Relating N transformation and transport to microbial activities in forest soils

This project aims at enlightening the mechanisms of nitrogen (N) transformation in forest soils. It bases on a long term clean rain experiment reproducing pre-industrial N-deposition in a spruce forest (Solling, Germany). Modifying the primary microbial attack and the following transformation cascade of organic nitrogen, the manipulation offers a unique opportunity for extensive process comprehension. To pay tribute to the high heterogeneity of soils and the resulting niche differentiation for specific functional groups of microorganisms, the program addresses three levels: (i) analysing the N-transformations along soil horizons by modern soil biogeochemistry and proteomics, (ii) localizing and quantifying enzyme activities with fluorogenic substrates and isotope techniques, (iii) relating these activities to diversity and expression profiles of corresponding genes in fungi and bacteria by molecular biology under involvement of biochips. The project bridges the expertise of its three applicants in the fields of soil ecology, soil microbiology and molecular ecology. Special attention was paid to integrate the different work packages, as the project has a central place in the application package "biochips to monitor N-transformations in soils" that will serve as crystallization point for a future Research Unit or Priority Program.