GEOLOGICA CARPATHICA, DECEMBER 2010, 61, 6, 513—533
doi: 10.2478/v10096-010-0032-1
Paleof loristic and paleofaunistic analysis of Dudváh River
oxbow and implication for Late Holocene paleoenvironmental
development of the Žitný ostrov Island (SW Slovakia)
PETER PIŠÚT1, EVA BŘÍZOVÁ2, TOMÁŠ ČEJKA3 and RADOVAN PIPÍK4
1
Department of Physical Geography and Geoecology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina,
842 15 Bratislava 4, Slovak Republic; pisut@fns.uniba.sk
2
Czech Geological Survey, Klárov 131/3, 118 21 Prague 1, Czech Republic; eva.brizova@geology.cz
3
Institute of Zoology, Slovak Academy of Sciences, Dúbravská cesta 9, 845 06 Bratislava 4, Slovak Republic; cejka@savba.sk
4
Geological Institute, Slovak Academy of Sciences, Ďumbierska 1, 974 01 Banská Bystrica, Slovak Republic; pipik@savbb.sk
(Manuscript received February 18, 2010; accepted in revised form October 13, 2010)
Abstract: Žitný ostrov, the largest island of the Danube River (SW Slovakia) gained its present shape in the Neoholocene
period. As a result of increased flood and geomorphological Danube river activity dated to 1378—1528 AD, the Lower
Dudváh River was abandoned and its alluvium became a part of the Žitný ostrov. Study of a Dudváh terrestrialized
paleomeander by means of pollen and macrofossil analysis provides new information about the paleoenvironments of
the Danubian Plain. The meander under study was cut-off during the Sub-Boreal period when the land was mostly
covered by oak-dominated mixed forest with a notable high frequency of Fagus and Abies. In low-lying depressions,
Alnus glutinosa formed typical alder carrs. The largest decline of the mixed forest occurred during the Sub-Atlantic
period. Until the mid-19th century the region was strongly influenced by shallow groundwater and periodical floods, as
reflected by pollen of aquatics and marsh species. Amongst non-arboreal taxa, pollen of Cyperaceae, Brassicaceae/
Cuscuta, Poaceae and Apiaceae prevailed. Local successional changes started with i) stage of abandoned oxbow still
with influx of moving water, poor in both macrophytes and molluscs, ii) shallow eutrophic oxbow lake with slowly
flowing or stagnant water overgrown with aquatics (Ranunculus subgen. Batrachium, Potamogeton sp., Ceratophyllum
demersum etc.) and abundant molluscs, iii) an open marsh dominated by Cyperaceae (mainly Carex riparia) with
Atriplex prostrata, supporting diverse molluscan and Ostracod fauna. Present-day habitat is a result of landscape changes,
which have been associated with draining, intensified agriculture, ruderalisation and spread of invasive species.
Key words: Holocene, SE Slovakia, paleoecology, palynology, paleomeander, Mollusca, Ostracoda, Dudváh River.
Introduction
River paleochannels are often filled with organogenous deposits, suited to paleoecological
analyses. Such layers represent valuable natural
archives (Břízová 2007).
Žitný ostrov, the largest intracontinental
Danube island (1600 km2), is a result of complicated sedimentary evolution and river pattern development. Its territory covers a substantial part
of a large alluvial fan of the Danube River extending downstream from the Devín Gate gorge
into a subsiding Danube Basin infilled with marine and limnic Tertiary deposits and overlaid by
Quaternary fluvial deposits on the top. The
present river subdivision into the Danube mainchannel, Lesser (Malý/Little) Danube and Moson
Danube (Fig. 1) is a result of nature conditions in
the postglacial period and their stabilization un- Fig. 1. Location of the study site – wider regional context. The small frame reder anthropogenic influence. The general geo- fers to the territory, depicted on the Fig. 2.
morphological features, geological structure and
lithology of Žitný ostrov are known (e.g. Lukniš & Mazúr ecological conditions in the Holocene, especially in comparison
1959; Vaškovská et al. 1978; Tkáčová et al. 1996), in contrast with the situation on other large European rivers and the Upper
to the particulars of its geomorphologic development and paleo- Danube alone (cf. Schellmann 1990; Buch & Heine 1995).
www.geologicacarpathica.sk
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PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
The terrain of the Žitný ostrov is shaped by numerous paleochannels of several generations. These geomorphological
features are the key to knowledge of its past development.
Although many earlier paleochannels are blurred by ploughing and barely discernable in the field, they may be easy to
recognize using old maps and aerial photography. These
forms are characterized by shallow groundwater, distinctive
soil types (Fulajtár et al. 1998) and vegetation. Most patches
of native and semi-natural floral communities are bound to
these old river landforms.
The most notable fen complex bound to former channels
(351 ha, with maximum peat thickness up to 5 m) was located
in the central part of Žitný ostrov (Raučina 1968 in Válková &
Stanová 2000). A major part of these fens fell victim to peat
harvesting in the 1960—1980s. Organic layers have been tentatively dated from Late Pleistocene to Mesoholocene (Lukniš
& Mazúr 1959; Krippel 1963; Krippelová 1967).
Our present knowledge of Holocene paleoenvironments of
this region is mainly based on the palynological studies of E.
Krippel (1963, 1986). Local paleoenvironmental data were
obtained by earlier study of molluscan taxocenes (Ložek
1955) and by studies of woodland, meadow- and marshy
vegetation (Jurko 1958; Zahradníková-Rošetzká 1965;
Krippelová, l.c.). They managed to document the remnants
of original flora persisting on Žitný ostrov Island until the
largest human interventions of recent decades, which have
included peat extraction, intensive agriculture and construction of the Gabčíkovo hydroelectric plant.
Žitný ostrov Island as the geographical unit known today
has been formed relatively recently, as late as in the High
Middle Ages (Püspöki-Nagy 1985; Pišút 2006). Until this
period its lower part formed a separated geographical unit
historically referred to as Vágköz with Dudváh as its dominant stream. Sometime between 1378—1528 AD serious
channel changes resulted in cutting-off the Lower Dudváh
due to formation of a new 16 km long avulsion channel of
the Lesser Danube between Topo níky and Kolárovo, so that
the whole district of Vágköz was incorporated into the Žitný
ostrov, together with the town of Komárno (Fig. 1).
Recently, this knowledge stimulated an investigation focused on the former Dudváh floodplain. The research comprised detailed study of present-day vegetation and
molluscan fauna, associated with several Dudváh paleomeanders (Kubalová 2006; Pišút et al. 2007). Attention was also
paid to paleoecological analysis of a terrestrialized oxbow
next to the village of Štúrová (Břízová et al. 2007; Pišút et al.,
l.c.). In this paper we present the summary results of our
study. Its major objectives are i) reconstruction of the regional
paleoenvironments mainly based on pollen record, ii) reconstruction of local successional series of the abandoned oxbow
in situ (based on local and extralocal pollen record, plant macrofossil assemblages, Mollusca and Ostracoda), iii) provide
evidence of the human impact on the regional vegetation and
iv) provide evidence for assumed essential changes of the
river network, which occurred on Žitný ostrov in the past, by
dating of the paleochannel. Reconstruction of the paleoenvironments is also based on the study of recent habitats associated with paleochannel landforms, such as vegetation
survey, study of subfossil and recent molluscs.
Study area
The study area is located in a depressed part of lower Žitný
ostrov, that has fine-grained deposits and impeded drainage
due to its subtle slope. Prior to cultivation and draining, this
Early Holocene depression was badly drained even by low
water and covered by almost continuous swamps, with fens
and wetland soils. The study area is located on the 3.5 km
wide and 20 km long lowland plain, slightly (1 m) elevated
above the depression bottom. This belt with the only medieval village (Čalovec) has been already previously identified
as the natural levee of the former Dudváh (Lukniš & Mazúr
1959). Dudváh is a 97 km long lowland river of SW Slovakia entering the Lesser Danube (catchment area of
1507 km2). The abandoned lowermost reach of the former
Dudváh is represented by more or less continuous river bed at
least 24 km long (Fig. 1), but also by remnant paleochannels.
The oxbow under study is part of a cluster of six such
paleomeanders located between the villages of Štúrová and
Čalovec in heavily managed, almost completely deforested
agricultural landscape (Fig. 2). The region is warm and very
dry with mild winters. Average annual air temperatures in
the period 1931—1990 was 9.6 °C (data from the Hurbanovo
meteorological station). The mean July temperature was
19.8 °C, mean precipitation total 553 mm (1961—1990 period;
Majerčáková et al. 2006).
Fig. 2. Paleomeanders of the Dudváh River with location of the coring site.
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
The study paleomeander (“Štúrová” site) is 37—50 m wide.
Bottom of terrestrialized S-shaped oxbow is lowered some
1.3—2 m when compared to the adjacent floodplain (108—
109 m a.s.l.). A gently elevated part of the paleochannel upper reach is currently planted with monoculture of Canadian
Poplar. There is also a minor patch of remnant semi-natural
willow stand with former pollard trees. Closed-canopy reed
beds cover the lower half of the former channel (Pišút et al.
2007). Roughly 8 % (0.5 ha) of the bed is overgrown by
large sedge communities (Magnocaricion elatae). Communities with Bolboschoenus maritimus agg. and Glyceria
aquatica also occur with patchy distribution (Kubalová
2006). Coring site is placed in the lower portion of the channel, within a tall-sedge habitat dominated by Carex riparia,
6 m from the edge of the former eroded channel bank
(47°50’20.99” N, 17°56’49.17” E) with supposed maximum depth of the paleochannel about 2.8 m (Fig. 2).
In the past, completion of protective embankments along
with partial draining of the territory led to slight lowering of the
regional groundwater. Since the mid-19th century the territory
had only been inundated during extreme floods that resulted in
levee breaches (Füry et al. 1986). In the period between 1962
and 1992 mean groundwater was gradually decreasing by an
additional 20—50 cm, but it rose again after the Gabčíkovo hydroelectric plant have been put into operation in 1992 (Hlavatý
& Banský 2006). Despite continuing warming of the entire region since the 1870s and prevailing moisture deficit conditions
(Fulajtár et al. 1998; Majerčáková et al. 2006) the groundwater
level in the paleomeanders fluctuates between 0.5—1.5 m. In the
spring, ground-water may spill above the ground surface of paleomeanders by up to 20—40 cm. Present-day conditions also
favour the probability of soil salinization.
Material and methods
In the first phase of sediment sampling (on October 24,
2006) a pit was opened by hand at the study site. Herb layer
was represented by Carex riparia, Atriplex prostrata, Symphytum officinale, Calystegia sepium and Cuscuta australis. Fully
grown shells of the largest molluscs (Lymnaea, Viviparus,
Planorbarius corneus, Unio tumidus) were hand-picked during the course of excavation. Samples of sediment were taken
directly from the face of a cleaned vertical section from the
depths 0 to 60 cm. Subsamples for pollen analysis were taken
at 5 cm interval, those for macrofossils at 10 cm intervals. Due
to shallow groundwater additional subsamples to 80 cm were
taken with steel flighted auger (© 15 cm) and samples from
80—100 cm with a split tube sampler (© 5 cm).
Due to extremely warm and dry weather in 2007 the regional groundwater level exceptionally dropped. This allowed us to describe the lithostratigraphy of the sedimentary
infill in more detail and also additional sampling for pollen
and macroremains analyses up to the depth of 130 cm (on
July 27, 2007). Description of the soil profile followed the
Guidelines for soil description (2006), soil colour was determined by Munsell Charts (2000). In total, 20 samples of sediment (from the depth of 0—130 cm) were retrieved for pollen
analysis and 10 subsamples for macrofossil analysis. Soil
515
samples were analysed in the Institute of Soil Science and
Protection, Bratislava for granulometry (pipette methods),
pH in both H2O and KCl, carbonates, humus content, content and quality of humic acids (colour index), respectively.
The sediments were rich in molluscan shells, but comparatively poor in palynomorphs. The samples also contained
plant macroremains, ostracods, leathery cocoons possibly of
Annelida/Turbellaria, insect fragments, numerous charcoals
(not determined yet), several bone fragments (cf. micromammalia) and a fish scale. Pollen and macrofossil analyses were
performed, two levels of sediment sequence were radiocarbon-dated.
Microscope slides of pollen subsamples were prepared using hydrofluoric acid HF and modified Erdtman acetolysis
(the standard procedure is described in detail in Břízová
(1999b, 2007). Two slides of each sample were observed under the microscope according to the concentration of sporomorphs in one sample. At least 300 arboreal pollen grains
(AP) were counted for each sample if available (for sum of
pollen counts see Fig. 3). Palynomorphs were determined
with the help of reference recent pollen and photographic
documentation, as well.
