Drought Dynamics and Impacts on China Shrubladns Vegetation Activities

Existing studies show that a persistently increasing trend of aridity dominates the global climate change in the future. Shrubs which are widely distributed in China, with their superior drought resistance and tolerance may play more and more important roles in global ecosystem function. In this paper, we calculated a drought index (Standardized Precipitation Evapotranspiration Index, SPEI) to analyze China shrublands drought dynamics from 1961 to 2013. We found that the SPEI of China shrublands decreased significantly and the trend was significantly changed in 1992, which means China shrubland experienced a persistently drought period, and intensified in recent years. We also analyzed the effects of SPEI variation on EVI, and found that different shrubland types responded differently to SPEI variation. Summer SPEI affects high-cold desert, temperate desert and temperate deciduous EVI positively, but affects subalpine evergreen and subtropical evergreen EVI negatively. Temperate deciduous EVI responded positively to spring SPEI, but negatively to autumn and winter SPEI. Furthermore, subtropical evergreen EVI was also positively affected by autumn SPEI. Learning the response of shrublands EVI to drought dynamics contributes to understanding of ecosystem process variation under the background of global persistently increasing trend of aridity in the future.