators, riparian insects act as 

reguf ators of vegetative growth, a role for 

which they are not usually accorded 

recognition. Qf prime importance is their 

role in pollination. Bees are the best 

known of the pollinators; solitary bees 

(Grigarick, 1968) and bumble bees (Thorp et 

a1 ., 1983) are major pol 1 inators of native 

California flowering plants. The

1 i terature on insect pol 1 ination is large 

but diffuse, and culling information on 

riparian plants is difficult. 

The niche occupied by any insect is 

dictated by its food and reproductive 

requirements, and the two are often 1 inked. 

Eggs are laid where the larvae will feed 

when they hatch. Brucs (1946) distinguished 

four types of insects in terms of 

their food habitat: (1) those that feed on 

1 iving plants, which includes about half 

the known species; (2) predaceous insects 

that consume living animals; (3) 

saprophagous insects whose food is 

dead/decaying animal matter; and (4) 

parasites, both internal and external. 

In occupying these niches, insects play 

a vital role in the ecological balance of 

their habitats. Not only are they actively 

eating, and thus regulating, the plants and 

animals with which they are associated, but 

they are serving as food for others farther 

up the food chain. 

There are no Southern Cal i fornia riparian 

insects listed as endangered or threatened. 

The recent inclusion of the greenest tiger 

beetle in a group to be considered for 

1 isting (Zembal , 1984a) is the first ripple 

in what may become a large wave. This 

beetle is restricted to the Santa Ana River 

basin in Orange, Riverside, and San 

Bernardino Counties where habitat alteration, 

particularly stream channel i zation, 

has sharply reduced its range (C. Nagano, 

pers. comm.). 

The impact of streambed alteration on 

aquatic insects has received 1 ittle 

attention and deserves more. One such 

study on the San Gabriel River showed that 

water beetles were extirpated from the 

cement-1 ined portions of the river and 

could be found only in a few places along 

its course on the coastal plain (Perkins, 

1976). The ecological imp1 ications were 

not discussed and probably not known. 

In summary, both in numbers of species 

and numbers of individuals, insects are the 

major fauna in riparian habitat. They 

occupy every ecological niche and serve as 

both predators (mostly on other insects) 

and prey (for all the vertebrate classes). 

Many are aquatic in one or more of their 

developmental stages; some are totally 

aquatic. Terrestrial insects in riparian 

habitat include soil -dwellers, flowersippers, 

leaf-eaters, bark-borers, bird 

parasites, and others. The 1 ife cycles of 

most species are poorly known, and on1 y the 

most general information is available for 

many famil ies. A monograph on the riparian 

insect fauna would be of great value. 

4.2 FISH 

The streams and lakes of Southern 

California have never supported a very 

diversified fish population. Coastal 

streams have a1 ways been intermittent, 

their flows dependent on good winter 

rainfall. Near the coast the smaller 

streams are often dry for several months of 

the year; as fish habitat, they have never 

been very hospitable. There are eight 

families of native freshwater fish, each 

represented by one or two species. Only 

four species of subspecies are endemic (see 

checklist below); they were found 

originally in the four rivers of the Los 

Angeles and Ventura Basins (Santa Ana, San 

Gabriel, Los Angeles, Santa Clara). 

According to Hubbs, these rivers used to 

interconnect in their headwaters during 

years of high water (Moyle, 1976). The 

following annotated check1 i st covers a1 l of 

the native freshwater f i sh (nomencl ature 

follows American Fisheries Society, 1980). 

4.2.1 Native Fish 

a. Petromyzonidae: lampreys. Pacific 

1 amprey, Lamoretra tridentata. The 

most primitive of its genus, this 

parasitic species is a wide-ranging, 

anadromous fish, found most from 

Monterey north (Moyle, 1976). Despite 

predaceous habits, it does not appear 

to affect populations of other local 

fish (Moyle, 19761, as does the 

introduced 1 amprey, Pteromyzon 

marinus, of the Great Lakes. Formerly 

in the Santa Ana River, it has been 

reported recently only from the Santa 

Clara River in Ventura County fC, 

Swift, Natural History Museum, Los 

Angel es County; pers. comrn, ). 

b. Salmonidae: trout and salmon. 

Rainbow trout, Salrno sairdneri (Figure 

36). This trout is native to coastal 

streams from the hos Angeles River

U E b W -W2- -a -UCDWC 

at o a~ w m c OF wr.- a,r.~.~- 

C, bCX U L m Z--A& N& 

- c m -aLw 

,mL 2 

n o rr- -U&hvr~ ar 

E- rnmm .COLT 

m m J .LOL.C-,~-~ -E L-Fwfi 

t a 3 0 %S rda m aPm 

m.-- o u.L,.- ha c,=e C)L m 

.? .*- > u C > L pTs CCB I C) J 

~ ~ m ~ - ~ a ~ r ~ i i , ~ r n o \ c , i v , 

c, WECX ~=L.u > n m m d m C L . ~ 

- 

I- 

i ' U W 

.- U? i n n 

i 

m -22% 

2 m >r- .&2

Gal ifornia State Universi ty 

j full erton) ; pers, camm. ) . 

(2) Speck1 ed dace, Rhinichthys oscu- 

- lus. This endemic fish is found 

throughout California, but not in 

most coastal streams (MoySe, 

1976). There is a real hiatus in 

its distribution along the coast; 

it is native only to the Santa Ana 

River system and to San Luis Obispo 

Creek (Miller, 1968). This is 

a riffle fish and a bottom browser, 

feeding on small invertebrates 

and plants. It is found mainly in 

cool, fast-moving streams with 

rocky bottoms, but sometimes in 

other types of freshwater habitats 

in the western United States 

(Hubbs et al., 1974). 

d. Catostomatidae: suckers. Santa Ana 

sucker, Catostomus santaanae. A small 

endemic of limited range, it is known 

only from the Los Angeles, San 

Gabriel, and Santa Ana Rivers and from 

the Santa Clara River, where it was 

probably introduced (Miller, 1968). 

A bottom- browser that feeds on small 

invertebrates and plants, it prefers 

clear, cool, rocky and gravelly 

streams with a moderate gradient (Lee 

et a1 ., 1980). The life history of 

this fish was studied by Greenfield 

and co-workers (1970 in the Santa 

Clara River, where it was then 

abundant. 

e. Cyprinodontidae: pupfish, killifish. 

California killifish, Fundulus 

parvi~innis. In shallow coastal 

waters from Monterey to southern Raja 

Gal ifornia, Mexico, these fish are 

still plentiful. Formerly found in 

freshwater streams in Southern 

California, such as San Juan Creek in 

Orange County in the 1940s (Moyle, 

19761, its current status as a 

freshwater fish is uncertain. Recent 

efforts to find a relict population in 

San Juan Creek were unsuccessful (A. 

Schoenherr, pers. comm. ) . 

f. Gasterostidae: sticklebacks. Unarmored 

threespine stickleback, 

Gasterosteus aculeahus will iamsoni 

(Figure 37). This small endemic fish 

was once abundant in the rivers of the 

Los Angeles and Ventura basins 

Figure 37. Unarmored three-spine stickleback 

(G~S&~Q= aculeatus williamsoni), an endangered 

fish of the Southern California coastal streams. 

Photo courtesy of Carnm Swift. 

(Miller, 1960); it is now found only 

only in the Soledad Canyon Section of 

the Santa Clara River and a few of its 

small tributaries. A natural river 

with clear, slow flow is its essential 

habitat; the rivers in the Los Angeles 

basin are no longer suitable. There 

are only four known populations in the 

upper Santa Clara River. It was 

listed in 1970 as an endangered 

species by the USFWS and in 1972 by 

the Cal i forni a Department of Fish and 

Game. There are introduced papuf a- 

tions of the partially armored 

stickleback, a. 2. microcephalus, in 

San Juan Creek in Casper" Park and in 

the San Joaquin Marsh on San Diego 

Creek, and care must be taken to 

prevent hybridization, 

g. Gobi idae: gobies. Tidewater goby, 

f_ucrclosabi us newberry1 . Adapted XQ 

both fresh- and saltwater, the goby's 

habitat is coastal lagoons and the 

1 ower reaches of' streams from Humboldt

County to San Diego County. It is no 

longer found in most coastal streams 

and is scarce in lagoons (C. Swift, 

pers. comm.). Gobies spawn in coarse 

sand on stream bottoms and in lagoons, 

preferring sl ow-movi ng areas of 

streams. Their status is under 

investigation by Swift, and appears to 

be desperate. The tidewater goby is 

a likely candidate for listing as an 

endangered species. 

h. Cottidae: sculpins. 

(1) Pacific staghorn sculpin, 

Le~tocottus armatus, and prickly 

sculpin, Cottus asper. These 

common bottom fishes are found in 

both salt- and freshwater; both 

appear to be adaptable to alterations 

in their environment and are 

not in apparent trouble. The 

staghorn sculpin is distributed 

from Alaska to San Quintin Bay, 

Baja Cal ifornia, and inhabits bays 

and inlets in the southern part of 

its range. It is common in 

freshwater close to the coast 

(Moyle, 1967). The prickly 

sculpin's southern 1 imi t is the 

Ventura River (Lee, 1980); it is 

found well inland in lakes and 

reservoirs as well as streams. 

(2) The striped mullet, Musil 

ce~halus, is a marine species that 

often moves up into the lower 

reaches of streams in Southern 

Ca1 ifornia (Moyle, 1976). Its use 

of freshwater in this area is 

considered casual. 

A minimum of 28 species of non-native 

fish have become established in Southern 

Cal ifornia's coastal streams. Moyle (1976) 

lists eight major reasons for their 

introduction: to improve fishing, to 

provide forage for game fishes, to provide 

bait, to use for insect and weed control, 

as pets, for aquaculture, and by accident. 

Most of the del i berate introductions were 

game and food fish such as bass, bullhead, 

and trout. The impact of these introductions 

is difficult to assess; competition 

between two species for a food supply and 

the elimination of a native species by an 

introduced predator are extreme1 y dd ff icul t 

to document. Introductions have often been 

concurrent with radical alterations of the 

waterways, and mu1 tiple variables have 

compl icated scientific analysis. There is 

one certainty, however: introduced species 

have radically changed the nature OF our 

fish fauna and are now the most abundant 

fishes in most of the State's lnland waters 

(Moyle, 1976). In terms of species, 

introduced fish far outnumber the 10 native 

species in Southern Gal iforni a. In 

addition to the 28 species listed by Moyle 

(1976), there are probably 18 more that are 

we1 l establ i shed in Southern Cal ifornia (A. 

Schoenherr, pers. comm. ). 

The status of native fishes in the 

coastal streams is catastrophic. Qf the 10 

species that once thrived, only the 2 

sculpin are apparently sustaining normal 

populations. The major reason For this 

alarming situation is destruction of 

habitat, Extensive damming and 

channelizing of coastal waterways and 

mining and other silt-producing operations 

have deprived fish, particularly stream 

fish, of most of their habitat. The few 

rivers that are still intact or have intact 

sections should be examined for possible 

re1 ict populations, particularly the Santa 

Margarita River, the upper reaches of the 

San Luis Rey River, and the mountain 

tributaries of the Santa Ana, San Gabriel, 

and Los Angeles Rivers. 

4.3 AMPHIBIANS AND REPTILES 

The characteristic herpetofauna of the 

San Gabriel Mountains was described by 

Schoenherr (1976); the description is 

generally appl icable to the other mountain 

ranges in coastal Southern Cat ifornia. 

Schaenherr delineated nine plant communities, 

and for riparian woodland he 

1 isted the following as obl igate amphibians 

(nomenclature fol laws Coll ins et a1 . , 

1978) : Gal ifornia treefrog, !&& 

cadaverina; red-legged frog, Rana aurora; 

foothi 11 ye1 low-1 egged frog, Rana bovlei ; 

mountain ye1 low-legged frog, muscosg; 

and the introduced bullfrog, Rana 

catesbeiana. The red-legged frog and the 

mountain yellow-legged frog are not widely

distributed; the latter occurs only in the 

San Gabriel Mountains and very locally 

el sewhere in Southern Cal ifornia (Stebbins, 

1966). Species commonly found in both 

riparian and other habitats were the 

Cal ifornia newt, Taricha torosa; ensatina, 

Ensatina eschschol tzi ; Cal i forni a s1 ender 

salamander, Batrachoceos neqriventi s--a 

recently revised taxon (Yanev, 1980) ; 

western toad, Bufo boreas; southwestern 

toad, BufQ microscaphus; Pacific treefrog, 

reeilf a; and western spadefoot, 

Scaphiorus hammondi. 

The obligate reptiles were the western 

pond turtle, Clemmvs marmorata, and the 

western aquatic garter snake, Thamnophi s 

couchi . Nonobl igate reptiles were the 

collared 1 izard, Crotaphvtus coll aris; 

western fence 1 i zard, Sceloporus 

occidental is; sideblotched 1 izard, !.I& 

stansburi ana; western ski nk, Eumeces 

ski1 tonianus; Gilbert's skink, Eumeces 

gil berti ; western whiptail, Cnemidoohorus 

tiqri s; southern a1 1 igator 1 izard, 

Gerrhonotus mu1 ticarinatus; Cal iforni a 

legless 1 izard, Annie] 1 a pul chara; ringneck 

snake, Diadoohus trivirqata; Cal ifornia 

mountain king snake, Lamoro~el tis zonata; 

striped racer, Masticophi s lateral is; 

gopher snake, Pi tuophi s me1 anoleucus; and 

western rattlesnake, Crotalus viridis. 

Many of these species are still fairly 

common; mountain streams have not generally 

been subjected to alterations as severe as 

those affecting valley streams. In the 

lowlands, a few natural river courses still 

support healthy communities of amphibians 

and reptiles, but such habitat is 

exceedingly rare. The Santa Margarita 

River is one such place, and in 1982 the 

following amphibians were found there in 

riparian habitat: Cal ifornia slender 

sal amander, Cal i forni a newt, western toad, 

southwestern toad, Cal iforni a treefrog, 

Pacific treefrog, western spade-foot, redlegged 

frog, and bull frog. Reptiles 

included the western pond turtle, western 

fence lizard, western skink, orangethroated 

whiptail (Cnemidophorus 

hvpervthrus), western whiptail, rosy boa 

(Lichanura trivirqata) , aquatic garter 

snake, western bl ind snake (Le~totvohlops 

humi 1 is), and western rattiesnake (Zemba?, 

1984b). The orange-throated whiptail has 

a restricted range; its northern limits are 

in Southern Orange County (Stebbins, 1966). 

Among the amphibians, the salamanders and 

tree frogs seem to be faring better than 

the true frogs, Salamanders are not 

restricted to the riparian community; they 

are adaptable to woodlands, gardens, and 

other habitats and thus have a range of 

choice. In general, amphibians dependent 

on riparian habitat are disappearing. 

Oddly enough, tree frog populations are 

fairly stable, even though the canyon 

treefrog is considered strictly riparian, 

The red-legged frog is becoming increasingly 

scarce in Santa Barbara County 

(McKeown, 1974), which was probably its 

last lowland stronghold in Southern 

Cal ifornia. Indiscriminate collecting and 

heavy recreational use of streams are 

blamed for its decline, along with habitat 

destruction. It is fully protected (CFG 

Commission Regulations, 1983, Title 14) and 

can be taken only by special permit, The 

foothill yellow-legged frog has 

mysteri ously disappeared from Southern 

Cal i fornia in recent years. Formerly 

widespread and fairly common in the 

Southern Cal ifornia coastal mountains, it 

has not been seen since 1975 despite 

repeated searches (Sweet, 1983). Damage to 

montane stream habitat by overuse, 

particularly from off-road vehicles, 

coupled with the coincidence of two major 

floods in the winter of 1969, are crediied 

with causing the apparent extinction of 

this species (A. Schoenherr and S. Sweet, 

Natural History Museum, Los Angeles County; 

pers. comm.) . 

The most threatened reptile is the 

western pond turtle. At home in streams 

and large rivers as well as lakes and 

ponds, this turtle is also well adapted to 

Southern Ca1 i forni a's summer-dry, winterwet 

Mediterranean cl imate (Bury, 19721, It 

was collected indiscriminately for the pet 

trade and by individuals until State law 

limited taking to two per person (CFG 

Commission Regulations, 1983, Title 14). 

During the 1970s, the turtle's status was 

under investigation by the Cal ifornia 

Department of Fish and Game as a possible 

candidate for listing. Passage of the 

above law has alleviated some of the 

pressure, and the turtle is reportedly 

doing well in Santa Barbara County, 

a1 though there is no information from other 

parts of Southern Cal ifornia.

Two introduced species appear to be 

threatening some of the native species. 

The bullfrog is now widespread in 

California, and its voracious appetite 

includes a taste for other frogs. In Santa 

Barbara County, efforts are being made to 

keep the bullfrog out of the Santa Ynez b. 

River drainage and Cuyama Val ley in order 

to protect the red-legged frog. A more 

recent introduction is the African clawed 

frog, Xenoous laevis which is spreading 

rapidly and is now in all the flood-control 

channels in Los Angeles and Orange counties 

(G. St, Amant, California Department of 

Fish and Game, Region 5, Long Beach; pers. 

comm.). The Fish and Game Department has 

initiated a control program in Agua Duice 

Canyon to keep this voracious predator out 

c. 

of the habitat of the unarmored threespine 

stickleback, an endangered fish. Other 

than that, the frog is not under 

investigation, and its inipacts and the 

extent of its spread are unknown. 

An interesting aspect of the re1 ationship 

between reptiles and riparran habitat is 

the use of stream washes by several 1 izards d- 

to expand their rdnges. The collared 

1 iaard has moved across the divide from the 

desert side to the Pacific slope of the San 

Gabriel Mountains and as 1 ocall y abundant 

in Cajon Wash, iytle Creek, and the upper 

east fork of the San Gabriel River in the 

1970s (Schoenherr, 1976). The zebra-tailed 

1 izard (Call i S ~II~IIS draconoides) , desert 

horned l izard (i)hrynoson\i j11 atyrtiinos) , 

leopard 1 iaard (Crataapwis wisl izenii), 

and coachwhr p (@\__tjroi~h~s_ fl aqel luni) 

appdrently have also moved v;a stredm 

channels in Cajon and Sulcdad canyons and 

are now in the San Jacirlto River drainage 

(Schoenherr, 1976; Stebbins, 1966). 

Ihe following annotated list covers only 

amphibians and rept i 1 os that are dependent 

upon, or prefer-, riparian habitat: 

a. Cal ifornia newt, Taricha torosa. 

Common in pools and slow-moving 

streams fron: !\car sea level to 2000 

meters (Stebbins, 19661, the 

Cal i forn i a newt is general 7 y 

restricted to the low parts of f. 

streams, even though ?urier r eaches ai-e 

often dry in summer, since high 

streams are too steep and fast 

(Pequegnat, 1951). It has been 

collected in oak woodland in the $an 

Gabriel Mountains as well as in 

streamside habitat. There is no 

indication that populations are in any 

stress (Schoenherr, 1976). 

Ensatina, Ensatina eschschol tzi . 

Ensatinas are found in a variety of 

habitats in the San Gabriel Mountains 

and appear well adapted to oak 

woodland and chappara1 as we71 as to 

riparian habitat (Schoenherr, 1976). 

Uncornmon in the Santa Ana Mountains 

(Pequegnat, 1951), they have been 

recorded from only a few locations in 

San Di ego County (Sf oan, 1964). 

Cal i forni a slender salamander, 

- Ratrachoceos mriventis. Common to 

abundant throughout coastal Southern 

California, this salamander is 

moisture-loving and is found in leaf 

1 i tter, under rocks, along streams, in 

oak woodland, and has adapted well to 

gardens (McKeown, 1974). 

Arboreal sal amander, Anei des I usubri s . 

Also called the oak salamander because 

of its affinity for oak woodland, the 

arboreal salamander is widespread 

throughout coastal Southern Ca? ifornia 

wherever there is appropriate habitat. 

It has been reported as locally common 

(Pequegnat, 1951; Schoenherr, 1976) 

except in San Diego County, where it 

was not easily found (Sloan, 1964). 

ea 

California canyon treefrog, 

cadavarina (Figure 38). Found in the 

San Gabriel Mountains, the Cal ifornia 

treefrog is restricted to riparian 

habitat and is most abundant in fast 

streams from 460 to 1,000 m 

(Schoenherr 1976). In the Santa Ana 

Mountains its lower limit is about 

where the streams dry up in summer 

(Pequegnat, 1951). ft has been 

reported as moderately common to 

abundant except in San Diego County, 

where it was uncommon even in typical 

habitat (Sl oan, 1964). 

Pacific treefrog, resi? 1 a. 

Usual?y considered the most abundant 

anuran in coastal Southern Cal ifornia, 

Pacific treefrog is found near almost 

every pool of standing water in the

tions. Its preferred habitat is fastflowing 

montane streams. While 

abundant in the San Gabriel Mountains 

in the 1950s (Schoenherr, 19761, its 

present status is not know. 

i. Foothill yellow-legged frog, Rana 

boulei. This frog is found at lower 

elevations than the mountain species 

and prefers slower moving water and 

wide pools (Schoenherr, 1976). It has 

not been sighted since 1975 and may be 

extinct in Southern Cal ifornia. 

Figure 38. A mating pair of California tree frogs 

w!lit ) on a stream gravel bank. 

Photagraph courtesy of Alan Schoenherr. 

San Gabriel Mountains (Schoenherr, 

1976). Unlike the canyon treefrog, it 

also occurs in many other habitats. 

It prefers slow streams and inhabits 

a wide range of elevations (Sloan, 

1964). 

g. Red-legged frog, Rana aurora. This 

frog is an inhabitant of permanent 

pool s, ponds, and marshes (Schoenherr, 

1976). Formerly widely distributed, 

it has become scarce and 1 ocal . Full y 

protected by the California Department 

of Fish and Game, it cannot be taken 

without a special permit. The 

bullfrog is a major predator on young 

red-legged frogs just emerging from 

the tadpole stage. It is still found 

in fair numbers locally along the 

Santa Margarita River (Zembal, 1984). 

Mountain yellow-legged frog, 

muscosa. This is one of two species 

of yellow-legged frogs in the mountains 

of Southern California, both of 

which have been collected in the same 

local i ty a1 ong the Worth Fork ~f the 

San Gabriel River in the San Gabriel 

Mountains. The mountain yellow-legged 

frog is found usually at higher eleva- 

j. Bull frog, Rana catesbeiana. An 

introduced pond-dwell ing species, the 

bullfrog has spread throughout coastal 

Southern California, except in the 

Santa Ynez River watershed. It has 

also been collected in streams 

(Schoenherr, 1976). Because it is a 

voracious predator, there is concern 

that is threatening the red-legged 

frog (S. Sweet, pers. comm.). 

k. African clawed frog, Xeno~is laevis. 

This is a recently introduced species 

that could spell disaster for some 

native amphibians, fish, and insects. 

Little is known about this frog except 

that it is spreading rapidly and has 

a voracious appetite. A study of its 

present distribution and impacts on 

native amphibians is urgently needed. 

1.Western pond turtle, Clemmvs 

marmorata. Found from British 

Columbia to Baja California, Mexico, 

mostly on the west side of the 

Cascade-Sierra crest to 2,400 m 

(Stebbins, 1966), this is the only 

turtle native to Southern California. 

Formerly abundant, it has declined in 

numbers as a result of habitat 

destruction and indiscriminate 

collecting. It is now protected by 

the Department of Fish and Game. 

m. Western aquatic garter snake, 

Thamno~his couchi, This is a riparian 

snake that appears to prefer slowmoving 

parts of streams where pools 

form (Schoenherr, 1976), A livebearer, 

it is found from sea level to 

the high mountains and feeds on fish 

and their eggs, frogs, toads, tadpoles, 

salamanders, earthworms, and

leeches (Stebbins, 1966). Uncommon in 

5anta Barbara Caunty (McKeown, 19741, 

It was not found in a recent survey of 

the coastal streams in Goleta (Onuf, 

1983). It was found regularly along 

the Santa Hargarita River in 1982 

(Zembal, 1984b) where riparian habitat 

is still in near-pristine conditions. 