For calculations of the pollen data and plotting of the pollen
diagrams – and for molluscan and plant macroremains diagrams as well – the programme POLPAL (Walanus &
Nalepka 1999) was used. The pollen sum of woody plants
(AP, arboreal pollen) and non-arboreal pollen (NAP) was considered to be 100 % (AP + NAP = 100 %). Identifiable plants
were grouped according to the life-form system into trees,
shrubs, dwarf-shrubs, herbs and graminids, local plants (the
latter including aquatics, telmatophytes and amphiphytes).
Pollen of some strictly wetland species was considered as a
part of local component, even if it was not recorded as macrofossil, but is recorded by present-day floral survey at the study
site or in its close vicinity. Pteridophytes, Bryohytes, Fungi
etc. were excluded from the pollen sum but also plotted on the
graph. On this basis the percentages of individual determined
pollen types were calculated. Relative dating of the pollen
spectra was done on the basis of its composition. Reconstruction of the vegetation development is based on modified classification for Central Europe (Firbas 1949, 1952; Dreslerová
et al. 2004). On the basis of the results and with the help of
principal component analysis ( = module of the POLPAL programme), the profile has been dated stratigraphically and pollen diagrams divided into local pollen assemblage zones
(LPAZ). Symbols in the lithology column follow the TroelsSmith system (Aaby & Berglund 1986). Pollen record was
also compared to the results of macrofossil analyses and study
of present-day vegetation.
For separation of plant and animal macroremains, bulk
samples of sediment (the amount ranging from 300—550 g)
were soaked for at least 24 hours (up to 3 days) in 10% solution of hydroxene peroxide in deionized water. Floating
shells, ostracods, cocoons of Annelida (Turbellaria), insect
remains and charcoals were picked and remnant macrofossils
were separated by wet sieving through the 0.25 mm mesh.
The most resistant crumbs of carbonaceous clay were also
treated with Calgon. Identification of seeds, fruits and molluscan shells was done upon drying with a low-power bino-
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PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
Fig. 3. Pollen diagram for the Štúrová-Dudváh paleomeander, arboreal pollen.
cular microscope. For determination of plant macroremains
primarily the authors’ own reference collection of recent flora
was used, but also atlases of seeds (e.g. Cappers et al. 2006).
Nevertheless, only determinable (at least to the family) taxa
were included in the plant macrofossil diagram. Identification
of molluscan death assemblages (taxocenes) was done visually using POLPAL diagram, but also verified with the help of
statistical cluster analysis (Ward’s method, Euclidean distance), performed with PAST software (Hammer 2009).
Correlation of pollen data is also supplemented by two radiocarbon dates of mollusc shells from 55 and 102 cm. Their age
was determined by the conventional decay-counting method using carbon isotope 14C. Radiocarbon dating was performed at
the Radiocarbon Laboratory of the Institute of Physics, Silesian
University of Technology in Gliwice, Poland.
Interpretation of fossil finds was also done based on the
survey of present-day vegetation of the adjacent portion of
abandoned Dudváh River (Kubalová 2006; Pišút et al.
2007). Vascular plant nomenclature follows Marhold &
Hindák (1998). Names of phytosociological vegetation units
(syntaxa) follow Jurko (1958), Mucina & Maglocký (1985),
O ahelová (1995a,b) and O ahelová et al. (2001).
Results
Lithology of paleomeander infill sediments – soil characteristics
At the time of detailed profile description (on 27 July,
2007) the groundwater was at a level of 130 cm. In the top-
soil up to 5 mm wide vertical cracks occurred, spaced up to
20 cm from each other, starting 11 cm below the surface and
reaching to the depth of 85 cm. The lithology of the studied
profile is shown in Table 1.
According to textural parameters of 5 selected diagnostic horizons, sediments were classed as silty clay and silty clay loam
with % clay ( < 0.2 Pm) ranging from 28.3 to 56.10 % (Guidelines for soil description 2006). The admixture of coarser material most apparent in 39—56 (74) cm was mainly represented by
very fine sand and coarse silt. The humus content of the studied
soil is very high (above 5 %), similarly to other hydromorphic
and texturally heavy soils of the region (cf. Fulajtár et al. 1998).
The CHA /CFA ratio (<1) indicates humus of lower quality with a
relatively low degree of humification and humus stability
(Q64 > 4.0). Slightly alcalic reaction of the soil is associated with
the strongly to extremely calcareous soil matrix (CaCO3 from
14 to 49 %), also correlating with the high pH of the soil (Table 2). The presence of secondary carbonate nodules along
with increased concentration of calcium carbonate content in
the subsoil layer of 40—52 cm is related to shallow groundwater and the water regime of the area. Currently the pedon is
classified as Gleyic, Calcic Fluvisol (Calcaric, Clayic; IUSS
Working Group WRB, 2006). Prior to draining the soil was
probably a typical waterlogged Gleysol with reducing conditions within 50 cm of the mineral soil surface.
Radiocarbon dating
Calibrated radiocarbon dates of two freshwater molluscan
taxa are shown in Table 3 and indicated on the pollen diagram (Fig. 3). They covered a period of 1600 years between
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
517
Table 1: Lithology of paleomeander sediment infill (soil horisons).
Horizon (cm)
Signature
Colour (Munsell,
when moist)
Morphological properties
0–20
A
10YR 2.5/2
dark brown-grey humus horizon, dry silty clay; granular to blocky subangular structure
(aggregates < 10 mm), consistence slightly hard; abundant mollusc shells and their fragments;
strongly calcareous material, gradual boundary with:
20–39
Cl1
10YR 3.5/1
strongly calcareous, dark brown-grey silty clay with apparent sand admixture; consistence
friable to firm; massive (coherent) structure; abundant fragments and whole shells of
molluscs; broken horizon transition into
39–56
Cl2
10YR 4.5/3
brown silty sand, consistence friable to firm; abundant fragments and whole shells of
molluscs; in the depth of 55–62 cm layer with abundant shells of Planorbarius corneus. Clear
transition into
56–74
Cl3
10YR 3.5/2
dark grey-brown silty clay with apparent admixture of coarser particles; massive coherent
structure, loose; slightly plastic; from 67 cm below diffuse rusty mottles; few fine- to
medium-size, weekly cemented carbonate concretions; mollusc shells and their fragments;
gradual boundary to
74–141
Cr4
141–260
Cr
silty clay with prevailing reductimorphic brown-grey colour. Plastic, slightly sticky material,
10YR 3.5/1.5 (5Y
massive coherent structure. Common, faintly contrast, medium-sized rusty mottles, also
4.5/1.5 when dry)
around voids. Few fine- to medium-size, weekly cemented carbonate concretions
(by drilling) grey silty carbonaceous clay, very sticky and plastic, structureless, massive,
extremely hard upon drying.
the levels 102 cm and 50—60 cm of the profile. Although the
real ages of molluscan shells could have been significantly
influenced by the freshwater reservoir effect (“hardwater” error), the radiocarbon data obtained seem to be in accordance
with the paleoecological data and relative dating and thus
can be considered reliable.
Pollen record
On the basis of pollen composition and also with help of
the principal component analysis and numerical analysis
pollen stratigraphy has been subdivided into five local palynological zones and two subzones, which are used as a
framework for the discussion of results and can be dated
stratigraphically. For better graphic representation the total
diagram has been divided into the partial ones (Figs. 3, 4, 5).
Selected palynomorphs are also shown in the Fig. 6.
Subzone DV-SK-1a-VIII: depth 130—115 cm
Abies—Fagus—Ulmus—Alnus—Quercus—Carpinus—Populus
In the lowermost layers of the analysed sequence pollen
grains of the native tree species were important, as in the following zone. Several forest formations can be deduced from
pollen data: i) bottomland floodplain forest, ii) lowland
woodlands, iii) (sub) mountainous Carpathian forest, iv) alder
carrs. The zone is characterized by high AP values reaching
up to 70—80 %, suggesting a mainly forested landscape.
Floodplain woodlands were characterized by relatively
greatest proportions of Ulmus (elm, 15 %) and Populus
(poplar, 8 %) of the entire profile, although oak (10 %) was
an important constituent of these woodlands. The proportion
of Abies (silver fir) pollen reached up to 19 % along with increasing share of Fagus (beech, 20 %) in this zone and at the
start of the next subzone DV-SK-1b. The percentage of Alnus
Table 2: Selected chemical soil parameters.
Horizon (cm)
Designation
5–15
25–35
40–52
55–70
90–100
A
Cl1
Cl2
Cl3
Cl4
CaCO3
(g/100 g)
29
29
49
14
13.6
Cox
(g/100 g)
5.29
3.21
5.91
8.57
1.95
Humus
content
9.12
5.53
10.19
14.78
3.36
HA/FA
Q 46 (HA)
0.51
0.55
–
–
–
4.68
4.31
CEC
(cmol+/kg)
37.70
35.03
–
–
–
pH/H2O
pH/KCl
8.21
8.47
8.34
8.16
8.01
7.66
7.82
7.76
7.60
7.59
Table 3:
Material/ Species Age 14C (BP)
Sample ID
Lab. No.
Dudváh
50–60 cm
Gd-12990
Planorbarius
corneus
Dudváh
102 cm
Gd-11901
Unio tumidus
Calibrated age range 68 %
Calibrated age range 95 %
1410 ± 55
590 AD–665 AD (68 %)
535 AD–695 AD (93.4 %)
700 AD–710 AD (0.4 %)
745 AD–765 AD (1.6 %)
2770 ± 45
975 BC–950 BC (12.1 %)
945 BC–840 BC (56.1 %)
1020 BC–815 BC (95.4 %)
Gd — Radiocarbon Laboratory Institute of Physics, Silesian University of Technology, Krzywoustego 2, 44-100 Gliwice, Poland
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
pollen (up to 15 %) along with Thelypteris palustris indicates presence of alder woods in the area.
At the start of this zone the pollen of Polypodiaceae also culminated (over 10 %).
As early as in this subzone, indicators of open
country and human impact are represented by
pollen of Chenopodiaceae, Artemisia, Carduus/
Cirsium, Centaurea, Plantago major-media, P.
lanceolata and Rumex t. acetosa and R. t. acetosella.
Aquatics, some littoral and marsh species are
represented by sporadic pollen of Potamogeton/
Sagittaria-type, some Myriophyllum (including
M. spicatum), Lemna minor, Thalictrum/Alismatype and of Cladocera. A rare find is that of Salvinia natans (floating fern). Stratigraphically the
sediment is classed into the Sub-Boreal period
(VIII 5 100/4 500—2 300 BP, Firbas 1949, 1952;
Dreslerová et al. 2004).
Subzone DV-SK-1b-IX: depth 115—85 cm
Abies—Fagus—Picea—Alnus—Salix—Quercus—
Cyperaceae
Fig. 4. Pollen diagram for non-arboreal pollen, plant taxa.
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Although at the start of this subzone the
AP : NAP ratio was high in favour of trees
(80 : 20), later the situation changed completely.
Therefore, this subzone is characterized by the
most pronounced decrease in pollen of trees indicating gradual forest clearance. At the beginning
pollen frequencies of Alnus (alder, 15 %), Carpinus (hornbeam, 12 %) and Corylus (3 %) culminated. The most prominent was the peaking
percentage of Fagus (beech) which occurred
shortly after the beginning of the zone, reaching
almost 40 %, although after that it was steadily
decreasing to reach very low values at the end,
similarly to Abies. In the course of the subzone
Alnus pollen gradually decreased to about 1—2 %.
Compared to the species of Quercetum mixtum,
there was a slight increase in pollen percentages
of Fraxinus and Acer. A maximum proportion of
Salix (willow, up to 10 %) in the latter half of this
zone may indirectly indicate increase in erosional
activity of rivers, since willows and poplars need
bare surfaces of freshly deposited channel bars
for their generative reproduction. This may also
be associated with pollen grains of “exotic trees”
of genus Pinus (of Tertiary age), Cupressaceae
(Tsuga), along with Dinoflagellata, redeposited
from the older layers, which appeared solely in
this zone.
Forest clearance and opening of the forest cover is also indicated by the appearance of several
shrubs (Sambucus nigra, Viburnum, Hedera,
Ephedra), including Juniperus as the characteristic indicator of grazing.
Apophytes and antropophytes were a common
part of plant ecosystems in this period (Fig. 4).
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
519
Fig. 5. Diagram of sporomorphs, excluded from the pollen sum.
