[1] Univ Buenos Aires, Dept Ecol, RA-1417 Buenos Aires, DF, Argentina
[2] Univ Buenos Aires, Inst Invest Fisiol & Ecol Vinculadas Agr, Fac Agron, RA-1417 Buenos Aires, DF, Argentina
[3] Univ Alaska, Inst Arctic Biol, Fairbanks, AK 99775 USA
[4] Univ Alaska, Inst No Forest Cooperat Res, Fairbanks, AK 99775 USA
[5] Univ Chile, Fac Ciencias, Santiago, Chile
[6] Univ Calif Berkeley, Dept Integrat Biol, Berkeley, CA 94720 USA
[7] Environm Def Fund, New York, NY 10010 USA
[8] Univ Nacl Autonoma Mexico, Inst Ecol, Mexico City 04510, DF, Mexico
[9] Tech Univ Munich, Lehrstuhl Grunlandlehre, D-85350 Munich, Germany
[10] New Mexico State Univ, Dept Biol, Las Cruces, NM 88003 USA
[11] Duke Univ, Dept Bot, Durham, NC 27708 USA
[12] Arizona State Univ, Dept Biol, Tempe, AZ 85287 USA
[13] Natl Inst Publ Hlth & Environm, NL-3720 BA Bilthoven, Netherlands
[14] Univ Notre Dame, Dept Biol, Notre Dame, IN 46556 USA
[15] Stanford Univ, Dept Biol Sci, Stanford, CA 94305 USA
[16] Colorado State Univ, Dept Biol, Ft Collins, CO 80523 USA
[17] Colorado State Univ, Nat Resource Ecol Lab, Ft Collins, CO 80523 USA
[18] Lund Univ, Ekologihuset, S-22362 Lund, Sweden
[19] Commonwealth Sci & Ind Res Org, Div Wildlife & Ecol, Canberra, ACT, Australia