1. Max Planck Institute for Biogeochemistry, MPI‐BGC, Postfach 100164, D‐07701 Jena, Germany
2. Department of Geography, University of Oregon, Eugene, OR 97403‐1251, USA
3. Laboratoire d'Ecologie Terrestre, Université Paul Sabatier, F‐31062 Toulouse cedex 04, France
4. School of Geography and the Environment, University of Oxford, Mansfield Road, Oxford, OX13TB, UK
5. EPHE, Department of Geology‐Oceanography, UMR‐CNRS 5805 EPOC, University of Bordeaux 1, F‐33405 Talence, France
6. University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK