Quantifying Climate Change and Ecological Responses within the Yangtze River Basin, China

The interactions between climate change and vegetation have a significant impact on the dynamics of the global carbon cycle. Based on the observed meteorological data from 1961 to 2013 and the temperature and precipitation data simulated by various climate models (simulations phase 5 of the Climate Model Intercomparison Project dataset), this paper analyzes the temperature and precipitation changes of the Yangtze River Basin (YRB) and finds that they are a similar trend, that is, the temperature presents a significant upward trend (R-2 = 0.49, p < 0.01), and the variation trend of precipitation is not significant (R-2 = 0.01). Specifically, based on observed meteorological data, the annual mean temperature increased significantly and the area of increasing temperature accounted for 99.94% of the total region (p < 0.05); however, there was no significant change in annual precipitation. Ecological indicators (normalized difference vegetation index (NDVI); enhanced vegetation index (EVI); leaf area index (LAI); gross primary production (GPP); and net primary production (NPP)) of the YRB showed an increasing trend, and annual NDVI, annual EVI, LAI, annual total GPP and annual total NPP increased at respective rates of 0.002 yr(-1), 0.001 yr(-1), 0.07 m(2)m(-2)decade(-1), 9 TgCyr(-1)yr(-1), and 6 TgCyr(-1)yr(-1), respectively. Correlation analysis between temperature/precipitation and NDVI/EVI/LAI/GPP/NPP was used to determine the relationships between climatic parameters and ecological indicators. Specifically, the temperature is significantly positively correlated with annual NDVI (R-2 = 0.37, p < 0.05), with annual mean LAI (R-2 = 0.35, p < 0.05) and with annual GPP (R-2 = 0.37, p < 0.05). In addition, there is a moderate positive correlation between mean EVI and mean growing season air temperature (R-2 = 0.24); annual mean air temperature is a moderate positive correlation with annual NPP (R-2 = 0.28). Our findings confirm that temperature is more closely related to ecological factors than precipitation over the YRB in these decades.