1. Natural Environmental Research Council (NERC) Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire, UK, GB-SL5 7PY.
2. Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland, CH-8057.
3. Lehrstuhl Biogeographie, Universität Bayreuth, Bayreuth, Germany, D-95440.
4. Departmentos de Engenharia Florestal e de Botânica, Universidade Tecnica de Lisboa, Tapada da Ajuda, Lisboa, Portugal, PT-1399.
5. Biodiversity Conservation Laboratory, Department of Environmental Studies, University of the Aegean, Karadoni 17, Mytilene, Lesbos, Greece, GR-811 00.
6. Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
7. Department of Forest Ecology, Swedish University of Agricultural Sciences, Umeå, Sweden, SE-90183.
8. Crop Science Section, Department of Agricultural Research for Northern Sweden, Box 4097, Swedish University of Agricultural Sciences, Umeå, Sweden, SE-90403.
9. Institute of Botany, University of Basel, Schoenbeinstrasse 6, Basel, Switzerland, CH-4056.
10. Laboratoire d'Ecologie, UMR 7625, Ecole Normale Supérieure, 46 Rue d'Ulm, F-72530 Paris Cedex 05, France, FR-75230.
11. Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, U.K., GB-S10 2TN.
12. Max-Planck-Institute for Biogeochemistry, Postfach 10 01 64, Jena, Germany, D-07701.