Impacts of soil disturbance on plant diversity in a dry grassland
Abstract Dry grasslands are among the most species rich habitats in Europe, but they are also among the most threatened. Threats include too high and too low levels of disturbance. The aim of this study is to examine the effect of soil disturbance intensity on species composition and diversity in a dry grassland in Mols Bjerge National Park in Denmark. We recorded vascular plant species inside and just outside patches of bare sand, and in the transition zone between these. We found that the number of species was highest in the dense vegetation, intermediate at the transition and lowest in bare sand areas. However, an analysis of plant traits showed that the number of small annual species was highest in the transition zone. High abundance of small annual species may therefore indicate intermediate disturbance regimes. Based on a literature study we demonstrate that many threatened species are adapted to such habitats. This suggests that dry grasslands should be managed to maintain areas with intermediate disturbances intensities to maintain optimal conditions for many threatened species. To our knowledge, this is the first time it has been documented that small annual species can indicate intermediate disturbance regimes in dry grasslands.