From the start of this zone, cereal palynomorphs appear in
the record, reflecting prehistoric agriculture: first Cerealia of
Triticum type, later on also C. type Secale. From the younger
part of the subzone the presence of cereals is almost
constant.
Pollen of predominantly local and extra local aquatics and
marsh species indicate a presence of marshy, littoral and
open water habitats, the latter with running-water but also
slowly flowing or stagnant lacustrine environment. In this
zone pollen of Sparganium/Typha angustifolia first appeared, indicating marshy and littoral habitats along with
Sagittaria-type. The increasing percentage of Cyperaceae,
representing the most frequent types amongst herbs ( > over
10 %), is also ascribed to local marshy plants. At the end of
the zone Brassicaceae/Cuscuta reached over 10 % and so did
Apiaceae, reaching its first maximum within the profile.
When compared to the vegetation development of an abandoned Labe oxbow near Stará Boleslav, this zone is palynologically correlated with the older Sub-Atlantic period (IX, 2
800/2 300 BP—500/650/700 AD, Firbas 1949, 1952). In terms
of archaeological chronology it probably coresponds to the
Iron Age (La Tene
è culture) and the Roman period (Břízová
1999a,b; Dreslerová et al. 2004). Stratigraphical classification is also supported by calibrated radiocarbon age
2770± 45 years BP of Unio tumidus shell in 102 cm, even if
the real age is significantly younger, due to the hardwater effect (for calibration see Table 3).
Zone DV-SK-2-Xa: depth 85—60 (80—60) cm
Cyperaceae—Poaceae—aquatics—Quercus
In this zone, the forest cover continued to decline, although at a markedly slower pace than previously. Of trees
Quercus (oak) prevailed with 6—7 %, Fagus, Alnus and Betula were represented with subtle percentages (2—3 %). Continuous presence of Juniperus in this and the next zones
indicates grazing in the territory.
Besides steadily increasing and prevailing pollen of Cyperaceae (almost 20 %), Poaceae and Apiaceae also reached a
higher proportion in this zone. Part of the Brassicaceae/Cuscuta pollen is attributable to local swamp species of the genus
Rorippa as reflected by finds of Rorippa cf. sylvestris seed in
70—80 cm. Cuscuta (dodder) has been reliably determined by
seed finds only in the youngest zone DV-SK-5-Xc.
Amongst indicators of cultivation, cereals and their weeds
appeared again. At the DV-SK-2 and DV-SK-3 transition, Artemisia reached its first maximum in the profile. Urtica, Carduus/Cirsium, Centaurea types jacea and scabiosa were also
more represented, while Plantago major-media, Polygonum t.
aviculare and Helianthemum vesicarium appeared. Green al-
520
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
Fig. 6. Microphotographs of selected sporomorphs. Štúrová—Dudváh – AP: 1 – Pinus, sample DV-SK 60/2, depth 0.60 m; 2 – Juniperus, sample DV-SK 90/2, depth 0.90 m; 3 – Carpinus, sample DV-SK 65/1, depth 0.65 m; 4 – Salix, sample DV-SK 75/2, depth 0.75 m; 5 – Populustype, sample DV-SK 95/2, depth 0.95 m; 6 – Fraxinus, sample DV-SK 70/2, depth 0.70 m; 7 – Vitis, sample DV-SK 95/2, depth 0.95 m;
8 – Ephedra cf. fragilis, sample DV-SK 100/2, depth 1.00 m; NAP: 9 – Nymphaea alba type, sample DV-SK 20/2, depth 0.20 m; 10 – Nuphar
lutea type, sample DV-SK 55/2, depth 0.55 m; 11 – Utricularia, sample DV-SK 65/1, depth 0.65 m; 12 – Lemna minor type, sample DV-SK
95/2, depth 0.95 m; 13 – Potamogeton, sample DV-SK 75/2, depth 0.75 m; 14 – Myriophyllum, sample DV-SK 35/1, depth 0.35 m; 15 – Alisma, sample DV-SK 50/2, depth 0.50 m; 16 – Trapa natans, sample DV-SK 80/2, depth 0.80 m; 17 – Sparganium/Typha angustifolia, sample
DV-SK 65/1, depth 0.65 m; 18 – Phragmites, sample DV-SK 75/2, depth 0.75 m; 19 – Brassicaceae/Cuscuta type, sample DV-SK 55/2, depth
0.55 m; 20 – Sagittaria-type, sample DV-SK 60/2, depth 0.60 m; 21 – Anemone-type, sample DV-SK 95/2, depth 0.95 m; 22 – Plantago lanceolata, sample DV-SK 100/2, depth 1.00 m; 23—24 – Artemisia, sample DV-SK 55/2, 75/2, depth 0.55 m, 0.75 m; 25 – Mentha-type, sample
DV-SK 95/2, depth 0.95 m; 26 – Cerealia T. Triticum, sample DV-SK 75/2, depth 0.75 m; 27 – Apiaceae, sample DV-SK 65/1, depth 0.65 m;
28 – Chenopodiaceae, sample DV-SK 80/2, depth 0.80 m; Spores: 29 – Salvinia, sample DV-SK 20/2, depth 0.20 m; 30 – Thelypteris palustris, sample DV-SK 115/2, depth 1.15 m; 31 – Algae: Botryococcus, sample DV-SK 30/2, depth 0.30 m. Photo E. Břízová.
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
gae were represented by Botryococcus and sporadically by
types of genus Pediastrum, which were hard to determine
due to their bad preservation.
This zone is characterized by a relatively high proportion
of taxa, indicating open water communities of predominantly slowly flowing or stagnant water. This pollen originated
mainly from local to extra local pollen deposition (Nuphar,
Nymphaea, Myriophyllum, Trapa natans, Potamogeton/
Sagittaria type, later on Lemna minor, Utricularia). An important part of this pollen was derived from submerged and
floating-leaf water plants, growing in situ, as indicated also
by numerous macrofossil finds (e.g. of genus Potamogeton).
The presence of littoral communities and reed beds existing
in the surroundings is indicated by culminating Phragmites
pollen in this zone (almost 15 %) with Iris, Sparganium/
Typha angustifolia, Thalictrum/Alisma type and Sagittaria.
In this and preceding zone microremains of Vermes-Trichuris trichiura (human whipworm) together with Ascaris
(cf. lumbricoides, roundworm) were recorded. Remnants of
eggs of these parasites of humans and swine are also often
found elswhere in medieval objects in sediments deposited
during this period (Břízová 1998, 1999a,b; Břízová & Bartošková 1994).
Stratigraphically, this zone most probably belongs to the
transition zone of the older Sub-Atlantic period (IX) and older phase of younger Sub-Atlantic (Xa, 500/650/700 AD—
1200 AD, Firbas 1949, 1952). From the archaeological
viewpoints, this zone could be correlated with the Migration
Period and Early Middle Ages (Břízová 1999a,b; Dreslerová
et al. 2004).
Zone DV-SK-3-Xa: depth 60—45 (55—45) cm
Brassicaceae/Cuscuta—Cyperaceae—Apiaceae
This zone is particularly characterized by the lowest percentage of arboreal pollen (maximum NAP sum over 95 %)
within the whole analysed sequence. This probably indicates
intensified forest clearance of virtually all types of woodlands.
At the transition to DV-SK-4, sporadic pollen of Sorbus appeared. Worthy of note is also the broken curve of Polypodiaceae. Pollen of Sub-Atlantic Calluna vulgaris (heather) also
recorded in the preceding zone indicating grazing is almost
certainly of extra regional deposition. The arboreal component
was replaced by an increasing proportion of herbaceous taxa
(Fig. 4). The highest frequencies in this zone are reached by
pollen types of family Brassicaceae/Cuscuta (over 35 %) and
Cyperaceae (steadily increasing). Apiaceae reach their second
maximum (almost 15 %) in the profile.
In this zone a total number of aquatic species decreased to
Myriophyllum, Nuphar, Nymphaea and Lemna minor, indicating gradual loss of open-water habitats. At the coring site,
this zone represents a transitional stage from shallow lake
with macrophytes into the marsh community. Terrestrialization of the lake was probably accelerated by influx of coarser
mineral material as shown by admixture of sand and coarse
silt particles between 39—56 (74) cm. Apart from several
Cyperaceae, littoral and marsh communities are indicated by
pollen of Potamogeton/Sagittaria type, Sparganium/Typha
angustifolia, Typha latifolia and Thalictrum/Alisma type.
521
This zone stratigraphically belongs to the older phase of
the Younger Sub-Atlantic period (Xa, 500/650/700 AD—
1200 AD, Firbas 1949, 1952), and it corresponds to the archaeological chronology of the Early Middle Ages (Břízová
1999a,b, Dreslerová et al. 2004). The dating is also supported by calibrated radiocarbon age 1410±55 BP of Planorbarius corneus shells from 50—60 cm.
Zone DV-SK-4-Xb: depth 45—20 (40—25) cm
Cyperaceae
In comparison with the preceding zone, arboreal pollen appear to subtly increase again in this zone to 10—20 %
(Fig. 3). Ulmus, Corylus, Carpinus, Tilia cordata, Acer and
Fraxinus reappeared, perhaps indicating recovery of some
forests or their understorey trees. This may also be related to
the disrupted pollen curve of Juniperus. At the transition to
DV-SK-5 Pinus reached its Late Holocene maximum in the
profile (over 10 %).
Prevalence of Cyperaceae (20—30 %) is associated with local floral succession reflected by macrofossil finds. Brassicaceae/Cuscuta reached around 15 % and Apiaceae receded
in comparison with the previous zone (to 5 %). Littoral and
marshy plants are represented by pollen of Potamogeton/
Sagittaria type (almost 10 %), Phragmites and Sparganium/
Typha angustifolia type. A good indicator of medieval cornfields, Centaurea cyanus (cornflower) first appeared. Artemisia reached its second maximum in this zone, around 10 %.
This zone stratigraphically belongs to the younger phase
of the younger Sub-Atlantic period (Xb, from 1200 AD until
now; Firbas 1949, 1952), into the High Middle Ages (Břízová 1999a,b; Dreslerová et al. 2004).
Zone DV-SK-5-Xc: depth 20—0 cm
Cyperaceae—Brassicaceae/Cuscuta—Pinus—antropophytes
The uppermost pollen zone is associated with the most recent human-induced changes of landscape and vegetation cover. The sum of Non-Arboreal Pollen (NAP) reaches 85—90 %.
Pollen of Quercus, Ulmus, Fraxinus, Acer, Carpinus, Fagus,
Alnus is completely absent from the major part of this zone.
On the other side, Pinus pollen remains at a value close to
10 % and percentage of Picea slightly increased for the first
time since the Roman period. Of shrubs, Viburnum and Cornus appeared.
Almost 50 % of total pollen is represented by Cyperaceae
pollen, reaching its maximum values in the whole studied
sediment sequence. As in the case of the Danube paleochannel at the site “Bláhová dedina” (Krippel 1963), a continuously increasing percentage of Cyperaceae towards the top
of the profile is related to the dominant proportion of local
palynomorphs. The latest stage of the paleochannel terrestrialization resulted in establishment of current community
dominated by Carex riparia. Other taxa of the Cyperaceae
family have also been present at the study site until today
(mainly Scirpus lacustris and Bolboschoneus maritimus
agg.), as shown by macrofossil record and present-day vegetation survey (Kubalová 2006). Aquatics and littoral/marsh
species are rare (Fig. 4).
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PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
Amongst anthropophytes, Asteraceae Liguliflorae reach
their maximum in this zone with 10 %. Second peak of Brassicaceae/Cuscuta pollen (20 %) is at least partially related to
local pollen deposition of neophytic parasithic species Cuscuta australis, shown by several seeds only in this zone.
Similarly, a peaking percentage of Chenopodiaceae (10 %) is
associated with the local presence of Atriplex prostrata. The
recent age of this zone is also indicated by pollen of neophytic
Ambrosia (whereas its occurrence in previous zones DV-SK-3
and DV-SK-4 is possibly the result of bioturbation).
This zone is stratigraphically classified into the younger
phase of the younger Sub-Atlantic period (Xc, 1700 AD
from end of the Middle Ages to the present; cf. Firbas 1949,
1952). Archaeology also shows that this zone corresponds to
the time period from post-medieval times to the present (cf.
Břízová 1999a,b; Dreslerová et al. 2004).
Plant macroremains
The plant macrofossil record is essential for reconstruction
of local successional series in abandoned paleomeanders
since it allows us to identify the local component of pollen
spectra. Plant macroremains in the macrofossil diagram have
been aligned stratigraphically (Fig. 7).
