We study biodiversity, plant community composition and structure, population and vegetation dynamics and successional processes, on micro-scale (including succession of Cyanobacteria in biological soil crusts) and macro-scale (including vascular plant species and wild bee-plant interactions). The spatial scales reach from cm² to landscapes, the temporal scales from seasonal to long-term (> 10 years). In our attempt to establish successional models and identify the key factors leading to different successional pathways, we include both, biotic and abiotic factors, particularly macro- and microclimate (e. g. effects of prolonged dry periods as in 2003 as a model of global change), atmospheric nutrient deposition and soil nutrients. We aim at determining the limiting factors for plant productivity, which are concurrently ensuring the typical species composition of sand grasslands. Regarding biotic factors, we scrutinize foremost the grazing impact of rabbits and livestock (sheep, donkeys). We analyze diet selection, nutrient flows, dynamics of seed dispersal and soil seed bank, changes in biodiversity, and possible increase of microsites for the establishment of low-competitive plant species.
The results of these studies help to clarify the causes of ruderalisation processes which threaten the nature conservation value of many ecosystem types throughout Europe. Furthermore, the insight into grazing effects is essential to generate models for “restorative grazing”, which becomes more and more important for nature conservation management. Apart from deterioration, a major threat for many ecosystem types is fragmentation. In an approach of “Technical Biology”, we focus on developing techniques in order to re-connect the small remnants. We could show that it is possible to create new habitats, e.g. on ex-arable fields. Meanwhile we have about five years experience with this approach, but nothing is known about the processes on the longer run until yet. The field of “Restoration Ecology” is just emerging and will gain in importance.
Concerning the methods we use approaches of complementation of field studies, common garden experiments in the Botanical Garden, and laboratory studies. The field studies include permanent plots and controlled experimental manipulations such as nutrient addition, grazing, seed addition or disturbance.
