Effects of altered precipitation regimes on plant productivity in the arid region of northern China

Climate change scenarios have predicted significant alterations in precipitation patterns over most of the mid-latitude land areas by the end of this century, but the degree to which altered precipitation regimes influence terrestrial ecosystem function in arid regions is uncertain. Precipitation is a primary climatic factor that regulates ecosystem function in arid regions. Based on remote sensing and meteorological data from 2000 to 2013, we analysed the spatiotemporal variations in annual net primary productivity (NPP) for different land cover types in the arid region of northern China and quantified the effects of growing season precipitation (GSP) and seasonal distribution of precipitation (SDP) on NPP variability by using the ecological process Carnegie-Ames-Stanford Approach (CASA) model. Our results suggested that significant NPP increases were found in most of the vegetated areas, especially in grasslands and shrublands. Responses of NPP to precipitation variability were related to land cover types. Grassland and shrubland were most responsive to precipitation variability followed by croplands and forests. Increased precipitation increased NPP, and NPP responded more strongly to higher precipitation than lower precipitation. We also found that increased precipitation concentration decreased NPP. GSP and SDP accounted for approximately 67% and 21%, respectively, of the variability in NPP. We concluded that growing season precipitation and its seasonal distribution were dominant factors controlling inter-annual variability in NPP in the arid region of northern China. Other factors, such as plant functional trait, antecedent soil moisture and human activities, might mediate NPP responses to precipitation variability through interaction with water availability. Our studies have implications for assessing and predicting vegetation responses to future climate change.