Project

Holocene development of temperate European biota: effects of climate, refugia and local factors tested by complex datasets of independent proxies

Goal: This project covers the last 15.000 years and uses an innovative interconnection of local sequences, their spatial heterogeneity, reconstructions of regional macroclimate using independent abiotic (stable isotopes) and biotic proxies, modelling of past landscape patterns and testing their effect on recent diversity, and continental-scale comparisons. Geographically, the project is focused on the Western Carpathians as the major biogeographical interface within Europe, and Northern France as a reference region with a different refugial history. Fossils of terrestrial molluscs in calcareous deposits act as a principal proxy. Pollen, testate amoebae and plant macrofossils act as important proxies for validations of local developments, macroclimate reconstructions and spatial modelling of past landscape diversification.

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Jan Divíšek
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In this document, I introduce a dataset of gridded bioclimatic and ENVIREM variables at a spatial resolution of 30 arc-seconds and temporal resolution of 100 years. This dataset covers the European continent (32.5°W–70°E; 32.5°N–82.5°N) and the period from 21,000 to 0 BP. For each 100-year bin, bioclimatic and ENVIREM variables commonly used in species distribution modelling were calculated based on the downscaled and debiased monthly temperature and precipitation simulations of the Community Climate System Model version 3 (CCSM3; Collins et al., 2006). CCSM3 simulations were downscaled using the delta-change method (Ramirez Villejas & Jarvis, 2010).
Jitka Frodlová
added a research item
The Western Carpathian Mountains have been attracting palaeoecologists for a long time, recently mainly to seek direct evidence of northern cryptic refugia in this region. We investigated a rich Holocene mollusc record in the White Carpathian Mountains, capturing a gradual development of forest malacofaunas under stable environmental conditions. To obtain precise data about colonisation and extinction events for particular species, we applied a high-resolution depth-age model. Early Holocene assemblages revealed both the presence of Early Holocene relics and an early appearance of closed-canopy forest species that might indicate a cryptic glacial refugium nearby. Many forest species peaking at the Holocene forest optimum, including anthropophobic arboricole land snails (e.g. Bulgarica cana and Macrogastra borealis), were present since the Early Holocene as well. After 4000 cal. a BP, forest vegetation composition changed, and the environment became less suitable for woodland snails (i.e. calcium and moisture level decreased). This change was indicated by the disappearance of many sensitive forest species. Most of the exclusively forest species reappeared during the early Middle Ages because of dense beech forest development. However, in the late Middle Ages, the study site was deforested and became an open wetland. The existence of pollen, plant macro-remains, and stable isotope data allowed us to compare the recorded mollusc succession to the signal derived from these proxies. Hence, we propose that the Mituchovci site should be considered a model for the Holocene development of mollusc woodland faunas in the (Outer) Western Carpathians and one of the main reference sites for Central European mollusc succession.
Salomé Granai
added a research item
The development of biotic communities since the last glaciation has been shaped by both dramatic climate changes and pathways of species colonisation from glacial refugia. Although the growing body of literature has emerged recently on possible scenarios of postglacial colonisation, less is known about the effect of climate. We analysed the dynamics of Holocene mollusc succession with an undetected human impact using three well-dated sequences from spring tufa deposits across temperate Europe. For the first time, the detailed Holocene mollusc successions can be compared with climate parameters in the corresponding time windows. High-resolution palaeoclimate data accompanied the species data, and the data derived from stable isotope analyses. The number of closed-canopy forest species that colonised the sites until 5000 cal BP and the maximum number of species per sample systematically increased towards the interior of the continent. We also observed earlier colonisation of forest snail species in the Western Carpathians. While the aridity index was the best predictor of local species richness in Normandy and Luxembourg, minimum January temperature drove the variation in snail data in Slovakia. The short period of an abrupt cooling and drying around 8500 cal BP was found to stop the colonisation, sharply reducing the number of local species across the continent. Our results document the importance of climate for the colonisation and development of forest biota during the first half of the Holocene, both at continental and local scales. They also elucidate processes shaping the current distribution of forest snail fauna across the European temperate zone.
