Bestimmende Umweltfaktoren für den Artenreichtum und die Artenzusammensetzung der Trockenrasen im nördlichen und mittleren Böhmen (Tschechien)

Central European dry grasslands are remarkably diverse plant communities that occur at the western edge of the Eurasian forest-steppe zone and harbour many species of continental distribution. Although their plant community types have been described in detail, the diversity patterns and their environmental determinants are still poorly known for these grasslands. Here, we study environmental drivers of species composition and richness in dry grasslands of northern Bohemia (České středohoří Mts) and central Bohemia (Křivoklát region), both in the Czech Republic. In vegetation plots of 100 m2 we recorded all vascular plant species, measured soil chemistry variables, above-ground biomass production and nutrient concentrations in biomass. Species richness in these plots ranged from 13 to 55. The relationships between species composition and the environment were explored using detrended correspondence analysis and canonical correspondence analysis, while the relationships between species richness and the environment were assessed using univariate and multiple regression models. In both regions, species composition and richness strongly responded to the soil pH (ranging from 4.0 to 7.8), which was positively correlated with calcium and magnesium concentrations and negatively with annual precipitation. The response of species richness to soil pH was unimodal with a peak at pH of about 6.5 in the České středohoří Mts, and positive in the Křivoklát region. Plots on soils with a pH higher than 5 consistently contained more than 35 species. In the České středohoří Mts, species richness was positively related to the aboveground biomass production, whereas in the Křivoklát region, this relationship was only significant for graminoid species. In both areas, plots with soils deeper than 20 cm and with aboveground biomass dry weight above 200 g/m2 harboured more than 40 species per 100 m2. Moreover, in the České středohoří Mts, nitrogen concentrations in the biomass had considerable effects on both species composition and richness: species numbers were lower at sites with higher nitrogen concentration. This indicates a threat to diversity of these dry grasslands under currently high atmospheric nitrogen deposition coupled with the absence of management at most of the studied sites.Die mitteleuropäischen Trockenrasen an der westlichen Verbreitungsgrenze der Eurasischen Waldsteppengebiete stellen bemerkenswert artenreiche Vegetationstypen dar und enthalten zahlreiche Pflanzenarten mit kontinentalem Verbreitungsschwerpunkt. In dieser Studie befassen wir uns mit den Trockenrasen des Böhmischen Mittelgebirges (Nord-Böhmen; České středohoří) und des Pürglitz-Gebietes (Mittel-Böhmen; Křivoklátsko) in der Tschechischen Republik (Abb. 1, 2). Das Böhmische Mittelgebirge umfasst den Kern der nördlichen und zentralen böhmischen Waldsteppen-Zone (MARTINOVSKÝ 1984, CHYTRÝ 2012) mit einer jährlichen Niederschlagsmenge von stellenweise weniger als 500 mm. Die dort vorkommenden primären Steppenrasen existieren höchstwahrscheinlich bereits seit Beginn des Holozäns (JUŘIČKOVÁ et al. 2013a, b). Das Pürglitz-Gebiet befindet sich dagegen ausserhalb der Waldsteppen-Zone mit höheren jährlichen Niederschlagsmengen. Trockenrasen kommen in diesem Gebiet vorwiegend an Felsbändern vor oder stellen Ersatzgesellschaften auf vorherigen Waldstandorten dar. Die Artenzusammensetzung und Syntaxonomie der Trockenrasen wurde in der Vergangenheit ausgiebig untersucht (z. B. KLIKA 1933, 1951, KOLBEK 1975, 1978, 1979, TOMAN 1981, 1988, KOLBEK et al. 2001, CHYTRÝ 2007). Dagegen sind ihre Diversitätsmuster mit den zugrundeliegenden ökologischen Faktoren weitgehend unbekannt. Sie wurden bislang nur exemplarisch am Oblík, einem vulkanischen Hügel des Böhmischen Mittelgebirges quantifiziert (SLAVÍKOVÁ et al. 1983). In der vorliegenden Studie analysieren wir den Einfluss bestimmter Umweltfaktoren auf die Artenzusammensetzung und Artenvielfalt der Trockenrasen im Böhmischen Mittelgebirge und im Pürglitz-Gebiet

Wagner et al. 2016. R scripts and data

Data and R scripts analyze how species shifts in soil pH niche parameter (optimum, width) are linked to regional changes in mean precipitation, substrate availability and species traits indicative of competitive ability.<br><br>Requirement: R (https://www.r-project.org/) and R packages (see scripts for further specifications)<br><br>Data structure is explained in the R scripts.<br

Benchmarking plant diversity of Palaearctic grasslands and other open habitats

Aims: Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location: Palaearctic biogeographic realm. Methods: We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m(2) and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results: Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file "GrassPlot Diversity Benchmarks" and the web tool "GrassPlot Diversity Explorer" are now available online () and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions: The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology

Benchmarking plant diversity of Palaearctic grasslands and other open habitats

Aims Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location Palaearctic biogeographic realm. Methods We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m2 and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology