Normalized difference vegetation index
Normalized difference vegetation index (NDVI) was used as a proxy for net primary productivity in this study. We extracted NDVI data (1-km² resolution) of January, April, July, and October for 4 consecutive years (2009-2012) in the Lebu Valley from the Computer Network Information Center, Chinese Academy of Sciences (CNIC, CAS) (http://www.gscloud.cn; date of the download: 2016/6/17).