Jan Divíšek
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Current species‐richness patterns are sometimes interpreted as a legacy of landscape history, but historical processes shaping the distribution of species during the Holocene are frequently omitted in biodiversity models. Here, we test their importance in modelling current species richness of vascular plants in forest and grassland vegetation. Western Carpathians and adjacent regions. Vascular plants. Numbers of all species and of habitat specialists were extracted from plot records of forest and grassland vegetation. For each plot, environmental and historical data were derived from thematic maps. Historical data related to the persistence of (a) temperate taxa during the Late Glacial and Early Holocene, (b) open‐landscape taxa during the Middle Holocene and (c) taiga taxa during the Late Holocene were based on 112 fossil pollen profiles. Boosted regression trees were used to model spatial patterns in species richness. Historical variables always appeared among the best predictors of current species richness. In light forests, species richness highly mirrored both the Late Glacial (12.5% contribution) and Middle‐Holocene (8.6%) landscape history. The latter factor became an important predictor also for species richness of steppe grasslands (8.3%) along with temperature seasonality (11.9%). Species richness of dark coniferous forests was best predicted by the Late‐Holocene occurrence of taiga forests (14.8%), which had an even stronger effect on the richness of habitat specialists (20.5%). Landscape changes since the Last Glacial Maximum are important predictors of current plant species richness. The historical effects were found to be habitat specific and, because they may interact with recent environmental conditions and anthropogenic pressures, they often show a nonlinear relationship with species richness. We provide one possible direction of incorporating past landscape changes to the models of species richness.
Anna Šolcová
added a research item
Research on past abrupt climate change and linked biotic response is essential for understanding of the future development of biota under changing climatic conditions, which, in turn, is necessary for adequate progress in ecosystem management and nature conservation. The present study presents the first comprehensive reconstruction of local and regional environment at the Western Carpathian/Pannonian Basin border, including a first chironomid-based paleoclimate reconstruction and δ18O and δ13C records from travertine, to investigate abrupt biota and climate shifts since the Marine Isotope Stage (MIS) 2. A range of biotic and abiotic proxy data in organic-calcareous sediment sequence were analysed using a multi-proxy approach to produce a detailed reconstruction of past ecosystem conditions. The results illustrate that the most prominent abrupt change in the local environment occurred directly at the MIS 2/ MIS 1 transition at 14,560 cal BP as a consequence of increased precipitation and an increase in reconstructed mean July temperature by ~2.2 °C. Abrupt changes in local environment during the early Holocene were closely linked to travertine precipitation rate around thermal springs and thus indirectly to the climate until the arrival of the Late Neolithics around 6400 cal BP. Regional vegetation response (derived from pollen data) to the climatic fluctuations lagged, with the most prominent changes around 14,410 cal BP and 10,140 cal BP. Our data suggest the presence of a steppe-tundra ecosystem with evidence for low amounts of temperate broadleaf trees during the MIS 2, indicating close proximity to their northern glacial refugium. We demonstrate the ability of δ18O and δ13C stable isotope record from travertine to reflect abrupt climatic and environmental changes. The study provides evidence about benefits using travertine deposits coupled with high-resolution paleoecological data to investigate past biotic and abiotic responses to abrupt climate change.
