4.1. Paleoecological Changes
Overall, the average dominating (identified) taxa in the top 280 cm of the sequence for Arbor Pollen are Pinus, Quercus, Salix, Corylus, Tilia, and Ulmus; for Non-Arbor Pollen are Poaceae, Chenopodiaceae, Artemisia, and Cerealia; for Aquatic Pollen are Pediastrum, Cyperaceae, and Nymphaea; for freshwater are Valvata cristata, Bithynia leachi, Bithynia tentaculata, Valvata macrostoma, Lymnaea palustris, Pisidium, Anisus spirorbis, Anisus leucostoma, and Armiger crista; and for terrestrial molluscs are Succinea putris, Sucinella oblonga, Oyloma elegans, Perforatella rubiginosa, Carychium minimum, Granaria frumentum, and Vallonia pulchella. Main pollen dominance can be more easily described, and their changes can be tied to climatic changes or environmental changes (lake phases) than mollusc changes, where there is more overlapping between phases and species (4) that are present during the whole sequence.
The investigated profiles at Lake Kolon roughly span the changes of the past 17.7 thousand years [
2], and the pollen, malacological, and macrobotanical studies are allowing the reconstruction of the vegetational and malacological changes [
3,
4] from the end of the Last Glacial Maximum (LGM) up to the end of the Holocene. Lake Kolon exhibits an exceptionally diverse development, from a sandy and loessy fluvial and aeolian [
2] sediment deposition to peat formation with rich avian species and diverse vegetation. The historical records, results and cross-sections suggest that the lake was much larger, had simultaneously multiple small beds in different elevations and that these connected from time to time and stayed connected from shorter or longer intervals.
Based on the results and remains, a boreal taiga–steppe evolved in the area at the end of the LGM with tundra-like vegetational patches [
3,
4]. The freshwater malacofauna can be synchronized to the European loess zone that developed during the cold maximum in the Ice Age. The terrestrial malacofauna showed correlation with the malacofauna from the loess sequences from the Great Hungarian Plain from this interval, although the lake’s water surface strongly affected the local climate and fauna elements. During the LGM, in the Danube–Tisza Interfluve, an open parkland-type boreal forest–steppe dominated with 7–8 °C cooler summers than today [
2,
4]. Between ca. 17,700–15,000 cal BP (240–280 cm), a significant amount of
Pinus charcoal was found, meaning that wild forest fires occurred after the LGM with the increasing temperatures that are also signaled by the summarized paleoecological results.
Poaceae also stagnated in this interval and started to increase after 15,000 cal BP for a short period but declined in significance from 13,700 years ago.
Betula also experienced a stagnation followed by a greater spike, after which it decreased.
After 15,000 cal BP, Pinus started to dominate (60–65%) for almost 4000 years, when the temperature started to change drastically in the Carpathian Basin and temperate forests started to rapidly spread. Between 13,700–11,700 cal BP (ca. 220–172 cm), during the mesotrophic Chara-lake phase, a really slow transformation into temperate forest–steppe vegetation occurred. Salix and Quercus had >1% values between ca. 15,000–11,000 cal BP (232–152 cm), and they started to first increase gradually, then had a huge increase, during which other temperate species showed up (Corylus, Tilia, and Ulmus). Based on the data, it appears that a relatively rich boreal forest–steppe fauna community in snail species transitioned into a relatively impoverished Holocene temperate forest–steppe fauna community during the Pleistocene/Holocene transitional phase. The changes occurred so concurrently and temporally in tandem that a clear relationship can be discerned among them, and as a result of these changes, it can be reconstructed that the forest–steppe structure was inherited, but in higher temperatures and drier microenvironments, elements that became prevalent during the Holocene period occupied various parts of the mosaic environmental structure. Although there are some studied species and taxa that are present during the whole sequence, flora and fauna diversity grows rapidly from 11,400 cal BP (160 cm), shortly after the peat accumulation and the Holocene started (11,700 cal BP).
