Long-term vegetation change in protected calcareous fens is driven by land-use change and management abandonment

AimsHistorical land use has shaped plant diversity in Central Europe for centuries, and many plant communities of high conservation value have been maintained by long-term traditional management. This study assesses how changes in land use over the past century have affected plant community composition and vegetation-based ecological indicator values in the management-dependent mire community Primulo-Schoenetum ferruginei. LocationSouth-western Germany. MethodsWe conducted repeated vegetation surveys at multiple sites, comparing historical records with recent surveys spanning up to 97 years. Changes in species composition were analysed using multivariate approaches, and shifts in habitat conditions were assessed using indicator values for nutrients, temperature, light and mowing frequency. Information on historical management was compiled from original vegetation sources, while current management data were obtained from responsible conservation authorities and regional administration. ResultsFen communities showed pronounced temporal changes in species composition. Community turnover was significantly associated with shrub encroachment, mowing frequency, hay transfer and early mowing. In addition, species-based indicator values suggested increasing nutrient availability and temperature affinity of the vegetation, alongside decreasing light availability. Disturbance indicators pointed towards less frequent but more severe disturbance regimes in contemporary compared to historical vegetation. ConclusionsOur results demonstrate that management-dependent fen communities are highly sensitive to changes in land-use regimes, i.e. disturbance frequency and severity that is indicated to have significantly changed in the protected areas in this study. These findings highlight the importance of maintaining traditional land management practices when aiming to maintain biodiversity in calcareous fens.