Modelling and assessing effects of N-deposition in forest ecosystems in Germany

Ralf Kiese, Sandra Wochele, Christoph Heinzeller, Rüdiger Grote and Klaus Butterbach-Bahl

Forschungszentrum Karlsruhe, Institute for Meteorology and Climate Research

,Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany

Over the last decades naturally N limited forest ecosystems in Germany were exposed to high rates of atmospheric N-deposition. Actual numbers show an input of about 40 kg N ha^-1 yr^-1 which is not likely to be decreased within the near future. Chronically long term N-deposition into forest ecosystems are significantly altering ecosystem turnover of carbon and nitrogen as well as the matter exchange with the adjacent compartments e.g. the atmosphere and groundwater bodies. Environmentally relevant consequences are numerous and reach from enhanced GHG emissions (N₂O, NO), nitrate leaching and acidification up to shifts in plant biodiversity due to changes of the soil acidification and nutrient status.

For assessing the multiple effects of N-deposition in forest ecosystems in Germany, MOBILE-Forest-DNDC realisation - a process oriented biogeochemical model for simulation of C and N turnover and soil acidification - was applied on site and on regional scale for actual and future climate and atmospheric deposition conditions to assess effects on GHG emissions, nitrate leaching, soil nutrient and acidification status. Finally, first results of the linkage between the biogeochemical Forest-DNDC model and the BERN and a stochastic ecosystem type model to address N-deposition effects on biodiversity will be demonstrated.