School of Resource and Environmental Science;
Wuhan University;
129 Luoyu Road;
Wuhan 430079;
China;
Key Laboratory of Geographic Information System of the Ministry of Education;
Wuhan University;
129 Luoyu Road;
Wuhan 430079;
China;
International Livestock Research Institute (ILRI);
P. O. Box 30709;
Nairobi 00100;
Kenya;
Department of Natural Resources;
International Institute for Geo-Information Science and Earth Observation;
P. O. Box 6;
Hengelosestraat 99;
7500 AA Enschede;
the Netherlands;
Resource Ecology Group;
Department of Environmental Sciences;
Wageningen University;
Droevendaalsesteeg 3A 6708 PB Wageningen;
the Netherlands;