1. Inst. of Ecology; Dep. of Soil Science; Berlin Univ. of Technology; Salzufer 11-12 D-10587 Berlin Germany
2. Geographic Inst., Professorship of Soil Geography/Soil Science, Johannes Gutenberg Univ.; Johann-Joachim-Becherweg 21 D-55128 Mainz Germany
3. Inst. of Chemistry and Dynamics of the Geosphere, ICGIII Phytosphere Inst.; Jülich Research Centre; D-52425 Jülich Germany
4. Inst. of Plant Sciences; ETH Zentrum LFW C56; Universitätsstrasse 2 CH-8092 Zurich Switzerland
5. Max Planck Inst. for Biogeochemistry; P.O. Box 100164 D-07701 Jena Germany
6. Inst. of Ecology, Friedrich Schiller Univ. of Jena; Dornburger Straße 159 D-07743 Jena Germany