1. a ALTERRA Green World Research , Wageningen University and Research Centre , PO Box 47, 6700AA Wageningen, The Netherlands E-mail:
2. f Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI) , Chinese Academy of Sciences (CAS) , Lanzhou 730000, P.R. China
3. b TRIO/LSIIT , Université Louis Pasteur , 5 Bld Sebastien Brant, 67400 Illkirch, France E-mail:
4. c Institute of Geographical Sciences and Natural Resources Research , Chinese Academy of Sciences , Beijing 100101, P.R. China
5. d National Aerospace Laboratory , 8316 PR Marknesse, The Netherlands
6. e Institute for Computational Earth System Science , University of California , Santa Barbara, USA