1. Dep. of Natural Resource Management; Heinrich-Buff-Ring 26-32, Justus-Liebig University Gießen D-35392 Gießen Germany
2. Fraunhofer Institute for Atmospheric Environmental Research (IFU); Div. Biosphere/Atmosphere Exchange, Dep. of Soil Microbiology; Kreuzeckbahnstr.19 D-82467 Garmisch-Partenkirchen Germany