1. Department of Ecology and Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la Agricultura, Faculty of Agronomy, University of Buenos Aires, Avenida San Martı́n 4453, Buenos Aires 1417, Argentina.
2. Institute of Arctic Biology,
3. Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
4. Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
5. Environmental Defense Fund, 257 Park Avenue, New York, NY 10010, USA.
6. Instituto de Ecologı́a, UNAM, México 04510, México.
7. Lehrstuhl fur Grunlandlehre, Technische Universitat Munchen, D85350, Germany.
8. Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA.
9. Department of Botany, Duke University, Durham, NC 27708, USA.
10. Department of Biology, Arizona State University, Tempe, AZ, 85287, USA.
11. National Institute for Public Health & the Environment, Bilthoven, Netherlands.
12. Department of Biology, University of Notre Dame, Notre Dame, IN 46556–0369 USA.
13. Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
14. Department of Biology and
15. Ekologihuset, Lund University, 22362 Lund, Sweden.
16. Division of Wildlife and Ecology, Commonwealth Scientific and Industrial Research Organization, Canberra, Australia.
17. Institute of Northern Forest Cooperative Research, University of Alaska, Fairbanks, AK 99775, USA.
18. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.