The communities contributed to environmental change by reducing the woody cover of the forest–steppe region and established a cultural steppe. The natural temperate forest–steppe with deciduous trees that developed during the early Holocene underwent significant transformation due to human influence over the past approximately 8000 years, evolving into human-induced open parkland, a transition that had already begun during the Iron Age. Corylus and Ulmus decreased and Tilia disappeared along with Fraxinus; meanwhile, Betula and Alnus increased, Fagus, Acer, and Carpinus, along with Abies, appeared. Quercus and Salix stayed relevant with Pinus and with a small amount of Picea. Along with these changes, herbaceous changes occurred with emerging species like Aser type, Achillea, Umbelliferae, Cruciferae, Centaurea sp., Plantago major/media, Galium, Secale, Cerealia, Triticum, and in the past few hundred years, Cannabis/Humulus, Cirisium type, and Ambrosia type. Based on charcoal remains, it can be inferred that forest burning has not occurred in the immediate vicinity of the lake since the medieval period. Pastures became the most important agricultural use of the area from the second half of the Middle Ages.
4.2. Medieval History
Hungary’s first written relic is connected to Lake Kolon. Although the environmental history of the area has changed since the Neolithic period [
2,
3,
4], it is clear from written sources [
12] (the Tihany Founding Charter, 1055: DHA I; PRT X) that the environmental transformations accelerated during the reign of St. Stephen (997–1038) when the agricultural system of the Kingdom of Hungary was established. The portion of the Tihany Founding Charter related to this study area, translated from Latin, reads as follows: “There is a place for grazing horses, which begins at U[gr]in’s idol, from here to a valley, then to a dune, then to pre-sand, then to three lakes, then to a fox hole, then to three mountains, then to Iohtucou, then to the sands of Báb, then to the place of Alap, then to Kövesd, then from the middle of the water called Kolon to the
fekete humuc, then to
fuegnes humuc, then to
cues humuc, then to Gunasara, then all the way to Szakadát and then to Sernyehalom, then to a ditch which goes all the way to the idol” [
12]. The former Kolon
praedium (estate, property) was donated by King Andrew I of Hungary (ruling 1046–1060) to the Tihany Benedictine Abbey in 1055 (
Figure 14). The tour of the border is a medieval legal practice, a field inspection, that was carried out by recording the natural or artificial boundary points of an estate, estate part or settlement [
32,
33].
From the perspective of Lake Kolon, those areas and boundary markers are of outstanding significance that in their naming—in most cases as a suffix of a compound word—the term sand (homok,
humuc(h),
humuk,
homoka) or its Latin equivalents (
arena,
sabulum) are mentioned, which presumably refers to the material of the area [
34]. A good example of this is the sandy boundary area mentioned in the deeds (e.g.,
terra sabulosa vel arenosa), the name of a wasteland/settlement (e.g.,
sabulum Bab = sands of Báb, [
35,
36]) or the mention of a sand dune (e.g., Sernyehalom [
37]). Significant information about the geographical conditions can be gained by further analyzing place names. Thus, with their help, some types of sandy soil can be identified (English/Hungarian/Old Hungarian: black sand—fekete homok—
fekete humuc, rocky sand—köves homok—
cues humuc, peaty sand—fövenyes homok—
fuegnes humuc).
According to the identification of historian György Györffy (1917–2000), the area covers the present-day border of the town of Izsák, and his studies and opinion suggest that a large part of the borders are in agreement with the current borders [
38]. From the Latin description, it is clear that on the Kolon
praedium, the stablemen of the Tihany Abbey lived; that is, the estate may have been of a livestock-raising nature [
39]. Prior to their direct capture and shaping into riding horses, three and four-year-old colts were raised (
harmadfű and
negyedfű, which literally means thirdgrass and fourthgrass, is said about foals and young cattle, which are already entering their third or fourth year of age, that is, they step out onto the fourth new grass), grazed, and they ran them (due to mosquitoes, they had to move, gallop, and train) on the meadows around the marshy strip of Lake Kolon. Geographically, the accurate description of the sand dunes and the presence and mention of the marshes and lakes (
semlyék,
semlyékek in plural form), is mostly used between the Danube and Tisza area and is a wet, periodically covered shallow depression, meadow, brackish, watery area, wind furrow, and in another interpretation, plant sediment washed into a lump by water [
40,
41,
42,
43] is interesting in the 11th century founding charter.
