Biodiversity in Berlin and its potential for nature conservation

Selected habitats in Berlin (Germany) were investigated with a focus on the diversity of flora and land use patterns. On the one hand, the correlation between the number of plant species and the diversity of land use patterns is shown for a transection running from the center to the outskirts of Berlin. The greatest variety of land use patterns and the highest number of species per square kilometer can be found in the transition zone between the city center and the outskirts where urban structures are closely associated with open spaces like large parks, urban forests, and larger wastelands. In accordance with the intermediate disturbance hypothesis, the mosaic of land use patterns in the transition zone with moderate frequencies or intensities of disturbance positively affects habitat diversity, as well as overall species diversity on the landscape level. Furthermore, in residential areas built in the 1920s and 1930s, the flora was studied from both a historical and a present-day perspective in order to assess the diversity of wild-growing indigenous and non-native plant species, wild-growing ornamental plant species, and planted trees. The highest numbers of species were recorded in less intensively managed habitats. In addition to structural factors (e.g. land use patterns) determining the diversity of flora and vegetation in cities, this study also demonstrates the importance of the historical factor for biodiversity. The differences in land use throughout the last 70 years (pre- and post-World War II era) can be seen as an explanation for the relatively high diversity of the flora in the investigated residential areas. Cities have to be regarded as a new type of environment with species compositions and habitats peculiar to urban-industrial areas. Future research and planning of nature conservation and sustainable development of urban-industrial areas should take the biological diversity in cities fully into account. Recommendations are given for the maintenance and development of biological diversity in cities, focussing on landscape and habitat as well as species diversity.