1. Initial—lowermost—assemblage of plant macroremains
(80—130 cm) corresponds to pollen LPAZ DV-SK-1a and
DV-SK-1b. It is represented by seed finds of Alnus glutinosa,
Aegopodium podagraria, Lycopus cf. europaeus, Ranunculus
subgen. Batrachium, Solanum dulcamara, Eriophorum sp.,
Fig. 7. Plant macrofossil diagram.
Fragaria cf. vesca, Linaria vulgaris, Persicaria lapathifolia,
Urtica dioica (also present in the assemblage 2), Lythrum salicaria, Poaceae and Caryophyllaceae seeds.
Solanum dulcamara commonly occurs in softwood floodplain woodlands, marshes and river banks. Persicaria
lapathifolia is a marshy plant growing on at least seasonally
damp habitats, including ruderal places and fields around
rivers. Urtica dioica (seeds found in 60—70, 120—130 cm and
pollen record) is strongly associated with high levels of nitrogen and phosphorus. It is a native component of inundated floodplain woodlands (abundant and dominant in
Salici-Populetum), but it also grows along with Aegopodium
podagraria in hardwood floodplain forests (Jurko 1958). On
the other side, stinging nettle is a typical indicator of disturbed lands and eutrophic habitats, associated with human
habitation and long abandoned buildings.
2. Sediment layers from 50—80 cm contained numerous
well-preserved seeds belonging to Ranunculus subgen. Batrachium, at least two different (not closely determined) species
of genus Potamogeton and seeds of Ceratophyllum demersum. They indicate the next important stage in the local succession, suggesting that permanent open water habitat – an
oxbow lake with only slowly flowing or stagnant water was
present at the site under study. The first plant to colonize the
lake was most probably Ranunculus subgen. Batrachium,
which already appeared in the assemblage 1. Seeds of Phellandrium aquaticum indicate, that parts of the studied paleomeander could have been temporarily exposed. This species,
together with record of Brassicaceae cf. Rorippa sylvestris al-
low us to suggest the presence of littoral communities of temporary waters of Oenanthetalia aquaticae
(O ahelová et al. 2001). Marsh and
littoral species are also represented by
seeds of Carex sp., Bolboschoenus/
Schoenoplectus, Lycopus cf. europaeus, Valeriana sp., Juncus sp. and
cf. Berula erecta. Among additional
finds, Urtica dioica and seed of Cirsium/Carduus type were also present,
the latter also indicated by pollen in
this zone. This stage of succession
roughly corresponds to pollen zone
LPAZ DV-SK-2.
3. The topmost assemblage of plant
macroremains from 0—50 cm, corresponding to LPAZ DV-SK-3 to DVSK-5 is characterized by numerous
macroremains of marsh plants along
with some anthropophytes present,
whereas the water plants (except cf.
Lemna) entirely disappeared. This assemblage is associated with the gradual conversion of the overgrown lake
into an open marsh during LPAZ DVSK-3. Besides seeds of Alisma sp.,
Bolboschoenus/Schoenoplectus, Lycopus cf. europaes, cf. Lemna and
Potentilla erecta/reptans type the assemblage is represented first of all by
numerous seeds and bracteoles of
Atriplex cf. prostrata (Chenopodiaceae) and by both perigynia and
achenes of Carex riparia. These species are related to the present-day late
successional plant community existing at the coring site. Only in the topmost layer 0—20 cm, corresponding to
LPAZ DV-SK-5, seeds of neophytic
twinner Cuscuta australis (Convolvulaceae), Symphytum officinale,
Stachys cf. palustris and Stachys recta were found. Common marshy species Stachys palustris and Symphytum
officinale grow on the site until today.
Potentilla reptans has been commonly
recorded during survey of the current
flora (Kubalová 2006). Seeds of Cirsium/Carduus type, Stachys recta and
Apiaceae cf. Conium maculatum indicate characteristic and frequent weeds,
that are commonly found in the fields
surrounding the study paleomeander.
Molluscan assemblages
In total, 2183 specimens representing
33 freshwater species (including 6 bi-
523
Fig. 8. Molluscan assemblages diagram.
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
524
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
valves) and 8 terrestrial taxa were recovered from the sediment samples. The most frequent species ( > 60 % of all samples) in the whole profile were Valvata cristata, Bithynia
leachii, B. tentaculata, Gyraulus albus, and Acroloxus lacustris. The samples also contained opercula of Bithynia tentaculata and B. leachii (not included in the diagram, in order to
avoid duplicate records). Molluscan data have been expressed
in absolute numbers and aligned stratigraphically (Fig. 8).
Four distinct molluscan death assemblages (taxocenes) have
been identified that are characterized as follows:
Taxocene A (80—130 cm): Unio tumidus
Almost the entire lower half of the profile was very poor in
molluscs. In total, it contained only 41 pieces of shells belonging to 5 species. However, in contrast to the dominating
minor shells, two excellently preserved large conchs of Unio
tumidus were excavated during sampling (in 83 and
102 cm). Low diversity and total number of shells are most
probably related to a permanently moving water environment with no or only scarce water plants. In such conditions,
limnophilous species that reproduce on submerged vegetation are missing, or occur only sporadically (brought by
flow), and are able to survive only for a short time (Anisus
vorticulus, Valvata cristata, Bithynia leachii and Gyraulus
albus; see Fig. 8). Only a few species are adapted to such
conditions, that usually do not create dense populations. This
is the case of the Unio tumidus, which occurs in moderately
or slowly flowing portions of large rivers or their major
channels. The assemblage concerned roughly corresponds
to LPAZ DV-SK-1a and DV-SK-1b.
Taxocene B (60—80 cm): Valvata cristata—Bithynia leachii—
B. tentaculata—Valvata piscinalis
The molluscan taxocene from 60—80 cm is indicative of a
paleoenvironmental change, probably towards a quieter environment, since the total number of species increased to 15.
Besides eurytopic species Bithynia tentaculata (13 %),
which was probably the first to colonize the new habitat, also
Bithynia leachii and Valvata piscinalis (10 %) appeared, indicative of channels with moving-water. In the latter half of
the zone Valvata cristata, typical for terrestrialized channels,
became the dominant species of the assemblage (42 %). This
taxocene corresponds to the lower part of LPAZ DV-SK-2.
Taxocene C (20—60 cm): Valvata cristata—Bithynia leachii
Samples from 20—60 cm contained the largest number of
shells and the most diverse molluscan fauna (37 taxa). The
assemblage is characterized by dominance of Valvata cristata (30 %) and Bithynia leachii (24 %), the latter able to live
in slow flowing waters. In the lower part of the zone, roughly
corresponding to LPAZ DV-SK-3 (40—60 cm), several additional species peaked (Anisus vorticulus, Acroloxus lacustris, Valvata piscinalis, Planorbis carinatus, Hippeutis
complanatus, Gyraulus albus). The layer between 55—62 cm
contained abundant conchs of full-grown Planorbarius corneus. This species is indicative of stagnant waters, overgrown with aquatics, such as cut-off channels and may also
occur in seasonal depressions. It is only exceptionally found
in channels with moving water. This taxocene corresponds
to LPAZ DV-SK-3 and DV-SK-4.
Taxocene D (0—20 cm): Valvata cristata—Anisus spirorbis—
(Bithynia leachii)
In total, 27 species were recorded in the uppermost part of
the sequence studied. Besides the absolutely prevailing Valvata cristata (35 %), this assemblage is also characterized by
declining Bithynia leachii and increasing abundance of
Anisus spirorbis (22 %). The abundance of Segmentina nitida and Galba truncatula also increased both indicative of
strongly terrestrialized channels or minor waterbodies,
which may be seasonally dry. Amphibious Galba truncatula
is also able to survive in a semi-terrestrial environment.
Ostracoda
Six extant freshwater taxa were determined in the samples
(Table 4); three are left in open nomenclature of which
Candona sp. 1 juv. and Pseudocandona sp. 2 juv. are of early ontogenetical stages (?A-3, ?A-4) and can represent only
juveniles of Candona weltneri and Pseudocandona compressa (Fig. 9). Elongated valves of Candona weltneri are attributed to forma weltneri (Meisch 2000). The Candonidae are
Table 4: Distribution and abundance of the ostracods in the samples. C – carapace, V – valve, juv. – juvenile.
Depth (cm)
0–10 10–20 20–30
Candonidae
Candoninae
1C
Candona weltneri Hartwig, 1899
2V 2C, 1V
Candona sp. 1 juv.
1V
Candona sp. 2 juv.
Fabaeformiscandona balatonica (Daday, 1894)
2C
Pseudocandona compressa (Koch, 1838)
Pseudocandona sp. 1 aff. P. hartwigi (G.W. Müller, 1900)
3C
Pseudocandona sp. 2 juv.
Cyclocypridinae
Cyclocypris laevis (O.F. Müller, 1776)
1C
3V
Cyclocypris ovum (Jurine, 1820)
Cyprididae
Eucypridinae
Prionocypris zenkeri juv. (Chyzer & Toth, 1858)
1V
30–40
50–60
60–70
80–90
3C, 5V
1C, 1V
1V
5C, 1V
1V
2C
2C
6C, 1V
1C
1C
1C
1C
1C
1C
110–120
1C, 1V
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
525
Fig. 9. Freshwater ostracods of Dudváh paleomeander. 1 – Candona weltneri Hartwig, 1899, RV ♀, internal lateral view; 2 – Cyclocypris
laevis (O.F. Müller, 1776), C, dorsal view; 3 – Cyclocypris ovum (Jurine, 1820) C, dorsal view; 4 – Pseudocandona sp. 1 aff. P. hartwigi
(G.W. Müller, 1900), RV♀ , external lateral view; 5 – Fabaeformiscandona balatonica (Daday, 1894), RV ♀, internal lateral view; 6 – Prionocypris zenkeri (Chyzer & Toth, 1858); RV, juvenil, external lateral view; 7 – Pseudocandona compressa (Koch, 1838), RV♀, external lateral view. RV – right valve, C – carapace, ♀– female. Scale bar 0.1 mm.
the most abundant family and they occurred in all samples.
The Cyprididae have been observed in one sample. The
amount of preserved carapaces in taphocoenosis is two times
higher, exactly 35 : 18, than open valves which signalizes a
rapid burial of the dead individuals (Oertli 1971).
Where the biogeography and ecology of the ostracods are
concerned all the determined species are extant freshwater
taxa widely distributed in the Holarctic (Cyclocypris ovum,
C. laevis), Palearctic (Candona weltneri, Pseudocandona
compressa (possibly Holarctic), Fabaeformiscandona balatonica (possibly Holarctic) regions and in Europe and Asia
Minor (Prionocypris zenkeri). Candona weltneri settles in
lakes, ponds, swamps and ditches. Prionocypris zenkeri prefers slow flowing streams with rich aquatic vegetation. It occurs also in dead arms, nor far from the river inflow (Meisch
2000). Pseudocandona compressa lives in permanent and
temporary water bodies. It prefers shallow areas of lakes, but
it is known also from bog and ditches.
Both the recognized Cyclocypris tolerate a wide range of
environmental factors. Cyclocypris laevis settles permanent
and temporary ponds with or without vegetation, springs,
streams and the littoral zone of lakes. Cyclocypris ovum is
known in almost every type of aquatic habitats, including
springs and swamps.
Fabaeformiscandona balatonica prefers the swampy,
shallow zone of lakes that dries up in the summer; but is also
known from small canals with vegetation and streams.
Paleoenvironmental reconstruction and discussion
The studied paleomeander of the Dudváh River was most
probably abandoned in the Sub-Boreal period (5100/4500—
2800/2300 BP), which correlates with the archaeological
chronology of the Bronze Age (1900—700 BC), Iron Age
(700—0 BC) or earlier. In this period the study area was a part
of the alluvium of the active Dudváh River. For this reason
high contents of CaCO3 in the soil matrix are also the result of
the suggested admixture of moved loessic material, originally
transported by the Dudváh River from the Trnavská pahorkatina Hill Land.
According to the pollen record supported by radiocarbon
data, the deposition of sediment layers between 70—130 cm
may have lasted over several centuries. During this period, the
abandoned paleomeander most probably remained connected
with the Dudváh River and had permanent influx of moving
water for most of the year. As reflected by the macrofossil
record, the littoral zone and the bottom of this side channel
were possibly still mostly free of aquatics. This oligotrophic
environment did not provide favourable conditions for molluscan and ostracod fauna, apart from the large bivalve Unio
tumidus (Swollen river mussel). Most of the molluscan shells
were recovered from the upper 80 cm of the sediment, whereas the lower part of the study profile (80—130 cm) was almost
shell free. This distribution pattern is comparable to that from
the typical fining-upward sequence of fluvial deposits from
Bratislava, where samples of 90—165 cm only contained few
shells of moving-water Lithoglyphus naticoides and some
marshy/littoral species Oxyloma elegans and Galba truncatula (Pišút & Čejka 2002). At Štúrová, a sample from 110—
120 cm also contained a well-preserved scale of Perca
fluviatilis (European perch). This common fish lives in slowflowing freshwater rivers, ponds, lakes, often close to underwater obstacles.
