## 3 Results
### Correlation Analysis between SDHI and NDVI
In terms of ecological benefits, the desertification process in the Wuliangsuhai watershed has been controlled, and the comprehensive improvement and restoration of the nature reserve and surrounding ecological environment have been effective. Wuliangsuhai has received sufficient ecological water supply; the ecological environment has been greatly improved and effectively protected, and the service function of the ecosystem has been greatly improved. The desert area in the central part of the Alexa League is subject to the implementation of key ecological construction projects, such as the National Natural Forest Protection Project, returning farmland to forest (grass), the \"Three Norths\" and wildlife protection, and the construction of nature reserves. The southeastern edge of the Geli Desert and the southwestern edge of the Desert have formed two large-scale sand-proof and Dust Storm Blocking Border Protection Forest and Grass Belts, which effectively curb the pre-invasion and spread of the Tengger Desert and the Ulanbuhe Desertb [47]. To understand in more detail the pattern of extreme events in different grassland vegetation types in Inner Mongolia, a partial correlation analysis was conducted between different vegetation types and the SDHI, SPI, and STI (Figure 10). The correlation coefficient results show that typical steppe and desert are positively affected by SPI, whereas desert steppe and forest area are more negatively correlated with SPI, and the forest is most significantly positively affected by STI. Deserts and desert grasslands show a negative correlation, indicating that these two areas are more sensitive to temperature conditions compared to woodland. The five types of grassland vegetation were positively correlated with the SDHI, and the area most affected by the compound dry and hot conditions was the desert steppe. The compound dry and hot conditions were also the dominant factors for the growth of the typical steppe. The correlations between NDVI and individual and compound climatic conditions in the different vegetation areas were quite different. The meadow steppe and typical steppe were positively correlated with climatic conditions, but the dominant factors of the two differed, with typical steppe being more sensitive to compound dry and hot conditions. Both the desert and desert steppe areas were negatively influenced by temperature conditions, with the most significant factor affecting the growth of desert grassland vegetation being compound dry and hot conditions. For forest, the response to temperature conditions was the strongest. In general, overall vegetation growth in Inner Mongolia was most influenced by temperature conditions, followed by compound dry and hot conditions, with drought conditions having the least significant effect, which shows that drought conditions are not the dominant factor in vegetation growth in Inner Mongolia. Mongolia [48; 49]. To further validate this conclusion, we chose the SDHI, SPI, and STI as factors to quantify the contribution of the three to NDVI (Figure 11) and obtained conclusions consistent with the correlation analysis.