Petra Hájková
added 3 research items
The southern part of the Western Carpathians is relatively poorly investigated from the perspective of vegetation changes in the Late Holocene. We analysed two fen profiles (Kláťa and Pálenica) in the Slovenské rudohorie Mts (Slovakia), aiming to reconstruct the regional vegetation composition before humans started to have a strong in-fluence to determine the major developmental stages of the woodland vegetation and to date significant deforestation events. According to the results of radiocarbon dating, the Kláťa fen initiated around 1230 AD whereas the Pálenica fen initiated around 570 CE. Both profiles exhibited small differences in their tree composition and its development. Pollen data indicate a prevalence of Fagus, Abies and Picea, with an admixture of Quercus, Ulmus, Fraxinus, Acer and Tilia in the oldest layers of both profiles. The abundance of spruce pollen was higher in the Pálenica fen, where fossilised stomata of spruce provide evidence of its local occurrence. The Kláťa fen, however, exhibited a lower abundance of spruce pollen and was locally more encroached by fir, as evidenced by its macrocopic remains. Young layers of both profiles showed signs of strong deforestation between ca 1530 and 1750 CE, which was indicated by a decrease in pollen of climax trees, an increase in pollen of grassland species and an increase in anthropogenic indicators. Such changes in the composition of pollen spectra clearly coincided with increased human pressure during the colonisation waves since the 16th century and with the development of industry. Human pressure has had a decisive influence on compositional changes in woodlands and their transformation into grasslands and arable fields
There is still not enough palaeoecological data from the southwestern part of the Western Carpathians, where mountain ridges steeply rise from the dry and warm Pannonian basin. The reason is a low availability of sites with sediments harbouring fossil remains. In the Považský Inovec Mts, two small protected calcareous wetlands occur in different geographical position and contain suitable sediments. One represents a foothill site (initiated ca 13,000 cal. BP) whereas the other a low-mountain site (initiated ca 7,400 cal. BP). We investigated fossil pollen, spores, and macroscopic remains of plants and molluscs from their sediments. We further reviewed archaeological data, constructed a macrophysical climate model (MCM) and confronted it with other palaeoclimatic proxies. Temperate deciduous trees (Quercus, Corylus and Ulmus) occurred since the Allerød, but their expansion was blocked by a harsh climate in Younger Dryas, when Larix, Pinus and Betula nana still occurred. The climate firstly moistened at ca 9,500 cal. BP and more distinctly at ca 8,500 cal. BP, which was reflected by a strong calcium carbonate precipitation and expansion of Tilia cordata t., Hedera helix, and Ustulina. Although the MCM predicted a rather stable climate since 8,000 cal. BP, certain changes in aquatic mollusc abundances may indicate hydrological fluctuations, as they are paralleled by changes in climate humidity indicated by other evidence from the Western Carpathians. Younger hydrological fluctuations may be alternatively explained by human activities as they correspond with macro-charcoal abundance and indicators of wetland openness. During their existence, both fens harboured only few fen plant and mollusc species specialized to low-productive sedge-moss fens. In the Middle Holocene both sites were encroached by woody plants (Alnus, Picea and Salix), as most other spring fens in the Western Carpathians. Contrary to some other spring fens with similar site conditions in the Western Carpathians, few fen specialists established in the study sites since deforestation, presumably because of severe disturbances caused by grazing and/or hemp retting instead of the usual mowing.
Modern databases containing large amounts of botanical data are a promising source of new results based on large data analyses. We used a new database of plant macrofossils of the Czech and Slovak Republics to compare the recent distributions of putative relict species of fen bryophytes with their past distributions since the late glacial. All the species studied occur in lateglacial sediments, but mostly in regions where they are recently recorded (19–21st centuries). There are specific regions rich in putative relict species of fen bryophytes both in late glacial / early Holocene times and recently. In some cases the target species were, however, found outside the recent distribution range where environmental conditions are no longer suitable for their occurrence. We further found that the total number of the glacial and early-Holocene records greatly exceeds the total number of records for the middle Holocene, when succession to woodlands or bogs resulted in a reduction in species of bryophytes that are specific to open rich fens. The observed patterns may imply a relict status of the target species. We especially documented a substantial decline in the abundance of species requiring a high and stable water level (Drepanocladus trifarius, Meesia triquetra and Scorpidium scorpioides), both throughout the Holocene and during the most recent transformations of the landscape. In contrast, those species that tolerate transient decreases in water level persisted into recent times at more localities (Calliergon giganteum, Hamatocaulis vernicosus, Paludella squarrosa). Macrofossil data cannot, however, provide a quantitative analysis of the distribution of a species, because the number of recent data usually greatly exceeds the number of fossil records. The reason is that the area sampled in palaeoecological research is very small as it is time-consuming and expensive; cores or excavations usually are of only a few square centimetres. Despite this shortcoming, macrofossil data are an important, but not the only, source of evidence for the identification of the relict status of a species.
