Land management and soil property effects on soil microbial communities and carbon storage in temperate forest and grassland systems This thesis is part of a new large scale and long term project for functional biodiversity called the Biodiversity Exploratories which includes a hierarchical set of standardized field plots in three different regions of Germany (Schorfheide Chorin Hainich Dün Schwäbische Alb) encompassing various management types and intensities in forests and grasslands. This study design made it possible to address the following objectives in the present thesis: to understand how soil microbial biomass microbial community composition and enzyme activities are influenced by grassland management and soil properties across the regional scale to investigate enzyme activities and nutrient supply and demand for whole soil profiles in forests and to evaluate the proportion of the total variance in enzyme activities that can be attributed to large scale differences between regions long term forest management and soil properties in different soil horizons and to assess the organic carbon storage and radiocarbon signatures in three density fractions of forest and grassland sites under diverse management practices and soil properties in different regions. Overall it can be concluded that soil microbial biomass microbial community composition enzyme activities organic carbon storage and turnover in density fractions were more affected by soil properties than by forest and grassland management practices at the regional scale. Further the results presented here highlight the need for large scale studies including different regions and their environmental conditions in order to draw general conclusions about the impact of land management and soil properties on soil microbial communities and organic carbon storage. This knowledge should be included in future research and models of soil organic matter as well as applied to effective environmental management to enhance organic carbon storage in soils.