Search

The presence of Last Glacial Maximum (LGM) biotic communities without modern counterparts is well known. It is particularly evident in central European fossil LGM land snails whose assemblages represent an odd mix of species that are currently limited to either xeric or wetland habitats. Here we document a genetically verified discovery of the modern calcareous wetland species Pupilla alpicola on Iceland, where it is limited to dry grasslands. This species also represents a common European LGM fossil, and its new records from Iceland help explain puzzling shifts of some glacial land snails of xeric grassland habitats to open wetlands today. Similarities between the climates of modern Iceland and LGM Eurasia suggest that this species did not become limited to wetlands in continental Europe until after the Late Pleistocene–Holocene climate transition. These results are a strong reminder that assumptions of ecological uniformity must be questioned and that the quality and robustness of palaeoecological reconstructions is dependent upon adequate knowledge of the full autecological range of species over time. [ABSTRACT FROM AUTHOR]

Increasing evidence for the effects of Holocene history on modern biotic communities suggests that current explanations of community patterns and conservation strategies require revisiting. Here we focused on Central European rich fens that are at high risk among mire habitats because of their relatively low environmental stability, and hence sensitivity to successional shifts. At each of 57 study sites, inventory of specialist species of bryophytes, vascular plants and land snails, measurements of local environmental conditions, area, and radiocarbon dating were conducted. We used Moran's I spatial autocorrelation, multiple linear regression models, MDS, db-RDA, and null models to identify drivers of species richness and occurrence. We tested the importance of site age and historical metacommunity dynamics expressed by regional age of the habitat for the diversity of three taxonomic groups of fen organisms differing in dispersal and life history strategies. The richness of specialist species was affected by local environmental conditions and area in all three groups, but the effect of regional age was significant and positive for vascular plants and snails, once the effect of fen area was set as a covariable. We identified 11 species significantly associated with ancient fens independently of site area and pH effects; this group includes species currently considered to be umbrella species in European habitat conservation (the moss Hamatocaulis vernicosus and the snail Vertigo geyeri). The effect of fen age per se on the communities of specialists calls for the incorporation of age into conservation schemes. Restoration or de novo construction of peat-forming fens cannot compensate for a loss of ancient fens. [ABSTRACT FROM AUTHOR]

Aim: We present the first continental-scale study of factors controlling the species richness of groundwater-fed fens, comparing land snails, vascular plants and bryophytes. We separately analyse two ecologically distinct groups differing in conservation value and colonization/extinction dynamics, that is habitat specialists, and matrix-derived species. Considering the island-like nature of fen habitats, we hypothesize larger differences in the species richness-environment relationships between habitat specialists and matrix-derived species than among the taxonomic entities. Location: Seven European regions. Methods: Richness was counted at 373 well-preserved fens with undisturbed hydrology using the same protocols. Relationships between the species richness and water pH, waterlogging, climate and geography were explored by GLMs. Results: Land snail richness responded mainly to water pH, regardless of habitat specialization. Richness of vascular plant and bryophyte specialists was strongly driven by geographical location of the sites, while that of matrix-derived species was driven by waterlogging and water pH. The richness of matrix-derived species of all taxa significantly increased with the decreasing waterlogging. Residual richness of specialists of all taxa decreased towards southern Europe. Main conclusions: In island-like terrestrial habitats, differences between specialists and matrix-derived species may outweigh differences among taxa, unless there is one strong physiological determinant of species richness such as pH in land snails. The richness of specialists seems to be strongly related to difficult-to- measure regional factors such as historical frequency and connectivity of fen habitats. The richness of matrix-derived species depends mainly on local conditions, such as pH and waterlogging, determining the degree of habitat contrast against the surrounding matrix. Sufficient waterlogging maintains a high representation of habitat specialists in fen communities, and disturbance of water regime may cause the increase in the number of matrix-derived species and potentially trigger successional shifts towards non-fen communities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Knowledge of present-day communities and ecosystems resembling those reconstructed from the fossil record can help improve our understanding of historical distribution patterns and species composition of past communities. Here, we use a unique data set of 570 plots explored for vascular plant and 315 for land-snail assemblages located along a 650-km-long transect running across a steep climatic gradient in the Russian Altai Mountains and their foothills in southern Siberia. We analysed climatic and habitat requirements of modern populations for eight land-snail and 16 vascular plant species that are considered characteristic of the full-glacial environment of central Europe based on (i) fossil evidence from loess deposits (snails) or (ii) refugial patterns of their modern distributions (plants). The analysis yielded consistent predictions of the full-glacial central European climate derived from both snail and plant populations. We found that the distribution of these 24 species was limited to the areas with mean annual temperature varying from −6.7 to 3.4 °C (median −2.5 °C) and with total annual precipitation varying from 137 to 593 mm (median 283 mm). In both groups there were species limited to areas with colder and drier macroclimates (e.g. snails Columella columella and Pupilla loessica, and plants Kobresia myosuroides and Krascheninnikovia ceratoides), whereas other species preferred areas with relatively warmer and/or moister macroclimates (e.g. snails Pupilla turcmenica and P. alpicola, and plants Artemisia laciniata and Carex capillaris). Analysis of climatic conditions also indicated that distributional shifts of the studied species during the Pleistocene/Holocene transition were closely related to their climatic tolerances. Our results suggest that the habitat requirements of southern Siberian populations can provide realistic insights into the reconstruction of Eurasian, especially central European, glacial environments. Data obtained from modern populations also highlight the importance of wet habitats as refugia in the generally dry full-glacial landscape. [ABSTRACT FROM AUTHOR]