Anna Šímová
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Landslides are an important natural phenomenon of the flysch Outer Western Carpathians that diversify the local topography and provide valuable microrefugia in the geomorphologically uniform region. For the first time, we reconstructed the continuous history of Carpathian landslide wetland – the Kotelnice mire, which initiated at the Pleistocene-Holocene transition, using joint analysis of abiotic proxies, pollen, plant macrofossils and testate amoebae (TA). We utilised modern training datasets of plants and TA to define ecological requirements of species and to determine indicators of either bog or fen habitats. We further compared pollen representation of selected woody species between two landslide-related wetlands and two spring fens, not related to landslides within the study region. The unique feature of the Kotelnice mire is the development of a nearly ombrotrophic bog at ∼2500 cal BP that was after ∼1500 years reversed to a poor fen by intense deforestation and pastoralism. Pollen analysis and its intra-regional comparison demonstrate a dual refugial role of landslides in the Carpathians. In the Early Holocene and perhaps even in the Late Glacial, landslides provided refugia for warmth- and moisture-demanding species (e.g. lime, elm, hazel, beech, maple). On the contrary, they provided shelter for cold-demanding boreal species (e.g. spruce, Eriophorum vaginatum, Sphagnum medium/divinum) in the Middle and Late Holocene. Because the analogous refugial role of landslides at both the recent and the Quaternary time scales has been reported from the flysch-like and volcanite bedrocks across the Northern Hemisphere, landslides deserve more attention in searching for regionally or even globally crucial refugia.
Jitka Horackova
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Although the Carpathians in Europe have often been considered a glacial refugium for temperate plants, vertebrates, and molluscs, the fossil records, the only indisputable evidence surviving glacial periods, are as yet scarce. Moreover, the distribution of fossil records is uneven, and some areas have remained unstudied. We present here three molluscan successions from such an area—the border between the western and eastern Carpathians. This area is not only a geographic border but also a border between the oceanic and continental climate in Europe, and the molluscan fauna reflects this. We found a fluctuation of this zoogeographical border during the late glacial period and the Holocene for several snail species with their easternmost or westernmost distribution situated at this border. Such a fluctuation could reflect a small-scale shifting of climate character during the Holocene. For the first time, we recorded the fossil shells of three local endemics, Carpathica calophana, Petasina bielzi , and Perforatella dibothrion . We also found a fully developed woodland snail fauna radiocarbon dated to the Bølling period. This early occurrence of canopy forest snails indicates a possible eastern Carpathian glacial refugium for them, including local endemics, and may reflect a more moderate glacial impact on local biota than expected.
Julie Dabkowski
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Calcareous tufas are great archives of geochemical information for the reconstruction of past climate. Their importance increases in the regions where other proxies are rare, such as Western Carpathians. Here, we present the first whole-Holocene palaeoclimatic reconstruction for this region based on geochemical proxies. We analysed δ 18 O, δ 13 C and Mg/Ca ratio on tufa calcite of the Mituchovci site (White Carpathian Mountains, W Slovakia) and compared these with pollen, plant macrofossil and mollusc data. According to δ 18 O, two distinct thermal maxima occurred in the region, around 11.4 ka and between 7.3 and 6.9 ka BP. According to δ 13 C and Mg/Ca ratio, a steep increase in moisture and rainfall took place around 8.5 ka cal. BP, preceded by a cold and dry event. These events are well reflected in the biotic proxies and are suggested also by other palaeoenvironmental studies from the Carpathians. We found some later fluctuations, with dry and warm Bronze Age (ca. 3.6 ka cal. BP), cold and wet Urnfield period (ca. 2.8 ka cal. BP), warm Roman period (ca. 2 ka cal. BP) and cold but humid Migration period (ca. 1.5 ka cal. BP). We observed extreme abruptness and amplitude of the variation in all geochemical proxies in the last 500 years, when biotic proxies imply a very intense human deforestation. Land-use changes may have altered both the temperature regime in the studied fen and the carbon cycle in the recharge area.