According to our results, the riverine landscape along the
lower Váh and Dudváh was still mainly forested in the Sub-
526
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
Boreal period (pollen zone DV-SK-1). Floodplain and bottomland woodlands, which were growing along rivers or/and
on adjacent hilly lands are clearly indicated by pollen of several tree species of Quercetum mixtum.
The pollen record along with some macrofossil finds (e.g.
Aegopodium podagraria, Fragaria vesca) indicate the presence
of a Pannonian hardwood floodplain forest of Fraxino pannonicae-Ulmetum, particularly of its subtypes Ulmo-Fraxinetum
aegopodietosum, U.-F. hederetosum and Ulmo-Quercetum
convallarietosum. Such woodlands with oak (Quercus sp.), elm
(Ulmus laevis or U. carpinifolia), ash (Fraxinus sp.), hazel
(Corylus avellana) in the shrub layer and with other tree species were probably growing on the slightly elevated Dudváh
levee not far away from the coring site. Excellently preserved
seeds of Aegopodium podagraria (Ground elder) are most
probably related to the patches of mesophilous floodplain forest, which may have occupied relatively elevated terrain in the
immediate vicinity of the meander or along the adjacent reach
of Dudváh River. Ground-elder is a nitrophilous plant which
grows in shady places and readily spreads vegetatively by underground rhizomes. Along the Danube in Slovakia, it is a
characteristic species of the hardwood elm-ash forest and particularly of its typical subassociation Ulmo-Fraxinetum aegopodietosum. This habitat is less frequently to seldom
inundated. The notable finds are those of Fragaria vesca and
Linaria vulgaris. Woodland strawberry naturally grows along
trails and roadsides, embankments, hillsides, stone and gravel
laid paths and roads, meadows, young woodlands, sparse forest, woodland edges and clearings. From the floodplain woodlands it has been only sporadically cited from the relatively
dry woodland habitat of Ulmo-Quercetum convallarietosum.
The seed could also originate from a cultivated plant. In Slovakia, strawberries are documented by archaeobotanical finds
from habitation areas already from the Roman and Migration
periods (Hajnalová 1989). A find of the common-toadflax
(Linaria vulgaris) may also reflect the presence of humans in
the landscape. Although it may grow naturally on the dunes, it
is widespread on ruderal spots, along roads, on disturbed and
cultivated land.
It is suggested that in the Sub-Atlantic period rarely flooded
Ulmo-Quercetum woodland community was one of the most
extensive on the Žitný ostrov (Krippelová 1967). The presence of oakwood from the turn of Sub-Boreal and Sub-Atlantic is also shown by wood remnants from a Hallstatt burial
mound in Dolné Janíky. The main tree species represented
were oak (Quercus, 52 samples), some Ulmus (5 samples), 1
Alnus and 1 Populus (Hajnalová & Mihályiová 1998).
Concerning the substantial percentages of Fagus pollen in
DV-SK-1 (up to 20 %, and even 30 % in the DV-SK-1b) and
the peaking proportion of Abies (silver fir, up to 19 %), it must
be said, that pollen of these trees could have come both from
local and extra regional pollen deposition, corresponding to
their present-day and post-medieval distribution. Beech is
abundant in upper basin of Dudváh (Malé Karpaty Mts) and
one of the nearest places where it grows is Gerecse Mts in
Hungary, 40 km from the coring site. Some archaeobotanical
finds (Krippelová 1967) do not exclude the existence of an additional type (no longer existing) of not inundated woodlands
with European Beech during the Sub-Atlantic period directly
on the alluvial plain or on levees and lower terraces close to
Váh, Dudváh and other rivers. Stands with at least admixture
of beech and silver fir could have created minor patches intermingled within habitats of mesophilous floodplain forest
(Krippelová 1967). Similarly quite high pollen frequencies –
with respect to the lowland area – of both species were found
in the contemporary fen peat of Kameničná (Váh River oxbow; Fig. 1), where peat deposition started in the Atlantic and
ceased in the Sub-Atlantic period (Krippel 1963). On the other
side, Pinus pollen with 26—55 % was much more represented
at Kameničná where the total AP : NAP ratio reached 2 : 1 to
1 : 2 in the same period. At Blahová site, the Pinus pollen even
reached 46—94 % (Krippel 1963), probably indicating local
dominance of pine. The country in general seems to have been
already much more open there, with AP : NAP reaching from
1 : 1 to 1 : 5. In the case of Štúrová, Pinus pollen frequencies did
not exceed 6 % until the zone DV-SK-4, indicating that pine forests grew at a quite appreciable distance from the studied site.
The striking culmination of Fagus (up to 40 %), Alnus and
Carpinus in the samples from 110—115 cm could be associated with abrupt climate change to more oceanic at the Sub-Boreal-Sub-Atlantic transition (between 850 and 760 calendar yr
BC) as a consequence of climatic deterioration (for details see
van Geel et al. 1996).
Close to the banks of the cut-off meander or not far away
upstream woodlands with alder existed. Alder could not be
the only component of Salicion albae floodplain forest,
which has been assumed to have covered large low-lying areas
with high groundwater of this region in the past (Michalko et
al. 1987). In accordance with Krippelová (1967), both pollen
and macrofossil record allows us to suggest that at least part
of this territory which originally had fen soils (the presentday histic and/or gleyic subtypes of mollisols due to draining; cf. Fulajtár et al. 1998), may have been occupied by
characteristic alder carrs of the alliance Alnion glutinosae
during the Sub-Boreal and Sub-Atlantic periods. These are
not only indicated by palynomorphs and seeds of Alnus glutinosa (from 90—130 cm), but also by pollen of Thelypteris
palustris and Filipendula, the latter almost exclusively restricted to the LPAZ zones DV-SK-1a and DV-SK-2. Thelypteris palustris (marsh fern) is one of the dominant plants
in the field layer of regional alder carrs (Jurko 1958; Krippel
1965, 1967). Filipendula ulmaria is also a regular constituent of these forests, although it may also grow on moist
meadows (it declined in DV-SK-3). The last minor isolated
fragments of alder carrs (Carici elongatae-Alnetum) still existed on Žitný ostrov Island in the 1950s (Jurko 1958). At
present, there are no alder trees – neither Alnus glutinosa,
nor A. incana – in the wider surroundings of the study site.
Among trees, poplar and willow prevail completely (Pišút et
al. 2007). The pollen record of alder in this period corresponds to comparable 5—18 % pollen percentage of Alnus reported by Krippel (1963) from peat of the Váh oxbow at
Kameničná from the Sub-Boreal period.
In the course of the older Sub-Atlantic period and in the
earlier phase of the younger Sub-Atlantic (samples from
110—55 cm), the most pronounced changes of vegetation
cover occurred in the region. These are first reflected by the
DV-SK-1b pollen zone, in SW Slovakia corresponding to Celt-
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
ic habitations (La Tene
è period, 420—0 BC), later on to the presence of Germanic settlements and Roman garisons. The second stage is correlated with the Migration Period (0—600 AD)
and Early Middle Ages (600—1000 AD), with nomadic Huns,
early Slavs and eventually Avars (DV-SK-2).
In the course of this period the arboreal pollen sum within
the region of SW Slovakia continuously decreased until it
reached roughly the present-day level, indicating the most
pronounced decline of woodlands. The decrease in AP coincides with occurrence of shrub pollen, among which some
species were represented in the pollen diagram only during
this period (Hedera, Vitis, Ephedra), but also with start of
continuous presence of Juniperus pollen in the LPAZ zones
DV-SK-2 to DV-SK-4. Presence of Hedera pollen (which has
poor dispersal) may be associated with clearance and disturbance of the original woodlands of Ulmo-Fraxinetum hederetosum, where the common ivy (Hedera helix) used to grow as
a ground cover and dominant species of the herb layer. This
mesophilous hardwood floodplain forest community with
elm, oak and ash used to be much more widespread along the
Dudváh and Váh (Jurko 1958). The presence of Vitis (Vine)
pollen in the DV-SK-1b zone, is also notable. It could belong
to wildly growing Vitis or to its cultivated form (Maděra
2002). The latter possibility is supported by archaeobotanical
finds of Vitis vinifera in objects from the Roman period and
from the start of Migration period in Bratislava and in Iža
(Leányvár) – Roman castellum (Fig. 1), the latter located
only 21 km from Štúrová study site (Hajnalová 1989).
Over this period the total forest area already steadily decreased in the wider surroundings of the study site. Woodlands were used for fodder production, either thinned out and
becoming more open due to deliberate burning, cutting and
girdling (rind-barking). Arboreal pollen recorded at the Dudváh site also correspond to trees and shrubs, represented by
charcoals found in the remains of Roman marching camp in
Iža from the same period. The species could have grown in
mixed oak forest with shrubs in understory affected by man,
more or less open, which existed in the hinterland of the
camp on the bank of the Danube or on its higher and further
situated terraces (Čejka & Hajnalová 2000).
Eventually, woodlands were completely transformed into
pasturelands, later on into hay-meadows. Grazing and pannage of livestock first occurred on relatively drier places,
slightly elevated levees and on sand dunes in the surroundings of the settlement sites next to the Danube, Dudváh and
Váh rivers. On particular sites animal husbandry could have
contributed to reestablishment of forest steppe and steppe
habitats. These may be related to the presence of Ephedra
pollen in samples from 70 and 100 cm. The only local representative of this genus is Ephedra distachya, a lower shrub.
In Slovakia it is currently extremely rare and only growing
along the Danube on the northernmost edge of its native
range. In the nature reserves next to Čenkov E. distachya
grows on sand dunes along with Populus alba and Juniperus
communis. Such conditions may have existed, for example,
on Haplic and Gleyic-Haplic Chernozems near Ve ké Kosihy
or Kameničná, only few kilometers away from the study site.
The character of secondary grasslands and meadows in the
region varied accordingly to soil type, groundwater level and
527
exposure to floods. These communities were described in detail by Krippelová (1967). Common alder carrs (Alnion glutinosae) on Histosols and Gleyic soils were gradually
transformed into the wet meadows of alliance Molinion coerulae. Soft floodplain forest of Salicion albae (on Fluvisols
and Gleysols) was replaced by secondary communities of
Rorippo-Agrostidetum stoloniferae. Pasturelands of association Trifolio-Lolietum originated on relatively dry places after
the mesophilous and subxerophilous hardwood floodplain
Ulmenion forest had been cleared. The community PotentilloFestucetum pseudoovinae originated by grazing of original
fragments of steppe habitats on Gleyic-Haplic Chernozems. In
low-lying areas a community of association Artemisio-Festucetum pseudoovinae developed on saline soils (Krippelová
1967). The possible presence of above cited secondary communities is indicated by pollen of several species of herbaceous vegetation (Fig. 4).
From the younger part of the zone DV-SK-1b the presence
of cereals is almost constant. These data are in accordance
with the recent archaeobotanical data, according to which
Triticum spelta (spelt) had the decisive proportion in the
finds from the La Tene
è period (420—0 AD). Grains of Secale
cereale (rye) also occur. It probably originally appeared as a
weed in the fields of Triticum aestivum (common wheat),
è
which was cultivated from the middle La Tene.
During the
Roman and Migration periods T. aestivum takes a decisive
role and wide distribution on fields, along with the types
Triticum aestivo-compactum (Hajnalová 1989).
A seed of Caryophyllaceae from 100—110 cm belonging
either to Arenaria serpyllifolia or Silene armeria type is also
associated with plants of arable fields or ruderals. Caryophyllaceae are also indicated by pollen from the same LPAZ
DV-SK-1a and from DV-SK-4, as well. Seed of A. serpyllifolia was also found in the samples from a filled trench of
the Roman camp1. at Iža—Leányvár (Čejka & Hajnalová
2000).
