[1] Univ Alberta, CEOS, Edmonton, AB T6G 2R3, Canada
[2] Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2R3, Canada
[3] Smithsonian Trop Res Inst, Panama City, Panama
[4] Peking Univ, Inst Remote Sensing, Beijing 100871, Peoples R China
[5] Peking Univ, GIS, Beijing 100871, Peoples R China
[6] Univ Florida, Sch Forest Resources & Conservat, Gainesville, FL 32611 USA