Vegetation remains, specialist species fade: changes in Pannonian sand grasslands

Inland sand grasslands are highly threatened habitats in central Europe and the Pannonian biogeographical region. They harbour several specialized and threatened species adapted to the dry, nutrient-poor conditions of sandy soils. The area of these grasslands decreased dramatically in the 19th and 20th centuries. Many remaining patches have been included in protected areas, and their conversion to other land-use types has been limited in recent decades. However, changes in these plant communities may have occurred due to environmental changes and altered management practices. To assess temporal changes in plant diversity and species composition in sand grasslands in the Vienna Basin (Czech Republic, Slovakia and Austria), we resurveyed 86 vegetation plots in 2023–2024 that were first sampled between 1952 and 2010. We compared changes in species composition using principal coordinate analysis and distance-based redundancy analysis. We tested changes in species richness of vascular plants using a linear mixed-effect model, proportions of specialized, ruderal, threatened, alien and woody species using generalized estimating equation models, and ecological indicator values using permutation tests. We compared these changes among three main vegetation types of sand grasslands (pioneer, acidophilous and basiphilous). The results indicate that the main types of sand grasslands in the Vienna Basin have persisted over recent decades and have not been replaced by other vegetation types. However, specialized species of sand and dry grasslands, as well as species adapted to grazing, have declined. In contrast, species with higher nutrient and moisture requirements have increased. This indicates an effect of eutrophication and natural succession following the abandonment of previous management. The decline in sand specialists was most pronounced in the pioneer sand vegetation, where species with higher Ellenberg-type indicator values for temperature also decreased, indicating a transition to more closed sand grasslands. These results indicate that appropriate conservation management and future monitoring are needed to maintain the habitat quality of inland sand vegetation.