Drought stress triggers differential survival and functional trait responses in the establishment of Arnica montana seedlings

Gefördert im Rahmen des Projekts DEALDeutsche Bundesstiftung Umwelt. Grant Number: 20016/46

Summer aridity rather than management shapes fitness‐related functional traits of the threatened mountain plant Arnica montana

Gefördert durch den Publikationsfonds der Universität Kasse

Extreme droughts in oligotrophic mountain grasslands cause substantial species abundance changes and amplify community filtering

Gefördert im Rahmen des Projekts DEALDeutsche Bundesstiftung Umwelt. Grant Number: 20016/46

Long‐term vegetation changes in Nardus grasslands indicate eutrophication, recovery from acidification, and management change as the main drivers

Gefördert im Rahmen des Projekts DEA

Synopsis of Nardus Grassland Resurveys Across Germany: Is Eutrophication Driven by a Recovery of Soil pH After Acidification?

Questions: How have Nardus grasslands (i.e., unfertilised grassland on acid soils) in Germany changed in recent decades? What are the ecological drivers of these changes? Were the changes in species composition caused by the decrease in atmospheric deposition of nitrogen (N) and sulphur (S) and mediated by the recovery of soil pH? Have climate change and changes in management contributed to changes in species composition? Location: Six regions within the German low mountain range and the northern Alps (230 m—2120 m a.s.l.). Methods: For a synoptic analysis of vegetation change, we compiled vegetation and soil data (pH, C:N ratio) of 375 quasi‐permanent plots in Nardus grassland sampled between 1971–1989 and 2012–2021. We analysed changes in different species groups, mean ecological indicator values and soil parameters and tested for effects of time and elevation with mixed effect models. Path analyses and redundancy analysis were used to identify the drivers of vegetation change, including data on N and S deposition, annual temperature, annual precipitation and management. Results: Soil pH increased and C:N ratio decreased across study regions in Germany. We also found overall increases in mean Ellenberg indicator values for N and soil reaction. Species of nutrient‐rich grasslands increased, as did total species richness. In contrast, character species of Nardus grassland and dwarf shrubs decreased. However, these patterns were less pronounced at high elevations. Declining total N and S deposition was associated with higher pH values and lower C:N ratios, which had positive effects on nutrient‐demanding grassland species and negative effects on cover of Nardus grassland character species and on dwarf shrubs. We also found indications for effects of climate warming, for example, increased mean Ellenberg indicator values for temperature and a negative effect on character species. Management compared with abandonment had negative effects on woody species, including dwarf shrubs and favoured low‐growing herbaceous species. In addition, management effects contributed indirectly to eutrophication. Conclusion: Nardus grasslands across Germany are affected by a decline in floristic quality associated with eutrophication (e.g., increase in nutrient indicators and decline in characteristic species). Our results suggest that after a period of airborne acidification in the 20th century, the recovery of soil pH following the reduction of acidifying S and N deposition in recent decades has been a major driver of eutrophication because of improved conditions for mineralisation and nutrient release from accumulated and ongoing N deposition. An adapted management focusing on more efficient nutrient removal will be required

ReSurveyGermany: Vegetation-plot time-series over the past hundred years in Germany

Vegetation-plot resurvey data are a main source of information on terrestrial biodiversity change, with records reaching back more than one century. Although more and more data from re-sampled plots have been published, there is not yet a comprehensive open-access dataset available for analysis. Here, we compiled and harmonised vegetation-plot resurvey data from Germany covering almost 100 years. We show the distribution of the plot data in space, time and across habitat types of the European Nature Information System (EUNIS). In addition, we include metadata on geographic location, plot size and vegetation structure. The data allow temporal biodiversity change to be assessed at the community scale, reaching back further into the past than most comparable data yet available. They also enable tracking changes in the incidence and distribution of individual species across Germany. In summary, the data come at a level of detail that holds promise for broadening our understanding of the mechanisms and drivers behind plant diversity change over the last century

Assessment of genetic diversity among seed transfer zones for multiple grassland plant species across Germany

Species diversity and intraspecific genetic diversity play a critical role in conservation and restoration of grassland ecosystems. To maintain regional adaptations of native wild plants, seeds for restoration projects are produced regionally. The delineation of regions is organised by seed transfer zones (STZs). Generalised STZs that apply uniformly to many species have been established in several European countries. Ideally, generalised STZs should be based on comprehensive data of intraspecific genetic and phenotypic diversity for a larger number of species. However, such underlying data is missing. The project RegioDiv aims to fill this gap and generate empirical data on genetic variation of multiple grassland plant species across Germany. Here we describe the driving principles and main methods of the project. A total of 33 species were collected at an average density of ∼1 sample/1000 km2 across the 22 existing STZs, and a total of 11,976 samples were genotyped with SNP markers. The analysis of genetic population structure included cluster analysis and analyses of isolation-by-distance and isolation-by-environment. An exemplary within-species analysis for Agrostis capillaris, a widespread grass, revealed five intraspecific genetic clusters, distributed in spatially coherent ranges that did not fully match the STZs. Most of the STZs differed genetically following a pattern of isolation-by-distance and isolation-by-environment. In an across-species analysis, genetic differentiation was affected by mating system and ploidy. Outcrossed and polyploid species were less differentiated than self-compatible and diploid species. However, genetic differentiation did not significantly differ between grasses and herbs, highlighting the variability among species within these groups. The dataset of the RegioDiv project will advance both basic and applied research on genetic variation of grassland plant species. The results will allow the assessment of the current German STZ system and guide potential improvements