During the Migration period (0—600 AD) and in the Early
Middle Ages (600—1000 AD) the Lower Dudváh still existed
as a river but pollen of several water plants of pioneer communities of the classes Lemnetea and Potametea with Potamogeton, Myriophyllum, Nuphar (including N. lutea),
Nymphaea, Trapa natans also indicate the presence of shallow, stagnant or only temporarily flow-through waterbodies
in close vicinity of the study site. These plants grew in previously abandoned oxbow lakes and remnant Dudváh meanders. Higher flows gradually filled them with carbonaceous
mud, so that became shallower and progressively more overgrown with aquatics. Also at the coring site numerous macrofossil finds from the depth of 40—80 cm indicate a
significant change in paleoecological conditions. When an
influx of running water into the abandoned oxbow gradually
ceased, the shallowing lake started to be largely overgrown
by macrophytes. First Ranunculus subgen. Batrachium appeared, shortly followed by different species of the genus
Potamogeton and Ceratophyllum demersum.
The prevailing paleoecological conditions of these oxbow
lakes can be reconstructed based on knowledge of the
present-day distribution and ecology of typical water plant
communities in Slovakia (O ahelová 1995a,b). According to
528
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
them, the overgrowing waterbody at the coring site had
slowly flowing or stagnant water for most of the year. The
oxbow lake reached a mean depth from 0.3 to 1.2 m. So, for
instance the currently common community Potamo perfoliati—Ranunculetum circinati with dominant Batrachium circinnatum typically grows in stagnant and slow waters of
oxbows and side channels, where its cover area may reach up
to 100 %. It is tolerant of moderate salt content, the mean
water depth is 0.8 m (0.35—1.3 m). Myriophyllum verticillatum and M. spicatum form submerged stands, frequently
with Ceratophyllum demersum, Potamogeton lucens and
Utricularia vulgaris. The community with dominant C. demersum grows in stagnant and slow running waters, as in dead
arms. It indicates warm, eutrophic reservoirs with rich influx
of nutrients. The mean water depth is 0.3—1.2 m, pH range
from neutral to slightly alkalic. Nymphaea alba and Nuphar
lutea ( = vulnerable plant taxa of Slovakia) are characteristic
of the community Nymphaeetum albo-luteae (with mean water depth 0.8—1.2 m). Trapa natans is a relict and endangered
species of Slovakia, forming a monodominant community
Trapetum natantis (O ahelová 1995a,b).
Furthermore, the water level in the abandoned oxbow fluctuated over the year and parts of the river bed became seasonally exposed. This is reflected for instance by Utricularia
vulgaris, indicated by pollen from 65 cm. Carnivorous bladderwort is an indicator of infilled and overgrown meso- to
eutrophic waters with a mean water depth of 0.3 m. It is a
characteristic species of the hydro-littoral ecophase of dead
arms and depressions and of the community Lemno-Utracularietum vulgaris. On the seasonally exposed bed we also
suggest the presence of the community Oeanantho aquaticae—Rorippetum amphibiae. Its typical species Phellandrium aquaticum is indicated by the seed record from 60—80 cm
and also a part of the pollen grains of the Apiaceae family is
ascribed to this species. This small-scale community optimally grows in seasonally drying marsh habitats in the medium stage of their terrestrial conversion or in the littoral zone
of slowly flowing lowland rivers, with a depth of water level
up to 30 cm (O ahelová et al. 2001). Local occurrence of natural plant communities of the alliance Oenanthion aquaticae
characteristic of dead arms and shallow, slowly flowing waters with fluctuating water regime is also indicated by a record
of the additional species Bolboschoenus and Sagittaria.
Water plant communities of the studied oxbow and neighbouring shallowing paleomeanders bordered on or made
mosaic with communities of reed beds, large sedges and
marshy plants of the class Phragmito—Magnocaricetea
(O ahelová et al. 2001). Several characteristic species of this
class are indicated by pollen or macrofossils, such as Alisma
(cf. lanceolatum), Lycopus cf. europaeus, Schoenoplectus/
Bolboschoenus, Lythrum salicaria (seed). The presence of
Iris-type pollen in the zones DV-SK-2 and DV-SK-3 is also in
good accord with the demands of the common marshy plant
Iris pseudacorus, which could grow on the banks and bottom
of the paleochannel. The plant grows best in very wet conditions, both in open and wet forest habitats, where it tolerates
submersion, low and anoxic soils.
In the same period (LPAZ DV-SK-2) the pollen of
Phragmites also reached its maximum values. Phragmites
australis (common reed) in its characteristic community
Phragmitetum vulgaris may have occupied shallower parts
of the paleochannel or could have formed line belts along
its banks. It could also form extensive reed beds in depressed areas elsewhere in the surroundings. Local toponyms referring to historical occurrence of reed beds were
common on Žitný ostrov Island (Unti 2002).
At the end of the zone DV-SK-2 the proportion of Lemna
minor pollen also significantly increased. L. minor is a typical representative of the class Lemnetea. Structurally simple
plant communities of unrooted pleustophytes occupy mesoand eutrophic, stagnant and slowly-flowing waters. They
mainly occur in the hydro-littoral ecophase, but also tolerate
fluctuations of the water table. They are found both ephemerally and in mosaic with communities of the classes Potametea or Phragmiti-Magnocaricetea. This explains the
almost constant presence of Lemna minor pollen in the
whole profile until the present. The community with dominant Salvinia natans (O ahelová 1995a), indicated by the
pollen record throughout the profile, also belongs to the
Lemnion minoris alliance.
Altered water regime in the abandoned channel and gradual
transformation of the shallowing overgrown lake into open
marsh in LPAZ DV-SK-3 and DV-SK-4 was associated with
the optimum development of molluscan and ostracod fauna.
Freshwater molluscs seemed to have reached their maximum
abundance and diversity during the LPAZ DV-SK-3 (taxocene
C). Besides Valvata cristata and Bithynia leachii which dominated the molluscan assemblage, Anisus vorticulus, Valvata
piscinalis, Acroloxus lacustris, Hippeutis complanatus, Gyraulus albus, Planorbis planorbis, P. carinatus and Planorbarius corneus were also more abundant. Ostracods
particularly thrived in the sampled interval from 60 cm to
20 cm. According to their ecological demands, they lived in a
shallow, slow flowing cold water environment (Table 5) covered with aquatic vegetation and fed by river and springs. The
calcium content of the water was 18—72 mg Ca/l, occasionally
above this level; salinity could occasionally reach oligohaline
range (0.5—5 ‰).
Table 5: Ecological characteristics of the ostracod species. Explanation of used terms: mesotitanophylic – occurring at 18—72 mg Ca/l;
polytitanophylic – occurring at > 72 mg Ca/l; titanoeuryplastic – occurring indifferently on Ca content (according Meisch 2000).
Candona weltneri, form weltneri
Fabaeformiscandona balatonica
Pseudocandona compressa
Cyclocypris laevis
Cyclocypris ovum
Prionocypris zenkeri
Temperature
cold stenothermal
?mesothermophilic
mesothermophilic
thermoeuryplastic
thermoeuryplastic
oligothermophilic
Water velocity
oligorheophilic
–
oligorheophilic
mesorheophilic
rheoeuryplastic
mesorheophilic
Ca content
titanoeuryplastic
–
meso-polytitanophilic
meso-polytitanophilic
titanoeuryplastic
polytitanophilic
salinity
oligohalophilic
–
oligo-mesohalophilic
mesohalophilic
mesohalophilic
–
pH
–
–
euryplastic
euryplastic
euryplastic
–
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
529
Table 6: List of reconstructed or suggested phytosociological syntaxa, based on paleobotanical data or mentioned in the text.
Class
Querco–Fagetea
Br.-Bl. et Vlieger in Vlieger
1937
Order
Fagetalia
Pawlowski in Pawlowski
et al. 1928
Alliance
Ulmenion
Oberd. 1953
Salicetea purpurae
Moor 1958
Quercetalia pubescentis
Br-Bl. 1931
Salicetalia purpurae
Moor 1958
Aceri tatarici – Quercion
Jakucs et Fekete 1957
Salicion albae
(Oberd. 1933) Th. Müller et Görs
1958
Alnion glutinosae
Malcuit 1929
Molinion coerulae Koch 1926
Ranunculo repentis – Rumicenion
crispi Hejný et Kopecký 1979
Lolio–Potentillion
R. Tx. 1947
Festucion pseudoovinae
Soó in Máthé 1933
Festucion valesiacae
Klika 1931
Lemnion minoris
de Bolós et Masclans 1955
Utricularion vulgaris
Passarge 1978
Hydrocharition
Rübel 1933
Nymphaeion albae
Oberd. 1957
Alnetea glutinosae
Br.-Bl. et R.Tx. 1943
Molinio–Arrhenatheretea
R. Tx. 1937
Alnetalia glutinosae
R. Tx. 1937
Molinietalia Koch 1926
Agrostietalia stoloniferae
Oberd. in Oberd. et al.
1967
Festuco–Puccinellietea
Soó 1968
Festuco–Brometeta
Br.-Bl. et R. Tx. 1943
Lemnetea
de Bolós et Masclans 1955
Potametea
R.Tx et Preising 1942
Artemisio – Festucetalia
pseudovinae Soó 1968
Festucetalia valesiacae
Br.-Bl. et R. Tx. 1943
Lemnetalia minoris
de Bolós et Masclans 1955
Lemno-Utricularietalia
Passarge 1978
Hydrocharitetalia
Rübel 1933
Potametalia
Koch 1926
Phragmito – Magnocaricetea
Klika in Klika et Novák 1941
Callitricho–Batrachietalia
Passarge 1978
Phragmitetalia
Koch 1926
Oenanthetalia aquaticae
Hejný in Kopecký et Hejný
1965
Ranunculion aquatilis
Passarge 1964
Phragmition communis Koch
1926
Magnocaricion elatae Koch 1926
Oenanthion aquaticae
Hejný ex Neühäusl 1959
Deforestation of the region seems to have culminated in
the pollen zone DV-SK-3 probably correlated with the historical early medieval period (600—1000 AD). Between the
7 th—9th and 10 th—13th century a number of new settlements
were established in SW Slovakia and population density
markedly increased (Čaplovič 1998). Probably in this period
the last major remnant patches of until then relatively untouched floodplain forest (due to impeded drainage and periodical flooding) around the Lower Dudváh and Váh River
started to be methodically cleared and grazed. Until then –
until the start of the zone LPAZ DV-SK-3 – pollen of Quercus (oak) was constantly present with over 5 %. Also Ulmus
(elm) and Corylus (hazel) were part of the forest. From the
depth of 55 cm up-section in relation to the forest clearance
the presence of pollen of additional tree species also decreased (Fagus, Abies, Carpinus, Picea). The pollen count of
Alnus diminished as well, although its curve remained continuous. It can be assumed that although closed woodlands
with dominant Alnus glutinosa probably disappeared from
the wider surroundings, alder remained a component of the
Association/Community
Fraxino–pannonicae Ulmetum
Soó in Aszód 1936 corr. Soó 1963
Ulmo-Fraxinetum aegopodietosum
Jurko 1958
Ulmo-Fraxinetum hederetosum
Jurko 1958
Ulmo-Quercetum convallarietosum
Jurko 1958
Junipero-Populetum albae
Zólyomi 1950
Salici-Populetum
(R. Tx. 1931) Meijer Drees 1936
Carici elongatae–Alnetum
Koch 1926
Trifoli repentis– Lolietum
Krippelová 1967
Rorippo-Agrostidetum stoloniferae
(Moor 1958) Oberd. et Th. Müller 1961
Artemisio-Festucetum pseudoovinae
Soó (1933) 1945
Potentillo-Festucetum pseudoovinae
Soó 1933
Salvinio-Spirodeletum polyrhizae
Slavnić 1956
Lemno-Utracularietum vulgaris
Soó 1947
Ceratophylletum demersi
Hild 1956
Nymphaeetum albo-luteae
Nowiński 1928
Trapetum natantis V. Kárpáti 1963
Potametum natantis von Soó 1927
Potamo perfoliati–Ranunculetum
circinati Sauer 1937
Phragmitetum vulgaris von Soó 1927
Oeanantho aquaticae–Rorippetum
amphibiae Lohmeyer 1950
Dudváh riparian belts, even though it did no longer grew on
the study site.
During the period concerned the eutrophic oxbow lake
gradually developed into a marsh habitat. Local aquatics were
eventually replaced by a tall-sedge community with dominant
Carex riparia (indicated by numerous achenes and perigynia),
which have persisted on the site until the present. This community is also indicated by pollen frequencies of Cyperaceae,
steadily increasing from the bottom of the profile with maximum at the topsoil. Molluscan assemblage indicates open
marsh conditions, although trees may have grown along the
banks of a paleochannel. From the establishment of this
swamp community Atriplex prostrata also became its important
component. This obligatory halophyte species indicates periodical slight salinization of the topsoil which may occur in dry seasons. Other characteristic plants growing in this marsh were
Bolboschoenus and/or Schoenoplectus lacustris (Cyperaceae),
Alisma sp., Lycopus and Potentilla reptans (or P. erecta).
The entire molluscan taphocoenosis at Štúrová was dominated by freshwater species. Moreover, among land snails,
530
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
woodland and/or shade-demanding species were completely
missing, providing no evidence of closed woodland either at
the study site or nearby. Even at present, when the banklines
of the paleomeander are vegetated with poplars and willows,
only Cepaea hortensis is present here from the eurytopic
woodland species.
During the High Middle Ages (1000—1300 AD) paleoecological evidence is already supplemented by written records
about the character of the historical landscape. Despite a large
degree of deforestation the whole countryside was still strongly affected by surface water and shallow regional groundwater. The entire territory around the Lower Dudváh River was
seasonally inundated and characterized by excessive water.
There were extensive open wetlands, many marshes, numerous lakes, reed beds and places covered by large sedges. According to a record from 1268 the village of Čalovec on the
Dudváh was “located among reed beds”. There is also written
evidence of tall-sedge habitats, oak, elm, alder, willow, poplar
and other tree species (Fejér 1829; Marsina 1987). Some tree
species are also recorded by archaeologists. In the 13th century, Alnus, Betula and Salix were used for the construction of a
garden fence, unearthed in Šamorín (Urminský 2005).
A number of lakes mentioned in the 13th century charters
along the Dudváh indicates that the terrestrial conversion of
its former paleochannels had not been completed yet. Lakes
were used as fish ponds or as profitable fishing places. Several lakes were shallowing and developing into inundated
swamps in this period (Fejér 1829).
In the Late Middle Ages (1300—1526 AD) the Lower Dudváh became subjected to serious geomorphological changes
that probably occurred in response to a new phase of intensified Danube activity. Sometime between 1378 and 1528 AD
a new avulsion course of the Lesser Danube was formed between the villages of Topo níky and Kolárovo (Fig. 1). This
resulted into the abandonment of at least a 24 km long lower
stretch of the Dudváh River. Significantly increased erosion
activity of the Danube River also seems to be reflected from
the southern Danube branches (Pišút 2006). This activity coincides with the period of increased soil erosion and transport of sediments in the northern part of the Bavarian stretch
of the Danube (Buch & Heine 1995). The largest Danube
flood of the past millenium also occurred in this period in
August 1501 AD with an estimated peak flow in Vienna of
15,000 m3. s—1 (Rohr 2005).
After these channel changes, gradual siltation began in the
cut-off Lower Dudváh. Nevertheless, the river still kept on
carrying some running water at least seasonally even in the
18th century (Alapy 1933).
In the youngest phase – post medieval period until the
present (since 1526 AD) – the cultural landscape in the surroundings of the study site was almost completely open, similar to the present day situation. Most of the trees were
growing in riverine belts along paleochannels or in only
small patches and clusters of floodplain woodlands. Waterlogged and seasonally flooded meadows and pasturelands
dominated the countryside, so that ploughland was still underrepresented. This structure of cultural landscape is already well documented also by map sheets of the 1782—1785
military mapping (Arcanum 2004). During this period several
farmsteads with minor areas of isolated fields were established
on the levee of the former Dudváh. In the pollen record a
slight increase in Pinus and Picea (spruce) can be distinguished, coming from extra regional pollen deposition. Increased pine pollen is thought to be associated with intentional
large-scale plantings of Pinus sylvestris (Scotts pine) on
blown sands of the Záhorská nížina Lowland, which were
most intensive between 1650—1740 AD (Krippel 1965; Budke
1981). A slight increase in spruce pollen is related to introduction of its monocultures mainly in the 19th and 20th centuries.
The complete absence of Quercus, Ulmus and Carpinus
pollen is essentially in accord with the current negligible representation of these species in surroundings of the study site.
Nevertheless, apart from this most recent period, the pollen
curve of oak was continuous within the whole profile. These
data are also in agreement with the charcoal record from the
total of 45 archaeological sites located in the Trnavská pahorkatina Hill Land and the Váh alluvial valley, according to
which oak has prevailed from the Atlantic period until the
present with mixed oak forest being the main woodland type
in this territory (Hajnalová 1990).
The late successional stage of the abandoned oxbow at
Štúrová was largely dominated by the molluscan assemblage
of freshwater Valvata cristata and Bithynia leachii. Several
modern analogues of this community have been recorded
from SW Slovakia by Čejka (personal data) from side channels, streams and dead arms with much aquatic vegetation, as
in the Čičov oxbow (47°46’33” N, 17°43’52” E), the Čierna
voda Stream at Turňa (48°11’42.86” N, 17°24’4.66” E) and
the Šrek backwater of the Morava River near Stupava
(48°16’35.39” N, 16°56’32.5” E). The molluscan assemblage consisted of several species, which are currently rare,
endangered or extinct. The most notable are Anisus vorticulus
(abundant in taxocene B), Gyraulus riparius (a single shell in
taxocene A), Gyraulus rossmässleri (three shells in taxocene
B), Planorbis carinatus (taxocene B), Valvata macrostoma
(one shell in taxocene B and D), Pisidium pseudosphaerium (3
shells in taxocene B). Most of these species are now scarce
not only in the study area, but in the whole Danubian Lowland; some are probably already extinct here (Gyraulus
rossmässleri, Valvata macrostoma).
The current habitat at the coring site is a result of the
most recent landscape changes during the 19th and 20th century, which have been associated with drainage, intensified
agriculture, ruderalization and spread of invasive species.
After the completion and strengthening of the embankments
along the Danube in the 17th and 18th centuries, problems
due to waterlogging and deteriorated outlet of floodwaters
exacerbated. The study site was first affected by drainage in
1822 (Gyulai 1896). Nevertheless, even in 1876 large territories of lower Žitný ostrov Island were predominantly used
for pastures and wet meadows, with only small patches of arable lands (Bálint map, reproduced by Krippelová 1967).
The establishment, refinement and completion of the drainage network from the late 19th century to the 1960s caused
lowering of the mean regional groundwater table by about
60—100 cm. Thus, parts of the original open swamps in
paleomeanders came to be occupied by secondary softwood
floodplain woodlands (Salici—Populetum). Several willow-
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
dominated woodland patches have been planted intentionally,
being used mainly as pollard trees. The last remnant of shallow open waterbodies rapidly disappeared and organic soil
layers have been partially mineralized. As a result, originally
waterlogged soils have developed into the current prevailing
Calcaric Mollic Fluvisols and Mollic Gleysols (Fulajtár et al.
1998). Consequently, this drying has resulted in retreat of
original swamp habitats and enabled the large-scale transformation of pastures and meadows into arable lands. This process was completed by the establishment of a new agricultural
colony – the current village of Štúrová – near former Dudváh in 1950s.
Conclusions
The Late-Holocene biostratigraphy at the Štúrová site has
been subdivided into different local pollen assemblage zones
that are correlated with the general Holocene climatostratigraphic subdivision for Central Europe. Five zones and two
subzones were identified as follows: DV-SK-1a-VIII: depth
130—115 cm, Abies—Fagus—Ulmus—Alnus—Quercus—Carpinus—opulus; DV-SK-1b-IX: depth 115—85 cm, Abies—Fagus—Picea—Alnus—Salix—Quercus—Cyperaceae; DV-SK-2-Xa:
depth 85—60 cm, Cyperaceae—Poaceae—aquatics—Quercus;
DV-SK-3-Xa: depth 60—45 cm, Brassicaceae/Cuscuta—Cyperaceae—Apiaceae; DV-SK-4-Xb: depth 45—20 cm Cyperaceae;
DV-SK-5-Xc: depth 20—0 cm, Cyperaceae—Brassicaceae/Cuscuta—Pinus—anthropophytes. Paleoecological analysis provides
new information about the paleoenvironments of the Danubian
Plain from the Sub-Boreal to the younger Sub-Atlantic period.
Apart from the two lowermost subzones DV-SK-1a-VIII and
DV-SK-1b-IX, non-arboreal pollen prevailed in samples including several indicators of cultivation, reflecting an open
cultural riverside landscape.
The paleomeander of the Dudváh River at Štúrová site was
cut-off during the Sub-Boreal period when the land was still
mostly covered by oak-dominated mixed forest, although
with a notable high frequency of Fagus and Abies with respect to the lowland basin. Floodplain woodlands with Quercus, Ulmus, Tilia, Fraxinus, Populus and Salix were the
most important part of the regional forest vegetation. In lowlying depressions, Alnus glutinosa formed typical alder
carrs. The largest human-induced decline of the regional forest occurred during the Sub-Atlantic with peaking forest
clearance in the early medieval period. The results confirm
earlier palynological (Krippel 1963, 1986) and archaeobotanical data, and provide new data on the composition of
vegetation in this part of Žitný ostrov. Until the mid-19th
century the region was strongly influenced by shallow
groundwater and periodical floods, as reflected by abundant
pollen of aquatics and marsh species. Amongst non-arboreal
taxa, pollen of Cyperaceae, Brassicaceae/Cuscuta, Poaceae
and Apiaceae prevailed. Paleobotanical, macrofossil and ostracod records allowed the local species to be recognized in
the paleorecord and individual stages of terrestrial conversion of paleomeander to be identified. Local successional
changes started with i) stage of abandoned oxbow still with
influx of moving water, poor in both macrophytes and mol-
531
luscs, went on through ii) a shallow eutrophic oxbow lake
with slowly flowing or stagnant water overgrowing with
aquatics (Ranunculus subgen. Batrachium, Potamogeton sp.,
Ceratophyllum demersum etc.) and with abundant invertebrates that finally developed into iii) an open marsh dominated by Cyperaceae (mainly Carex riparia) with Atriplex
prostrata, supporting diverse molluscan and ostracod fauna.
The molluscan assemblages were almost completely dominated by freshwater taxa, typical of a still aquatic habitat and
shallow open marsh. The current habitat with Cyperaceae
and subdominant Atriplex prostrata established itself on the
site already in medieval times.
The results contribute to the historical biogeography of several plant and molluscan taxa of conservation concern. These
taxa no longer exist at the studied site at all, and are scarce
nowadays in Slovakia, and in the whole Danubian Lowland,
many being vulnerable, endangered and protected (water
plants Nymphaea, Nuphar, Trapa natans agg., Utricularia,
Salvinia etc., molluscs Anisus vorticulus, Gyraulus riparius,
G. rossmässleri, Planorbis carinatus, Valvata macrostoma,
Pisidium pseudosphaerium). Some species are probably already extinct in this region (e.g. molluscs Gyraulus
rossmässleri, Valvata macrostoma).
Acknowledgments: We wish to acknowledge anonymous referees whose comments considerably improved the text. This paper is dedicated to the memory of Dr. Eduard Krippel, who
carried out pioneer pollen investigations in Slovakia. We also
appreciate the kind assistance of Dr. M. Kováčová in preparation of pollen samples. We thank Prof. K. Hensel who determined the fish scale. This study was made possible by funding
from the Slovak Grant Agency VEGA (Projects No. 2/5016/25,
2/5014/25, 1/0362/09, 2/0060/09) and by Dr. Žofia Murgašová.
It was also supported by the research design of the Czech Geological Survey, Prague (MZP000257801 – Regional Geology
and Mapping), Project IGCP 518 (Czech Republic) and by the
Research design Global Climate Changes and by internal
Project No. 326500 of the Czech Geological Survey.
References
Aaby B. & Berglund B.E. 1986: Characterization of peat and lake deposits. In: Berglund B.E. (Ed.): Handbook of Holocene, palaeoecology and palaeohydrology. John Wiley & Sons Ltd.,
Chichester—New York—Brisbane—Toronto—Singapore, 231—246.
Alapy Gy. 1933: History of fishing at Žitný ostrov Island. Komárno
1—166 (in Hungarian).
Arcanum 2004: The first military mapping. DVD-ROM. The Institute of Military History, the Map Archives and Arcanum Adatbázis Kft., Budapest.
Břízová E. 1998: Prague, medieval Sněmovní street – pollen analysis
of its sediments. Archl. Prag. (Praha) 14, 317—328 (in Czech).
Břízová E. 1999a: Changes of plant ecosystems in the Labe River
floodplain during Late Glacial and Holocene (pollen analyses).
Zpr. Čes. Bot. Společ., 34, Mater. 17, 169—178 Praha (in Czech).
Břízová E. 1999b: Late Glacial and Holocene development of the
vegetation in the Labe (Elbe) River flood-plain (Central Bohemia, Czech Republic). Acta Paleobot., Suppl. 2 – Proceedings
5th EPPC, Kraków, 549—554.