Anna Šímová
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The Puścizna Wielka bog is situated in the Orawa-Nowy Targ Basin, surrounded by the Western Carpathians. It is a large raised bog (area over 480 ha, peat thickness up to 10 m) and represents an excellent peat archive of Holocene hydrological changes and climate variability in central Europe. We have collected a 6.3 m long peat sequence from the intact part of the bog. Here, we present preliminary results of testate amoeba subfossil record from the upper 4 m long sequence. Depth to the water table and water pH were reconstructed using an unpublished training dataset from central European peatlands. Our results show that before the 14th century the hydrology was rather stable with moderately wet surface conditions and the dominance of wet indicator species Archerella flavum and Hyalosphenia papilio. We recorded a distinct and short-time wet shift around 1440 AD, corresponding with the onset of the Little Ice Age. Since the mid-16th century, the water table has been gradually decreasing as suggested by the dominance of drought indicator species (e.g. Difflugia pulex, Heleopera sylvatica, Nebela militaris and Trinema lineare). The cause of the water table decrease is unclear because it is difficult to distinguish between climatically and anthropogenically driven changes of the bog hydrology in this development phase. Our preliminary results are in good agreement with other reconstructions derived from bog sequences in the Orawa-Nowy Targ Basin and central Europe. We acknowledge the support of grant no. 17-05696S from the Czech Science Foundation.
Michal Horsák
added a research item
We document global phylogenetic pattern in the pupillid land snail genus Vertigo by analyses of nDNA (ITS1 and ITS2) and mtDNA (CytB and 16S) sequence from 424 individuals representing 91 putative specific and subspecific Vertigo taxa. nDNA and mtDNA data were separately subjected to neighbor-joining, minimum evolution, maximum likelihood and Bayesian reconstruction methods, with conclusions being drawn from shared topological structures. Six highly supported, reciprocally monophyletic subgeneric level clades were identified: Vertigo, Alaea, Boreovertigo new subgenus, Isthmia, Staurodon and Vertilla. 88 species or subspecies were also confirmed, nine of which are new and formally described herein: V. beringiana, V. chiricahuensis, V. chytryi, V. genesioides, V. kodamai, V. kurilensis, V. lilljeborgi vinlandica, V. pimuensis and V. pisewensis. Thirteen taxa were synonymized: V. arthuri basidens, V. arthuri hubrichti, V. arthuri paradoxa (= V. arthuri); V. allyniana (= V. modesta); V. andrusiana (= V. columbiana); V. conecuhensis (= V. alabamensis); V. dedecora tamagonari (= V. dedecora); V. elatior, V. idahoensis (= V. ventricosa); V. eogea (= V. ovata); V. modesta insculpta (= V. modesta concinnula), V. modesta microphasma, V. modesta sculptilis (= V. modesta castanea). Qualitative observations of conchological features, ecological preferences and geographic coverage were conducted for each subgenus and genetically supported species or subspecies-level taxon. These demonstrated that: (1) a suite of diagnostic shell features usually exists to demarcate each species-level taxon; (2) shell features were incapable of defining genetically validated subgenera; (3) all subgenera had transcontinental ranges; (4) of all species possess continental or trans-continental ranges, with very few having range extents < 1,000 km; (5) all subgenera and fully of global Vertigo species and subspecies are found in North America, more than 2.5 times the number found in central and eastern Asia, the second most diverse region. This is similar to several other molluscan groups, such as the polygyrid land snails and unionid bivalves for which North America is the global biodiversity hotspot.
Jitka Horackova
added 2 research items
While general trends in Central European postglacial recolonisation dynamics are relatively well known, we often lack studies on intermediate (meta-population, landscape) scales. Such studies are needed to increase our understanding of, for example, the location of refugia; emergence of endemism, rates and trajectories of postglacial migrations; and anthropogenic landscape changes. Here, we focused on the outer Western Carpathian mountain chain Malá Fatra, which is currently characterised by high biodiversity and endemism and is thus considered a likely refugium of the Last Glacial period for the temperate biota of Eastern–Central Europe. We used molluscs and vascular plants as reference taxonomic groups and supported palaeoenvironmental interpretations of their (sub)fossil assemblages using high-resolution geochemical data. Generally, postglacial biotic successions from the study region fit the standard developmental pattern well in Middle and Eastern European uplands. Nevertheless, we found important biogeographically based peculiarities. In total, more than 50 species per (sub)fossil community at the reference site Valča, including 30 woodland species and 11 Carpathian endemites, make site of the highest known Holocene mollusc species diversity in Europe. Our palaeoecological analysis of this long-term biodiversity hotspot suggests that the Western Carpathians were likely an important source of the postglacial recolonisation of Central Europe by forest biota and, at the same time, an area of refugium-based endemism.
Julie Dabkowski
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Calcareous tufas are continental open-air carbonates that routinely host evidence of past environmental conditions via well-preserved faunal and floral assemblages. As they mostly comprise of calcite precipitated at ambient temperature, tufas are also suitable targets for geochemical research, especially concerning oxygen and carbon isotopes, and thus palaeoclimatic reconstructions. At Mituchovci in the Slovakian NW White Carpathians, a ca. 3 m-high tufa deposit has been extensively studied since 2010. The profile covers most of the Holocene as supported by 10 radiocarbon dates (from 9980±40 to 210±20 yr BP) and a detailed depth-age model (created in OxCal 4.2.4). Accumulation rates estimated from this age-depth model together with lithological/sedimentological information (especially CaCO3 content) provide preliminary assumptions on long-term climate and environment dynamic: e.g. maximal calcite precipitation between ca. 8 and 6.5 ky cal. BP suggests optimal conditions for tufa development (warm and wet). The Mituchovci tufa also provides abundant palaeoenvironmental data from a detailed continuous malacological record completed by plant macrofossil and pollen analyses. They show the progressive expansion of vegetation from ca. 11.3-11.0 ky cal. BP to a maximal development between 8.6 and 6.6 ky cal. BP. After this optimum, human activities increasingly impact the forest cover. From 500 years cal. BP, all biomarkers suggest that the site was entirely deforested and maintained as a meadow. Parallel, geochemical data (including calcite δ18O and δ13C, and Mg/Ca ratio) provide independent palaeoclimate reconstructions showing strong correlations with the palaeoenvironmental records. Some short-term climate variations to drier and cooler conditions are also well recorded in the Mituchovce geochemical signal. Those multidisciplinary data allow discussing (1) the potential effects of some globally significant Holocene rapid climate changes (especially the 8.2 ky event and the Little Ice Age) and (2) the increasing impact of human activities on the White Carpathian environments.
Anna Šolcová
added a research item
Travertine deposits are unique archives for multidisciplinary studies of past climate changes, associated vegetation development and the evolution of human societies. Despite their high potential in palaeoecological and palaeoclimate reconstructions, investigations of travertines are rather scarce in central Europe and particularly in Slovakia. Therefore, this study focused on a travertine deposit situated on the border between the Pannonian Basin and the Western Carpathians in a small valley in Santovka village (SW Slovakia), which is unique due to the presence of archaeological artefacts with known radiocarbon ages in the palaeoecological profile. Using a multidisciplinary approach combining macrofossil, pollen, mollusc, lithological and geochemical analyses, this study investigated climate–human–vegetation interactions. The Holocene onset was marked by the early arrival of oak trees; however, forest-steppe with a high representation of pine predominated until 9880 cal. a BP, followed by an expansion of temperate trees. The local ecosystem changed around 8600 cal. a BP when the valley was probably dammed by a travertine accumulation, probably resulting in the existence of a small travertine lake. This was associated with wetter climatic conditions, which were also documented in other sites in the Western Carpathians at that time. Surrounding temperate forest possibly retained a certain degree of openness, or local steppe habitat may have persisted on adjacent loess terraces until the neolithization of the area. Archaeological evidence represented by a ceramic shard dated to 7339 cal. a BP suggests the first appearance of humans at the site, yet pollen analysis records a significant change in vegetation first at 6650 cal. a BP. The local ecosystem records an abrupt change linked with human settlement earlier, at c. 7000 cal. a BP. Deforestation activities of the Neolithics resulted in the formation of an open calcareous fen occupied by numerous light-demanding mollusc species. The present study provides new important data about the spread of temperate trees at the onset of the Holocene, about further vegetation changes caused by activities of the first Neolithic farmers and about climate changes in the region of southwestern Slovakia.
