# Impact of Climate Change on the Major Eco-Hydrological Parameters in the Dongting Lake Basin
## 3 Results and Discussion
### Contributions of Long-Term Changes to GPP and ET  
#### 3.3.1 Relative Contributions of Climate Change to GPP and ET  
The contributions of temperature, precipitation, and radiation to GPP are shown in Figure 12 and Table 3. In the Dongting Lake Basin, the main climatic factor controlling the trend of GPP was found to be temperature (the average relative contribution was 44.73 \(\pm\) 14.54%), with precipitation (the average contribution was 44.04 \(\pm\) 17.58%) playing a slightly smaller role than temperature, with radiation (the average contribution was 11.22 \(\pm\) 8.13%) being the smallest. In the Xiangjiang River Basin, where crops, trees, and buildings are the main vegetation types, the fluctuation of GPP was found to be primarily influenced by temperature, with the average contribution reaching 41.38 \(\pm\) 11.54%. Precipitation had a slightly smaller role, with an average contribution of 41.32 \(\pm\) 17.70%. Radiation had a relatively small effect on GPP, with an average contribution of 17.29 \(\pm\) 7.73%. Crop, tree, and grass are the main vegetation types in the Zishui River Basin. Temperature was found to play a major role in the changes in GPP, with an average contribution of 44.28 \(\pm\) 6.94%. The role of precipitation was slightly smaller than temperature, with an average contribution of 40.54 \(\pm\) 11.16%. The role of radiation (average contribution of 15.18 \(\pm\) 7.83%) was the smallest. The vegetation cover type in the Yuanjiang River Basin is mainly trees, and the greatest influence factor on the trend of GPP change was found to be precipitation (average contribution of 46.41 \(\pm\) 16.80%). The role of temperature (average contribution of 44.57 \(\pm\) 14.85%) was slightly smaller compared to precipitation. The role of radiation (average contribution of 9.03 \(\pm\) 6.37%) was the smallest for GPP change (Figure 12d). The role of temperature in the Lishui River Basin on GPP was slightly smaller than that of precipitation, with an average contribution of 45.47 \(\pm\) 14.71%. The role of radiation was the smallest among the climate factors in the present study, with an average contribution of 5.08 \(\pm\) 4.5%. The role of radiation was the least important climate factor in the study, with  
Figure 11: Spatial distribution of GPP (**a**) and ET (**b**) in the Dongting Lake basin from 2000 to 2017. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & **Dongling Lake** & **Xiangliang** & **Zishui River** & **Yuanliang River** & **Lishui River** & **Dongling Lake** \\  & & **Basin** & **River Basin** & **Basin** & **Basin** & **Basin** & **Region** \\ \hline \multirow{3}{*}{GPP} & PRE (\%) & 44.04 \(\pm\) 17.58 & 41.32 \(\pm\) 17.70 & 40.54 \(\pm\) 11.16 & 46.41 \(\pm\) 16.80 & 49.44 \(\pm\) 13.86 & 44.04 \(\pm\) 22.29 \\  & TEM (\%) & 44.73 \(\pm\) 14.54 & 41.38 \(\pm\) 11.54 & 44.28 \(\pm\) 6.94 & 44.57 \(\pm\) 14.85 & 45.47 \(\pm\) 14.71 & 50.59 \(\pm\) 19.68 \\  & SAD (\%) & 11.22 \(\pm\) 18.13 & 17.29 \(\pm\) 7.73 & 15.18 \(\pm\) 7.83 & 9.03 \(\pm\) 6.57 & 5.08 \(\pm\) 4.84 & 5.37 \(\pm\) 4.46 \\ \hline \multirow{3}{*}{ET} & PRE (\%) & 17.77 \(\pm\) 11.76 & 16.95 \(\pm\) 12.40 & 24.88 \(\pm\) 12.38 & 17.27 \(\pm\) 10.58 & 21.92 \(\pm\) 6.62 & 13.27 \(\pm\) 11.24 \\  & TEM (\%) & 64.6 \(\pm\) 12.89 & 57.14 \(\pm\) 10.00 & 53.52 \(\pm\) 8.10 & 67.34 \(\pm\) 12.18 & 69.41 \(\pm\) 5.58 & 77.40 \(\pm\) 8.14 \\  & SRAD (\%) & 17.63 \(\pm\) 10.73 & 25.91 \(\pm\) 8.73 & 21.60 \(\pm\) 10.73 & 15.38 \(\pm\) 8.92 & 8.66 \(\pm\) 7.37 & 9.33 \(\pm\) 6.65 \\ \hline \hline \end{tabular} Data are presented as mean \(\pm\) standard deviation.  
\end{table} 
Table 3: Relative contributions of factors to GPP and ET in the Dongting Lake Basin and its sub-basin. an average contribution of 5.08 \(\pm\) 4.84%. The Dongting Lake region is mainly covered by crops, water, and grasslands. The temperature was found to play a dominant role in the change of GPP, with an average contribution of 50.59 \(\pm\) 19.68%.