Patterns Of Distribution In Vegetation Productivity Of Southwest China Under Drought

Based on the data of Palmer drought severity index(PDSI)and MODIS for the period 2000-2013,the spatiotemporal changes in drought and vegetation productivity in Southwest China were assessed by methods of trend analysis and correlation analysis.The objective was to determine if there was a correlation between drought and vegetation productivity.The key results are summarized below:1.Over the study period,Southwest China suffered varying degrees of drought disturbances,with overall increasing severity and most widespread drought in 2006 and 2010.The GPP anomalies for 2000,2001,2010,and 2012 were extremely negative,with values of-67,-66,-47,and-62g C·m-2·yr-1,respectively;the corresponding negative NPP anomalies(SAI)accounted for 37,29,35,and 31%of the study area,respectively.2.For typical drought events,the reduction of GPP ranked in the order of:spring 2010>winter 2009>autumn 2009>summer 2006.The relative changes in productivity of various vegetation types ranked in the order of:shrubland>farmland>coniferous forest>savanna>broadleaf forest>mixed-wood forest.3.PDSI was significantly correlated with GPP anomaly and SAI in some of the pixels(p<0.05),mainly in grassland ecosystems of northwestern Sichuan and mixed-wood forests of northern Yunnan.In both summer and autumn,there were significantly correlations between PDSI and GPP in some of the pixels(p<0.05)Overall,the vegetation productivity in Southwest China displays a declining trend under the influence of drought,with shrubland being most susceptible.