![Dictmanus albus [(c) Christian Ristok]](/im/1401451667_284_0.jpg "Dictmanus albus [(c) Christian Ristok]")
Population ecology of rare and endangered plant species
A plenty of rare and endangered plant species occurs in xerothermic habitats which are characterized by a high biodiversity. Related to the ongoing global environmental change such as traditional land-use change, eutrophication by atmospheric nitrogen deposition and climate warming these species strongly decline. In order to counteract the expected species loss, the population structure in terms of size, demographic composition, pollination systems and viability must be investigated. Most of the species are flowering and fruiting very well in the natural habitats, but the knowledge of the germination biology is low. So, we conducted a lot of germination experiments under different ecological conditions (more than 300 species are still now investigated). The next issue is, to investigate the chance and success of establishment of the rare species in vegetation stand with different density in open-field and pot-experiments. In intact plant communities the plant-plant interactions are important to effect competition or facilitation between the co-existing species and led to reconstruction of the communities under the changing environmental conditions. So, we investigate the positive and negative interactions between rare, endangered and dicotyledonous species and currently expanding grass species and simulate different environmental change such as abandonment of grazing, eutrophication and climate warming. The results of the different approaches allow prognoses of the further development of the species and to drawn plans for conservation management.