## 4 Analysis of Results
### Climate Effects on Interannual Vegetation NDVI  
In order to analyze the influence of climatic factors on vegetation NDVI, path analysis was introduced to analyze the interrelationship between precipitation, temperature, and vegetation NDVI. Figure 5 shows the spatial distribution of the influence of precipitation and temperature on the vegetation NDVI, including direct effect, indirect effect, and comprehensive effect. Direct effect means the direct influence on vegetation growth of precipitation or temperature change. The indirect effect was used to indicate the indirect influence on vegetation growth of precipitation change deduced from temperature variation or temperature change deduced from precipitation variation. Because the increase in precipitation can turn down the temperature, and the increase in temperature will reduce precipitation. In contrast, comprehensive effect equals the grand sum between the direct and direct effect of precipitation or temperature change, respectively. The increase in precipitation showed a positive effect on vegetation growth in the northern part of Hangjin Banner, the western part of Etoke Banner, and the western part of Etoke Front Banner (shown in Figure 5a), which covers 78.83% of the whole city. The mean direct influence of precipitation is 0.542 (shown in Table 3) in the whole city, which indicates that an increase in precipitation promoted the growth of vegetation directly. The increase in temperature showed an active influence on the growth of vegetation in Dongsheng District, Kangbashi District, and other eastern parts (shown in Figure 5b), which covers 35.46% of the whole city. The mean direct effect of temperature on vegetation NDVI is \(-0.043\) (shown in Table 3) in the whole city, which indicates that the increase in temperature has no direct effect on vegetation growth. Figure 4: Proportion of future variation trend of vegetation NDVI in different seasons. Because the increase in precipitation will reduce the temperature, thus precipitation has an indirect effect on vegetation growth. The indirect effect of precipitation on vegetation NDVI is 0.014 (shown in Table 3), which could be ignored (shown in Figure 5c). In contrast, the increase could reduce the precipitation; thus, temperature also has an indirect effect on vegetation growth. The indirect effect of temperature on vegetation NDVI is -0.158 (shown in Table 3), which indicates that the increase in temperature inhibited vegetation growth by reducing the precipitation. The indirect effect, mainly distributed in the central part of Hangjin Banner, most of the former banner of Etoke Banner, the western part of Etoke Banner, and the southern part of the Wushen Banner (shown in Figure 5d), is larger than the direct effect. The comprehensive effect of precipitation on vegetation NDVI is 0.5556 (shown in Table 3), which showed that precipitation promoted the growth of vegetation. In contrast, the comprehensive effect of temperature on vegetation NDVI is \(-0.205\) (shown in Table 3), which indicates that temperature increase had an inhibitory effect on the growth of vegetation. In spring, the direct effect of precipitation and temperature on vegetation NDVI are both positive, which means both temperature increase and precipitation increase could promote vegetation growth. The direct effect of precipitation on vegetation NDVI is 0.645, while the direct effect of temperature on vegetation NDVI is 0.184 (shown in Figure 6). Figure 5: Spatial distribution of effects of precipitation and air temperature on vegetation NDVI. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Climate Factors** & **Direct Effect** & **Indirect Effect** & **Comprehensive Effect** \\ \hline Precipitation & 0.542 & 0.014 & 0.556 \\ Temperatures & \(-0.043\) & \(-0.158\) & \(-0.205\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Influence of multi-year mean climate on vegetation NDVI. It could be considered that the direct promotion effect of precipitation on vegetation growth is greater than temperature.