In more detail, the 1211 charter that confirms the abbey’s property rights speaks of the lake itself [
38,
44]. The descriptions and analysis reveal to us the image of the former Kolon praedium (
Figure 14). The area exhibits the characteristic landscape of the Kiskunság region, featuring sand dunes, the shallow depressions between them (
semlyékek [
40,
41,
42]), flat meadows, marshes, natural vegetation, as well as ditches, settlements and roads. The presence of the conquering Hungarians in the area may be indicated by the burial sites containing partial, palmette-decorated horse saddles from Soltszentimre and Izsák-Balázspuszta, suggesting that the area may have been a prominent settlement site for them [
45]. Later, permanent settlements, which still exist today (Izsák, Páhi, Soltszentimre [originally Pusztaszentimre], Csengőd, Akasztó), developed around the lake [
46], and their churches were typically built from locally sourced meadow limestone.
Given that the utilization of the landscape and the economic utilization of a particular area are closely intertwined with the former soil and its quality, the investigation of the type of sandy soils in this case can provide important information for the study of the history and environmental history of the medieval Lake Kolon and the surrounding Homokhátság region. However, the research on medieval soil types is not an easy task, partly due to the lack of systematic research and the limited opportunities provided by written sources. Furthermore, the study of mediaeval soil types is even more complex as contemporary maps cannot be relied on, and instead, the mention of border inspections in the charters must be relied upon. An important reference point for the analysis is the terminology used in the classification of soils in Hungary, as in some cases it is possible to compare the modern terms used for soil types [
40,
41,
42,
47,
48,
49,
50,
51] with the terminology translated from medieval Latin.
The 1211 land survey (before the Mongol invasion of Hungary, which occurred between March 1241 AD and April 1242 AD) conducted at the Lake Kolon property provides detailed information about the mediaeval agricultural environment, as the property was thoroughly surveyed over several days (
Figure 14). The size of the
praedium is indicated by the fact that it took approximately three days to cover 40 km on horseback and foot, discussing and recording the boundaries. Approximately one-third of the survey focused on the Lake Kolon area and its surroundings, while a smaller amount, one-fourth, covered the meadows and their surroundings of Orgovány and Ágasegyház. One of the significant values of both the 1055 and 1211 land surveys is that both started from a point called Bálvány (1055:
baluuana, 1211:
Balanus), and then proceeded south, then west (going around Lake Kolon) and finally east [
12,
38].
The Kolon Lake is now a nature reserve, but its development history is also closely related to the changes in the land in the 11–13th centuries after Christ. The 1055 charter [
12] (
Figure 14) distinguished three types of sand on the western shore of the lake, in the Bikatorok sand dune area: black sand—fekete homok—
fekete humuc, rocky sand—köves homok—
cues humuc, and peaty sand—fövenyes homok—
fuegnes humuc. The term
fekete humuc probably referred to the dark-colored sandy slime that formed on the periodically wet and dark-colored algal mat on the shore of the lake, or the dark-colored sandy slime that formed in the intermediate zone between the two dry running sands (bucka—mound) that make up the dune [
52]. The term
fuegnes humuc probably referred to the darker, peaty, more humus-rich sands that were located west of the black sands and likely belonged to the highest dune range in the area, which rose 120 m above sea level [
12,
38]. This provided an extraordinary opportunity for spatial identification in the 1211 property survey, as it also separated sand hills (
ad monem sabulosum). The term
cues humuc probably referred to the diagenetic and cemented sand fragments and pebbles that were formed as a result of the influence of the limey and alkaline groundwater in the Reveckei-halom dune formation. Probably the modern Reveckei-halom can be identified with the Cuest (Köves) dune of the 1211 charter. The shape of the dunes belonging to the Lake Kolon is well reflected in the term
mont iculus (small hill, small mound), as this term well describes the longitudinal mounds that stand out 10–20 m from their environment and are characterised by steep edges [
53]. In the 1055 charter, the SW border of the Kolon estate is referred to as Gunusara (Gönyüs ár), which hypothetically can be identified as a lower-lying, periodically flooded meadow on the western shore of the lake. In the 1055 boundary survey, the term
aqua (water) is used in relation to Lake Kolon, which clearly indicates an open water surface [
12,
54]. The 1211 charter uses the term
as tagnum (smaller still water, lake) four times and with the mention of
rippa (shore, water front, waterside) clearly indicates that in the 13th century, the Kolon system also appeared as a lake (
Figure 14). Therefore, it is questionable to describe Lake Kolon as a marsh [
38], rather it is more likely to be a stable water surface with significant vegetation (eutrophic lake) [
55].