Like ather riparian-dependent vertebrates, 

it may be in trouble and its 

status should be investigated. 

In surnariary, only a few species of amphibians 

and reptiles in Southern California 

are riparian dependent. These include the 

California treefrog, red-legged frog, 

foothill yellow-legged frog, mountain 

ye1 low-legged frog, and western pond 

turtle. Many nrsre use riparian habitat but 

are also Found in other habitats. The 

ubl igate riparian species in general have 

suffered serious popul at ion dccl ines, and 

carre, the foothill ytlllow*legged frog, is 

grtlbabty extinct. The combined effects of 

hahi tat destrtrctlon (danrming, channel izing, 

and cementing s treatrtb~ds f , in troduet ion of 

exutfc species, degradation of habitat by 

improper recreational use, and natural 

catcr~trwphes such as inajor flouds have all 

been dcvaslatjng. The introduced bullfrog 

and African clawcd Frog are expanding their 

ranges at the expense of native anurans. 

lo prc?vent ftrrther loss, coastal streams 

that still have naturqnl scgmcrits should be 

praaservc*d ~mnd pr-otcc ted, iind corrtrot of 

orrt t-oditccc! spec ies should Re top priority. 

ltre sn?f~plex subject of ripdrian btrds can 

bi: difdrcssrrl try dncilyzing types of use 

(br.et?d tnc~ 3rd nunbrcotfinij) ; seasonal i ty 

[blnlrr iny birds, fillgrants, summer visi - 

tctrar;, re%ttlc>rtt S ); or re1 at ive abundance 

f rtr~irnori to rdre spec ips) . tlerc th~ aai faurid 

arc2 drvidtlcl trltu brcctling and nonbrcedrng 

q~c~c~ub, attd other relovant topics arc 

d9:cusied rn relatron to 4h1s dichotomy. 

In tryrng to r.fraw the 1 illtits of riparian 

Rabi tat for birds in Southern California, 

It 1s nut posbibte Lo adhere to the strict 

definition gfven by the hford m1& 

QL$Lj99n_arv, 1.e. 'kuf, pertaining to, or 

?i:ling at? the bank of a river." Ponds, 

lakes, fi~arskes, and wet montane rneadows are 

a? l intinrately assnciat ed with streams in 

Southern Caf ifornia, and birds do not 

acknowledge boundaries, Riparian habitat 

thus has been divided into two major 

categories: streams and other types of 

freshwater communities. There is abundant 

overlap; many streamside birds also use 

marshes, wet meadows, and other freshwater 

habitats. 

4.4.1 Breedf nq Birds 

A checklist of the breeding birds, 

compiled from seven recent sources, is 

provided in Appendix A. Included are a1 l 

species that have been documented as 

nesting in riparian habitat, whether or not 

they nest in other habitats as well. There 

are 140 species 1 isted; 88 are riparian in 

the strict sense (nesting along valley and/ 

or four montane streams); 23 nest along 

streams but also on ponds, lakes, marshes, 

and/or wet meadows; and 29 are not 

associated with streams but breed in other 

freshwater habitats. The degree of 

dependency on riparian habitat is noted for 

each species in column three; it 

encompasses obl igate nesters, preferential 

nesters, birds that nest in many habitats 

including riparian, and occasional nesters. 

Miller (1951) rated the birds of California 

by nesting-habi tat preference, recognizing 

21 habitat types (including riparian 

woodl and, freshwater marsh, etc .). For 

each species he listed all of the habitats 

where nesting had been documented, in order 

of preference. For some species there was 

only one listing; for others there were up 

to 12. Although the presentation here is 

different, there is no confl ict between the 

data in the appended table and Miller's 

findings. Scientific nomenclature in the 

checklist follows the American 

Ornithologists Union Check1 ist (1983). 

4.4.2 Qistribution of Breedina Birds 

Most breeding species are not limited by 

latit~de and can be found throughout the 

Southern Cat i farnia coastal region. 

Exceptions are the wood duck (Aix suonsa), 

which breeds only on the Santa Ynez River 

and occasionally in the Santa Monica 

Mountains; 

the chestnut-backed chickadee 

(Parus rufescens) and ye1 low-bi l led magpie 

(U nut tall i i ) , whose southern 1 imi t is 

Lhc fehachapi Hountatnst and the common 

ground-dove (Col umbina ~asserina) , which is 

not found north of Orange County (Garrett 

and Dunn, 1981).

Altltudinal limjtations are much more 

significant, as can be seen in Appendix A. 

Val ley riparian habitat hosts 66 species of 

passerines, 29 of which are restricted to 

valley streams; the rest can nest from sea 

level to at least 2,800 m. Seven montane 

species are not found below 1,300 m 

{Grinnell and Miller, 1944). 

The topography of the habitat is a major 

underlying factor in bird distribution, as 

it dictates the amount and type of vegetation, 

and thus nesting habitat. Broad, 

sl ow-movi ng vall ey rivers deposit 1 arge 

belts of sediment that support a rich and 

dense flora. The density and diversity of 

bird species along such watercourses (which 

are now relict in Southern California) are 

very great compared to that along mountain 

streams. Narrow gorges, steep grades, and 

fast flows characteristic of mountain 

streams prevent the deposition of sediment 

and thus 1 imi t the establ i shment of plants. 

Where the 1 and flattens, whatever the 

a1 ti tude, wet meadows, ci enegas, and even 

ponds develop, and the resul ting vegetation 

provides nesting habitat. 

4.4.3 The Breedinq Season 

The great wave of nesting takes place 

from May through July, when migrants 

returning from Central and South America 

join the resident birds, many of which have 

already been breeding for several months. 

The breeding cycles of resident birds in 

lowland riparian habitat are more attuned 

to the wet/dry cycle in Southern California 

than to such factors as photoperiod, temperature, 

or flowering, which trigger the 

migrants. Harrison (1979) gives beginning 

dates for nesting as early as December for 

Anna's hummingbird (Calwte u) and Cali - 

fornia thrasher (Toxostoma redivivum), 

February for common bushti t (Psal triparus 

minimus) and Hutton's vireo (Vireo hutm), 

and March for Nuttall's woodpecker 

(Pi coides nuttall i i) , hairy woodpecker 

(Picoides villosus), plain titmouse (Parus 

inornatus) , and red-winged blackbird 

(Aqelaius hoen nice us). The record for the 

longest nesting season probably goes to the 

resident subspecies of Allen's hummingbird, 

which has bred on Palos Verdes Peninsula in 

Los Angeles County every month except 

September and October (Wells and Baptista, 

1979). Resident species that nest at high 

elevations, such as red-breasted sapsucker 

) and Cassin's finch 

(Car~odacus cassinii), follow a more 

restricted seasonal schedule similar to the 

migrants. 

4.4.4 Needs of Breedins Birds 

Riparian birds nest in living and dead 

trees, shrubs, reeds, grasses, rocky 

cliffs, soft banks, and rock ledges in 

streams and behind waterfalls. They also 

build floating nests on still waters. 

Throughout the a1 ti tudinal range covered 

by coastal streams, wi 1 lows (particularly 

willow thickets) are used for nesting. 

Val 1 ey species that prefer wi 11 ows i ncl ude 

the ye1 low-bi 1 led cuckoo (Coccvzus 

americanur) , will ow flycatcher (&gtraillii), 

Bell's vireo (Vireo bellit), and 

blue grosbeak (Guiraca caeruleg) . These 

species nest in the same type of habitat in 

the Sacramento Valley (Gaines, 1977). At 

higher altitudes, MacGillivrayfs warbler 

(O~ororni s tolmiei) and bl ack-headed 

grosbeak (Pheucticus me1 anoceohal ug) are 

closely associated with willows. 

Oaks, which are often a component of the 

riparian tree community in the foothills, 

are preferred (and often essential) trees 

for the band-tailed pigeon (Col umbq 

fasciata), spotted owl {strix 

occidental i s) , saw-whet owl (Aesol ius 

acadi cus) , acorn woodpecker (Me1 aneraes 

formicivorus) , plain titmouse, Hutton's 

vireo, phainopepl a (Phaino~e~la ni tens), 

and dark-eyed junco (Junco jwemal i s) 

(Verner, 1979). 

Dead trees and snags of sycamores, 

wi 1 lows, cottonwoods, oaks, and alders 

provide essenti a1 habitat for a large 

number of cavity nesters. All of the 

woodpeckers are in this group, plus such 

diverse species as the wood duck, American 

kestrel (Fa1 co s~arveri us f , several species 

of owl, ash-throated flycatcher (Mviarchus 

ci nerascens) , purple mart in (Prome subi s) , 

house wren (Troof odvtes aedon) , and 

European star1 ing (Sturnus vulaari~) 

(Grinnell and Miller, 1344). 

Several species, such as the belted 

kingfisher (Cerv1 e a1 cvon) , rough-winged 

swallow (Stels4doptervx serrioennis), and 

bank swal law (Rirsaria rjparla), burrow into 

soft banks along streams to make nest

Twenty-three species described as common 

or fairly common before 1940 are now much 

reduced in numbers: American bittern, 

least bittern (Ixobrvchus exi 1 i s) , great 

blue heron, snowy egret, great egret, 

whitefaced ibis (Pleqadis chihi), Cooper's 

hawk (Acciaiter coooeri i) , Virginia rail, 

sora, American avocet, barn owl, screech 

owl, hairy woodpecker, wi1 low flycatcher, 

purple martin, bank swall ow, western 

bluebird (Si a1 i a mexi cana) , 1 oggerhead 

shrike (Lanius 1 udovici anus), yellow 

warbler, Wilson's warbler (Wil sonia 

pusilla), yellow-breasted chat (Icteria 

vi rens) , blue grosbeak, and Lazul i bunting 

(Passerina amoena). Six species that were 

already showing population reductions by 

the 1930s have continued to decline: 

northern harrier (Circus cvaneus) , redshouldered 

hawk (Buteo 1 ineatus), yellowbilled 

cuckoo, be1 ted kingfisher, least 

Bell's vireo, and ye1 low-headed blackbird 

(Xanthocenkal us xanthoceohalus) . The black 

rail (Laterallus lamaicensis), now a rare 

breeding bird in Southern California, is so 

secretive that its status in the past is 

uncertain; it may never have been more 

abundant (Wilbur, 1974). A few species 

apparently have increased in numbers; they 

are birds that adapt well to urbanization: 

American kestrel , American crow (Corvus 

brachvrh~nchos), northern mockingbird, and 

house finch (Car~odacus mexicanus). 

4.4.8 Soecies of Special Concern 

Riparian-associated species considered 

endangered, rare, sensitive, or of speci a1 

concern by the California Department of 

Fish and Game (1980), the USFWS (1982, 

1983), or the National Audubon Society 

(NAS) (Tate and Tate 1982) are shown in 

Table 9. Some of the species listed by 

NAS, such as Bewick's wren (Thryomanes 

Table 9. Endangered, rare, and sensitive bird species in Southern California. 

Species 

CDFG USFWS NAS 

E R S E S BL SC 

American bittern 

Least bittern 

White-faced ibis 

Northern harrier 

Cooper's hawk 

Red-shouldered hawk 

Black rail 

Ye1 low-bil led cuckoo 

Long-eared owl 

Hairy woodpecker 

Will ow flycatcher 

Purple martin 

Western bluebird 

loggerhead shrike 

least Bell's vireo 

Ye1 low warbl er 

Ye1 low-breasted chat 

CDFG = Ca1 ifornia Department of Fish and Game, 1980; Remsen, 

1979 

USFWS = U.S. Fish and Wildlife Service, 1980, 1982 

HAS = Rational Audubon Society, Tate and Tate, 1982 

E = Endangered Species, R = Rare, S = Sensitive, 

BL = Blue List, SC = Special Concern

ewicki i) , are considered scarce in various 

parts of their ranges, althaugh not in 

Southern California; they have not been 

included here. Eight species appear on 

more than one list, and the willow flycatcher 

is 1 isted by a1 l three compilers. 

There are others not yet listed but 

acknowledged as becoming scarce in Southern 

Cal i forni a: bl ue-grey gnatcatcher 

(Pol iootila caerulea) and warbl ing vireo 

(Vireo Q~~VUS) are almost extirpated as 

breeders in San Diego County (Unitt, 1984); 

blue grosbeak, Lazul i bunting, and Wilson's 

warbler are now uncommon breeders in the 

1 owl ands; be1 ted ki ngf i sher and ye1 lowheaded 

blackbird are now extremely rare 

breeders in coastal Southern Cal i fornia, 

and bank swall ow has virtually disappeared 

(Garrett and Dunn, 1981). 

The following birds appear to be of most 

concern in Southern California; they are 

listed in order of the American 

Ornithologists Union Check1 ist (1983), not 

necessarily in order of priority of 

concern. Some species listed in Table 9 

are not included because they are doing 

well in Southern California or have always 

been scarce. Unless otherwise stated, 

documentation is from the same sources 

listed in 4.4.7. 

a. Cooper's hawk, Acci~iter coogerii. 

Cooper's hawk nests preferenti a1 ly in 

riparian habitat from sea level to 

about 2,600 m, most often in live oaks 

and sycamores, but more often in the 

lowlands. The major reason for its 

decline is habitat loss. 

b. Ye1 low-bil led cuckoo, Coccvzus 

americanus. Nesting only in valley 

riparian habitat, the yellow-billed 

cuckoo prefers old-growth willows and 

cottonwoods with a dense understory of 

blackberry and grape. It is almost 

extirpated as a breeding bird in 

coastal Southern California, the only 

recent record being on the Santa Ana 

River in 1983. Loss of habitat is 

considered the major reason for 

decline, but other factors such as 

pesticides may a1 so be involved 

(Gaines, 1977). 

c. tong-eared owl, Asio otus. The longeared 

owl breeds only in valley 

riparian habitat, preferring tall 

wil lows, cottonwoods, and l ive oaks. 

Already declining in the 1930s and now 

extremely rare, it has been found 

recently in small numbers along the 

Santa Margarita River, Santa Ana 

River, and on Starr Ranch Audubon 

Sanctuary. In San Uiego County it has 

been documented recently only in the 

desert. Loss of habitat is the major 

reason for its decline. 

d. Be1 ted kingfisher, Cer~le alcvon. The 

be1 ted kingfisher nests in burrows 

excavated in earthern banks along 

streams or lakes. By 1940, already 

reduced in numbers, it was targeted by 

fishermen as "vermin" and shot 

regul arly (6rinnel and Miller, 1944). 

The only recent records for San Diego 

County show two nesting pairs on the 

Santa Margarita River in 1982-83. 

This bird is not on any list. Its 

present rarity is presumably due to 

lack of suitable nesting habitat. A 

survey of the breeding population 

should be done to ascertain status. 

e. Hairy woodpecker, Picoides villosus. 

This woodpecker nests in montane 

forests where there are dead trees or 

limbs for nest holes; in foothill 

canyons in the lowlands it nests in 

riparian trees. Considered common and 

sometimes abundant formerly, it is 

still fairly common in the mountains, 

but much reduced at lower elevations. 

Destruction of low1 and riparian 

habitat is the prime cause of decline 

(Yeager, 1955). 

f. Willow flycatcher, Empidonax traillii 

(Figure 39). Nesting only in willow 

thickets along valley streams and 

mountain canyons, the willow flycatcher 

was formerly common where 

conditions were suitable; it is now 

extremely rare in Southern Cal ifsrnia. 

The presence of a few singing males on 

the Santa Margarita River, Sun Luis 

Rey River, and several other locales 

in San Diego County in 1982 and one an 

the Santa Ana River in 1983 indicate 

that there are still a few pairs 6n 

the lowlands. There is no information 

for the mountains, A combination af 

habitat loss and parasitism by the

cn' - 

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endangered status (Figure 40). In May 

1986 it was added to the Federal 

endangered species fist (51FR 15474). 

Marbling vireo, Vireo qili~us. This 

vireo nests in deciduous trees Sn 

riparian habitat; it was said by 

Grinnell and Milier (1944) to be 

dependent on the trees rather than on 

the proximity of water. It was common 

in valley and montane riparian habitat 

up to 3,400 m, but the effects of 

cowbird parasitism were a1 ready 

evident in the early 1940s. Now it is 

uncommon in valley riparian habitat 

and nearly exterminated in San Diego 

County, with only a few pairs still 

breeding on the Santa Margarita and 

San Luis Rey Rivers. It still breeds 

in coastal Santa Barbara County in 

1 imited numbers (13 pairs were found 

on San Jose Creek in 1983). It may be 

Faring better in the mountains, but 

its status needs investigation. It is 

not yet on any list; its decline is 

probably due chiefly to parasitism by 

cowbirds and 1 oss of habitat. 

me Yellow warbler, Dendroica petechia. 

This warbler nests in deciduous trees 

and shrubs in riparian habitat in the 

lowland valleys and up to about 

2,800 m. It was common and even 

locally abundant in the 1940s; it has 

decl i ned considerably in the 1 owl ands, 

a1 though pockets of breeding birds are 

still present in Santa Barbara County, 

along the Santa Ana River in Riverside 

County, and along the Santa Margarita 

and San Luis Rey Rivers and probably 

several others in San Diego County. 

Its status in the mountains is not 

known. Cowbird parasi ti sm and loss of 

habitat are major factors in its 

decl i ne. 

n. Wilson's warbler, Wilsonia pus.tlla. 

This bl ack-capped warbler nests close 

to the ground in willow thickets and 

dense shrubs along streams, favoring 

the humid coastal belt and high, wet 

montane meadows. It is now an uncommon 

breeder in both habitats. A 

few may still nest along the Santa 

Ynez River. It is not on any list. 

Cowbird parasi ti sm and 1 oss of habitat 

are the major problems. 

Figure 40. Least Bell's vire~ (Vireo bellii pusilfus), 

recently listed as an endangered species, suffers 

from habitat loss and cowbird nest parasitism. it is 

shown here feeding a brawn-headed cowbird. 

Drawing by Cameron Barraws. 

o. Yellow-breasted chat, Icteria virens. 

Nests are placed in low, dense 

riparian growth, particularly willow 

thickets and tangles of blackberries 

and grapes in lowland valleys and 

foothill canyons. Formerly fairly 

common, it is now an uncommon and 

1 ocal breeder in smal l numbers a1 ong 

the Santa Ynez and Santa Ana Rivers. 

Loss of riparian habitat is the majar 

reason for its decline; cowbird 

parasitism may be involved and should 

be investigated. 

p. Blue grosbeak, Guiraca caerulea. The 

blue grosbeak nests in low, thick 

riparian vegetation in the valleys and 

foothills to about 1,600 rn. It was 

once f air1 y common m here appropriate 

habitat occurred but is now reduced in

numbers. The greatest concentration 

reported recently was about 25 pairs 

on the Santa Ana River. It is rare 

and localized in coastal Santa Barbara 

and San Qiego Counties. It is not on 

any list. Causes of its decline 

include loss of habitat and perhaps 

cowbird parasitism. Its status needs 

investigation. 

q. Lazul i bunting, Passerina amoena. 

This songster breeds along watercourses, 

usually in adjacent 

vegetation on drier ground, from sea 

level to at least 3,000 m. It was 

common and is still fairly common 

locally in the lowlands in Santa 

Barbara County and along the Santa Ana 

and Santa Margarita Rivers, but its 

status is not well known. It is 

probably still doing well in the 

mountains. It is not on any list. 

Several species that breed preferenti a1 ly 

in freshwater marshes have declined sharply 

in numbers since the 1940s. The Virginia 

rail, sora, American bittern, and least 

bittern are rarely found breeding now. 

These birds, like the black rail, are 

secretive and hard to count, but used to be 

common enough to be reported regularly. 

The ye? 1 ow-headed bl ackbi rd, never common 

in Southern Cal i fornia, was a1 ready reduced 

in numbers in the 1940s. There has been no 

recent documentation of nesting, and it may 

be extirpated as a breeding bird in coastal 

Southern Cal i forni a. 

4.4.9 Exoandinq Species 

Four species that have expanded their 

ranges into Southern California (as opposed 

to introduced species) are of concern 

because of their impact or potential impact 

on native birds: 

a. Cattle egret, Bubulcus a. First 

recorded in California in 1964 at 

Imperial Beach, San Diego County, this 

adaptable heron has spread widely and 

is now common in coastal Southern 

Cal ifornia, including Santa Barbara 

County. The first documented nesting 

was at the Saltan Sea in 1970; 5 t f s 

now the most abundant heron there and 

has largely displaced the snowy egret. 

It has nested recently in brackish 

lagoons and freshwater marshes in 

coastal San Diego and Riverside 

Counties and is still expanding its 

range northward. 

b. European star1 ing, Sturnus vulqari s. 

Now an abundant bird in Southern 

California, the European starling 

first appeared in the late 1940s. A 

cavity-nester and an aggressive, 

social species, it often breeds in 

vall ey riparian woodl and, usurping the 

nest holes of other birds. Although 

it has often been stated that the 

starling is causing the decline of 

other species such as the common 

flicker and purple martin, there are 

no data to confirm this assumption. 

Troeschler (1976) studied the impact 

of starlings on a community of acorn 

woodpeckers and found that, a1 though 

the starlings usurped their holes, the 

woodpeckers excavated new ones and 

their population remained stable over 

the 6-year study period. 

Troeschl er 

also reviewed the l iterature and could 

find no documentation of the decline 

of a species attributable to 

star1 ings. 

c . Brown- headed cowbird, Mol othrus ater . 

The cowbird was not IistedTs 

occurring in Los Angeles County in 

1898 (Grinnell, 1898) but was we11 

establ ished by 1933 (Millet, 1933). 

Its rapid range expansion and 

exploding population in Cal ifornia in 

this century are associated with the 

spread of agri cul ture and cattle 

grazing. It is a brood parasite that 

lays its eggs in the nests of other 

birds, particularly small passerines. 

The host species incubates the eggs 

and then feeds the young at the 

expense of its own progeny. It is 

strongly imp1 icated in the decline of 

the least Bell 's vireo (Goldwasser, 

1980); indeed, the first published 

acc~unt of cowbird breeding in San 

Diego County was a case of parasitism 

of the Bell's vireo (Unitt, 1984). 

The cowbird also parasitizes the 

willow flycatcher, warbling vireo, 

bl ue-gray gnatcatcher, yellow warbler, 

and Wi 1 son ' s warbl er in 1 owl and 

riparian habitat. As of 1977, cowbird 

eggs had been found in the nests of 

216 species, including some unl i kely 

hosts that do not feed their young,

such as the spotted sandpiper and 

killdeer (Friedman et a 1977)- 

Recent accounts of cowbird activity in 

the Sierra Nevada document its 

ubiquity in the high mountains, where 

it parasitizes at least 22 species of 

small passerines (Rothstein, 1980) and 

is implicated in the decline of the 

warbl i ng vireo (Verner and Ri tter, 

1983). Cowbird control has been 

advocated by several investigators 

(Goldwasser, 1980; Sal ata, 1983), 

particularly where remaining small 

populations of the least Be1 1's vireo 

are threatened. 

d. Great-tailed grackle, Oui scalus 

mexicanus. A newcomer to coastal 

Southern Cal i forni a, the great-tailed 

grackle was first found nesting in 

riparian habitat in sizable numbers 

along the Santa Ana River in 1983. 

The grackle population has increased 

in size and expanded its range in 

interior southeastern Cal i forni a since 

the first record of its appearance in 

1964. Associated with farming and 

ranching, it is 1 ikely to become a 

common resident, as have the cowbird 

and starling. Its impact on native 

birds remains to be seen. 

4.5 NONBREEDING BIRDS 

Great waves of migrants, mostly 

passerines, move through Southern 

California's riparian areas in spring and 

fall. They are transients, but the habitat 

is nevertheless critical for their needs; 

food and rest stops are an essential 

feature of successful migration. Yearround 

nonbreeding users compose a small 

group, foraging in riparian habitat but 

breeding in grassland, pine forest, or 

other nearby habitat. This group includes 

such species as the introduced ring-necked 

pheasant (Phasianus colchicus), mountain 

chickadee (Parus gambel i), and pine siskin 

(Carduelis pinus). A few species are 

present only in summer as visitors, such as 

the California least tern (Sterna 

antillarum) and lesser nighthawk 

(Chordeiles acutipennis), which feed in or 

over lakes and marshes while breeding 

elsewhere in the region. It may seem odd 

to list the California least tern as a 

freshwater forager, but there is amp1 e 

documentation for this statement (Lehman, 

1982; Atwood and Minsky, 1983). 

