Environmental control of species richness and composition in upland grasslands of the southern Czech Republic

Biodiversity of Central European semi-natural upland grasslands is steadily declining, due to either abandonment or management intensification. Although there are several descriptive overviews of their vegetation, quantitative information on the relationship between their species richness or composition and environmental factors is still scarce. We sampled upland grasslands in the southern part of the Czech Republic in order to determine the main soil variables affecting diversity of their vegetation. The relationships between species richness and environmental variables were tested using correlation analysis and regression trees, and the relationship between species composition and environment using detrended correspondence analysis and canonical correspondence analysis. Of soil variables, species richness of vascular plants was most strongly affected by phosphorus and, less so, by potassium and organic matter, with higher richness in habitats with less phosphorus, potassium, and organic matter. Grasslands on soils with pH < 4.6 were species-poor, but across the rest of the pH range richness was independent of pH. Most bryophyte species were present on low-pH soils poor in calcium and phosphorus and on organic soils. Red List species were best represented in fen meadows on organic soils with high calcium and low pH. Major determinants of floristic composition were soil moisture, nutrient availability, and soil pH. This study shows that conservation management of these grasslands should focus on reducing phosphorus input and protecting groundwater discharge areas from drainage.