Jitka Frodlová
added a research item
This study investigates the effects of sample volume, resolution and accumulation time on the interpretation of a mollusc record from terrestrial deposits. We tested (i) if, and to what extent, small sample sizes impoverish the reconstructed mollusc species richness, and (ii) whether fine-resolution sampling is worth the effort. We analysed three mollusc sequences, covering continuously the entire Holocene, which were collected in a tufa-forming spring fen and differed in sample size and resolution. More than 36 000 specimens of 76 species were processed. Using a rarefaction method, we observed that different sample volumes had a significant effect on the recorded species richness in this type of environment, and 100-cm3 samples seemed to be sufficient for a reliable reconstruction in tufa deposits. Although the thickness of the sampled layers had no influence on the palaeoecological interpretation, we observed a shift in the mollusc diversity peak once different resolutions were applied. Furthermore, the layers of finer resolution allowed detailed radiocarbon dating and better understanding of trends in species dynamics. We also observed significant confounding relationships among the number of species, number of specimens and accumulation time that can be disentangled if a precise depth–age model is available.
Jan Divíšek
added a research item
Vertigo lilljeborgi (Westerlund, 1871) is one of the rarest terrestrial snail species in temperate mainland Europe, where it is traditionally considered a glacial relict. This contrasts with its occurrence in northern Europe where it is a widespread species. This species prefers constantly wet habitats that are neutral to slightly acidic and avoids highly alkaline conditions, which is an extremely rare ecology for a Eurasian mollusc. Until 2012, only five historical records of this species were known in mainland Europe to the south of its main distribution in northern Europe. Since then, 20 new sites have been discovered, mostly located in the Hercynian Mountains (Bohemian Massif in the Czech Republic and Massif Central in France). In comparison with the boreal European and Alpine populations, those from the Hercynian Mountains inhabit acidic, rather soligenous and productive fens, strongly dominated by Sphagnum. Vertigo lilljeborgi does not occur in some sites with apparently suitable habitats as indicated by species composition of the vegetation. We observed a surprising correspondence between the occurrence of V. lilljeborgi and mean July air temperature and we report its first fossil record from the last glacial period from Central Europe. Although the number of its sites has increased recently, these sites represent highly unusual and unique habitats, vulnerable to drainage and destruction from human activities. This highlights the need for conservation efforts in most of the newly discovered isolated sites.
Michal Horsák
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Land-snail species richness has repeatedly been found to increase with the increasing site calcium content and humidity. These two factors, reported as the main drivers of land-snail assemblage diversity, are also among the main habitat characteristics of calcareous seepages. Here we explore local species richness and compositional variation of forest spring-fed patches (i.e. seepages), to test the hypothesis that these habitats might act as biodiversity hotspots and refugia of regional snail faunas. In contrast to treeless spring fens, only little is known about land snail faunas inhabiting forest seepages. Studying 25 isolated calcareous forest seepages, evenly distributed across the White Carpathians Protected Landscape Area (SE Czech Republic), we found that these sites, albeit spatially very limited, can harbour up to 66% of the shelled land-snail species known to occur in this well-explored protected area (in total 83 species). By comparing land snail assemblages of the studied seepages with those occurring in the woodland surroundings of each site as well as those previously sampled in 28 preserved forest sites within the study area, we found the seepages to be among the most species rich sites. Although the numbers of species did not statistically differ among these three systems, we found highly significant differences in species composition. Seepage faunas were composed of many species significantly associated with spring sites, in contrast to the assemblages of both surrounding and preserved forest sites. Our results highly support the hypothesis that calcareous forest seepages might serve as refugia and biodiversity hotspots of regional land snail faunas. Protection of these unique habitats challenges both conservation plans and forest management guidelines as they might act as sources for the recolonization and restoration of forest snail assemblages particularly in areas impoverished by harvesting and clearcutting.