Wintering birds are major users of 

riparian habitat (see 4.5.1); these are 

migratory birds that stay through the 

winter in Southern Cal iforni a, as opposed 

to migrants that continue south to winter 

in the tropics. The winter population 

includes also those breeding birds that are 

residents. 

4.5.1 Winter Bird Use 

Avian use of valley riparian habitat in 

the upper Santa Ana River wash was well 

documented earl ier in the century by Ingles 

(1929). He found 43 species in a 6-month 

period between October and April. For 33 

of them, riparian was the preferred habitat 

among the four plant communities investi - 

gated. All but three were residents; the 

three wintering species were ruby-crowned 

kinglet (Resul us calendula), ye1 1 ow-rumped 

warbler (Dendrocia coronata), and whitecrowned 

sparrow (Zonotrichia Ieuco~hrvs) . 

The most abundant species were lesser 

go1 df i nch (Carduel is ~sal tri a) and bushti t 

(Psal trioarus minimus). 

Since 1975 there have been many winter 

bird population studies in valley and 

foothill riparian habitats in coastal 

Southern Cal i forni a. Areas covered include 

creeks, lakes, marshes, and rivers in Santa 

Barbara, Los Angeles, Orange, Riverside, 

and San Diego Counties. 

Appendix B lists species from 25 winter 

bird counts reported in American Birds 

between 1975 and 1984. Eight of these 

winter bird counts were done on the Santa 

Margarita River in San Diego County in 1982 

(American Birds, 38(1) :46-51). They give 

the most comprehensive data on current 

winter bird use because they were all done 

along one 12-mi stretch of the river. 

Ninety-four species were detected, 

including a71 of those seen by Ingles in 

1929. In order of abundance the 15 most 

common were: song sparrow (Me1 as~i za 

me1 odi a), ye1 low-rumped warbler, bushtit, 

1 esser go1 dfinch, common ye1 lowthroat 

(Geothl v ~i s trichas) , ruby-crowned Kinglet, 

Bewick's wren, rufous-sided towhee (Pioflo 

ervthroahthal mus) , American goldfinch 

(Carduel is tri stusj, house finch (Car~oda- 

- cus mexicanus), wrenti t (Chamaea fascf ata),

ed-winged blackbird, plain titmouse (Parus 

inornatus), white-crowned sparrow, and 

Hutton's vireo. A17 but three fyellowrumped 

warbler, ruby-crowned kinglet, 

white-crowned sparrow) were residents. 

Song sparrow and ye1 1 ow-rumped warbl er were 

the most abundant; each was more than twice 

as numerous as the next most abundant bird 

on the list. Nine species were among the 

top fifteen in both the Ingles (1929) study 

and the 1984 Santa Margarita study: 

bushti t, Bewick's wren, ye1 low-rumped 

warbler, rufous-sided towhee, brown towhee 

(Pi~ilo scus) , song sparrow, whitecrowned 

sparrow, house finch, and lesser 

goldfinch. 

Montane riparian habitat has been 

neglected in winter bird censuses; there 

are no published studies of current winter 

bird use. 

4.5.2 Taxonomic Aspects of the Riparjan 

Bird Community 

The importance of riparian habitat for 

birds is discussed in Chapter 5; however, 

it is interesting to note that birds 

breeding in riparian habitat in coastal 

Southern Gal i fornia belong to fourteen 

different orders. Table 'aC lists them 

phyl ogenet i call y (AOU, 1983) and shows 

species preferences within the riparian 

habitat (the tree/shrub community along the 

streams or the more open lake/rnarsh/wet 

meadow habitat). Three general izations can 

be made from examination of the list. 

First, passerines (Passeri formes) are the 

dominant order, comprising 54 percent of 

the avian species that breed in Southern 

Cal ifornia's coastal riparian habitat. 

Second, birds that nest in marshes, 

lakes, and wet meadows are predominantly 

estuarine birds (grebes, herons, rails, 

waterfowl, shorebirds) that have moved 

in1 and to use freshwater habitats similar 

to coastal lagoons and marshes. Many are 

large and not particularly aerial; they 

tend to nest on the ground or on water and 

find their food in the water or in soil 

associated with water. 

Table 70. Avian species breeding in riparian habitat In Southern California (listed 

by order). 

Order 

Habi tat2 

Stream Marsh Both Total 

Podicipedi formes (grebes) 

Ciconiifarmes (herons) 

Anseri formes (swans, geese, ducks f 

Fa1 coni formes (hawks, fa1 cons) 

Gal 1 i formes (quai 1, grouse) 

Grui formes (cranes, rails) 

Charadri i forrnes (shorebirds) 

Co l umbiformes (pigeons, doves) 

Cucul i formes (cuckoos) 

Strigiformes (owls) 

Apadiformes (swifts, hummingbirds) 

Coraci iformes (kingfishers) 

Piciformes (woodpeckers) 

Passeriformes (perching birds) 

TOTALS 

aStream = streamside habitat; Marsh = marshes, lakes, wet meadows. 

78

Third, passerines are the predominant 

streamside birds, both in number of species 

and in number of individuals, They are 

generally smaller, nest in trees and 

shrubs, and are predominant] y insectivorous. 

Many are migratory. 

The close association of passeri nes with 

riparian habitat, and particularly the 

affinity shown by tropical species that 

migrate north to breed (e.g., flycatchers, 

swall ows, vireos, warbl ers) , i s so marked 

that it deserves more attention. This 

group is now under severe pressure because 

of destruction of the tropical forests 

where they winter; they are thus pressed 

for habitat on both breeding and wintering 

grounds. 

In summary, the riparian areas of coastal 

Southern California provide breeding 

habitat for 140 species of birds. The vast 

majority are residents, joined in spring by 

migrants from south of the U.S. border. 

Nest sites include trees, dead snags, 

shrubs, reeds, grasses, cliff banks, and 

water (floating nests). Food for these 

birds ranges from minute invertebrates to 

small mammals. Only a few species are 

granivorous; the largest group, the passerine~, 

consists mainly of insectivores. 

Loss of riparian habitat in this century 

has resulted in the decline of many 

species, particularly those that have 

inflexible breeding requirements. Several 

are close to extirpation from coastal 

Southern California, including the yellowbilled 

cuckoo, least Bell's vireo, and 

willow flycatcher. Seventeen species are 

1 isted by various agencies as endangered, 

threatened, or of speci a1 concern. 

Conversely, a few of the more adaptable 

species have increased in numbers (e.g., 

northern mockingbird, house finch) . 

In addition to providing nesting habitat, 

riparian areas serve as major stopovers for 

migratory birds and as wintering areas for 

many species that go ta northern latitudes 

to breed. 

The value of riparian habitat for birds 

has been well documented; it supports more 

species of breeding birds than any other 

type of pl ant communi ty in Cal ifornia. As 

nesting habitat for passerines it has 

special importance; 54 percent of the avian 

breeding species in riparian areas are 

members of this order. 

4.6 MAMMALS 

Forty-four species of mammals can be 

found in association with Southern 

Cal ifornia's riparian habitat. Appendix G 

lists them and indicates the degree of 

dependency for each. Numeri ca1 values are 

intended only as indicators; some are 

undoubtedly open to challenge. Four 

species are not native to Southern 

Ca1 i forni a; one, the Virginia opossum 

(Didel~his virqiniana), was introduced from 

the eastern United States, but the beaver 

(Castor canadensis), red fox (Vul~es 

fulva), and black bear (m arnericanus) 

were resident in the Sierra Nevada and 

introduced into Southern California from 

there. 

Several species are limited in their 

latitudinal range. The northern flying 

squirrel (61 aucomvs sabri nus) does not 

occur south of the San Jacinto Mountains 

and is localized in the San Gabriel, San 

Bernardino, and San Jacinto mountains 

(Keeney and ioe, 1984). The porcupine 

(Erethizon dorsatum) has its southern 1 imi t 

in the San Bernardino Mountains (Keeney and 

Loe, 1984). The l ong-tongued bat 

(Choeronvcteris mexicana) is a Mexican 

species that barely extends north into 

lower San Diego County (Bond, 1977). 

Several species have a1 t i tudinal range 

1 imits. The Virginia opossum, ringtail 

mouse (Bassariscus astutus), and pinyon 

mouse (Peromvscus true!) are not reported 

from the high mountains; the northern 

flying squirrel is found only at high 

elevations. 

Streams serve as corridors for the spread 

of some mammal i an species. Gri nnell (1933) 

noted that the opossum fa1 3 owed stream 

courses up into the faathills. The westersa 

grey squirrel (Sci urus ari seus) is 

restricted to oak woodland, and its geographic 

distribution in Southern California 

has been influenced by the presence or 

absence of riparian "bridges" between 

mountains (Pequegnat, 1951), The red fox 

has spread by moving along rivers and has 

become well established in several salt

marshes--e.g., in Mugu Lagoon and at Seal 

Beach National Wildl ife Refuge--within the 

past decade by using riparian corridors. 

4.6.1 Ri~ari an-Associ ated Mammals 

The following annotated 1 ist includes 

mammals that are most closely associated 

with riparian habitat (Category 1, column 

4, Appendix C) or use riparian as well as 

other habitats (Category 21, but not casual 

users (Category 3). The nomenclature 

follows Hall (1981). 

a. Virginia opossum, Didel ~hus 

virainiana. The Virginia opossum is 

not native to the Pacific Coast, but 

is found throughout Cal ifornia except 

in the coldest and driest regions 

(Ingles, 1965). A1 ready present in 

the San Gabriel River bottom in 1906 

(Grinnell , 1933), it occurs commonly 

around human habitation, in woodlands, 

and along streams (Burt and 

Grossenheider, 1964) and is still 

common in riparian habitat along the 

Santa Margari ta River (Zembal , 1984b). 

Omnivorous, it is known to eat fruit, 

eggs, young birds, and small mammals 

(Ingles, 1965). 

b. Ornate shrew, Sorex ornatus. The 

ornate shrew is resident along streams 

in valleys, foothills, and high 

mountains throughout coastal Southern 

Cal i forni a. Closely associ ated with 

riparian habitat, it is very common 

along the Santa Margarita River 

(Zembal, 1984b). Its diet is not well 

known but includes the larvae, pupae, 

and adults of many insects (Ingles, 

1965). Its role in riparian ecology 

merits study. 

c. Broad-footed mole, Sca~anus 7 atimanus. 

Widely distributed in Gal ifornia at 

all elevations, this mole is most 

common in mountains where it burrows 

in soft soil in stream valleys and 

meadows. Its habitat may be dictated 

more by the presence of soft soil than 

by water (Bond, 1977). 

d. Botta's pocket gopher, Thomomvs 

bottae. A ground-burrowing mammal 

widely distributed in California 

(except in the highest mountains), 

Botta's pocket gopher also burrows in 

soft s~il in valleys and meadows. 

Found up to 3,680 m in wet meadows of 

the San Bernardino Mountains (Grinnel, 

1908), it is also quite common in the 

riparian/upl and interface and locally 

in riparian habitat along the Santa 

Margari ta River (Zembal , 1984b). It 

is eaten by ~wls, hawks, coyotes, 

foxes, badgers, and snakes (Ingel s, 

1965). A vegetarian, feeding on 

grasses and plants in natural 

situations (Ingles 19651, it is 

considered benefici a1 in mountains, 

where it "ploughs" the soils, but a 

pest in orchards, grain fields, and 

farms, where it gnaws roots and stems. 

e. Bats. As an order, bats are closely 

associated with freshwater habitat. 

Most species are aerial insectivores 

and feed on concentrations of insects 

over or close to streams and lakes. 

In Southern California only one 

species does not feed on insects: the 

long-tongued bat, a tropical nectar 

feeder that occasionally strays north 

into San Diego County (Bond, 1977). 

The thirteen species on the checklist 

(Appendix C) are represented by 

mu1 tiple specimens in museum 

collections in Cal ifornia. There are 

no major roosts in coastal Southern 

California, as there are no large 

caves or mines. The most common bat 

in Southern California riparian 

habitat is the western pipistrelle 

(Pi pi strell us 

hes~erus) , which 

frequents both lowlands and mountains. 

Other common species are Yuma myotis 

(Mvoti s yumanensi s) , Cal ifornia myotis 

(Mvoti s cal i fornicus), big brown bat 

(Eotesicus fuscus), and Mexican freetailed 

bat (Tadarida brasil iensis) . 

The hoary bat (Lasiurus cinereus) used 

to be much more common; it was often 

collected in summer in the mouths of 

canyons in Beverly Hi1 1 s, Glendale, 

and Pasadena (D. McFarl ane, Natural 

Hi story Museum, Los Angel es County; 

pers. comm.). Loss of habitat has 

reduced the local distribution of this 

and several other species now found 

mostly at higher elevations. 

Bats in Southern California roost in 

trees flong-eared myotis, red bat, 

hoary bat), in buildings (Cal i fornia 

myotis, big brown bat), and on cliff

~3 

- m 

L r - u m ~ 

II) , 

m 2 

C - 

. r ~ 

C.',,,-.r J fi, 

oLsLLr.rGE~~ma~ 

~-z.-Z+a 

r o E 

'u 

&PZ f;;P$%.. z*.f.'" E 0 3 c 

.~-r-~a.r.r~~ 

7,- 0 m-o L 3-0 a, 0 w 

3 ~ ~ u . r 

@ m o r m m r d s C C * a ) L E 

v u 3: OOZE rd m - r S z - 0 

C 

mu-m - a, 

sc -m 

0 a r 

7- C-CI 

m 3 m E C 

ou m 

u- CNvl 

" =Iu 

m ara 

,mbQJ 

-& 

v, 0.25 

c s m, 

. . . 

m m a r 

GL 4.r 

c w m., 

3>-?- < 

a, L-g 

=zF- ' 

ma z 

-r 5 a, 

LL w'C L 

-> OC,

(Ingles, 1965), it is itself prey for 

many birds and mammal s . 

i . Deer mouse, Peromyscus manicul atus. 

Widely distributed across the United 

States, the deer mouse is found in all 

habitats. A1 though not particu? arly 

identified with riparian habitat, it 

was found there abundantly in winter 

along the Santa Margarita River 

(Zembaf , 19846). It feeds on seeds, 

nuts, acorns, insects (Burt and 

Grossenheider, 1964) and is prey for 

many birds and mammal s. 

j. Brush mouse, Peromyscus boy1 i i . 

Although supposedly a resident of arid 

regions, this mouse has been Found 

regularly in riparian habitat in the 

San Bernardino Mountains (Grinnell, 

1908), the San Gabriel Mountains 

(Vaughn, 1954), the Santa Ana 

Mountains (Pequegnat, 1951), and along 

the Santa Margarita River and its 

drainage in the coastal lowlands 

(Tembal, 1984b). It was the most 

common rodent trapped in the 

streamside/wi 1 low wood1 and communi ty 

in the Santa Ana Mountains by 

Pequegnat (1951). It feeds on pine 

nuts, acorns, seeds, and berries (Burt 

and Grossenheider, 1964) and is prey 

for many birds and mammals. 

k. Dusky-footed woodrat, Neotoma 

fusci~es. Widespread in California 

from sea level to high in the foothi 

1 l s, the dusky-footed woodrat 

prefers heavy chaparral, streamside 

thickets, and deciduous and mixed 

woodlands (Burt and Grossenheider, 

1964). It is widely reported in the 

San Bernardino Mountains (Grinnell , 

1908), the San Gabriel Mountains 

(Vaughn, 19541, and the Santa Ana 

Mountains (Pequegnat, 19511, as we1 l 

as along coastal streams in Santa 

Barbara County (Onuf, 1983) and San 

Diego County (Zembal , 1984b). It is 

vegetarian and itself food for owls, 

foxes, csyotes, and large snakes 

(Ingles, 1965). 

I. California vole, Microtus ca1 i- 

fornicus. The Ca? ifgrni a vg?e prefers 

marshy ground and meadows along 

streams from lowlands to high rnountains 

the length of the state (Burt 

and Grossenheider, 1964). Comlon in 

the local mountains [Grinnell, 1908; 

Vaughn, 1954; Pequegnat , 1951) and 

along coastal creeks in San Diego 

County (Zembal, li984b), it feeds on 

grasses, sedges, and other green vegetation 

(Burt and Grossenheider, 1964). 

m. Raccoon, Procyon lotor. Raccoon is 

widely distributed in Ca1 ifornia along 

watercourses and lakes in valleys and 

foothills, but not at high elevations 

(Ingles, 1965). Omnivorous, it 

frequently washes its food before 

eating it. Its preferred habitat is 

close to streams, 1 akes, and marshes 

(Grinnell, 1933). It is probably an 

important predator on bird eggs, and 

this merits study. 

n, Ringtail, Bassariscus astutus. A 

secretive, nocturnal mammal , ringtai I 

until recently was be1 ieved to prefer 

brush and rocky slopes (Ingles, 1965). 

Two studies have now documented a 

preference for riparian habitat; one 

in Texas (Toweill and Teer, 1980), 

another in the Central Valley of 

Cal i forni a (Be1 lournini , 1983). Found 

in lowlands and foothills, but not 

often at high elevations, it feeds on 

small rodents, occasional birds, and 

fruit (Ingles, 1965). 

o. bong-tailed weasel, Nustel a frenata. 

long-tailed weasel has been found in 

all habitats that are close to water 

and at all elevations (Ingles, 1965). 

Carnivorous, feeding on small rodents 

and occasional rabbits, birds, and 

eggs, it is active in daylight but 

also hunts at night. An agile 

c1 imber, it may be an important 

predator on bird eggs. 

p. Spotted skunk, S~ifosale putorius. 

Spotted skunk is found in brush or 

wooded areas near streams at all 

elevations (Ingles, 1965). In 

Southern California it is most often 

noted at low elevations (Grinnel, 

1908; Pequegnat, 1951; Bond, 1977) and 

i s Frequently near human habitation. 

Distributed through most of the 

western Ynited States, !t is a necturnal 

hunter that preys on insects, 

rodents, birds, and eggs. It can 

carry rabies .

q, Striped. skunk, Menhitis meahitis, 

Striped skunk is found in logged-over 

areas, weedy fields, and streamside 

thickets where food is abundant 

(Ingles, 1965) in lowlands and 

mountains up to at least 2,600 m 

(Grinnell, 1908). It is distributed 

throughout the United States. 

Primarily a nocturnal hunter, it also 

forages by day, eating insects, 

rodents, eggs, carrion, and almost 

anything available. It is taken for 

its fur. It sometimes carries rabies 

(Burt and Grossenheider, 1964). 

4.6.2 Status of Riaarian Mammals 

The role of mammals in riparian ecology 

and the value of riparian habitat for 

mammals are discussed in Chapter 5. There 

are no ripari an-dependent mammal s on either 

State or Federal 1 ists of endangered, rare, 

or sensitive species. There are some whose 

status is not well known and should be 

investigated. The ringtail is a secretive 

animal about which little is known. 

Belloumini (1983) found densities of 10.5 

to 20.5 ringtails per hectare in riparian 

habitat in California's Central Valley. A 

comparative study in Southern California 

would be of interest. Bats are an even 

more difficult object of study; the range, 

population size, habitat preferences, and 

needs of the 13 species associated with 

riparian habitat in Southern California are 

poorly known. Most scientific work on bats 

has been taxonomic, and an atlas of the 

bats of Southern California is in 

preparation at the Los Angeles County 

Museum. Field studies would also be 

useful. 

In summary, 44 species of mammals are 

associated with riparian habitat in coastal 

Southern California; they range in size 

from the tiny California vole to the black 

bear. Although the large mammals (deer, 

bighorn sheep, bear) are not associated 

primarily with riparian habitat, they use 

it daily for water and forage. Mamals are 

both predators and prey in the food chain; 

small rodents are prey for both birds and 

1 arger carnivorous mammal s . Bats are the 

least-known order of mammals associated 

with riparian habitat, although there are 

13 riparian-associated species. 

4.7 SUMMARY 

Cal ifornia's insect fauna is huge, 

encompassing an estimated 27,000 to 28,000 

species. Riparian insects fill a variety 

of ecological niches and play an important 

role in the riparian community as both 

predators and prey. 

Fish populations in Southern California 

are limited in diversity and size and are 

disappearing rapidly because of habitat 

destruction, particularly from dams and 

channelization projects. 

Amphibians are present around undisturbed 

mountain streams and lowland rivers but are 

scarce or eliminated where riparian habitat 

is disturbed or destroyed or where 

recreational use is heavy. 

Of 140 species of breeding birds listed 

for Southern California, 88 are strictly 

riparian and 23 are users of riparian 

habitat. Eighty-two species of nonbreeding 

birds are 1 i sted, and many of these depend 

on riparian habitat for food and rest 

during migration. The loss of riparian 

habitat most directly affects the 76 

species in the passerine order of birds, of 

which 59 nest in riparian habitat and are 

predominantly insectivorous. 

Forty-five species of mammals in Southern 

Cal i fornia are associated with riparian 

habitat.

CHAPTER 5. 

ECOSYSTEM PROCESSES AND VALUES 

5.1 ECOSYSTEM PROCESSES 

5.1.1 Primary Productivity 

Green plants are distinguished from other 

living organisms principally by their 

abil i ty to assimilate carbon dioxide, 

oxygen, water, nitrogen compounds, and 

minerals and to synthesize them into 

organic sugars, starches, and proteins. 

The total amount of organic matter manufactured 

by green plants is called the 

gross primary productivity of an ecosystem. 

Net primary productivity is the total 

amount of organic matter manufactured and 

stored by green plants beyond their own 

respiratory needs. 

Primary productivity 

may be in the form of leaves, woody tissue, 

fruit, nectar, pollen, or detritus 

(Bill ings, 1978; Mum et a1 . , 1984). 

Determination of the net primary productivity 

of a riparian forest is complex 

because calculations must take into account 

the rapid turnover of short-l ived herbaceous 

plants and the accumulation of productivity 

of shrub layers and of still 

longer-lived trees (whittaker and Niering, 

1975). 

The major environmental gradient or 

limiting factor of a riparian system is the 

availability of moisture. The percentage 

of winter-deciduous trees and the 

percentage of large-leaved trees closely 

follows this gradient from xeric slopes to 

perennial streams (Whi ttaker and Niering, 

1365; Campbell, 1988). The riparian zone 

is characterized by vegetation that 

requires large amounts of free or unbound 

water, as shown in Figure 42. The leaves 

and annual increment of woody biomass of 

riparian trees and shrubs are larger than, 

for example, those of chaparral or coastal 

scrub species; thusl net primary productivity 

figures for riparian vegetation 

would be expected to be higher than those 

for drier habitat types, particularly for 

older, more mature stands. According to 

Whi ttaker (Lieth and Whittaker, 1975), the 

productivity of temperate wood1 ands and 

shrub1 ands (excluding dese:ts) appears to 

be between 250 and 800 g/m /yr. There are 

no productivity estimates for the riparian 

community in Southern Cal i forni a; however, 

Ho1 stein (1981) states that California's 

riparian communities are its most 

productive because they receive abundant 

water during hot, cloudless summers which 

are ideal for maximum photosynthesis. 

The primary productivity of green plants 

serves as a direct energy source for 

decomposing bacteria and detri tivores, 

which further fragment decomposing plants. 

These organisms, part of the secondary 

productivity of a riparian ecosystem, 

serve, at least in part, as an energy 

source for a succession of other organisms 

and are an important component of a rich 

food web that culminates in large insects, 

reptiles, birds, and mammal s. Biomass 

produced within the riparian ecosystem can 

be used entirely within the riparian 

community, moved to and used in adjacent 

communities, or used by animals moving 

between riparian and adjacent communities. 

