Ruben ter Harmsel: The History and Current Floristic and Abiotic State of Dutch Calcareous Grasslands

Radboud Universiteit

Dutch calcareous grassland is a rare, semi-natural, species rich habitat type, protected by EU law. Understanding which factors influence its floristic composition could help conservation and restoration efforts. To research this, I made vegetation relevés and took soil samples across calcareous grasslands in Southern Limburg. I also collected historical vegetation data. My research showed that areas have their own floristic and abiotic identity, and that this identity has been present during the past century. I found that the current differences in floristic composition could not be directly explained by current differences in size, exposition, inclination, or type of management of an area. I found that the levels of nitrate and ammonium in the soil could be related to the current floristic composition of calcareous grasslands, but only slightly. I also found that there have been large changes in floristic composition in the last century on a habitat-level and on an area-specific level. Because of the uniqueness of each area, a sustainable conservation-strategy should focus on conserving and increasing habitat quality of areas, as well as on increasing the total surface area and connecting existing areas. Furthermore, species-specific interventions are needed to prevent more local extinctions of rare species. (Foto: l. Ruben ter Harmsel, r. Wiene Bakker)