# Quantifying Climate Change and Ecological Responses within the Yangtze River Basin, China
## 3 Results
### Trends in Ecological Indicators in the YRB  
The annual mean NDVI and EVI values for the YRB during 2001-2013, which are produced from the annual 500-m data in proved NDVI and EVI products (MOD 13A1), are illustrated in Figure 10. The annual mean NDVI is 0.565, with a maximum of 0.577 in 2007 (0.012 above the mean) and a minimum of 0.548 in 2001 (0.017 below the mean); the annual mean NDVI increased by 0.017 in 2001 (0.548) to 2013 (0.577), a rate of 0.002 yr\({}^{-1}\). The annual mean EVI is 0.31, with a maximum of 0.321 in 2007 (0.011 above the mean) and a minimum of 0.298 in 2001 (0.013 below the mean); the annual mean EVI increased by 0.016 in 2001 (0.298) to 2013 (0.313), a rate of 0.001 yr\({}^{-1}\) (Figure 10). Figure 8: Modeled temporal variations of climate change over the YRB during 1961–2013. (**a**) Mean annual temperature, (**b**) mean annual precipitation. The data are based on multiple model simulations from the WCRP CMIP5. _b:_ regression coefficient, Significance level: ** means the significant of the 99% confidence interval, \(p\) < 0.01, * means the significant of the 95% confidence interval, \(p\) < 0.05. Figure 9: Comparison of trends in (**a**) annual precipitation and (**b**) mean annual air temperature of meteorological stations and CMIP5 model outputs for the YRB during 1961 to 2013 (A non-parametric test was used). Figure 11 illustrates the spatial distribution of the mean value of NDVI in the growing season (Figure 11a), the mean value of EVI in the growing season (Figure 11c), the mean value of annual NDVI (Figure 11b), and the mean value of annual EVI (Figure 11d), for the YRB from 2001-2013. The mean values of both annual NDVI and EVI, including the Han River Basin, the Wu River Basin, most of Jiangxi and a small part of Zhejiang Province, exhibit higher values, and the Jinsha River Basin and the urban areas of the MLYRB exhibit lower values. In general, the annual NDVI and EVI increased from 2001 to 2013, and these increases are consistent with the changes in the mean values of NDVI and EVI in the growing season, which are illustrated in Figure 12. The results are summarized in Table 3 and they show that the annual NDVI and EVI exhibit increasing trends, accounting for 65.29% and 60.23% of the YRB, respectively. As shown in Figure 12, the increasing trend occurred mainly in the central and north-eastern parts of Hanzhong Basin, in the Jialing and Wujiang River basins, and in the north-eastern part of Sichuan Basin. The areas with a decreasing trend are chiefly distributed in arid and semi-arid areas of the SRYR and in the urban  
Figure 11: Spatial distribution of (**a**) mean growing season NDVI, (**b**) mean annual NDVI, (**c**) mean growing season EVI, (**d**) mean annual EVI in the YRB during 2001–2013. Figure 10: Inter-annual variations of annual mean NDVI and EVI over the YRB during 2001–2013. During the last 30 years, the annual mean LAI increased significantly, from 1.57 m\({}^{2}\)m\({}^{-2}\) in 1982 to 1.79 m\({}^{2}\)m\({}^{-2}\) in 2011(a rate of 0.07 m\({}^{2}\)m\({}^{-2}\) per decade) across the YRB (Figure 13). The spatial distribution of growing season LAI is similar to that of annual mean LAI in the YRB; the values are higher in the foothills of the Tibetan Plateau, the Han River Basin and the Poyang Lake Basin; and the values are lower in the MLYRB and in the densely urbanized area of Taihu Basin (Figure 14). Spatially, for 83.35% of the pixels, the annual mean LAI exhibits an increasing trend during 1982-2011 (Table 3). The mean LAI in the growing season and the annual mean LAI increased significantly in the basins of the Jialing and Wujiang Rivers and in the Dongting and Poyang lakes' basins. Areas of reduced values are mainly concentrated in MLYRB and in the Taihu Basin (Figure 14). The results of linear regression analysis reveal a slight increasing trend in annual total GPP for the entire YRB, with an annual rate of change of up to 9 TgCyr\({}^{-1}\) yr\({}^{-1}\).