5.1.2 Riuarian Veqetation and Stream 

&osvstemq 

Riparian vegetation i s important not only 

within the riparian ecosystem but beyond it 

to the structure and function of the 

adjacent stream ecosystem. Some of the 

major contributions of riparian vegetation 

to in-stream components are shown in Figure 

43, a model developed from a study of 

Sierra Nevada streams.

Sagebrush and grass 

\ 

Sedges and rushes 1 

Emergents, 

I 

Figure 42. Riparian vegetation requires large amounts of free or unbound water (adapted from 

Thomas, 1978). 

a. Detri tal Food Base. Woodl and streams 

derive most of their biological energy from 

organic materi a1 that comes from adjacent 

terrestrial comuni ties (Knight and 

Bottorff, 1984; Hynes, 1970). Detritus 

provided by riparian vecetation is a source 

of up to 90 percent of the nutrients consumed 

by instream aquatic communities 

(Hubbard, 1977; Cumins, 1975; Merri tt, 

1978; Hart, 1975). Detritus and nutrients 

from adjacent up1 and ecosystems (e.g., 

chaparral and coastal scrub) are recycled 

through natural processes of fire and flood 

and transported downstream in the riparian 

ecosystem (R. Vogl, Gal ifornia State 

University (Los Angel es) ; pers . comm. ) . 

The contributions of organic matter from 

riparian vegetation to stream ecosystems 

has been appreci ated only recently 

(Cumins, 1974). Natural changes in ripari 

an vegetation and the biotic processing of 

detritus, among other factors, determine 

the kinds and abundance of aquatic invertebrates 

7 iving in streams, from headwaters 

to the river delta (Hynes, 1970).

LTERS WATE 

FOOD, REST, AND 8 LIFE CYCLES 8 QUALITY FOR 

HIDING FOR 

OF AQUATIC 

INVERTEBRATES 

Figure 43. Relationships between riparian vegetation and stream components (from Knight and Bottorff, 

1981). 

Knight and Bottorff (1984) summarize the 

role of aquatic organisms in continually 

processing and transforming organic matter 

from the time it enters the stream. The 

process of leaching dissolved organic 

matter (DOM) from coarse particulate 

organic matter (CPOM) such as leaves, 

pollen, and fruit begins once it reaches 

the water. Fungi and bacteria rapidly 

colonize organic matter undergoing 

leaching, and aquatic insects such as 

stonefly nymphs, cranefly 1 arvae, and 

caddisfly larvae shred or break down CPOM 

and are called "shredders. " 

CPOM is broken down into fine particulate 

organic matter (FPOM) by the feeding action 

of shredders and microorgani sms, the 

physical abrasion of stream turbulence, and 

the fine particles that are eroded from 

streambed algae or the surrounding 

watershed. The fine particles are food for 

organisms known as "cot 1 ectors, " which 

gather or filter partfcles from flowing 

water. A third group of aquatic animals, 

cal led "scrapers, " have mouth parts adapted 

to scraping up and consuming algal scum, 

which a1 so contains microscopic animals. 

Still other aquatic invertebrates and 

vertebrates prey on shredders, coll ectors, 

scrapers, and each other. The amount, 

kind, and timing of vegetative additions to 

the stream and the shading provided by 

streamside plants will determine, to a 

degree, which feeding groups prosper at any 

given site, but, particularly, which 

species within each feeding group will 

prosper. 

The structure and 

function of aquatic 

communities along a river system have been 

organized into a River Continuum Concept 

(Cumins, 1974, 1975; Vannote et a1 . , 1980) 

which involves several stream factors that 

interact to influence the avail abil ity of 

food for stream animal s- -temperature, 

substrate, water velocity, stream marpho- 

logy, and energy inputs from adjacent 

terrestrial communities or from sources 

within the stream. According to this

concept, these factors should vary 

predictably from headwater tca downstream 

and should produce predictable 

distributions of feeding groups (shredders, 

col 1 eclors, and scrapers) a9 cang the 

continuum. This model should be appl icable 

to streams and rivers in the study area, 

taking into account the reduced temperature 

fluctuations, extended periods of leaf 

fa1 I, and the wet/dry annual cycle common 

in Southern Cal ifornia. 

b. Stream Shade from Ri~arian 

Vegetation. Shade created by riparian 

vegetation is a major factor controlling 

light intensities reaching algae and 

macrophytes, particularly in headwater 

streams, and, therefore, the level of 

primary productivity in streams. Shade 

removal has been demonstrated to increase 

primary productivity and cause algal mats 

in small streams (Brown and Krygier, 1967, 

1970; Brown et al., 1971; Likens, 1970; 

Graynoth, 1979). Shade moderates stream 

temperatures, often preventing summer 

temperatures that may be lethal to invertebrates 

or fish. Stream water temperature 

affects numerous stream functions: processi 

ng rates of organic matter, chemical 

reactions and concentrations, metabolic 

rates of stream invertebrates, and cues for 

l ifecycle events (Knight and Bottorff, 

1981). Table I1 provides figures for water 

temperature changes in small streams caused 

by removal of riparian vegetation. Studies 

of clear-cut watersheds show that when 

riparian buffer strips remain, stream 

temperatures a1 so remain essentially the 

same as in untouched watersheds (Brown and 

Krygier, 1970; Swift and Messer, 1971; 

Table 11. Water temperature changes in small streams caused by riparian 

vegetation removal in relation lo undisturbed conditions (from Knight and 

Bottom, 1984). 

Tem~erature chanqe 

Location Forest type Summera Winter 

Oregon 

A1 aska 

Kansas 

New Hampshire 

coniferous 

coniferous 

deciduous 

deciduous 

+ 8 (A) 

+15 (B) 

+ 8 (A) 

West Virginia 

North Carol i na 

New Zeal and 

deciduous 

deciduous 

mixed coniferous 

and deciduous 

+ 7 (A) 

+13 (E) 

'Sumer increase in water temperature based on: 

(A) mean monthly maximum water temperatures 

(8) instantaneous water temperatures recorded for one year 

(C) instantaneous water temperatures recorded for one 

summer day 

(D) mean weekly water temperatures 

(E) weekly maximum water temperatures

Graynoth, 1979) and stream macroinvertebrate 

diversities remain high (Erman et 

al., 1977). 

c. life Cycles of Aauatic Insects. 

Vegetation growing adjacent to streams 

plays an important role in the life cycles 

of many aquatic insects (Knight and 

Bottorff, 1981). Some emerge into terrestrial 

ecosystems as adults with wings for 

dispersing and searching for mates. Fol i - 

age is used for feeding, resting, hiding, 

and sometimes in mating rituals. Some 

insects lay eggs on riparian vegetation 

overhanging the stream so that upon 

hatching the larvae will drop into the 

water for the aquatic life stages. With 

reduced vegetation, the number of niches 

for insects is reduced, resulting in 

reduced numbers of species and populations. 

Insectivorous birds, particularly those 

feeding on leaf-feeding insects, consequently 

lose both food supply and cover. 

5.1.3 Role of Fire in Nutrient Cvclinq 

Between Ecos~stems 

A vast amount of the riparian habitat of 

Southern Cal ifornia intergrades with 

chaparral or coastal scrub communities. 

Chaparral vegetation is particularly prone 

to fire because of its dense, contiguous 

growth and lack of moisture. Often the 

chaparral community produces an abundance 

of fuel that accumulates faster than it 

decomposes because of resistance to decay 

or cl imatic factors. These plant 

accumulations are highly flammable; thus, 

fire is a regular occurrence under natural 

conditions and infrequent but inevitable 

under fire-excl usion pol icies, particularly 

near urban areas. 

R. Vogl (pers. comm.) suggests that the 

riparian community serves an important role 

in f i re/f?ood sequences in Southern 

California, resulting in energy flows 

between plant comuni ties. Fires reduce 

organic matter to a bouyant ash and 

charcoal. 7he flotsam component is usually 

transported in an emulsion that resists 

burial and assures widespread surface 

deposition, During winter rains and 

ft oods, charcoal and emu? s jf ieb mineral 

products are carried into streams, where 

they are redeposited onto the land by flood 

waters or carried downstream toward coastal 

wetlands. Nutrients bound in l ight, 

vaowwettable fragments of charcoal and ash 

emulsions are bouyant and remain in the 

upper 1 ayers of flood-deposited sediments, 

readily available to new plant growth. 

Nutrients derived from a chaparral 

comuni ty in a f ire/flood cycle may remain 

in the same comunity or be transported to 

the banks or floodplain of an adjacent 

riparian community; to a flooded adjacent 

coastal scrub, oak, or broadleaved 

evergreen wood1 and community; or downstream 

to a coastal freshwater or saltwater marsh. 

The riparian corridor thus becomes a kind 

of circulatory system linking plant 

communities in this fire/flood model. 

In areas where riparian cover has been 

removed, leaf-1 i tter 1 eve1 s are reduced or 

eliminated and soils are exposed. As a 

result, stream sediment loads from erosion 

are increased and water velocity increases, 

minimizing the energy-transfer potential of 

fire/flood cycles. Nutrients may then be 

transferred in fast-flowing waters 

downstream and lost in the ocean. 

No energy flow studies exist for the 

riparian habitat of Southern Cal ifornia. 

The model presented in Figure 43 is 

hypothetical and the size of the energy 

flows is unknown. In years of heavy, 

gentle rain, the contribution of an 

adjacent upland ecosystem to the riparian 

system is greater than in dry years, when 

there is l i ttle movement of nutrients, 

detritus, and leaf litter. In years of 

flash floods, material and nutrients move 

though the system too quickly to be made 

available to riparian organisms (R. Vogle, 

pers. comm. ). 

5.2 RIPARIAN HABITAT VALUES 

5.2.1 Water Qua1 i t v and Ouanti ty 

and Stream Maintenance 

The riparian ecosystem, with its 1 inear 

form, plays important and little-recognized 

roles in tying together adjacent 

ecosystems: in nutrient recycling, as a 

source for seed dispersal, and as corridors 

for wi l dl i fe moving between ecosystems. 

The riparian ecosystem enhances the habitat 

val ue of adjacent systems. Where ri pari an 

vegetation is removed, entirely or in part, 

habitat values are diminished. This is 

particularly true for the lush understory

growth, so frequently ignored or cleared as 

a nuisance to man (Odum, 1978). 

Riparian vegetation plays a major role in 

downstream water qua1 i ty. It stabil izes 

streambanks by reducing the erosive energy 

of rainfall and of flowing water. Trees, 

shrubs, herbs, and their leaf litter all 

cushion the force of falling raindrops and 

thus reduce the amount of sediment carried 

into streams. For a given amount of precipi 

tation the quantity of sediment eroded 

from plowed land is 80 times that from 

grassland (Leopold et al., 1964). In areas 

undergoing rapid urbanization and subjected 

to poor watershed planning and careless 

construction techniques for roadways and 

housing projects, erosion rates may be 

several thousand times as great as those 

found i n an undi sturbed forest (Bormann and 

Likens, 1977; Jones, 1982). 

In addition, the shading effect of 

riparian vegetation affects water quality 

by moderating water temperatures and thus 

the kinds and rates of chemical reactions. 

Organic matter in the soil retains moisture 

and influences pH and ion exchange 

(Leopold, 1964). Vegetation a1 so plays an 

important role in stream maintenance, 

protecting streambanks from watercourse and 

surface runoff erosion by binding the soil 

with extensive root masses, by maintaining 

soil porosity, and by impeding the rate of 

surface runoff through the accumulation of 

leaf litter (Knight and Bottorff, 1981). 

In these ways the severity and frequency of 

minor floods are reduced (Jones, 1982). 

Ground-water basins in Southern 

California are in arid valleys, while most 

precipitation occurs in the mountains. 

Natural recharge of ground-water basins 

occurs mainly by percolation of water from 

streams after they enter the permeable 

alluvial soils of valleys. The interaction 

of riparian vegetation with associated 

streams is critical to this process of 

ground-water recharge. Vegetation promotes 

maximum infiltration of rainfall bv 

creating a loose organic soil, ready to 

absorb either sparse rainfall or the 

occasional flood. During floods, riparian 

vegetation reduces the velocity of moving 

of ground-water recharge QBormann and 

Likens, 1977). Since the roots of riparian 

trees can be located in perennial groundwater 

or in the capillary fringe above the 

water table, they reduce ground-water 

level s through transpiration, and, in dry 

areas, water yields have been increased by 

the removal of riparian vegetation (Ohmart 

and Anderson, 1977). To determine the best 

management practices for a given site, 

close examination of vegetation and soi 1 s 

is required. 

5.2.2 Habitat for Wildlife 

The riparian plant community in Southern 

Cal i forni a covers 1 ess acreage than other 

communities such as chaparral or oak 

woodland, but it receives 

disproportionately heavy use by animals 

(Beidleman, 1948, 1954; Dumas, 1950; 

Wooding, 1973; Bottorff, 1974; Kelly, 1975; 

Kirby, 1975; Gaines, 1977; Hubbard, 1977; 

Hinschberger, 1978; Jahn, 1978; Ohmart and 

Anderson, 1980). Much of the information 

in this chapter is based upon work carried 

out in riparian systems outside the study 

area, since almost no documentation of the 

above statement has been undertaken in 

Southern California. In an unpublished 

report, Warner points out that there is a 

growing body of information regarding 

previously unrecognized functions and 

values of riparian habitat, but predicts 

that it would be a decade or more before 

all of the major values of this complex 

dynamic ecosystem could even be identified. 

The ninth annual report of the U.S. Council 

on Environmental Qua1 ity (1978) states that 

"no ecosystem is more essential than the 

riparian system to the survival of the 

nation's fish and wildlife." Johnson at 

a1 . (1977) calcul ate that western riparian 

ecosystems contain 42 percent of the mama1 

species of North America, 3% percent of the 

reptiles, and 14 percent of the breeding 

birds. Wubbard (1979) states that 75 

species of fish of the southwest are 

dependent on riparian ecosystems. 

While there are numerous reasons why 

riparian habitat is important to wild1 ife, 

the full list sf values does not apply to 

water, causing it to remain in contact with each stream or watercourse. The size of 

soil banks and floodplains for l onger the water source, the physical parameters 

periods of time and enhancing the process of iradivldual riparian zones, the diversity

Studies of the feeding habits of aquatic 

insects have shown that many are omnivorous 

and that food needs change with 

devel opmental stages (Chapman and Demory, 

1963; Winterbourn, 1971 ; Mecom, 1972; 

Anderson and Cumins, 1939; Erman, 1981). 

An insect that exists on algae produced 

within the stream in its early stages may 

later shred decaying leaves from the 

riparian zone and later still become 

carnivorous (Erman, 1981). 

The second aspect of riparian use by 

aquatic insects is that their terrestrial 

stages can be divided into five areas: 

feeding; case-building (in Trichoptera); 

pupating on land along stream edges and 

banks or in decaying shoreline trees or 

stumps ; emergence and mating, using 

vegetation for resting or as mating 

platforms; and egg-laying, usually on 

overhanging vegetation so eggs or newly 

hatched larvae drop into the water (Erman, 

1981). 

5.2.6 Riparian Habitat Oeoendencv of Fish 

Though fish are not usually considered 

part of a riparian community, they interact 

with and are dependent on thi s community in 

a number of ways (Nunnally, 1978; Baltz and 

Moyle, 1981). They feed on terrestrial 

insects, use overhanging vegetation as 

cover, or use flooded vegetation for 

spawning. Nutrient recycling and the 

effect of riparian vegetation on water 

flows and temperatures are also important 

to fish habitat. The most important 

physical parameters for fish are stream 

depth, current velocity, substrate 

composition, cover, and temperature. All 

of these change when the riparian comuni ty 

is altered because the riparian system ties 

together aquatic and terrestrial components 

through energy exchange, interaction with 

flow regimes, and impact on temperature 

regimes (Baltz and Moyle, 1981). In 

addition, spawning success is adversely 

affected by increased sediment loads 

(Cordone and Kelley, 1961). 

5.2.7 Rioarian Habitat De~endencv of Birds 

California (Miller, 1951) and is well known 

for the abundance and diversity of its bird 

fauna (Gaines, 1977). The extensive loss 

of riparian habitat in Southern California 

has caused a rapid decline in several bird 

species (Remsen, 3379). Breedi ng 

popul ations are particularly important 

because they include species that occur in 

virtually no other Cal i fornia habitat 

(Hol stein, 1981). Miller (1951) del ineated 

21 plant communities in the State and 

listed the breeding birds for each; there 

were 75 species nesting in riparian 

habitat; in montane forests, the habitat 

with the next highest number of species, 

there were 70. Gaines (1977) has shown 

that many of these birds are insectivorous 

fol i age-gl eaners that winter in tropical 

forests, habitat with high net 

productivity. Insects, which are primary 

consumers, would be expected to increase in 

abundance with increasing warmth and 

primary productivity . Cody (1978) found 

that insect biomass does, in fact, peak in 

the spring and fluctuates with primary 

productivity throughout the year in 

California upland vegetation. 

Pequegnat (19511, in his study of the 

biota of the Santa Ana Mountains, noted 

that in oak woodlands 75 percent of the 

birds were resident species and only 20 

percent were summer breeders; in streamside 

vegetation only 35 percent were residents 

and nearly 60 percent summer visitors. Me 

attributed this discrepancy to differences 

in the availability of food. The huge 

insect populations in spring in riparian 

habitat create a niche for migrants to use 

for their brief nesting period. No other 

class of vertebrates has a large component 

of migrants that can exploit this seasonal 

food source. Holstein (1981) found that 

bird abundance appears to be related ts 

comunity productivity, suggesting that 

riparian bird populations would be 

augmented re1 at i ve to up1 and habitats when 

contrasts between drier up1 and and moister 

riparian prodtactivi Ly are the greatest. 

Such contrasts occur when aerenni a1 streams 

bring water to semiarid lands such as those 

found in the study area. 

Riparian habitat, w.i th its 1 ush pl ant 

understory, thermal cover, and special Riparian manes are usually dominated by 

microcl imate, supports more species of deciduous vegetation that provides one type 

birds than any ather habitat type in of habitat during the full foliage of

summer and another following winter leaf- important Lo ni Id1 ife, particularly birds 

fall. In a study of the tower Colorado (Bottorff, 1974; Patton, 1975). Where 

River, Anderson and Bhmart (1977) streams flow through canyons, the canyon 

determined that bird usage and requirements wall s combine with the ri parian zone to 

of riparian habitat varied seasonally and form a unique habitat complex. Many vegethat 

dense vegetation is more important in tative strata can be exposed in stairstep 

the early summer than at other times of the fashion, often of contrasting form (deciyear. 

They found that winter residents may duous vo. evergreen; shrubs vs. trees), 

have 1 arger populations and be more which provides diverse nesting and feeding 

specialized in habitat use than local opportunities for birds and bats (Figure 

populations of permanent residents. They 45). The association of particular birds 

suggest that since winter requirements are with distinct layers of vegetation has been 

different from, but as important as, repeatedly demonstrated (Thomas, 1978). 

breeding requirements, they should receive 

at least equal attention, particui arly in 

view of the greater specialization of 

winter migratory birds. 

The dramatic contrast between a riparian 

plant assemblage and one from a drier 

surrounding upland community adds to the 

structural diversity of the area (Jain, 

1976). Open wet meadows or groves of 

deciduous trees around seeps provide 

habitat edges with sharp contrasts, 

particularly when they are surrounded by 

drier grasslands or shrub1 ands. The l inear 

shape common to riparian zones maximizes 

the development of habitat edge which is so 

VEGETATIVE STRATA 

EDGES 

e 

Flgure 45. Riparian zones have high numbers of strata levels and edges; five strata levels (1-5) and 

five verticaf edges (as) are shown (adapted from Thomas, 1978).

The degree of disturbance of riparian 

habitat is important, particularly here 

the understory is removed or altered. 

Where escaped exotics are invasive and 

dominant , habitat becomes 1 ess valuable to 

wildlife. Xn a study along the Santa Clara 

River, 24 species of birds were observed in 

a stand of riparian woodland trees with an 

undisturbed understory, in contrast to 6 

species observed in a similar stand of 

riparian woodland trees with a disturbed 

understory (Smith, 1979). Nests in the 

open are more susceptible to predators, 

inclement weather, and other environmental 

factors (Best and Stauffer, 1980). 

Alteration of rivers and streams has 

almost invariably resulted in loss of 

wild1 ife habitat value. Ohmart and 

Anderson (1978) studied avian use of ten 

freshwater habitat types along the lower 

Colorado River: river be1 ow dam, old river 

channel, oxbow left by river-straightening, 

unchannel ized river with adjacent riparian 

vegetation, Phra~mi tes marsh, dense cattail 

marsh. moderately dense cattail marsh, 

bulrush marsh, - reservoir, rip-rapped 

channel ized river, and unchannel ized river 

with adjacent canyon walls. There were 

consistently higher numbers of birds in the 

first seven areas, which represent 

re1 atively undisturbed sections of the 

river. Unusually heavy use of the old 

river channel was demonstrable for several 

months of the year; moderately dense 

cattail marsh showed the greatest species 

diversity, 

The interface between riparian and 

agricu? tural systems supports a 1 arge 

number of bird species and individual s 

because it offers a variety of food and 

structural resources that are especially 

apparent in winter (Emmerich and Vohs, 

1982). Anderson et al. (1984) suggest that 

such an interface can be used effectively 

to mitigate loss of natural habitat by 

interspersing agricultural 1 ands with 

native vegetation. This, of course, would 

not compensate for loss of habitat for 

riparian species of birds such as the 

yellow-billed cuckoo or the willow 

flycatcher. Gaines (1977) cites reports 

that attribute the decline of riparian 

birds to the brood parasitism of the 

recently introduced brown- headed cowbird, 

but notes that its introduction to Arizona 

occurred before a decline in riparian 

avifauna. Wauer (1977) cites the linkage 

of the cowbird with the virtual extirpation 

of the riparian and insectivorous least 

Be1 1 's vireo from Cal ifornia and Arizona, 

but notes that these species coexist in the 

less agricultural Rio Grande area of Texas. 

Holstein (1981) suggests that the massive 

quantities of insecticides used in 

agricultural areas adjacent to riparian 

corridors should be investigated for 

impacts, particularly on the breeding 

success of insectivorous species. 

Invasion of exotic plants has usually 

diminished the qua1 ity of riparian habitat 

for birds. On the lower Colorado River, 

riparian birds show a strong preference 

within the habitat for two plant 

communities : cottonwood/wi 11 ow and honey 

mesquite, and eschewed the introduced salt 

cedar (Meents et al., 1981). Clearing of 

salt cedar from heavi 1 y invaded riparian 

areas resulted in increased use by birds 

(Anderson and Ohmart, 1981). 

5.2.8 Habitat for Mammals 

Unl i ke birds, which are primarily 

predators, mammals are both predators and 

prey. Small rodents form the principal 

prey group; the California mouse, duskyfooted 

woodrat, and others are food for the 

carnivores--coyote, ringtail, long-tailed 

weasel, bobcat- -p? us hawks, owl s, and 

snakes. Some of the carnivores are 

omnivorous, such as the black bear, which 

feeds on roots, fruits, nuts, grasses, 

insects, and small rodents--and garbage. 

The raccoon has an even more varied diet, 

including crayfish, turtles, frogs, birds, 

eggs, and fruit, as we'll as insects and 

rodents (Ingles, 1965). 

Several orders of mammals are primarily 

insectivorous, notably the shrews and m01 es 

(lnsectivora) and bats (Chiroptera) . Their 

prey is different; the shrews and moles are 

fossorial and forage below or on the 

ground, while bats are strictly aerial 

feeders, 

Pequegnat (1952), in his study of the 

biota of the Santa Wna Mountains, noted 

that the number of mammals in riparian 

habitat was small compared with their 

numbers in chaparral and sagebrush

communities. Several recent studies, 

however, report very di fferent findings, 

Of the eight habitats Bleich (1973) 

examined on the Fallbrook Naval Annex, the 

most diverse rodent fauna present was in a 

streamside woodl and community, a? though 

larger numbers were found in the coastal 

sage community. In a more recent study on 

the Santa Rosa Plateau, capture rates were 

better in riparian woodland than in 

chaparral (R. Zembal , USFWS, Laguna Niguel ; 

pers. comm.) . 

In a USFWS study (Zembal , 1984b) on the 

Santa Margarita River, the highest capture 

rates and greatest species diversity were 

in riparian habi tats--far above values 

found in coastal scrub habitat, usually 

considered the most productive for rodents. 

The diversity and abundance of small 

mammals on the Santa Margarita River 

appeared to be related to the near-ground 

habitat structure; the more diverse 

habitats had l arger and more diverse rodent 

populations. Riparian habitat, with its 

abundant cover in the form of 1 itter, lowgrowing 

vegetation, and structural re1 ief, 

afforded small rodents both food and water, 

and was the most diverse of the habitat 

types along the river. 

Larger species of mammals--deer, bighorn 

sheep, mountain l ion, and bear--use streams 

and adjacent riparian habitat for water and 

forage. Availabil ity of water, forage, and 

thermal cover is critical for their 

survival, even though they are not 

primarily associated with riparian habitat. 

Along the Santa Margari ta River, bedding 

pads where deer take cover are abundant, 

particul arly in the summer, when deer 

seek relief from the heat and browse on 

green vegetation near the water (Zembal, 

1984b) . 

5.3 PBSJTiVE VALUES FOR PEQPLE 

5,3.1 Air and Water Oualitv 

Inherent in the riparian ecosystem are 

beneficial values for man that have not 

been adequate1 y recogni zed. Riparian 

habitat is capable of improving air and 

water qua1 i ty through its abil i ty to f il ter 

pollutants, Riparian vegetation removes 

particulates from the air by direct 

adsorption onto leaf su~faces and gases by 

absorption into leaves, Chemical 

detoxification of sulfur dioxide, ckf orine, 

and carbon monox'rde can then occur (one 

acre of trees can remove 3.7 tons of sulfur 

dioxide and 12,9 tons of dust per year) 

(Bormann, 1977). Nitrous oxide, a common 

pollutant in automobile exhaust, is 

absorbed by vegetation and soil organisms 

and thus restricted from entering ground 

and surface water suppl i es . Other 

pollutants removed from water as it 

percolates through soi 1 include zinc, 

copper, nickel , 1 ead, manganese, some 

radioisotopes, and pesticides. Substantial 

quantities of nutrients move between 

riparian vegetation and the soil; however, 

little escapes into the watercourse, except 

during periodic flooding. If the 

vegetation is disturbed or removed, the 

nutrient-holding capacity of the system is 

reduced, nutrients leach out of the soil, 

and pollution of runoff water results. 

Currently, some land managers favor the 

maintenance of natural stream channels as 

the best management practice in areas of 

limited water resources (R. Vogl, pers. 

comm.). An equil i brium can be reached by 

permitting a stream to meander and by 

stabilizing its banks with native 

vegetation. The results produce less 

erosion, higher stream productivity, and 

better water quality than in streams 

altered and channelized. Ground water is 

recharged more efficiently because water 

can percolate more slowly and the rate of 

runoff is slowed (Xarr and Schl osser, 

1978). 

5.3.2 Benefits to Asricul ture 

Although riparian vegetation is 

frequently removed to reduce 

transpi rational 1 osses (Robinson, 19851, 

riparian barriers can benefit agricultural 

1 andowners. By providing a natural fence, 

riparian vegetation can prevent trespassing 

and potent i a1 vandal i sm of property. 

Riparian habitat a1 so supports predators of 

rodents and insects that are agricultural 

pests. Birds sf prey require perching 

sites where they hunt, Most riparian bird 

species feed exclusively on insects and 

thus provide pest contra1 for those who 

allow their riparian forests to remain 

(McFarl ane, 1976; McNichol , 1982). In 

addition, because of the high soil moisture 

and soil qua1 ity adjacent to streams, there

is a small potential for sustained yields 

of timber for firewood or specialty 

hardwood production, such as the native 

black walnut (R. Vogl , pers. comm. ) . 

5.3.3 Aesthetic and Recreational Values 

Many direct benefits accrue to local 

residents from the preservation of riparian 

habitat and wildlife. Some of the same 

qualities that attract wildlife, such as 

water and shade, also attract people seeking 

recreation (Figure 46). The vegetation 

canopy can act as a visual screen and a 

noise buffer to create a feeling of wilderness, 

even though a busy freeway may be 

just over the adjacent levee. The linear 

parks in riparian corridors are some of the 

most popular in Sand Diego County. Picnicking, 

camping, nature study, fishing, 

hunting, hi king, canoeing, and photography 

are all activities enhanced by the quality 

of riparian habitat. However, the value of 

parkland for wildlife is almost always 

diminished when the riparian understory is 

removed to open up the area for trails, 

picnic tables, rest rooms, campsites, and 

1 aw enforcement patrol routes, particularly 

if the ensuing use is heavy (Heberlein, 

1977; Lewis and Marsh, 1977; Schmidly and 

Ui tton, 1978). 

5.4 HUMAN IMPACTS ADVERSE TO THE 

RIPARIAN ECOSYSTEM 

The genera? topic of human impacts and 

di sturbance in riparian systems has been 

well covered (Carothers, 1977a; Schmidly, 

1978). There is little or no riparian 

habitat in Southern Cal i fornia that has not 

been affected to some degree by man's 

activities. Some activities, such as 

stream channel ization, el iminate all 

riparian habitat and wild1 ife values. 

Other activities cause severe disturbance. 

Figure 46. 

habitats, 

The Wiiderness Gardens Preserve along the San Luis Rey River protects a remnant of riparian

5.4.1 Sensitivity to Disturbance 

In Southern Cal ifornia, riparian zones 

occupy small areas and are particularly 

vulnerable to severe a1 terat i on. More 

mature stands of vegetation provide more 

distinct strata and ecological edges and 

thus a greater diversity of habitats. 

Disturbance usually reduces the structural 

and species diversity of the plant 

community, which in turn reduces the 

diversity of habitats for wild1 ife (Figure 

47). Disturbance also alters the microclimate 

of the riparian corridor (Ames, 

1977). Changes in canopy cover can alter 

water qua1 i t y, quantity, and temperature 

with dire consequences for the fauna 

(Boussu, 8954; Ccll ings and Myrick, 1966; 

Tuinstra, 1967; Gunderson, 1968; Campbell, 

1970). 

The amount and size of sediments in 

stream substrates is a result of many 

processes, some of which can occur in the 

riparian zone. Sediment loads may be 

increased from such human activities as 

logging, clearing for development, 

agricul ture, and road building or from such 

natural causes as landslides. Table 12 

shows the change in suspended sediment in 

a watershed after logging. 

~ s f i i cstructure 

t 

I 

Figure 47. Riparian zones must be considered delicate due to the combination of restricted 

area, distinct microclimate, vegetative structure and composition, and water quantity (adapted 

from Thomas, 1978).

Table 12. Average percentage increase in been shown to kelp protect the integrity of 

suspended sediment in the Alsea, Oregon, a stream system. Figure 48 shows changes 

watershed 7 years after Isgging. in transportabt e sediment in narrow 

buffered and nonbuffered streams. Vegeta- 

Method % Change tion is important not only in protecting 

Control 0-1 

Clearcut with buffer strip 54.0 

Ct earcut 205.0 

How fast sediment loads are moved through 

the stream depends on such factors as 

slope, instream sediment traps, and the 

frequency of large storms. It may easily 

take 5 years for a pulse of sediment to 

flow completely through a stream system 

(Dunne and Leopold, 1978). Thus the amount 

of sediment in a stream at any given moment 

is the summation of all the land-use 

activity adjacent to the stream and the 

weather patterns that have prevailed in the 

stream basin for several preceding years 

(Mahoney, 1981). 

Buffer strips of vegetation left along 

streams affected by human activities have 

the stream immediately adjacent to it, but 

also in protecting the biota downstream 

from excessive sediment pul ses (Cordone, 

1961). Downstream benefits usually are not 

included in cost-benefi t analyses of preserving 

buffer strips adjacent to streams; 

they need to be more realistically evaluated 

(Mahoney and Erman, 1981). 

As shown in Figure 49, proliferation of 

domestic or agricultural we1 1 s adversely 

affects riparian trees growing on 

floodplain terraces by lowering water 

tables from levels that once supported 

their 1 arge growth. 

5.4.2 Recreational Activities 

Stream courses and associated riparian 

vegetation and wild1 i fe sometimes are 

drastically impacted by recreational use 

when they are readily accessible to a large 

urban population, as in the San Gabriel 

Mountains. Dirt bikes use the stream 

a SEDIMENT 

I 

NARROW BUFFER 

NO BUFFER 

Figure 48. Percentage change from control In transpanable sediment, detritus, and the 

detrituslsediment ratio in narrow buffered and unbuffered streams In Northern California 

(dates are year of initial logging; from Mahoney and Erman, 4981).

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eleased as rivers recede. Seed vi abi 1 i ty 

is short -1 ived, and successfu? germination 

and seed1 ing establ i shment are dependent on 

freshly deposited a1 l uvi urn (Fenner, 1984). 

Studies conducted before and after canstruction 

of the Glen Canyon Dam on the 

Colorado River show that, prior to construction, 

the river overflowed its banks 

during annual floods and created backwater 

and marshy areas, habitats critical as 

breeding areas for fish and other organisms 

(Carothers and No1 an, 1982). These natural 

high/low flow patterns no longer occur 

because of controlled discharges from the 

reservoirs resulting in reductions in 

numbers and abundance of several species. 

Along with altered waterflows are 

drastically reduced downstream sediment 

concentrations, since most sediments and 

associated nutrients are retained behind 

the dam. These nutrients, normally carried 

by annual floodwaters, are thus no longer 

available for recharging soils. The bottom 

and banks of the river will eventually be 

scoured free of sand and silt, leaving 

boulders, cobbles, and gravel in the 

riverbed. Changes in 1 ight penetration of 

the water column and of the substrate will 

provide a different habitat, suitable for 

different organisms. Releases of reservoir 

water have a narrow range of temperature 

fluctuation, which further a1 ters habitat, 

particul arly for those whose reproductive 

behavior is cued to temperature fluctuations. 

The presence of year-round flows 

can cause increases of riparian vegetation 

and expand habitat for birds, rodents, 

reptiles, and amphibians. On the Colorado 

River, least Bell's vireo and several other 

small birds and reptiles have increased in 

population as a result of increases in 

breeding habitat (Carothers, 1982). Water 

impoundments affecting streams and rivers 

in the study area are smaller in scale, but 

the impacts are similar. 

5.4.5 Asricul ture and Grazing 

Most of the floodplain or river-bottom 

land in Southern California has been 

converted to urban, grazing, or agricultural 

uses, Citrus groves along the Santa 

Clara River extend from the bluffs to the 

edge of the river course, covering the 

entire floodplain for miles between Interstate 

5 and the ocean. Riparian animals 

are restricted to a narrow strip of vegeta- 

tion at the river's edge. Increasingly, as 

a resuf t of favorable tax benefits, avocado 

groves are being planted on steep hillsides, 

particularly in San Diego and Riverside 

counties. These orchards are particularly 

devastating because of the extensive 

disruption of native soil -binding vegetation 

and the resultant silt loads. In some 

of these new avocado groves, future rains 

will carry unprecedented sediment loads to 

the streams. 

Grazing of the forest may lower reproduction 

densities in floodplain areas. When 

grazed, forests are kept clear of ground 

cover and young trees. When grazing is 

excluded, regrowth of a thick understory 

may also prevent seedlings from becoming 

establ ished. Thus, grazing could be 

responsible for the 1 ack of establ i shment 

of certain age classes in the flood-induced 

age structure through seedling elimination 

(Strahan, 1981). 

5.4.6 Urbanization and Road Buildinq 

Extensive areas of flood plains have been 

converted to housing and other urban 

developments with a concomitant loss of 

natural cover. The need for flood control 

inexorably accompanies such development . 

In both urban and suburban planning, the 

economic benefits of preserving riparian 

habitat are often ignored (Figure 51). 

Following loss of this habitat, repair of 

erosion damage is costly and technically 

difficult in Upper Newport Bay in Orange 

County and the lagoons of San Diego County, 

In addition, it is not the developer but 

the public that usually pays the long-term 

costs of stream repair and erosion control. 

Rarely have there been attempts to preserve 

riparian habitat in the process of flood- 

control projects. The lower flood plains 

of the Los Angeles, San Gabriel, and Santa 

Ana Rivers, all channelized by 1930, show 

how channelization of river courses may 

eliminate most riparian features, 

Road construction can have major adverse 

impacts on riparian habitat. Roads in 

stream and canyon bottoms not only destroy 

the habitat on which they are built, but 

alter nfcro- climates, as shown in FSgure 

52. Roads introduce disturbances from 

people, pets, and vehicles; they compact 

soils; and they impact water quality

Figure 51. A cement apron replaces the riparian understory in a development in Ternecula. 

ROADS IN RIPARIAN ZONES 

1. Destroy habitat 

2. Alter microclimate 

3. Introduce disturbance 

4. Impact water quality 

Figure 52. Road construction in riparian zones reduces their usefuiness as wildlife habitat by 

altering vegetative structure and microclimate, reducing the sire of riparian zones, disturbing 

wildiife, and lowering water quality (adapted from Thomas, 1978).

through siltation from road construction 

(Thomas, 1978). 

5.5 SUMMARY 

In summary, vegetation of the highly 

productive riparian pl ant community is used 

within the riparian community or in 

adjacent stream systems. The riparian 

plant community serves an important role in 

fi re/fl ood sequences in Southern Cal i forni a 

in nutrient recycling. Riparian habitat 

protects water qua1 ity and quantity; it 

provides wildlife with water, shade, and 

migratory corridors; it maintains natural 

barriers and habitat for pest predators for 

agriculture; and it offers aesthetic and 

recreational opportunities. 

Remaining riparian habitat and downstream 

areas are sensitive to disturbance. 

Adverse human impacts result from such 

activities as clearcutting to stream 

borders, gravel mining , water impoundments, 

overgrazing, urbanization, recreation, and 

road building.

CHAPTER 6. GOVERNMENT JURISDICTIONS AND RELATIONSHIPS 


A1 though many 1 aws and regulations affect 

riparian habitat, generally they fail to 

protect this ecosystem. Federal and State 

1 aws have created overlapping juri sdictions 

and rarely set minimum standards. In 

addition, budgetary problems result in weak 

monitoring and enforcement. Local 

governments, plus hundreds of independent 

special districts, are largely unacquainted 

with the management of watersheds or 

riparian resources (Kusler, 1978; John Muir 

Institute, 1979; Shute and Mihaly, 1981). 

The result is a lack of statewide or 

local ly coordinated programs to protect the 

riparian ecosystem. 

6.2 FEDERAL GOVERNMENT 

6.2.1 Federal Laws 

a. Clean Water Act. Section 404 of this 

act (PD 92-500) authorizes the Corps to 

regulate the discharge of dredge spoils or 

fill into the waters of the United States. 

This has been interpreted by court 

decisions and regulations to mean navigable 

waters, lakes over 10 acres, and streams 

even beyond their headwaters (the point 

where the flow is 5 ft3/s). A MWF & 

-- Marsh settlement in 1984 caused the Corps 

to revise their regulations and increase 

their responsibil i ties in wet1 ands above 

the headwaters of streams. More directly 

applicable to riparian systems is Section 

208 of the act, which has led to regional 

"non-point" pol lutian-control plans 

intended to impact area-wi de water probl ems 

such as erosion and sedimentation. These 

plans universal Sy endorse the "best management 

practice" of retention and enhancement 

of vegetation, especial 1 y at ong streams, to 

dimini sR bank erosion and filter overland 

runoff before it reaches water bodies. 

However, regul atory standards have not 

evolved from these plans. 

b. Fish and Wildlife Coordination Act 

(16 USC Sec 661 et sea. This act provides 

for consul tat ion by Federal agencies 

with the Service, as well as the state's 

wild1 ife agency, when "waters of any stream 

or other body of water are proposed to be 

controlled or modified." The USFWS also 

advises the Corps in its regulatory role. 

Resources are to be conserved to the degree 

possible, consistent with the primary 

purposes of the project. 

c. Endanqered S~ecies Act (16 USC 1531 

et sea.). The section of primary interest 

in this act allows the Service ta define 

critical habitat areas for endangered 

species. Threats to these areas can 

thereafter be addressed by acquisition, 

development reviews, or establishment of 

mitigation and enhancement measures. 

However, it should be noted that habitat 

does not necessarily have to be defined as 

critical to be considered important by the 

USFWS. 

d. Small Watershed Protection and Flood 

Prevention Act (PL84-566; 16 USC 10021. 

Often referred to as the act for PL566 

projects, it authorizes the Secretary of 

Agriculture to direct the Soil Conservation 

Service (SCS) to conduct soil conservation 

and flood-control projects in areas not 

exceeding 250,008 acres and for reservoirs 

storing not more than 25,000 acre-feet of 

water. Current funding arrangements have 

resulted in Federal monies being used to 

fund stream channel ization, while financing 

only half of the fish and wildlife 

mi tigation measures. PL566 projects have 

almost uniformly resulted in destruction of 

riparian systems (Jones, 1982).

e. Federal Flood Disaster Preve~tfon Act 

iQL93- 2341. Thi s act establ i shed the 

Federal Flood Insurance Program, which has 

provided some incentives for construction 

outside f'lood-prone areas. To a 1 imited 

degree, this has reduced destructfon of 

riparian vegetation by developments. 

President Carter issued two executive 

orders in a related effort: E011988 

directed Federal agencies to avoid 

construction in flood-hazard areas and to 

seek restoration and preservation of the 

natural and beneficial values of 

floodpl ains; E011990 directed Federal 

agencies to minimize the destruction, loss, 

or degradation of wet1 ands. 

f. National Environmental Pol icy Act (42 

USC 4321 et sea. l. This act sets general 

goals of environmental protection for 

Federal agencies and requi res preparation 

of Environmental Impact Reports (EIRs) for 

many federally financed projects. Like the 

Cal i fornia Environmental Qua1 i ty Act 

(CEQA), it is frequently treated in a 

perfunctory fashion (Jones, 19821, but has 

potential for flood-pl ain management 

(Williams, 1979). 

6.2.2 Federal Proarams and Asenci es 

a. Armv Cor~s of Ensineers. The Corps 

is responsible for a broad mix of programs, 

including regulation (Section 404 permits 

under the Clean Water Act) and construction 

of water, flood, and navigation projects. 

The Corps was given nationwide 

responsibility for flood works by the Flood 

Control Act of 1936, and these projects 

generally result in substantial removal of 

riparian vegetation. 

b. Farmers Home Administration. The 

Farmers Home Administration in the 

Department of Agriculture, is a rural 

credit service agency for farmers, rural 

residents, and small communities. Loans 

can be for improvements on farm lands and 

forests, including development of drainage 

and other soil and water conservation 

faci l i ties. There are r;o firm conditions 

on these loans to ensure that they are not 

used to remove riparian vegetation. 

c. Soil Conservation Service. 7 he SCS 

in the Department of Agriculture, provides 

a broad range of services from soil 

conservation to flood control, working with 

farmers through the States' Resource 

Conservation Districts. Projects funded 

under the Small Watershed Act (PL 84-566) 

usually involve stream channel ization and 

riparian vegetation removal. In addition, 

Section 216 of the Flood Control Act of 

1950 allows the SCS to provide emergency 

actions to control runoff and reduce 

erosion, The Office of Coastal Zone 

Management prepared a paper on the role of 

the conservation districts in the Coastal 

Zone Management Program (NACD, 1980). 

d. U.S. Fish and Wildlife Service. The 

USFWS, in the Department of the Interior, 

is the Federal agency responsible for 

planning and management of many of the 

nation's fish and wild1 i fe resources 

(anadromous fish are the concern of both 

the USFWS and the National Marine Fisheries 

Service). The USFWS implements the Fish 

and Wildlife Coordination Act (16 USC 661, 

- et seq. ) and Endangered Species Act (16 USC 

668, seq.). It also acquires habitat 

areas under the Migratory Bird Conservation 

Act (16 USC 715 et sea.) and the Land and 

Water Conservation Fund Act (PL 88-578; 16 

USC 4601 et sea.). The USFWS has been the 

most active of all Federal and State 

agencies in promoting protection of 

riparian systems (Jones, 1982). One of its 

products with the SCS is "Channel 

Modification Guide1 ines," (Federal 

Register, March 1, 19781, which includes 

the following: 

It is the pol icy of the SCS and the 

USFWS that care and effort will be 

made to maintain and restore streams, 

wetlands, and riparian vegetation as 

functioning parts of a viable 

ecosystem upon which fish and wildlife 

resources depend. 

e. U.S. Forest Service. The USFS, in the 

Department of Agriculture, manages 20 

million acres of land in California. As 

early as 1975 the California region of the 

USFS issued a booklet entitled "Management 

of Riparian Mabi tats, * which offered 

objectives to "preserve the productivity of 

riparian habitats through maintenance of 

vegetative stratification and integrity." 

Nationally, the USFS Manual, Section 2526 

(1980), includes an objective of 

recognizing the "unique values of riparian 

areas and emphasize the protection, 

management, and improvement of them during

the planning and implementation of land and 

resource management activities. " USFS 

Region 5 (including California) has a 

pol icy seeking buffer strips for streams, 

recognizing riparian habitat as "one of the 

most productive areas for flora and fauna 

in the forest environment," and call ing for 

"minimum disturbance from management 

activities." 

6.3 STATE OF CALIFORNIA 

6.3.1 California Laws 

California laws with the most significant 

effects on riparian resources are listed 

be1 ow. 

a. Doctrine of the Publ ic Trust. This 

doctrine, derived from Engl ish common 1 aw, 

provides an important philosophical, 

historic, and legal base for governmental 

regu? atisns to protect tidal and submerged 

lands and navigable waterways. The Pub1 ic 

Trust Doctrine does not affect riparian 

vegetation directly, but has been relied 

upon to justify the reservation of instream 

flows necessary to support fish, wild1 ife, 

and habitat. 

b. Land use. 

1. Act (Pub1 i c Resources Code 

Sections 21000 et sea. 1. The CEQA pravides 

a mandate to arotect California's 

environmental qualiiy but is too often 

circumvented (Jones, 19821, as shown in 

Figure 53. 

2. Resource Conservation Act (Pub1 ic 

Resources Code Sectjon 9001 et sea. ) . This 

law provides for a good state-local 

Figure 53. Public works projects carried out in the riparian corridor are frequently exempt from the 

CEQA process, as shown here in a project on a tributary to the Santa Margaaita River in San Diego 

County. Photograph by Anne Sands. 

104

cooperative process that could greatly 

advance the use of "best management 

practices" for soils and streams 

management. Inadequate funding of the 

State Resource Conservation Comission and 

the Division of Soils Conservation, 

Department of Conservation has 1 eft 

resource conservation districts to their 

own initiatives. In fact, these districts 

work more closely with the SCS than with 

the State of California (Jones, 1982). 

3. Surface Minina and Reclamation Act 

(PRC2710 et sea.1. This act requires the 

State Mining and Geology Board to adopt 

State policy for the reclamation of mined 

lands. Buffers and protection of water 

resources and riparian vegetation are 

required. 

c. Water manasement. 

1. Gal i forni a Water Code, Sect ions 

1243. This section declares the 

reservation of water for the enhancement 

and protection of fish and wildlife to be 

a beneficial use. 

2. Davis-Dolwia Act (Water Code, 

Sections 11900-11925). This act funds the 

mitigation of adverse impacts from water 

project development and requires direct 

planning efforts to protect resources as 

part of project design. The act sets forth 

explicit State policies requiring projects 

to avoid or minimize impacts on waterways. 

3. Porter-Colosne Water Oual i tr 

Control Act. This is the State's primary 

water law, it gives the State Water 

Resources Control Board (SWRCB) and the 

nine regional water qual i ty control boards 

substantial authority to regulate water 

use. In 1983 the SWRCB established 

standards for retention of instream 

reservation of waters. This effort 

promises to be one of the State's most 

important programs to protect the integrity 

of waterways, wetl ands, and adjacent 

riparian vegetation. 

d. River and stream manasement. 

1. California biater Code. Section 

8125-8127. This is the authority for 

counties to improve (that is, alter for 

fl ood-control purposes) non-navigable 

streams. It is not matched with clear 

State policy or mandates to preserve the 

environmental features of these streams or 

to avoid or minimize the placement of fill 

in them. These sections could be amended 

to establish a State policy supporting 

conservation of streams (Jones, 1982). 

2. Stream A1 teration Controls (Water 

Code, Sections 5653, 1505, 1601-1606). The 

Department of Fish and Game's authority 

over the use of suction dredges (Fish and 

Game Code, Section 5653), alterations of 

fish spawning areas (Fish and Game Code, 

Section 1505), and alterations of stream 

beds in general (Fish and Game Code, 

Sections 1601-1606) are all useful tools 

for the protection of i nstream resources 

(but general 1 y not for riparian vegetation 

outside of the stream or overflow areas). 

The 1601- 1603 agreements (1601 covers 

pub1 ic projects, while 1603 addresses 

private work) do not have the status of 

State approval s under 1 aw, instead 

providing for a negotiation and agreement 

process. 

e. Flood~lain management. The State has 

substantial legislative vehicles for 

constructing flood-control facil i ties, but 

1 ittle statewide authority to establish 

regulations 1 imi ting development in 

floodways and flood-risk areas, ca7 led 

"non-structural fl oodpl ain management. " A 

comprehensive State floodplain management 

act could provide an effective umbrella for 

protecting all water-related resources-- 

streams, wetl ands, overflow areas, and 

riparian vegetation--as we1 l as upgrading 

the protection of public health and 

safety. 

f. Coastal zone manasement . The Coastal 

Act (Pub1 ic Resources Code, Section 30000 

et sea.1. The most effective wetland and 

stream protection pol icies in any Federal 

or State law are found in the Coastal Act 

of 1976, especially Section 30231 as 

foll ows: 

The biological productivity and the 

qual i ty of coastal waters, streams, 

wetl ands, estuaries, and 1 akes appropriate 

to maintain optimum populations 

of marine organisms and for the 

protection of human health shall be 

maintained and, where Feasible, 

enhanced through, among other means, 

minimizing adverse effects of waste

water discharges and entrainment, 

control l ing runoff, preventing 

depletion of ground-water suppl ies and 

substantial interference with surface 

waterflow, encouraging waste water 

reclamation, maintaining natural 

vegetation buffer areas that protect 

riparian habitats, and minimizing 

a1 teration of natural streams. 

Policies such as the above have been 

administered through the Coastal Cornission's 

permit authority. Certification of 

local coastal programs transfers resource 

protection into local government processes. 

Of special interest is the Coastal 

Commission's document, Inter~retive 

Guidelines for Wetlands Other Wet 

~nvironmentafi Sensitive Habitat Areas 

(adopted February 5, 1981). These 

guidel ines have improved management of 

coastal resources, and particularly the 

maintenance of "environmentally sensitive 

habitat areas. * Regarding development near 

these areas, the guidel ines rely on the use 

of hundred-foot nondevelopment buffer 

zones. No attention is given to criteria 

for the design and siting of adjacent 

construction to minimize adverse impacts 

(Jones, 1982). The Gomission has 

attempted to provide an example for other 

jurisdictions in preserving riparian 

habitat on the south-central coast; 

however, the area of jurisdiction is narrow 

and the outlook uncertain as local 

governments take over authority (Zentner, 

1981; Capelli and Starkey, 1984). 

g. Wildlife Habitat Conservation. The 

State has substantial declarations of 

pal icy regarding the preservation of rare 

and endangered species and the wise management 

of all 1 iving resources. However, 

there is little legal or regulatory 

process--except in the Coastal Act--to 

reduce and mitigate impacts on wildlife 

habitat (much of which is waiter-related) . 

Cal i fornia, for example, l acks the Federal 

Endangered Species Act requirements that 

pub? ic investments and act ions be withheld 

where they would damage critical habitats 

of threatened species (Jones, 1982). 

6.3.2 State Resul at ions and Asencies 

a. Deaartment of Fish and Game. Much of 

the work of Department of Fish and Game is 

oriented toward saving wetland, aquatic, 

and riparian habitat, but the agency has 

few tools to do so. Of special interest is 

the Department of Fish and Game authority 

in Sections 1601-1606 of the Fish and Game 

Code to execute stream-bed a1 teration 

agreements for any activity that will 

divert, obstruct, or change the natural 

flow or bed of a river, stream, or fake. 

This is an important negotiation and 

mediation process, but it suffers from 

personnel shortages and lack of public 

awareness (Jones, 1982). Long- term 

preservation of riparian habitat would be 

advanced if Department of Fish and Game 

were to initiate programs to solicit. land 

donations of riparian corridors and to 

restore riparian habitat on public lands. 

b. Deoartment of Water Resources. Under 

the previous administration, Department of 

Water Resources increased its pol icy 

support for preservation of riparian 

vegetation and instream retention of water 

(see Policies and Goals 

California 

Water Manaqement for the Next 20 Years, 

public review draft of Bulletin 4, 

September 1981). Under the current 

admini stration, pol icies protecting 

riparian vegetation have been given low 

priority (Jones, 1982). In 1982 Department 

of Water Resources began an Urban Streams 

Cleanup and Restoration Program that 

included vegetation pl anting and 

restoration. The program was refunded in 

October 1984. 

c. State Coastal Conservancy. Thi s 

agency works with local agencies, 

landowners, and nonprofit organizations to 

enhance, restore, and protect coastal 

resources. Since 1978 it has been funding 

coastal restoration and enhancement 

projects, including several wetl ands in 

Southern California. In recent years a new 

emphasis has been placed on watershed 

management and the restoration of streams 

and riparian zones ; however, the agency's 

wetl and program does not require cosponsoring 

local jurisdictions to offer 

guarantees that they wi 7 1 establ i sh 

adequate erosion control s j i ncl ud i rig the 

use of riparian vegetation zones) in the 

watershed to minimize sedimentation that 

could erase pub1 ic investments in wet1 ands 

by a severe winter storm (Jones, 1982).

d, Department of Parks and Recreation. 

This agency is responsible tor the purchase 

and management of lands suitable for pub1 ic 

recreation. Department of Parks and 

Recreation can class1 fy wet1 ands, streams, 

and riparian forests within the park system 

as natural preserves, which prohibits 

development of these areas for parking 

lots, camping grounds, and other intensive 

uses. According to the deparlment, the 

designation has not been used extensively 

(Jones, 1982). 

e. De~artment of Conservation. The 

department is concerned 1 argely with regulating 

mining and gas/oil operations, but 

a1 so has a l imi ted soil -conservation program. 

Its Division of Mines & Geology 

regulates gravel and sand mining. A condi - 

tional use permit is required, as is a 

recl amat ion plan under the Surface Mining 

and Reclamation Act of 1975. The status of 

riparian systems and river restoration is 

supposed to be monitored annually in mining 

areas. In its useful but never officially 

released pub1 ication, Cal ifornia Soils: An 

Assessment (19791, the department ranked 

streambed erosion as the third most severe 

of California's 11 soil problems. 

Retention of riparian vegetation as a 

protective measure was not stressed in this 

document. The otherwise excellent Erosion 

- and Sediment Control Handbook (1978) 

suggests only that "vegetative lining 

reduces the erosion along the channels and 

provides for the filtration of sediment.. . 

and improves wild1 ife habitat." In Southern 

Cal ifornia each county has a Department 

of Conservati on-approved ordinance regulating 

sand and gravel operations. 

f. De~artment of Health Services. 

Concerns of this department illustrate the 

competing interests that must be considered 

in water-re1 ated resources management. For 

instance, thickets of streamside growth, 

especially blackberry tangles in urban 

areas, can harbor rats and are, therefore, 

di scouraged by the department. 

g. Wi ldl i fe Conservation Board. The 

Gild1 ife ConservatSon Board has an active 

wetland and riparian forest acquisition 

program that can include restoration of 

such areas. Within the study area, for 

example, the W i Id1 i fe Conservation Board 

has purchased the Hidden Valley Wildlife 

Area on the Santa Wna River (1,267 acres). 

6.4 LOCAL GOVERNMENT 

6.4.1 Local Government Plans 

There is great variation among 

jurisdictions in the plans and ordinances 

used for resource management. In most 

cases there are no state standards for 

consistency, adequacy, or effectiveness of 

1 ocal pl ans and ordinances. Tool s 

avai 1 able to 1 ocal governments for resource 

management are listed in Table 13. This is 

followed by a description of some of these 

tools. 

a. General ~lans. The local government 

general plan, as defined in Government 

Code, Sections 65300 through 65403, is a 

vehicle for the collection and presentation 

of local and State policies (including 

goals, objectives, and sometimes 

recommendations) regarding the future 

development of the area. The text of the 

general plan is essentially a nonbinding 

statement of intent. However, the land-use 

maps that are part of the general plan 

(usually the land use and circulation 

elements) must be compatible with the 

zoning designations, as mandated by the 

legislature in 1971 in Government Code, 

Section 65860. Policies in local plans can 

be presented as a call for action or as a 

recommendation for future consideration, 

which is often a misleading substitute for 

commitment (Jones, 1982). 

b. Area olans. These are mini -general 

plans developed for a specific region or 

portion of the jurisdiction. They have the 

advantage of allowing a jurisdiction with 

many types of terrain or varying 

devel opment pressures to address 1 and -use 

concerns more thoroughly. Their 

effectiveness, however, still depends on 

the specificity and integrity of the 

implementing ordinances. 

c. Stream conservation a1 ans, Local 

government interest in streams has been 

1 imited 1 argely to flood-contra7 projects, 

Conservation plans and programs for 

watewlrays have not been cornan.

Table 43, Local took far resource management. 

- 

1. Plans 

- General plan (including 1 and use/circul ation elements; open space/conservation 

elements; recreation/scenic highway elements; and safety elements). 

- Area plan 

- Stream conservation plans 

- Significant resource area inventories 

2. Ordinances 

- Zoning ordinances 

- Local ordinances 

- Use permits 

- Open space, conservation, or resource management districts 

- Overlay or combining districts 

- Watercourse or streamside protection ordinances 

- Fl oodpl ai n management ordinances 

- Setback requirements 

- Grading ordinance 

- Erosion control ordinances 

- Surface mining and reclamation ordinances 

- Design control district ordinance 

3. Jnteqrated Plans and Ordinances 

- Pl anned unit developments 

- Specific plans 

- Special planning area ordinances 

- Subdivision ordinances 

- Local coastal programs 

d. Siqnificant resource areainventories. 

The identification of "significant" 

resource areas, with policies for 

their protection, can be incorporated into 

the conservation/open space element of the 

general plan or placed in a separate document. 

For example, Los Angeles County has 

incorporated an inventory of 65 significant 

ecological areas in its conservation/open 

space element (19791, including streams, 

riparian vegetation areas, and marshes. 

The use of zoning or some variation of the 

police power is, of course, the vital 

element. Lists of such areas accomplish 

protection only when they are connected 

with Gal i forni a Environmntal Qua1 i ty Act 

(CEQA) and regulatory processes. 

6.4.2 Ordinances 

a. The zonin~ ordinance. The zoning 

ordinance is one expressian of the pal ice 

powers available to local governments to 

regulate land use. Typically the zoning 

districts include blocks of Sand for 

residential, comrcial, Ondustrial, 

agricultural, and, since the 1970s, some 

open-space uses. There are variations and 

subgroups with each category (such as 

residential/single-dwelling and 

residential/multiple-dwell ing) . Designations 

and names of zoning districts vary 

among jurisdictions. While most open-space 

districts do not include specific 

comprehensive standards for all forms of 

uses and impacts, there is no reason why 

they cannot. 

b. Local ordinances. Other ordinances 

can be used to manage or protect resources, 

especially when a uniform rule of conduct 

is needed for consistent appl ication across 

a17 land use zones (such as for the 

protection of stream resources). 

c. The use permit. Local governments 

have numerous types of permits for the many 

uses they must regulate. A use permit is 

simply a regulatory tool that, when backed 

up with an explicit ordinance, allows the 

jurisdiction to authorize developments or 

uses subject to conditions that protect

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equires that a new diversion channel be 

built around the excavation area and that 

a minimum 60 ft-wide buffer zone on both 

sides of the channel be "maintained free of 

all excavation and other operations to 

protect riparian vegetation and control 

sediment." 

In the county's Local Coastal Program, 

Environmentally Sensitive Habitat Areas are 

designated for use in the coastal zone. 

Included in the LCP discussion is the 

impartance of protecting riparian 

vegetation along creek corridors, but there 

are no specific policies or ordinances to 

implement that goal. 

c. Los Anseles County. The Conservation/Open 

Space Element for Los Angeles 

County (adopted as part of the general plan 

revision of 1979) includes language that 

states the need "to protect ... watershed, 

streams, and riparian vegetation to minimize 

water pollution, soil erosion, and 

sedimentation, maintain natural habitats, 

and to aid in ground water recharge." 

There are 65 identified significant ecological 

areas in this element that are 

listed in a report entitled "Land Capabi 

1 i ty/Sui tabi 1 i ty Study, Los Angel es 

County General P1 an Revision Program" 

(1976). Streams, riparian vegetation 

areas, and marshes are included in this 

listing, but are protected primarily 

through the CEQA environmental review 

process (1 ocal permits can be conditioned 

Lo protect them but are not required to be 

so written) . 

The county's Flood Protection District 

requires that structures be kept away from 

stream courses to prevent bank erosion. 

d. Oranqe Countx. The Orange County 

General Plan Land Use Element (March 1975) 

contains general pol icy language to 

restrict development in designated flood 

plains and on or adjacent to rivers, 

creeks, streams, and other riparian areas. 

Additional policies support the concept of 

maintaining stream courses, estuaries, and 

other water bodies in their natural state, 

consistent with pub1 ic safety. 

The Open Space Element (June 1973) seeks 

Ba preserve "the natural resources of the 

county, plant and animal 'rife, fish and 

wild1 ife habitat, study areas, rivers and 

streams and their banks, bays and 

estuaries, and watershed 1 ands. " 

The Conservation Element (January 1978) 

is more detailed in its recommendations and 

text but again is not backed up by 

implementing ordinances. The local Coastal 

Plan has not yet been completed by Orange 

County or certified by the Coastal 

Commission (November 1985). 

e. Riverside County. As part of the 

Riverside General PI an, an open- space and 

conservation plan has been developed to 

preserve, protect, and manage resource 

areas identified in the Open Space and 

Conservation Inventory. This is 

accomplished through resource maps and 

programs throughout the Environmental 

Hazards and Resources Element of the 

general plan. A vegetation resources map 

identifies riparian areas. It is the 

policy of the county to maintain and update 

these inventories, but review of all 

development proposal s in identified 

ri pari an areas i s accompl i shed only through 

the CEQA process. 

Critical habitats are del ineated on the 

Vegetation Resources Map as either water 

resources/fl ooding areas or wildl i fe/ 

vegetation areas. Both are restricted to 

open-space and 1 imi ted recreational uses; 

research and educational uses are 

additionally permitted in wild1 ife/ 

vegetation areas. The county's open space 

zoning designations further carry out the 

objectives and policies of the Open Space 

and Conservation PI an. 

f. San Dieclo County. The following 

policies are set forth in the Conservation 

Element (May 1983) of San Diego's General 

PI an: 

Fl aod control measures shal 1, whenever 

practical, util ize natural floodways 

and floodplains, maintaining riparian 

habitats and historic stream flow 

volumes. No structures or excavations 

which adversely affect flood-plain 

vegetation and wildl i fe, or decrease 

their value as migration corridors 

should be permitted. 

Storm drain runoff should be planned 

and managed to. . .enhance wi 1 dl i fe, and 

reduce the impact of erosion.

She county will act f.s conserve and 

enhance vegetation, wildlife, and 

Bi sheries resources. 

The element also calls for the lase of 

mitigating measures for projects with 

unavoidable adverse impacts on habitat. 

It recognizes the Resource Conservation 

Area (RCA) overl ay designation, as 

defined in its Land Use Element, which is 

applied to several areas with riparian 

wood1 and. 

in the county's open-space element 

(August 1977) are objectives seeking 

conservation of the habitats of rare or 

endangered plants and wildlife, plus the 

"use of streams as 1 ocal open spaces. " The 

el ement call s for the development of 

"comprehensive plans for the floodplains" 

of all major rivers under the County's 

control . One such plan, prepared for the 

San Dieguito River (March 1982), states 

that: 

maintaining the floodplain in an open 

condition provides the opportunity for 

an environmental system involving a 

riparian and floodplain ecosystem ... 

and live stream. A natural riparian 

system ... will maintain the scenic 

quality of the river area. 

These goals would be accomplished by 

prohi bi ti ng devel oprnent in the fl oodway and 

encouraging clustering of houses outside 

the boundaries of the floodplain. There is 

no specific prohibition against removing 

riparian vegetation or encouragement of Its 

enhancement. 

The county's Local Coastal Program 

includes the San Dieguito Land Use Plan 

(July 1382). ~n a section on 

environmentally sens jti we habitats is a 

prohibition of "any development or other 

significant disruption" of riparian habitat 

in the study area. The LCP also includes 

a zoning ordinance (March 21, 1984) that 

establ i shes an Ecol ogi cal Resource Area 

that is designed primarily to protect 

wetlands but is also applied to "lagoons 

and their tributary streams and adjacent 

up1 ands within the Cal i fornia Coastal 

Zone." Removal of riparian vegetation is 

not specifically prohibited or regulated, 

although development standards are intended 

to "conserve the widest variety of physical 

and vegetation conditions to maintain 

habitat diversity." 

6.5 SUMMARY 

There are numerous Federal and State laws 

and agencies, as well as local ordinances 

and districts, that have regulatory 

functions affecting riparian zones. Many 

of the laws and regulations conflict or 

overl ap. Some protect resources; others 

permit resource consumpti on or degradation. 

The best protections are offered by the 

Coastal Act of 1976; however, the 

boundaries of the coastal zone are narrow 

and do not extend upstream or consider 

watersheds (see Figure 1 in Chapter 1, 

which depicts the project study area). A 

comprehensive management program with a 

clear enumeration of resource priorities 

that apply to overl appi ng jurisdictions 

would provide greater riparian protection 

and restoration potenti a1 .

CHAPTER 7. 

RlPARIAN ECOSYSTEM RESTORATION 


Since the mid-1960s there has been 

increasing interest in protecting riparian 

habitat, both on a national level and in 

Cal iforni a (Jahn, 1978). The USFWS and the 

Cal i forni a Department of Fish and Game, 

both charged with wild1 ife management, have 

developed policies and goals relating to 

protection of riparian areas. A number of 

environmental groups, including the 

National Audubon Society, the Sierra Club, 

and The Nature Conservancy, have made the 

protection and restoration of riparian 

habitat a high priority. They view 

riparian areas as important up1 and 

extensions of marshes and wetlands. By 

protecting creeks, reducing erosion, and 

preserving or reestabl i shing riparian 

vegetation, they feel it is possible to 

improve the health of downstream marshes 

(Nunnal ly, 1978). 

Nevertheless, the primary social trend in 

Southern California is still toward 

development of the flood plains, which 

almost always involves elimination of 

riparian corridors of vegetation (Warner, 

1983). New requirements for restoration of 

degraded riparian habitat have been viewed 

as a nuisance by some developers, since 

restoration and mitigation pl ans cost money 

to implement and can add time to project 

schedules. In addition, riparian corridors 

are considered overgrown jungles rather 

than a feature that enhances property 

values. Examples of riparian habitat are 

listed in Appendix D. 

7.2 LAND USE AND OWNERSHIP PAUERMS 

One af the difficulties in carrying out 

significant stream restoration projects in 

southern coastal areas results from the 

need to gain the cooperation of numerous 

1 andowners and 1 ocal government juri s- 

dictions. In Northern California, there 

might be three large ranch properties 

located in one or two counties. In 

Southern Cal i forni a, however, 1 and ownership 

along a river usually includes many 

small parcels with frequent changes in 

ownership. In addition, there are many 

incorporated areas, and counties frequently 

manage small parcel s between incorporated 

cities. Projects become complex and 

require time-consuming coordination 

efforts. 

Rivers and streams in Southern 

California, some draining sizable watersheds, 

also are divided into numerous 

ownerships, and thus are not easily 

incorporated into a regional watershed 

management plan. In general, the more 

complicated the ownership along a river, 

the greater the chances for failure in 

reaching a management consensus among a17 

landowners. If any owner chooses not to 

participate, the overall success of the 

restoration program is diminished. 

Depending on the size of the parcel in 

question, any omission has the potential to 

reduce the effectiveness of a watershed 

management or riparian restoration plan. 

7.3 CQNFLlCTlNG OBJECTIVES 

Protecting and restoring riparian areas 

often is in direct conflict with traditional 

floodplain management (Detwi 1 er, 

1980; Goldner, 1981; Jordan, 1984). Since 

high priority is given to protection of 

public property, the majority of rivers in 

Southern California, in both urban and 

agricultural areas, have structural floodcontrol 

devices, dams, and concrete 

channels. Little or no attention has been

given to maintaining natural meanders, to 

kydraul ic processes in streams, to w if dl ife 

needs, or to impacts on downstream wetlands 

(Ki bby, 1978). Many activities permitted 

in flood plains, such as public parks, golf 

courses, and agriculture, el iminate or 

drasticall y reduce riparian habitat and are 

very damaging to riparian wild1 ife. 

Because of the lack of base1 ine data on 

restored riparian areas, uniform guidel ines 

for successful restoration projects have 

not been developed (Dawson, 1981). Each 

permit appl icat ion involving restorat ion 

work is conditioned independently. 

Conditions on permits vary considerably, 

depending on the qua1 ifications of staff 

and available time for review. Consultants 

preparing EIRs must propose mitigation 

measures for impacts on riparian areas in 

the absence of accepted criteria for 

measuring these impacts. As a result, 

restoration plans tend to be based on 

estimates of potential impacts of a project 

and restoration work that may be needed 

rather than on long-range habitat 

enhancement objectives (Prunuske and 

Morrison, 1982). The criteria for design 

of a revegetation plan should be agreed 

upon before the project is designed. 

Mi thout this early agreement among the 

parties involved, it is highly probable 

that a restoration program will fail. 

W i ldl i fe-management agencies wi 11 

sometimes agree on overall goal s of habitat 

restoration, but will fail to agree upon 

specific plans because of their focus on an 

individual species. Should vegetation be 

managed for red-shouldered hawk habitat and 

other raptors that require a mature 

overstory, or for the rare and endangered 

least Bell's vireo and willow flycatcher 

that require young willow thickets (Fitch 

et a1 ., 1946; Zembal, 1984b)? Determinations 

of management objectives must 

rely on subjective judgments since vireo, 

flycatcher, and raptors are all in need of 

habitat protection. Better interagency 

coordination could help in resolving 

management conflicts, but there will always 

be differences of opinion over which 

species "deserves" more protection. 

Negotiation is a critical step in 

determining revegetation pl an requirements. 

If this process is unsatisfactory for any 

of the parties involved, the solution is 

1 jkely to be a political one and the entire 

program may suffer (Fisher and Ury, 1984). 

7.4 TIMING CONFtlCTS IN RESTORATION 

PROJECTS 

A number of permitting procedures create 

confusion and conflicts for those 

implementing a restoration project. Most 

procedures do not provide for advance 

planning in ordering pl ants from nurseries. 

For example, the CALTRANS (Cal i forni a 

Department of Transportation) staff may not 

know what mitigation will be required by 

the USFWS and the Department of Fish and 

Game until just before construction begins. 

There is often too little time to ensure an 

adequate supply of a desired species from 

the nursery. 

The timing of construction may create 

another kind of difficulty in that 

construction may be 1 imited to late summer 

because of bird migration or nesting 

events. If construction is completed in 

fall, plantings may not be well enough 

established to survive winter rains; if 

planting is postponed until winter or 

spring, rains may cause extensive spoil 

erosion. In addition, early spring 

plantings may interfere with early spring 

nesting. 

