The work focuses on the detailed analyses and quantification of water, C and N states and fluxes in natural, semi-natural and agricultural ecosystems being sensitive to changes in climate, land use and management. Special emphasis is given to observation of environmental parameters, biogeochemical process rates and cross-compartment fluxes of e.g. C and N trace gases (CO2, CH4, NH3, N2, N2O, NO) and nitrate. Comprehensive datasets allow better understanding and documenting of global change effects on biogeochemical nutrient cycling in the terrestrial biosphere and exchange processes with adjacent compartments of the atmosphere and hydrosphere. The activities comprise the establishment and operation of long-term measuring stations (e.g. TERENO) and project based field sites as well as laboratory process studies applying state of the art measuring techniques and stable isotope approaches. Datasets are used for further development and testing of biogeochemical models such as LandscapeDNDC.