Břízová E. 2007: Aquatic and wetland ecosystems during the Late
532
PIŠÚT, BŘÍZOVÁ, ČEJKA and PIPÍK
Glacial and Holocene based on pollen analyses. Zpr. Čes. Bot.
Společ., Praha, 42, Mater. 22, 85—97 (in Czech).
Břízová E. & Bartošková A. 1994: Early medieval hillfort of
Budeč: reconstruction of environment of the basis of pollen
analysis. Sbor. Geol. Věd, Antropozoikum 21, 75—86.
Břízová E., Pišút P. & Uherčíková E. 2007: Reconstruction of the
forest vegetation development in the Žitný ostrov Island on the
basis of pollen analysis. In: Križová E. & Ujházy K. (Eds.):
Dynamics, stability and diversity of forest ecosystems. Technical University, Zvolen, 209—215 (in Czech).
Buch M.W. & Heine K. 1995: Fluvial geomorphodynamics in the
Danube River valley and tributary river systems near Regensburg during the Upper Quaternary – theses, questions and conclusions. In: Hagedorn J. (Ed.): Late Quaternary and present-day
fluvial processes in Central Europe. Z. Geomorphologie N.F.,
Suppl. Bd. 100. Gebrüder Borntraeger, Berlin, Stuttgart, 53—64.
Budke A. 1981: The history of the forest management in the Záhorie Lowland. Zbor. lesníckeho, drevárskeho a po ovníckeho
múzea 11, 45—99 (in Slovak).
Cappers R.T.J., Bekker R.M. & Jans J.E.A. 2006: Digitale Zadenatlas van Nederland. Groningen Archaeological Studies, 4,
Barkhuis Publishing, Groningen.
Čaplovič D. 1998: Early-medieval settlement of Slovakia. Acad.
Electronic Press, Bratislava, 1—268 (in Slovak).
Čejka T. & Hajnalová E. 2000: Reconstruction of environment in the
surrounding areas of Komárno in the Roman period on the basis
of the analysis of plant macroremains and molluscan thanatocoenoses. Archeologické rozhledy 52, 316—329 (in Slovak).
Dreslerová D., Břízová E., Růžičková E. & Zeman A. 2004: Holocene environmental processes and alluvial archaeology in the
middle Labe (Elbe) valley. In: Gojda M. (Ed.): Ancient landscape, settlement dynamics and non-destructive archaeology.
Academia, Praha, 121—171.
Fejér G. 1829: Codex diplomaticus Hungariae ecclesiasticus et civilis. Tomus 4, Vol. III. Buda (in Latin).
Firbas F. 1949: Spät- und nacheiszeitliche Waldgeschichte Mitteleuropas nördlich der Alpen. I. Allgemeine Waldgeschichte.
G. Fisher, Jena, 1—480.
Firbas F. 1952: Spät- und nacheiszeitliche Waldgeschichte Mitteleuropas nördlich der Alpen. II. Waldgeschichte der einzelnen Landschaften. G. Fisher, Jena, 1—256.
Fulajtár E., Čurlík J., Barančíková G., Sedláková B. & Šurina B.
1998: Impact of the waterwork Gabčíkovo on agricultural
soils. Výskumný ústav pôdnej úrodnosti, Bratislava, 1—201.
Füry J., Décsi L. & Stanovský J. 1986: The Danube Catchment Company yesterday and today. Povodie Dunaja, informačný spravodaj 1, 15—35.
Guidelines for soil description. 2006. FAO, Rome.
Gyulai R. 1896: History of the Joint Society for Protection against
the floods and for draining of internal waters at the territories
of lower Žitný ostrov Island (Csallóköz) and Csilizköz. Reedited 2003, Kalligram, Komárno, 1—592 (in Hungarian).
Hajnalová E. 1989: Archaeobotany in Slovakia: the state-of-the-art.
Acta Interdisciplinaria Archaeologica 6, 3—217 (in Slovak).
Hajnalová E. 1990: Anthrakotomische analysen aus archäologischen grabungen im Trnavaer Hügelland und Waagtal. Študijné
zvesti Archeologického ústavu SAV 26, 223—236 (in Slovak).
Hajnalová E. 1993: Geschichte des an archäobotanischen Funden
dokumentierten Anbaues von Getreidearten in der Slowakei.
Acta Interdisciplinaria Archaeologica 8, 3—147 (in Slovak).
Hajnalová E. & Mihályiová J. 1998: Archäobotanische Funde im
Jahre 1996. AVANS v r. 1996, Nitra, 61—67 (in Slovak).
Hammer Ř. 2009: PAST: Paleontological statistics software package
for education and data analysis. http://folk.uio.no/ohammer/past/
Hlavatý Z. & Banský . 2006: Ground water levels and soil moisture. In: Mucha I. & Lisický M.J.L. (Eds.): Slovak-Hungarian
environmental monitoring on the Danube. Ground Water Consulting Ltd., Bratislava, 85—88.
IUSS Working Group WRB 2006. World reference base for soil resources 2006. World Soil Resources Reports No. 103. FAO,
Rome.
Jurko A. 1958: Soil ecological conditions and forest communities of
the Danube Plain. SAV, Bratislava, 1—225 (in Slovak).
Krippel E. 1963: Postglacial Entwicklung der Vegetation des nördlichen Teils der Donauebene. Biológia, Bratislava 18, 10, 730—741.
Krippel E. 1965: Post-glacial development of forests in the Záhorie
Lowland. Vydav. SAV, Bratislava (in Slovak).
Krippel E. 1967: Alder carr (Alnetum glutinosae) in the Záhorie
Lowland. Geografický časopis 19, 2, 93—106 (in Slovak).
Krippel E. 1986: Post-glacial development of vegetation in Slovakia. Veda, Bratislava, 1—307 (in Slovak).
Krippelová T. 1967: Vegetation of the Žitný ostrov Island. The
communities of pasturelands and the reconstruction of the vegetation. Biologické práce 13, 2, 1—108 (in Slovak).
Kubalová S. 2006: Vegetation diversity of paleomeanders in agrarian landscape. In: Měkotová J. & Štěrba O. (Eds.): River landscape. (Říční krajina.) 4, Olomouc, 138—147 (in Slovak).
Ložek V. 1955: Report on the malacozoological study in the territory
of Žitný ostrov Island in 1953. Arbeiten der II. Sektion der Slovakischen Wissenschaftlichen Akademie, Biol. Ser. 1, 6, 5—31 (in
Czech).
Lukniš M. & Mazúr E. 1959: Geomorphological regions of the Žitný
ostrov Island. Geografický časopis 11, 3, 161—195 (in Slovak).
Maděra P. & Martinková M. 2002: Assessing the occurrence of Vitis
vinifera subsp. sylvestris (C.C. Gmelin) Hegi in the Czech
Republic. J. Forest Sci. 48, 11, 482—485.
Majerčáková O., Faško P., Pecho J. & Š astný P. 2006: Evaluation
of the climate monitoring in the area of the Gabčíkovo hydraulic structures. In: Mucha I. & Lisický M.J.L. (Eds.): SlovakHungarian environmental monitoring on the Danube. Ground
Water Consulting Ltd., Bratislava, 55—59.
Marhold K. & Hindák F. (Eds.) 1998: Checklist of non-vascular and
vascular plants of Slovakia. Veda, Bratislava, 1—688.
Marsina R. 1987: Codex diplomaticus et epistolaris Slovaciae 2.
Obzor, Bratislava, 1—640.
Meisch C. 2000: Freshwater Ostracoda of Western and Central Europe.
Spektrum Akademischer Verlag, Heidelberg—Berlin, 1—522.
Michalko J., Magic D., Berta J., Rybníček K. & Rybníčková E.
1987: Geobotanical map of C.S.S.R. Slovak Socialist Republic. VEDA, Bratislava, 1—168.
Mucina L. & Maglocký Š. 1985: A list of vegetation units of Slovakia. Documents Phytosociologiques N.S., Camerino 9, 175—220.
Munsell Soil Color Charts 2000: Revised washable edition. Gretagmacbeth, New York, 1—10.
Oertli H.J. 1971: The aspect of ostracode faunas – a possible new tool
in petroleum sedimentology. In: Oertli H.J. (Ed.): Paléoécologie
des Ostracodes. Bull. Centre Rech., Pau-SNPA 5, 137—151.
O ahelová H. 1995a: Lemnetea. In: Valachovič M. (Ed.): Plant
communities of Slovakia. 1. Pioneer vegetation. Veda, Bratislava, 130—150 (in Slovak).
O ahelová H. 1995b: Potametea. In: Valachovič M. (Ed.): Plant
communities of Slovakia. 1. Pioneer vegetation. Veda, Bratislava, 151—179 (in Slovak).
O ahelová H., Hrivnák R. & Valachovič M. 2001: Phragmito—Magnocaricetea. In: Valachovič M. (Ed.): Plant communities of Slovakia. 3. Wetland vegetation. Veda, Bratislava, 53—183 (in Slovak).
Pišút P. 2006: Changes in the Danube riverbed from Bratislava to
Komárno in the period prior to its regulation for medium water
(1886—1896). In: Mucha I. & Lisický M.J.L. (Eds.): SlovakHungarian environmental monitoring on the Danube. Ground
Water Consulting Ltd., Bratislava, 59—67.
Pišút P. & Čejka T. 2002: Historical development of floodplain site
HOLOCENE PALEOENVIRONMENTAL DEVELOPMENT OF THE ŽITNÝ OSTROV ISLAND (SLOVAKIA)
using Mollusca and cartographic evidence. Ekológia, Bratislava
21, 4, 378—396.
Pišút P., Uherčíková E., Břízová E., Hamerlík L. & Čejka T. 2007:
Contribution to the genesis and present-day diversity of softwood floodplain forest at Žitný ostrov Island. In: Križová E. &
Ujházy K. (Eds.): Dynamics, stability and diversity of forest
ecosystems. Publ. House of the Technical University, Zvolen,
217—226 (in Slovak).
Püspöki-Nagy P. 1985: History of the hydrographical picture of
Žitný ostrov Island from the Strabo’s Geography until the age
of the King Béla IVth. Új Mindenes Gyujtemény, 63—124 (in
Hungarian).
Rohr Ch. 2005: The Danube floods and their human response and perception (from 14th to 17th C). History of Meteorology 2, 71—86.
Schellmann G. 1990: Fluviale Geomorphodynamik im jüngeren
Quartär des unteren Isar- und angränzenden Donautales. Düsseldorfer Geographische Schriften 29, 1—131.
Tkáčová H., Kováčik M., Caudt ., Elečko M., Halouzka R., Hušták
J., Kubeš P., Malík P., Nagy A., Petro ., Piovarči M., Pristaš
J., Rapant S., Remšík A., Šefara J. & Vozár J. 1996: Podunajsko – DANREG. Final Report of the Project No. 109 91 01.
Geocomplex, a.s. & Geological Survey of the Slovak Republic,
elaborated for the Ministry of Environment, 1—266 (in Slovak).
533
Unti M. 2002: Geographical names of the Žitný ostrov Island
(Csallóköz). The district of Dunajská Streda. Csemadok Területi
Választmánya, Dunajská Streda, 1—240 (in Hungarian).
Urminský J. 2005: Medieval Šamorín in archaeological finds. In:
Strešňák G. & Végh L. (Eds.): Kapitoly z dejín mesta Šamorín.
Lilium Aurum, Šamorín, 9—20 (in Slovak).
van Geel B., Buurman J. & Waterbolk H.T. 1996: Archaeological
and palaeocological indications of an abrupt climate change in
The Netherlands, and evidence for climatological teleconnections around 2650 BP. J. Quat. Sci. 11, 6, 451—460.
Vaškovská E., Vaškovský I. & Schmidt Z. 1978: Formation, structure and comparison of Holocene sediments of the Žitný ostrov
island, Danube lowland, Czechoslovakia. Acta Universitatis
Ouluensis A 82, Geologica 3, 155—163.
Válková D. & Stanová V. 2000: Selected peatlands of the district
Dunajská Streda. In: Stanová V. (Ed.): Peatlands of Slovakia.
DAPHNE, Bratislava, 157—160 (in Slovak).
Walanus A. & Nalepka D. 1999: POLPAL program for counting
pollen grains, diagrams plotting and numerical analysis. Acta
Palaeobot. 2, 659—661.
Zahradníková-Rošetzká K. 1965: Geobotanical characteristics of the
fen meadows and pasture (Molinion Koch 1926) at the Žitný ostrov Island. Biologische Arbeiten 11, 5, 5—43 (in Slovak).