The third type of conflict occurs when a 

time limit is set on agency funding. For 

example, when CALTRRNS funds a mitigation 

project as part of a bridge construction 

project, the mitigation is considered to be 

part of the project cost. CALTRANS, 

however, considers any activities after the 

2-year construction period to be maintenance, 

and that agency does not pay for 

maintenance. If a riparian revegetation 

program has not been imp1 emented before the 

2 -year period has el apsed, CALTMNS 

considers itself no longer responsible for 

funding the program (J. Rieger, CALTRANS, 

Sacramento; pers. comm., 1984). 

7.5 ENFORCEMENT OF MITlGATlQN 

A major constraint in achieving restoration 

of riparian habitat is the lack of 

regul atory mechanisms to enforce mi tigal.ion 

conditions. In a Rumber of cases in the 

Southern Cal ifornia study area, permits for

construction projects have been issued and 

a bridge or facility has been built, but no 

revegetation has been attempted (Wheeler 

and Fancher, 1981). A1 though considerable 

time may have been devoted to working out 

conditions to mitigate project impacts, 

nothing was done to enforce these conditions 

and the mitigation never took place. 

Funds are not generally available to 

city, county, State, or Federal agencies to 

conduct a monitoring program for riparian 

habitats. These agencies usually do not 

have the inhouse expertise needed to 

monitor and interpret results observed 

during revegetation projects. When 

inspections do occur, the inspectors often 

do not have the training to determine 

whether the vegetation specifications are 

being followed or to understand what the 

specifications mean and how critical they 

can be. For example, in one case, time 

requirements for revegetation were wai wed 

so that when the vegetation was finally 

installed at the wrong time of year the 

plants did not survive (3. Rieger, pers. 

comm.). There is no formal process or 

enforcement power to ensure that permit 

conditions are compl ied with or are carried 

out in a way that ensures success. 

In addition to lack of enforcement and 

follow-up of revegetation conditions, local 

grading ordinances often contain weak 

language such as "where feasible. " 

Riparian corridors often are severely 

damaged during clearing and grading 

operations by bul ldozer operators who are 

not given specific guidelines to follow 

when working near creeks. Slopes may be 

properly or improperly formed, and erosion 

from winter rajns may create gullies and 

carry off valuable soil (Gray and beiser, 

1982). Because of these limitations, the 

enthusiasm of field staff of local, State, 

and Federal agencies for protecting 

wildlife habitat too often wanes due to 

lack of enforcement and followup at the 

administrative level. 

7,6 RESTQRP\tlON PQTENTIAL IN SOUTHERN 

GALlFaRNIA 

Hany rivers and streams in Southern 

California still support large stands of 

riparian vegetation, although some are 

severe1 y degraded, particularly the under- 

story. Other rivers have 1 ittle remaining 

vegetation but have not been extensively 

channel i zed* Where sufficient water flows 

for some portion of the year, and the river 

has not been channelized, there is a 

potenti a1 for restoration of riparian 

habitat. Where water tab1 es have been 

lowered by gravel mining and the natural 

stream contours severely a1 tered, the 

potenti al for restoration is reduced. 

The following sections discuss a basic 

approach to riparian habitat restoration, 

much of which is derived from the experience 

of those involved in a summary of 

restoration projects carried out in Southern 

Cal ifornia and 1 isted in Appendix E. 

7.6.1 Develo~ment of Restoration PI ans 

At the outset of a restoration project, 

the following questions need to be 

answered: 

- Who are the interested parties and 

what roles will each play? 

- Who will pay? Who will benefit? 

- What public agencies and interest 

groups wi 11 be involved? 

- What are the restoration goals? 

- What work needs to be done? 

- Who will take the lead in design and 

implementation? 

- Who will manage and maintain the site 

and for how long? 

- Who will monitor and how often? 

- What activities will be allowed or 

restricted? 

The size of the project and the number of 

interested parties will influence the 

complexity of the answers to these 

questions. An advisory committee to 

oversee the project, to establish goals, 

and to keep energies focused on the desired 

outcome may be helpful to all parties 

concerned (EPA, 1972; Detwi 1 er, 1980; 

Werbkersman, 1982). 

7.6.2 Establishins Goals 

Often, the primary goal of a restoration 

plan is to mitigate the effects of 

unavsidabl e habitat losses by creating or

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of appropriate understory plants. In 

disturbed areas, the understory may be 

difficul t to re-establ ish because of the 

dominance of non-native introduced plants, 

specifically tamarisk (Tamarix spp.), cane 

plant (Arundo donax), and castor bean 

(Ricinus communis) . Nevertheless, it is 

feasible to remove the undesirable plants 

and revegetate with native understory 

species. 

c. Buffers. Buffers are an essential 

part of many riparian restoration plans, 

but few planners agree on how wide a buffer 

should be or on what activities are acceptable 

in a buffer zone. More needs to be 

known about what actually happens to 

riparian vegetation with and without buffer 

areas. At present, it is generally assumed 

that buffers are necessary, yet requirements 

vary from project to project. 

Buffers, which include native plants, 

should be designed to provide some habitat 

values as well as aesthetic values. They 

should serve as a transition zone between 

the orderly urban landscape and the 

naturally random riparian forest, 

Features allowed in the buffer area could 

include bike paths, pedestrian walkways, 

and other passive recreational facilities. 

Motorized vehicles should be prohibited, 

except as necessary for safety or maintenance. 

Criteria for establishing the 

size of buffer areas will depend on such 

standards as: 

- biological significance of the 

adjacent riparian lands; 

- sensitivity of wildlife to disturbance, 

- susceptibility of riparian area to 

erosion from landward development; 

- use of natural topographic features to 

buffer development ; 

- use of existing man-made features 

(roads, l evees, etc.) to locate buffer 

zones ; 

- type and scale of development proposed. 

The appropriate buffer width will vary 

according to the standards menti oned above, 

but a minimum of 100 ft is desirable. 

d. Corridors. There is a need to l ink 

riparian wi l dl i fe corridors whenever 

feasible, rather than to allow continued 

isolation of small riparian groves. In 

designing a revegetation plan, it is 

important to maintain or re-establish 

continuity with adjacent habitats. This 

means a1 1 owing "fingers" of chaparral 

vegetation to extend down into the riparian 

zone. This allows movement of upland 

wildlife into the riparian corridor and 

provides additional foraging habitat for 

riparian wildlife species. 

Likewise, there is a need to re-establish 

connections between riparian groves 

separated by development. This can be 

accompl i shed by rep1 anting narrow bands of 

vegetation to link the disjunct groves. 

Riparian corridors are logical candidates 

for greenbelt and open-space designation 

and can add aesthetic qualities as well as 

biological values to the property (Sal ata, 

1983). Any existing and potential wild1 ife 

habitat on the site should be considered 

for incorporation into the revegetation 

plan. Flood retention basins are 

candidates for revegetation and can greatly 

enhance the property's value for wildlife. 

Suitable vegetation can be planted in a 

corridor connecting a pond or basin with a 

riparian revegetation area, increasing 

overall wildlife use by providing a 

protected travel route between the two 

habitat types. 

7.6.4 Implementation 

As a general rule, a vegetation plan 

should be implemented during or immediately 

after project construction (Figure 54). 

Restoration should be performed in stages, 

each with a specific date of completion. 

This a1 1 ows careful monitoring of progress 

and assures that a planting schedule will 

be followed. Whenever pass i bl e, construction 

should be done before or after 

critical nesting and rearing periods for 

ansite wildlife to avoid unnecessary 

impacts. If vegetation must be removed, 

this should be accompl ished we1 1 before the 

nesting season. If a long section of river

3.6.5 Manaqement and Maintenance 

Figure 54. Mitigation of a construction project has 

resulted in riparian restoration along an urban 

portion of the San Diego River. 

will be affected, work should be phased, 

where possible, so that small increments 

are carried out at disjunct locations in 

order to avoid massive wildlife impacts. 

While one area is disturbed during 

activities such as channelization and 

vegetation removal, wildlife can move to 

an undisturbed site nearby. After restoration 

is achieved, wild1 ife can gradually 

move back into recovered and restored 

habitats. 

One approach is to allow only a certain 

percentage of the river reach to be disturbed 

at any one time. 'Subsequent phases 

of a project could not be undertaken until 

prior phases are completely restored and 

well estabf ished. Phasing decisions should 

be based on site-specific biological and 

hydroiogical data. ihi s approach should 

reduce the cumulative loss of wildlife 

habitat that occurs when an entire project 

is built at once. 

A plan for management, maintenance, and 

monitoring of the project site should be 

developed at the same time as the 

restoration plan. Although this may seem 

an obvious point, most revegetation 

programs do not include a mechanism for 

long-term management and maintenance. Once 

the plants are in the ground, there is a 

strong tendency to move on to other 

projects. 

To ensure the success of a revegetation 

program, the plan must include provi sions 

for ongoing maintenance. Typical 

activities that must be planned for are 

rep1 acement of di seased and dying pl ants; 

maintenance of irrigation systems; 

protection of young plants from tramp1 ing, 

vandalism, and browsing; control of 

erosion; judicious use of herbicides, 

pesticides, and rodenticides; pruning, 

topping, or removal of vegetation; and 

any other activities necessary to maintain 

the site in a condition that meets the 

original goals of the program (Gray and 

Lieser, 1982). The pf an must specify who 

will be responsible for carrying out and 

funding maintenance and management. 

General ly , the devel oper wi 11 be expected 

to do this under terms of a maintenance 

agreement between the developer and the 

permi tt in,g agencies. 

7.6.6 Technical Monitoring 

A technical monitoring program is essential 

to judge the success of a revegetation 

program. Thi s monitoring effort should be 

specified in the maintenance agreement 

described above and include a determination 

of who will be responsible for carrying out 

the work. Reports should be required for 

a minimum of 5 years as part of the 

maintenance agreement and should be sent to 

the appropriate permitting agencies, Local 

university students might be involved in 

annual monitoring as a class project. 

Two indicators are typically used to 

monitor success of revegetation programs: 

vegetation devei opment and bird usage. Any 

professional monitoring work should include 

hydrol~gica'i data. The emphasis of the 

monitoring program must be on analysis and

conclusions rather than simp1 y the 

col f ection of data. 

Data col lection techniques could include 

use of aerial infrared photography to may 

vegetation extent and monitor health. 

Photos should be taken in spring (May-June) 

and just before fa1 1 dormancy (August- 

September); they may be used to locate 

dying trees as well as to assess any 

stresses affecting the health of the 

plants, inct uding overdrafting of water 

tables, increases in upstream diversions, 

diseases, compaction of soil in root zones, 

~nundation for long periods, and drought. 

51 ack-and -whi te or color photos should a1 so 

be taken from permanent stations on the 

ground to provide a record of progress. 

Other niore traditional techniques for 

measuring veget atran growth Involve 

t ransct l andlysis to determine fol ?age 

dens~ty, diversity, patch~ne\r. and 

spec tt.5 lip@( t f !C growth rate and surv rval . 

Mvttlcld\ developed for rxpari dn sys teins are 

tfrsc r 1 tted r n MdcArthi~r dnd MdcArChur (1961) 

dtiti Ancicrson dnti Ohmart (1977). t3ird 

surveys shokrltf bc conducted to dtlttlrmi ne 

nrit ~ng, wrnterlng, dnd migratory uses of 

the zttc Elmien, 1911, 1377; Anderson artd 

Ohrn~)*f , X 984) . 

I f vciqc" dt ton dnd wi it11 i re are present on 

t lit, i t prror ta project devt.lopnit;nt, 

bas6.l rrw wrldltfu and plant datd should be 

The City of San Diego's Planning 

Department staff was required, under a 

Corps permit condition suggested by the 

USFWS, to develop a %betlands management 

plan for the San Diego River, particularly 

the stretch flowing through Mission Valley. 

The result was the 1983 San Diego River 

Wet1 ands Management Pl an, the primary 

purpose of which was to establish a means 

of maintaining and improving the qua1 ity of 

the wetlands associated with the San Diego 

River while still allowing for development 

in Mission Valley. A strong goal of the 

plan was to incorporate biological considerations 

into planning for development 

and flood management. 

Private developers took the next step and 

formed their own plan for a portion of the 

Mission Valley corridor. Their plan, 

FSDRIP, i s a locally proposed combinati on 

of flood control, natural area, and 

parkway. The Corps is involved only as a 

permitting agency under Section 404 of the 

Clean Water Act, not as a constructing 

agency. The City of San Diego, the 

Cal ifornia Department of Fish and Game, and 

the USFWS are represented on an advisory 

committee to oversee the development and 

implementation of the plan. 

In 1983 the FSDRIP plan was approved by 

the City of San Diego and an EIR was 

certified. The EIR called for a detailed 

revegetation plan, which was prepared by 

Nasl and Engineering, Mooney- Lett ieri and 

Associates, and Wier Biological (1984). 

A1 though heavily involved in the design of 

the revegetation plan, and aware that it 

was prepared by know1 edgeabl e 1 ocal 

revegetation biologists, some agency staff 

remained skeptical about the plan's 

feasibility. The two main concerns were 

that the results would not look natural and 

that the plan would not replace riparian 

values lost. Some biologists also were 

concerned about the time required for 

complete revegetation and the habitat loss 

and impact on wildlife in the interim. 

FSDRIP is a precedect-setting project. 

No other riparian vegetation plan of this 

scale has been attempted or proposed in 

Southern California. Other revegetation 

pa ans cjenerzlly have been associated with 

park construction, where recreation is the 

primary purpose and preservation of 

wi Id1 ife habitat secondary or even 

incidental. The only available model for 

FSDRIP is work done by Anderson et al. 

(1984b) in Arizona, who successfully 

transplanted and revegetated areas using 

native cottonwoods and who was consulted in 

connect ion with the FSDRIP pl an. Anderson, 

however, has not emphasized understory 

vegetation, and the results have been a 

form of greenbelt park rather than 

restoration of a complete riparian 

ecosystem. 

Since no other revegetation efforts of 

this magnitude have been attempted in 

California, the FSDRIP plan is designed to 

provide a model and data base for future 

riparian restoration efforts. The plan 

emphasizes specific vegetation development 

and management milestones with assured 

funding for remedial measures along with 

long-term protection. The intent is to 

mitigate impacts on plants and animals from 

the channel ization of approximately 7,000 

ft of the San Diego River in the Mission 

Valley area. Under this plan, the newly 

constructed earthen channel would be 

planted with riparian woodland and 

freshwater marsh vegetation to enhance its 

value as wild1 ife habitat. About 42 acres 

of woodland and 15 acres of marsh would be 

created and maintained. Construction was 

scheduled to begin in late 1986. 

The channel has been designed to allow 

commercial and residential developments 

approved by the City as part of the FSDRIP 

project. The channel has been engineered 

to handle up to the 100-year flood event. 

It has been designed to function with fully 

developed riparian vegetation along its 

banks. Is1 ands constructed in the channel 

would also be planted with native riparian 

vegetation. This section of the San Diego 

River has been subjected to varying degrees 

of disturbance from sand extraction, fills, 

unauthorized dumping, and off-road vehicle 

use. Nevertheless, a considerable amount 

of wetland habitat still exists along this 

portion of the river. 

The plan anticipates creation of wetland 

and riparian habitat types typical of 

native woodl ands and marshes, These habi - 

tat types are used by wildlife, particularly 

these species that have declined due 

to destruct ion of ?owl and riparian and 

freshwater marshes. The emphasis is on 

including a large number of plane species

and a high diversity of stand types with 

variation in height and density. The plan 

does not attempt to provide for natural 

succession of community types. The proposed 

revegetat i on would repl ace 1 ost 

wetland habitat at a ratio of 1 to I or 

more. 

Since the plan was developed in consul tation 

with wildlife management agencies, it 

provides developers some assurance that, if 

they adhere to the plan, their projects 

will be approved. It should also discourage 

some projects that would overdevelop 

the floodplain and reduce the 

friction that now occurs between developers 

and permitting agencies . 

One weakness of the plan is that much of 

the 1 anguage requires interpretation by 

city planners in assessing consistency 

between the plan and proposed projects. 

The success of FSDRIP will depend on the 

dedication of project proponents and 

government agencies to the principles of 

the plan. It does, however, a1 low the City 

of San Diego to integrate preservation of 

valuable wetlands into the planning process. 

Other cities in Southern California 

will certainly be following the progress af 

this unique effort; based on the experience 

of San Diego, they will be able to design 

their own flood-pl ain management plans, 

giving full recognition to the need to 

include riparian vegetation and wild1 ife 

habitat as part of a floodway design. 

Enforcement is still available through the 

Fish and Game Code (Section 1600 to 1606) 

and the Corps 404 Permit Program. The 

planning process has tended to de-emphasize 

the proponent's role in the control of the 

project, but it has assured that funds are 

avai l able for an adequate program. 

7.8 RECOMMENDED REFERENCES 

Information on designing revegetation 

plans can be found in the following 

documents. A1 1 are recowended reading for 

anyone attempting riparian revegetation. 

Nasl and Engineering, Mooney-Lettieri and 

Associates, and Vier Biological. 1984. 

Revegetation PI an for the First San Dieso 

River Im~rovement Pro_iect (FSDRIP). 

Nasl and Engineering, 4855 Ruffner, San 

Diego, CA 82111. 38 pp., maps. 

An excel lent example of a we? l -designed 

plan. Includes design criteria and 

guidel i nes for site preparation, 

irrigation, pi anting, maintenance, and 

monitoring and lists criteria for river 

corridar developments. 

Stanley, John T., and Winthrop A. Stiles, 

111. 1983. Revesetation Manual . 

Alameda County Flood Control and Water 

Conservation District, 399 Elmhurst 

Street, Wayward, CA 94544. 183 pp., 

appendixes. 

Includes guidel ines for p1 anting pl ans, 

irrigation systems, contract specifi - 

cations, maintenance, plant descriptions, 

and list of nurseries. Easy to use and 

we1 1 organized. 

Smith, Gregory. 1980. Arroyo Cone.io 

Reforestation Re~ort. City of Thousand 

Oaks, P.O. Box 1496, Thousand Oaks, CA 

91360. 79 pp., appendix. 

Report on reforestation of a major 

wastewater pipe1 ine instal 1 ation. Includes 

step-by-step discussion of repl anting 

effort, illustrated with before and after 

photographs, descriptions of plants used, 

and discussion of follow-up planting after 

heavy fl oods . 

Gray, Donald, and Andrew T. Leiser. 1982. 

Biotechnical Slope Protection Erosion 

Control. Van Nostrand Reinhold. 271 pp. 

Guide to erosion control using vegetation 

in conjunction with other bank-protection 

techniques. Covers detai 3 s of site 

analysis, species selection, seeds and 

planting stocks, site preparation, planting 

techniques, aftercare maintenance. We1 1 

written, with case studies and sample 

designs and specifications for structural 

components of bank protection. 

Schiechtl , Hugo. 1980. Bioensineerinq for 

- Land Recl amat i on and ~onservati on. 

University of ~l berta-ess. 

404 pp. 

Handbook on erosion control and slope 

protection techniques, including 

windbreaks, avalanche wall s, rockfall 

barriers, and waterway bank prstectian. 

Technical examples, plant selection 

criteria, common mistakes in bioengineering 

projects and how to avoid them.

Restorati~n & Manaqement Notes. Journal 

pub1 ished by University of Wisconsin 

Press, Journals Divisaon, 114 N. Murray 

Street, Madison, W I 53715. 

Described as "a forum for the exchange of 

news, views , and i nf ormat S on among 

ecologists, land reclamationists, managers 

of parks, preserves, and rights of way, 

naturalists, engineers, landscape 

architects, and others committed to the 

restoration and wise stewardship of pl ant 

and animal communities." 

7.9 SOURCES OF PLANTS AND SEEDS 

There are many native plant nurseries in 

California, and a current listing may be 

obtained from nursery trade magazlnes and 

the State Department of Forestry. The USDA 

Forest Service pub1 ishes a 1 ist of 

nurseries and seed suppliers dealing in 

species used in forest and conservation 

planting. The USDA Soil Conservation 

Service and forestry agencies have suppl ies 

of some native shrubs and forest trees. 

Cal i forni a Department of ldater Resources 

Bulletin No. 209 lists plants for 

Cal i forni a 1 andscapes. 

Lists of native plant nurseries and seed 

suppl iers are publ i shed in the Revesetation 

Manual (Alameda County, 1383) and the 

Arroyo Cone-io Reforestation Report (G. 

Smith, 1980). The Cal ifornia Native Plant 

Society journal, Fremonti a, contains 

articles on native species and also runs 

advertisements for nurseries and seed 

suppl iers. The Saratoga Horticultural 

Foundation publ i shes Selected Cal i fornia 

--- 

Native Plants with Commercial Sources. 

7.10 SUMMARY 

There is increasing interest in 

protecting and restoring riparian habitat 

in Southern California, but these efforts 

are complicated by highly fragmented land 

ownership patterns and confl icts with 

flood-control objectives. Mitigation 

measures in project permits are often 

inadequate or are not carried out at all. 

Successful restoration work requires early 

agreement on project goal s, si te-specific 

restoration design, correct project 

imp1 ementation, enforcement of permit 

conditions, a maintenance and management 

program, and long-range monitoring.

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known distribution and unknown future of 

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systems in the California coastal zone. 

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Hendrix, eds. Cal ifornia riparian 



Cal ifornia Press, Berkeley.

Birds That Breed in Riparian Habitat i n Coastal Southern California. 