Julie Dabkowski
added 2 research items
Tufa deposits are proven to record high quality palaeoenvironmental and palaeoclimatic information. They also appear to be influenced by human activities as indicated by the ‘late Holocene tufa decline’ observed in Europe from the Atlantic optimum, when tufa should be well developed regarding climatic conditions. The studied tufa comes from the Mamer Valley in Luxembourg: Direndall. As it covers a broad part of the Holocene, this deposit offered a great opportunity to discuss modalities and timing of the tufa decline and the human impact on fluvial formations since the early Holocene. Recent fieldwork at Direndall allowed the collection of new stratigraphic data and samples for a geochemical study. We investigate calcite stable isotopes as records of past temperature and humidity conditions. Comparisons with the environmental reconstructions from a previous malacological study show strong consistency with the δ13C record and suggest humidity might have been the main factor controlling environment evolution at Direndall. Despite the climatic variations observed, none explains the environmental change towards open conditions while optimum forest develops as recorded by molluscs at the top of the sequence. This episode is likely to be linked to local anthropogenic forest clearance during the Roman occupation. However, no clear impact of human activity has been observed in the tufa stratigraphy or precipitation rate. The exceptionally long Direndall tufa sequence thus provided outstanding palaeoenvironmental and palaeoclimatic data and might become, together with the underlying fluvial and colluvial deposits, a reference site for the Holocene and Tardiglacial in Luxembourg and surrounding areas.
A new multidisciplinary study is in progress at Direndall in the Mamer Valley in Luxembourg, combining stratigraphy, geochemistry, malacology and palynology. As it covers a wide part of the Holocene (C14 dating between c. 10 000 to 900 ka BP), the 8m-high tufa deposit provides a great opportunity to discuss modalities and timing of the so-called ‘late Holocene tufa decline’ (Goudies et al., 1993) and the combined controls of climate and human activity on fluvial formations since the Early Holocene. Recent fieldworks at Direndall allowed collection of new stratigraphical data and samples for a geochemical study. We investigate calcite stable isotopes (δ18O and δ13C) and Mg/Ca and Sr/Ca ratios from Direndall tufa as records of past temperature and humidity conditions. Comparisons with the environmental reconstructions from a previous malacological study (Meyrick, 2000) show strong consistency with the δ13C record suggesting that humidity might have been the main climatic factor controlling environment evolution at Direndall during the Holocene. Despite the clear climatic variations observed at Direndall, none can explain the environmental change toward open conditions while optimum forest develops as recorded by molluscs at the top of the sequence. This episode is very likely to be linked to local anthropogenic forest clearance during the Roman occupation of Direndall surroundings. However, no clear impact of human activity has been observed in the tufa stratigraphy or precipitation rate. The exceptionally long Direndall tufa sequence thus already provided outstanding palaeoenvironmental and palaeoclimatic data and might become, together with the underlying fluvial and colluvial deposits, a reference site for the Holocene and Tardiglacial in Luxembourg and surrounding areas.
Michal Horsák
added a project goal
This project covers the last 15.000 years and uses an innovative interconnection of local sequences, their spatial heterogeneity, reconstructions of regional macroclimate using independent abiotic (stable isotopes) and biotic proxies, modelling of past landscape patterns and testing their effect on recent diversity, and continental-scale comparisons. Geographically, the project is focused on the Western Carpathians as the major biogeographical interface within Europe, and Northern France as a reference region with a different refugial history. Fossils of terrestrial molluscs in calcareous deposits act as a principal proxy. Pollen, testate amoebae and plant macrofossils act as important proxies for validations of local developments, macroclimate reconstructions and spatial modelling of past landscape diversification.