1. Division of Biology, Kansas State University, Manhattan, KS 66506, USA;
2. University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532, USA;
3. Department of Plant Physiology and Biochemistry, Institute of Botany, PB 4005 CEP 01061‐970 São Paulo, Brazil;
4. Departamento de Ecologia, Universidade de Brasília, Brasília, DF, Brazil;
5. Division of Ecosystem Sciences, Mulford Hall, University of California, Berkeley, CA 94720, USA;
6. Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, University of California, Valley Life Sciences Building, Berkeley, CA 94720, USA;
7. Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, 39 College Road, Durham, NH 03824, USA;
8. Department of Botany, University of Florida, PO Box 118526, Gainesville, FL 32611, USA;
9. Department of Geography, Kansas State University, Manhattan, KS 66506;
10. Department of Terrestrial Ecology, Institute of Biology, Oester Farimagsgade 2D, DK‐1353 Copenhagen K, Denmark;
11. Lab. Ecologia Isotópica – CENA/USP, Universidade de São Paulo, Av. Centenário, 303, Piracicaba SP 13416‐000, Brazil;
12. USDA Forest Service, PO Box 968, Burlington, VT 05402, USA;
13. Unitat d’Ecofisiologia CSIC‐CREAF‐CEAB, Centre de Recerca Ecològica i Aplicacions Forestals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain;
14. Department of Forest Resources, University of Minnesota, 115 Green Hall, 1530 Cleveland Avenue North, St Paul, MN 55108, USA;
15. Centre for Ecosystem Management, School of Natural Sciences, Edith Cowan University, Joondalup 6027, Western Australia, Australia;
16. Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA;
17. Environmental Studies, Dartmouth College, Hanover, NH 03755, USA;
18. Environment and Natural Resources Institute, University of Alaska, 707 A Street, Anchorage, AK 99501, USA;
19. Department of Biological Sciences, Macquarie University 2109, Sydney, Australia