Responses of vegetation to climatic variations in the desert region of northern China

Global climate change is expected to impact vegetation dynamics. However, differences in the responses of vegetation in desert regions remain poorly understood. We analysed trends in normalised difference vegetation index (NDVI) and its correlations with climatic factors (temperature and precipitation) for typical vegetation in dry sub-humid, semi-arid, arid, and hyper-arid regions of northern China over the past three decades (1982-2015). We also evaluated the effects of climatic variations on vegetation using the vegetation sensitivity index (VSI). Over the study period, NDVI in the dry sub-humid and semi-arid regions showed a significant increasing trend, but no marked trend was noted in the arid region. Both precipitation and temperature had positive effects on NDVI, but that of the latter on NDVI decreased with increasing aridity. The VSI of vegetation dominated by Pinus sylvestris var. mongolica, Ulmus spp., and Caragana spp. was higher than that of vegetation dominated by Artemisia desertorum, A. ordosica, Haloxylon persicum, and H. ammodendron. Our analysis provides two important insights into the responses of vegetation to climatic variations: Firstly, vegetation in the different desert regions of northern China showed diverse responses to climatic variations. Secondly, vegetation dominated by trees (P. sylvestris var. mongolica and Ulmus spp.) and tall shrubs (Caragana spp.) was more sensitive to climatic variations than that dominated by drought-tolerant dwarf shrubs (e.g. A. desertorum and A. ordosica).