The 1055 and 1211 property inspections (
Figure 14) provided us with the opportunity to reconstruct the vegetation along the shore of the lake [
56,
57] (
Figure 14). The 1055 property inspection referred to the Kulun (Kolon)
praedium as “
est locus ad pascua equorum” (a place for horse grazing) [
12,
54]. This is also supported by the etymology of the name Lake Kolon, as it is likely to have originated from the Old Turkic word
qulun (foal). Grasses (
Poaceae), such as various
Festuca (csenkesz) and
Poa (perje) species, and the
Stipa (árvalányhaj) taxon are suitable for horse grazing. Based on pollen analysis [
3], these herbaceous taxa are likely to have been present in large quantities in the terrestrial environment around Lake Kolon during the Middle Ages. The 1211 document also confirms the significant presence of grasses, as a territory was referred to as “dús füvű völgy” (a lush meadow valley) in the border description, while the expression
ad campus (to the field) was mentioned on the eastern side of the lake. In addition, the 1211 property inspection used the terms
pinus or
feuneus five times. Both expressions can be associated with the presence of
Juniperus communis (common juniper, boróka), a pine species that still exists in the region around Lake Kolon [
58]. The final sentence of the 1055 founding property document “
haec loca, quicquid in sefrutectis, in arundinet is, in pratis continent” (this land, with all its shrubbery, reeds, and meadows), provided significant help in reconstructing the mediaeval vegetation, as it clearly indicated that the surface of Lake Kolon was likely covered by reeds and the periphery by meadows. Radiocarbon dated palaeobotanical data also clearly support this [
2,
3,
4]. The reconstructed image, based on the property inspections, suggests that larger and more continuous forests, which are present today (although some of them are artificial) in the environment of Lake Kolon, may have been absent during the Middle Ages—mainly based on the analysis of documents and certificates [
58]. Therefore, in the Middle Ages, the open vegetation, which was influenced by human activity, may have dominated the area instead of the forest–steppe environment that is observable today, particularly on the southern side of Lake Kolon, near the Páhi settlement, where mixed oak–hornbeam–sycamore forests (
Fraxino pannonicae—
Ulmetum) can be observed today [
15,
16]. However, it cannot be ruled out that these forests did not belong to the
praedium [
44].
Certificates provided opportunities for the reconstruction of mediaeval settlements existing around the lake, which had formed prior to the destruction of the Ottoman Conquest in the late Middle Ages and early modern period [
59]. The Hungarian village of Kolon, which was inhabited by 32 families, including 82 male family members, according to data from the 1055 property survey, emerged at the end of the Hungarian Conquest in the place where the city of Izsák is today [
38]. Similarly, the border survey of 1211 recorded 4 serfs, 13 stablemen and 22 servants living in the same area [
38,
60]. Kolon village had its own temple dedicated to the worship of the Holy Cross. The
villa Herbon (Herbon village), located on the eastern shore of Lake Kolon, a few kilometers from the lake, probably stood on the modern territory of the village of Orgovány, which is located on the Orgovány-bog shore [
61]. It is believed that the area was originally a noble estate belonging to the Csák family, and one of its members was named Herbon. Based on this, it can be assumed that the area was a secular (noble) property, and it came under the control of the Cumans in the late Middle Ages as a secular property. Additionally, the presence of a location named “Vár Fehére” (the white of the castle) near Herbon village suggests that a portion of the land in the village was also held by the (Transdanubian) Fehérvár Church. The village of Herbon (after it was excluded from the property of the Csák family) was named Szentmária after the patron saint of their church in 1359 [
62,
63]. It is noteworthy that the area around Lake Kolon underwent significant changes during and after the first Mongol invasion of Hungary, with the settlement of the Cumans and the development of a network of new settlements around the lake in the 15th century [
56,
57,
62]. This network of settlements was again transformed during the Ottoman conquest. As a result, the mediaeval settlement pattern underwent multiple transformations over the centuries and can only be reconstructed through archaeological excavations [
58]. Therefore, environmental analyses based on material examination and dating provide a more reliable foundation for determining the development of the area, including the vegetation, than written sources, which are limited in their usefulness due to interpretational and locational problems, as well as their limited temporal applicability [
63].