Name 

Pied-bi l f ed grebe, Podi l rrnbus podiceos 

Eared grebe, Podice~s nisricoll is 

Western grebe, Aechmo~horus occidentafis 

American bittern, Botaurus lentisinosus 

Least bittern, ~xobrvchus exilis 

Great blue heron, Ardea herodias 

Great egret, Casmerodius albus 

Snowy egret, Eqretta thula 

Cattle egret, Bubulcus ibis 

Green-backed heron, Butorides stri atus 

Bl ack-crowned night heron, 

Nvcticorax nvcticorax 

White-faced ibis, Pleqadis chihi 

Wood duck, Aix sponsa 

Ma1 1 ard, Anas pl atvrhvnchos 

Northern pintail, Anas acuta 

Cinnamon teal, Anas cvano~tera 

Northern shoveler, Anas cl v~eata 

Gadwall, Anas stre~era 

Redhead, Avthra ameri cana 

Ruddy duck, Oxvura jamai censi s 

Bl ack-shoul dered kite, El anus caerul eus 

Northern harrier, Circus cvaneus 

Cooper's hawk, Acci~i ter cooperi i 

Red-shouldered hawk, Buteo 1 ineatus 

Red-tailed hawk, Buteo jamaicensis 

Americen kestrel, Fa1 co soarverius 

Cal i fornia quail , Gal l ipeola cal ifornica 

Mountain quai 1, Oreortvx pictus 

Black rail, Laterallus .iamaicensis 

Virginia rail, Rallus 1 imicola 

Sora, Porzana carol ina 

Common moorhen, Gal 1 i nu1 a chl oroDus 

American coot, Fulica americana 

Killdeer, Charadrius voci ferus 

Black-necked stilt, Himanto~us mexicanus 

American avocet, Recurvi rostra americana 

Spotted sandpiper, Acti ti s macul ari a 

Common snipe, Gallinago sallinaso 

Band-tailed pigeon, Cot umba fasciata 

Spotted dove, Stre~to~elia chinensis 

Mourning dove, Zenaida macroura 

Common ground dove, Col umbi na ~asserina 

Ye1 1 ow-bi 1 led cuckoo, Coccvzus americanus 

Common barn owl, Tyto alba 

(Continued) 

139

Appendix A, 

(Continued) 

Name 

Habi tatB 

V M LM sourcesb Status/Dependency 

Fl ammul ated owl , Dtys fl arnrneol us 

Western screech owl, Otus kennicotti i 

Great horned owl, Bubo virqini anus 

Northern pygmy owl, Gl aucidium gnoma 

Spotted owl, Strix occidental i s 

Long-eared owl, Asin otus 

Northern saw-whet owl, Aeaolius acadicus 

Black swift, Cvpseloides niqer 

Bl ack-chinned hummingbird, Archil ochus 

a1 exandri 

Anna's hummingbird, Calvute 

Costa's hummf ngbird, Calv~te costae 

Call iope hummingbird, Stel 1 ul a call iope 

Allen's hummingbird, Selas~horus sasin 

Belt kingfisher, Cervl e alcvon 

Acorn woodpecker, Me1 anerpes formici vorus 

Red-breasted sapsucker, &h.vra~icus ruber 

Nuttall's woodpecker, Picoides nutall ii 

Downy woodpecker, Picoides uubescens 

Hairy woodpecker, Picoides villosus 

Northern flicker, Col antes auratus 

01 ive-sided flycatcher, Contouus boreal is 

Western wood pewee Contouus sordidulus 

Willow flycatcher, Emuidonax trail1 i i 

Western flycatcher, Emuidonax difficil is 

Bl ack phoebe, Savorni s nigricans 

Ash-throated flycatcher, Mviarchus cinerascens 

Cassin's kingbird, Tvrannus voci ferans 

Western kingbi rd, Tyrannus vertical is 

Purple martin, Procine subi s 

Tree swallow, Tachvcineta bicolor 

Violet-green swallow, Tachvcineta thal assina 

Northern rough-winged swallow, Stelsidopteryx 

serri ~enni s 

Bank swallow, Rioaria riparia 

Cl iff swal low, Wirundo ~vrrhonota 

Barn swall ow, Hi rundo rustica 

Steller's jay, Cyanocitta stelleri 

Scrub jay, Aphel ocoma coerul escens 

Ye1 low-billed magpie, Pica nuttalli 

American crow, Corvus brachvrhvnchos 

Common raven, Corvus corax 

Chestnut -backed chickadee, Parus rufescens 

PI ai n ti trnouse, Parus i nornatus 

Bushtit, Psal tri~arus minimus 

Whi te-breasted nuthatch, Si tta carol inensi s 

Brown creeper, Certhi a ameri cana 

Canyon wren, Cather~es mexicanus 

(Continued)

Appendix A. 

f Conti nued) 

Name 

Bewick's wren, Thryomanes bewickii x x 

Mouse wren, Troql odytes aedon x x 

Marsh wren, Cistothorus palustris 

x 

American dipper, Cincl us mexicanus x x 

Blue-gray gnatcatcher, Pol io~til a caerulea x 

Western bluebird, Sial ia mexicana 

x 

Townsend's solitaire, Myadestes townsendi 

x 

Swainson's thrush, Catharus ustulatus 

x 

American robin, Turdus mi sratori us x x 

Wrentit, Chamea fasciata 

x 

Northern mockingbird, Mimus pol vsl ottos x 

California thrasher, Toxostoma redivivum x 

Phai nopepl a, Phai nopep1 a ni tens 

x 

Loggerhead shrike, Lani us 1 udovicianus 

x 

European star1 ing, Sturnus vulqaris 

x 

Least Bell's vireo, Vireo bellii willus x 

Sol i tary vireo, Vireo sol i tarius x x 

Mutton's vireo, Vireo huttoni 

Warbl i ng vireo, Vireo qi 1 vus 

x 

x 

x 

x 

Orange-crowned warbler, Vermivora cel ata x x 

Ye1 1 ow warbler, Dendroica oetechi a x x 

MacGill ivray's warbler, Ooorornis tolmiei 

x 

Common ye1 l owthroat, Geothl Y D s ~ trichas x x 

Wilson's warbler, Wilsonia ousilla x x x 

Ye1 1 ow-breasted chat, Icteri a virens 

x 

Bl ack-headed grosbeak, Pheucticus 

me1 anoce~hal US 

01 ue grosbeak, Gui raca caerulea 

x 

x 

x 

Lazuli bunting, Passerina amoena x x 

Rufous-sided towhee, P i ~ 1 o i ervthrophthalrnus x x 

Brown towhee, Piui lo fuscus 

x 

Fox sparrow, Passerel 1 a i 1 i aca 

x 

Song sparrow, Melosuiza melodia x x x 

Lincoln's sparrow, Melospiza 1 incolni i x x 

Dark-eye junco, Junco hvemal is x x x 

Red-winged blackbird, Aselaius hoen nice us x x x 

Tri-colored blackbird, Aselaius tricolor 

x 

Western meadow3 ark, Sturnel la nealecta 

x 

Ye1 1 ow-headed blackbird, Xanthoceohal us 

xanthoceohal us 

x 

Great-tailed grackle, Ouiscalus mexicanus x x 

Brewer's blackbird, Eu~hasus cvanocephal us x x x 

Brown-headed cowbird, Mol othrus ater 

x 

Hooded oriole, Icterus ~ectoral is 

x 

Northern oriole, Icterus sal bu7 a x x 

Purple finch, Carpodacus pur~ureus x x 

Cassin's finch, Caroodacus cassinii 

x 

House finch, Car~odacus mexi canus x x x 

(Continued)

Append1 x A. 

(Concl uded) 

Name 

Habi tata 

V M LM ~ourcesbtatus/~e~endency 

Lesser goldfinch, Carduel i s psal tria x x 1,2,3,4,5,6,7 R 3 

Lawrence's goldfinch, Carduel is l awrencei x x 1,2,4,5,7 R 2 

American galdfinch, Carduel is tri stis x x 1,2,3,4,5,6,7 R 2 

House sparrow, Passer domesticus x x x 2,3,5 R 3 

a - Habitat: V = valleys; M = montane; LM = lakes, marshes, wet meadows. 

- Sources: 1 = Garrett and Dunn, 1981; 2 = Keeney and Loe, 1984; 3 = Onuf, 1983; 4 = 

Unitt, 1984; 5 - Zembal, 1984a; 6 = Zemba?, 1984b; 7 = Webster et al., 1980. 

Seasonal Status: R = Resident; M = Migrant 

Riparian Dependency: 1 = obl igate riparian nesters 

2 = riparian habitat preferred for nesting, but other habitats 

used 

3 = variety of habitats used for nesting, including riparian 

4 = riparian habitat occasionally used

Birds That Use Riparian Habitat for Other Than Breeding Purposesa 

Name 

Red-throated loon, Gavia stellata 

Doubl e-crested cormorant, Phal acracorax auri Lus 

Canada goose, Branta canadensi s 

Green-winged teal, Anas crecca 

Bl ue-winged teal , Anas di scors 

American wigeon, Anas americana 

Canvasback, A~thva val isineria 

Ring-necked duck, Avthya col laris 

Lesser scaup, Aythya affinis 

Common goldeneye, Buce~hal a cl ansul a 

Buff1 ehead, Buceohal a a1 be01 a 

Common merganser, Mersus mersanser 

Red-breasted merganser, Meraus serrata 

Turkey vulture, Cathartes aura x x 

Osprey, Pandion ha1 i aetus 

x 

Bald eagle, Hal i aeetus 1 eucoceohal us 

x 

Sharp-shinned hawk, Acci~iter stri atus x x 

Rough-J egged hawk, Buteo 1 asoous 

x 

Golden eagle, Aaui 1 a chrysaetos 

x 

Merl in, Fa1 co col umbarius x x x 

Prairie falcon, Falco mexicanus 

x 

Bl ack-bell ied plover, Pluvial i s sauatarol a 

x 

Greater ye1 l owl egs, Trinqa me1 an01 euca 

x 

Lesser yellow1 egs, Trinqa fl avioes 

x 

Wi 11 et, Catootro~horus semi oalmatus 

x 

Whimbrel, Numenius ohaeo~us 

x 

Long-bil led curlew, Numenius americanus 

x 

Marbled godwi t , Limosa fedoa 

x 

Western sandpiper, Cal idri s maurj 

x 

Least sandpiper, Cal idris minutilla 

x 

Dunlin, Calidris al~ina 

x 

Long-bi 11 ed dowitcher, Li mnodromus scol ooaceus 

x 

Bonaparte" gull, Larus phi ladel ~ hia x 

Weermann's gull, Larus heermanni 

x 

Mew gul I , Larus canus 

x 

Ring-bill ed gull, Larus del awarensi s 

x 

Cal ifornia gull, Larus ca9 ifornicus 

x 

Western gull, Larus occidental is 

x 

Caspian tern, Sterna caspia 

x 

Forster's tern, Sterna forsteri 

x 

Short-eared owl, Asia fl ammeus 

x 

Vaux's swift, Chaetura vauxi x x x 

Whi te-throated swift, Aeronautes saxatal is x x x 

Red-breasted sapsucker, S~h~ra~icus ruber 

x 

Say's phoebe, Savornis sava x 

(Continued) 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x

APPENDIX B. 

(Concl uded) 

Name 

Hammond's flycatcher, Em~idonax hammondi i x x 

Dusky flycatcher, Em~idonax oherhol seri x x 

Mountain chickadee, Parus qambel i x x 

Winter wren, Troqlodvtes troqlodvtes x x 

Golden-crowned kinglet, Resul us satrapa x x 

Ruby-crowned king1 et , Resul us cal endul a x x 

Hermit thrush, Catharus auttatu~ x x x 

Water pipit, Anthus soinoletta 

x 

Cedar waxwing, Bombvci 11 a cedrorum 

x 

Nashville warbler, Vermivora ruficapilla x x 

Ye1 1 ow-rumped warbler, Dendroi ca coronata x x 

Bl ack-throated gray warbler, Qendroica niqrescens x x 

Townsend's warbler, Dendroica townsendi x x 

Hermit warbler, Dendroica occidental is 

x 

Black and white warbler, Mniotilta varia 

x 

Western tanager, Piransa 1 udoviciana x x 

Green-tailed towhee, Pi~ila chlorurus 

x 

Rufous-crowned sparrow, Airnophila ruficeps x 

Fox sparrow, Passerel 1 a i 1 i aca x x 

Lincoln's sparrow, Melos~iza 1 incolni i x x 

Golden-crowned sparrow, Zonotrichi a atrica~i ll a x x 

Whi te-crowned sparrow, Zonotrichia 1 euco~hrvs x 

'Sources: Compiled from 25 winter bird population studies pub1 ished 

in American Birds: 1975, 29(3):765; 1976, 30(6):1068; 1978, 

32(1):39,40,41,44,45; 1979, 33(1):49; 1981, 35(1):29; 1982, 

36(1):37,42,43; 1983, 37(1):45; 1984, 38(1):46,47,48,49,50,51. 

b~abitat: V = Valley streams; M = montane streams; LM = lakes, 

marshes, wet meadows. 

'Season: W = winter use; M = migrant; YR = year-round use.

APPENDIX @ 

Mammals Associated With Riparian Habitat in Coastal Southern Cal ifornia. 

Name Sourcesa ~e~endency~ Comments 

Virginia opossum, Didel~hiq 

virsiniana 2,4,5,6,7,8?9 2 

Ornate shrew, Sorex ornatus 2,4,5,8,9 1 

Broad-footed mole, Sca~anus 

1 atimanus 1,2,3,4,5,6,7,8 2 

Cal i forni a 1 eaf-nosed bat, 

Macrotus waterhousi i 2,4,5 

Yuma myotis, Mvoti s yumanensis 1,2,4 

Fringed myotis, Mvotis thvsanodes 4,5 

Long-legged myotis, Mvotis volanx 4,5 

Long-eared myotis, Mvotis evotis 2,4 

California myotis, Mvotis 

cal i fornicus 2,3?475,8 

Western pipistrelle, Pi~istrellus 

hes~erus 2,4,5,8 

Big brown bat, E~tesicus fuscus 2,3,4,5,8 

Red bat, Lasi urus boreal is 4,5 

Hoary bat, I asiurus cinereus 2,4,5 

Big-eared bat, Plecotus townsendi i 4,5 

Mexican free-tailed bat, Tadarida 

brasi 1 inensis 4,5 

Western mastiff bat, Eumo~s peroti s 3,4,5,9 

Western grey squirrel , Sci urus 

ari seus 3,4,5,9 3 

Northern flying squirrel, 

Gl aucomvs sabrinus 3,4,5 3 

Botta's pocket gopher, Thomomvs 

bottae 2,3,4,5,6,7,8,9 2 

Beaver, Castor canadensis 2,5,8 1 

Western harvest mouse, 

Rei throdontomvs mesalotis 4,5,6,8 2 

California mouse, Peromvscus 

cal ifornicus 2,4,5,8,9 2 

Deer mouse, Peromvscus maniculatus 2,3,4,5,6,8 2 

Brush mouse, Peromvscus bovl i i 2,3,4,5,7,8,9 2 

Pinyon mouse, Peromvscus truei i 3,4,5 3 

Desert woodrat, Neotoma 1 e~ida 2,4,5,8,9 3 

Dusky-footed woodrat, 

Neotoma fuscipes 1,2,3,4,6,7,9 2 

California vole, Microtus 

cal i fornicus 1,2,3,4,5,7,9 1 

Porcupine, Erethi zon dorsatum 4,s 3 

Coyote, latrans 2,4,5,6,7,$ 3 

Gray fox, Urocvon cinereoaraenteus 2,3,4,5,6,8,9 3 

Red f ~ x , Vulues fulva 5 3 

Black bear, Ursa americanus 2,5,6 3 

Introduced 

Oak woodland 

Pine forest 

Introduced 

A1 l woodl ands 

All forests 

All forests 

Open forests 

Introduced 

1 ntroduced 

(Continued)

Appendix & . (Concl uded) 

Name Sourcesa Oependencyb Comments 

Ringtai 1, Bassariscus astutus 2,4,5,7,9 

Raccoon, Proc~on 1 otor 2,4,5,6,7,899 

Long-tailed weasel, Mustela frenata 2,4,5,6,8 

Badger, Taxidea taxus 2,4,5,6,8 

Spotted skunk, S~ilosale 

putorius 2,4,5 

Striped skunk, Mephitis mephitis 2,3,4,5,6,7,8 

Mountain l ion, Fel ix concol or 2,4,5,6,8 

Bobcat, Lynx fufus 2,4,5,6,7,8 

Mule deer, Odocoileus hemionus 2,3,4,5,6,8 

1 

1 

1 

3 Open country 

2 

2 

3 All forests 

3 chaparral 

3 All forests 

'Sources: 1 = requires or prefers riparian habitat 

2 = found equally in riparian and other habitat 

3 = uses riparian habitat but prefers other habitat

Santa Barbara County 

Exampl es of Rlpari an Habitat in Coastal 

Draining Watersheds of Southern California. 

Location Description Access 

Hol 1 i ster Ranch 

(sea level to ridge) 

Rattlesnake Canyon 

(above Skof i el d County 

Park, Las Canoas Rd., 

Santa Barbara) 

Upper Santa Inez River 

(be1 ow Lake Cachuma, 

elevation 3,000 ft) 

Middle Santa Inez River 

(elevation 2,000 ft) 

Lower Santa Inez River 


Coastal streams 

many overgrazed 

Re1 atively undisturbed 

riparian habitat 

Ranching has el iminated 

most habitat except in 

river bed: few young 

trees 

Several Forest Service 

campgrounds 

Intermittent creeks, 

A1 iso and Oso Creeks 

Permission required from 

Hollister Ranch, Gaviota 

Wal k- i n access 

Inaccessible except by 

4-wheel -drive or 

backpacking 

Poor access road 

Easy road access to 

Los Prietos Ranger 

Channel Is1 ands 


Santa Cruz Island Best riparian habitat at Contact The Nature 

Prisoner's Harbor, Valdez Conservancy 

canyon: depauperate 

compared mai nl and 

Ventura River Watershed 


Matilija Creek 

(elevation 3,000 ft 

Willows, cottonwood 

Cal i forni a wa1 nut 

Good roadside access 

Wheeler Gorge Campground Riparian corridor Matil i ja Campground 


Nature f rai 1 located 

Los Padres National 

along corridor, access 

Forest 

to undisturbed areas 

Ventura River Wash 

Route 150 crosses wash 

(elevation 650 ft) 

(Continued)

4-4 

0 0 

uu 

D, w 

13 

ma 

w w 

V)O 

rtw 

w a 

*'-c 

m 0 

3 

w rJJ 

-5- 

xa 

a 

*OD 

(D 0 - 

-5 rta 

T e m 

w0-5 

0 3 V) 

m z 

rn 0 0 

0 3 

a 

V) 

0 r+ 

3 -5 

m 

J W 

4- 3 

m 

s m 

(D n 

-5a 

CD

-- 

San Gabriel River (Continued) 

APPENDIX O (Continued) 


Chantry Flats We1 1 -developed riparian Above Arcadi a in Santa 

(elevation 2,000 ft) community with alder, Anita Canyon 

cottonwood, bay 

San Gabriel River Good remnant of alluvial Irwindale exit from 

(elevation 1,000 ft) scrub habitat Highway 210 

Santa Fe Regional Park 

Whi ttier Narrows 277 acres of riparian Trail access 

Wild1 ife Sanctuary habitat with many 

(elevation 300 ft) exotic species 

San Bernardino Mountains (Santa Ana River watershed) 

Locat i on Description Access 

Heartbar and Upper reaches of Santa Campground access 

Southfork Campground Ana River; willow and 

(elevation 6,600 ft) Jeffrey pine 

Southfork Campground Alder, wd l low, Jeffrey Campground access 

(elevation 6,200 ft) pine 

Mill Creek Scattered alder, Roadside access 

(elevation 4,000 ft) Cottonwood, willow, big- 

1 eaf maple, with sycamore 

and oak on higher terraces 

Mountain Creek Home Large alder grove Roadside access 


Mentone Beginning of Santa Ana Roadside access 

(elevation 2,000 ft) Wash fed by smaller creeks 

heavily scoured by 1932 

and 1968 storms; alluvial 

scrub 

Riverside Regional Half-mile-wideriparian Parkaccess 

Park (elevation 700 ft) corridor; willow forest, 

cottonwood, sycamore, oak 

on higher terraces 

River Road east of Wide riparian corridor of Limited roadside access 

Corona above Prado Dam wi 1 low thickets invaded 

(elevation 500 ft) by cane, cottonwood, 

sycamore 

(Continued)

Appendix D f Cont i nued) 

San Bernardino Mountains (Santa Ana River watershed) (Continued) 


Feather1 y County Remnants of riparian Gypsum Canyon Road near 

Park (el evation 300 ft) habitat with willow, Yorba Linda 

wild grape,mulefat, 

cottonwood, 1 arge 

sycamores on higher 

terraces; many exotics 

San Jacinto River 


Fuller and Mill Creek Wi 11 ow, alder, azalea Roadside access 

(elevation 6,000 ft) with Coul ter and 

ponderosa pine near 

streams 

Cranston Guard Willow, mulefat, cotton- Roadside access east of 

Station (elevation wood, large 1 ive oak on Valle Vista off Route 74 

2,000 ft) terrace above; coastal 

sage scrub on adjacent 

slopes 

Lamb Canyon (elevation Large willows: cotton- Roadside access 

2,000 ft) wood, willow beside 

underground river 

Santa Ana Mountains (Orange County) 


Santiago Oaks Regional 

Park un Santiago Creek 


Large oaks on upper 

terraces next to narrow 

riparian corridor 

518 east of Garden 

Grove Freeway; walk-in 

access 

OfNeil l Regional Park on 

Trabuco Creek, north of 

El Taro (elevation 

1,000 ft) 

600 acres of overgrazed Wal k- i n access 

riparian corridor; 

handsome 1 i ve oaks; Holy 

Jim Trail in nearby 

Cl eve1 and National Forest 

leads to unusual alder 

grove, waterfall 

Caspers Wilderness Park 

on San Juan Creek 


Sand mining has destroyed 

large sycamore and oak 

a1 ong creek terraces 

Off Ortego Highway 

(Continued) 

150

Appendix D (Gsnti nued) 

--- 

San Diego County (Santa Marqarita River) 

- 


Santa Rosa Plateau Vil low thickets; very Off Highway 79 near 

(elevation 1,000 ft) l arge sycamores, oaks on Near Temecul a 

terraces above stream 

Deluz Road Re1 atively undisturbed Roadside access north 

(elevation 600 ft) riparian habitat with of Fa1 1 brook 

willow, cottonwood, oak 

sycamore, understory 

Camp Pendl eton Sizable remnants of wide Permission required 

(near sea level) 

willow scrub forest with 

ponded areas 

San Diego County (San Luis Rey River) 


Wilderness Gardens Some willow, cottonwood, Ten miles east of 

Preserve (elevation sycamore, oak in a park Interstate 5 on Highway 

1,000 ft) planted with exotics 76 

Bridge at Bonsall and Over 160 acres of coastal Roadside access 

along Highway 76 

floodplain willow thicket 


with cottonwood, sycamore, 

freshwater marsh and 

riparian understory 

San Diego County (Santa Ysabel Creeks) 


Battle Monument 

(elevation 525 ftj 

Old Pasquale Road and 

San Pasquale Road 


Los Penesqui tos Canyon 

Preserve 

Good stands of willow and 

mulefat on river wash; 

most sycamore and oak 

removed 

Willow thicket beside 

freshwater marsh 

Five miles of riparian 

corridor with streamside 

wi 11 ow and mu7 efat , 

ponded areas with cat- 

Lai 1, and large sycamore 

and oak; some disturbance 

and exotics 

(Continued) 

5 miles east of Wild 

Animal Park on Highway 

7 8 

View from roadside 

only 

Foot access from 

Black Mountain Road 

west of Interstate 15 

to Sareno Valley Road 

Interstate 5

L 

V) u 

m e c 

w r m 

u m 

m - 

LOL 

0 U aJ 

u 

E ..,-

~ . 

- 

-_-_-___-- 

-- 

coastal region: a conimunity profile 

I 

- 

7 Author(s) 8. Performing Organtratron cot NO 

P.M. Faber, 

-- 

E. Keller, _ _ A. _- Sands, 

_ _ B.M. __ MasseY 

_I _-_ ___ 

9 Pcdormrng Orgsnlzat!on Name and Address 10 Prolect/Task/Work Und No 

1 l*.-C~~t~act(C> or GrantW No. 

I 

-.-. .. .- .-. ...- . -- -.- - -.-. . ".. -- -~ 

\-G.-&ponror:ng Organlration Name and Address 

U.S. Department of the Interior 

Fish and Wildlife Service 

Research and Development 

National Wet1 ands Research Center 

Washington, DC 20240 

..-_I_.-__ _ . 

! 

___l__l_ 

if. Supplementan Notes 

- . - - -- 

16. Abstract (Llmtt: 200 words) 

- .- ._ . . -.I-. _._I___ 

In the 200 years since California's settlement by Europeans, almost every river in 

Southern California has been channelized or dammed to allow development on the 

floodplains, causing the loss of a highly productive ecosystem. The riparian zone 

occurs a1 ong streambanks where soil s are fert i 1 e and water is abundant; amphi bi ans, 

reptiles, birds, and mammals all move back and forth across the riparian zone from 

streams into adjacent wet1 and and up7 and areas. Irreversible alterations of the 

riparian ecosystem result from the diversion or loss of transported water to the 

system through diking, damming, channel i zation, levee building, or road construction. 

Clearing for crops, grazing, or golf courses is potentially reversible as long as the 

water supply remains unaltered. Successful restoration work requires early agreement 

on project goals, si te-specific restorat ion design, correct project implementation, 

enforcement of permit conditions, a mai ntenance and management program, and longrange 

monitoring. 

- 

17. Document Analysis a Descriptors 

Ecology Habitat Fauna 

Flora 

Ecosystem 

Riparian 

Southern Cal i forni a 

F1 oodpl ai n 

Fluvial system 

Hydrology 

Restorati on 

c 

COSATl Fleld/Group 

- - __ -- - 

18 Auallabslity Statement 19 security class ,ih,s Rrporl, 

Unl imi ted distribution 

m. Security Class Chis Page) , 22. Pnre 

Unclassified 

(See ANSI-239 18) OPTIONAL FORM 292 (637 

(Formerly NTIS-35) 

GspiRment of Commerre 

-it&= 

irgts

The Ecology of Riparian Habitats of the Southern California Coastal ...

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