[1] Univ Maryland, Dept Geog, College Pk, MD 20742 USA
[2] Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA
[3] Woods Hole Res Ctr, Woods Hole, MA 02543 USA
[4] Carnegie Inst Washington, Dept Global Ecol, Stanford, CA 94305 USA
[5] Michigan State Univ, Dept Geog, E Lansing, MI 48824 USA