The impact of drought on NPP in China from 1982 to 2015

Terrestrial net primary productivity (NPP) plays an essential role in the global carbon cycle as well as for climate change. However, in the past three decades, terrestrial ecosystems across mainland China suffered from frequent drought and to date, the adverse impacts on NPP remain uncertain. This study explored the spatiotemporal features of NPP and discussed the influences of drought on NPP across mainland China from 1982 to 2015 using the Carnegie Ames Stanford Application (CASA) model and the standardized precipitation evapotranspiration index (SPEI). The obtained results indicate that 1) the total annual NPP across mainland China showed a slightly increasing trend from 1982 to 2015; the spring NPP exhibited a significant increasing trend while the summer NPP showed a higher decreasing trend. 2) Most areas of mainland China were spatially dominated by a positive correlation between annual NPP and SPEI and a significant positive correlation was mainly observed for Northern China; specific to the nine sub-regions, annual NPP and SPEI shared similar temporal patterns with a significant positive relation in Northeastern China, Huang-Huai-Hai, Inner Mongolia, and the Gan-Xin Region. 3) During the five typical drought events, more than 23% areas of mainland China experienced drought ravage and NPP decreased to different extents; the NPP in most of the sub-regions reduced by less than 30% while the NPP in the Qinghai-Tibet Plateau Region generally decreased by less than 10%.