## 4 Discussion
### The Impact of Climate Regions on Vegetation Restoration  
Vegetation is prone to losses during periods of drought [89]. However, once drought conditions ameliorate, vegetation that has not undergone complete mortality typically exhibits a certain level of recovery capability [90]. We evaluated vegetation recovery in arid regions of Central Asia using four indices representing different ecological significance as well as our self-developed RSVI. The distributions of vegetation recovery during the post-drought periods in 2012 and 2019 showed a high degree of similarity (Figures 7 and 8). However, the five indices exhibited inconsistent results in capturing the dynamics of vegetation recovery (Figures 7a-e and 8a-e). This was primarily due to the varying sensitivities of the selected indices to different vegetation characteristics; for instance, the EVI and FVC are more sensitive to vegetation greenness and coverage, respectively [91; 92]. Moreover, certain indices may be more suitable for early-stage vegetation monitoring, while others may be more appropriate for mid-to-late-stage monitoring [93]. This is related to the degree of alignment between the monitoring indices and the changing patterns of vegetation recovery during the post-drought restoration process. Furthermore, discrepancies in monitoring results can also arise from variations in data sources and spatial resolutions. In our study, all the indices utilized are based on MODIS data, and compared to other studies focused on large-scale regions or global analyses, the differences in spatial resolution are relatively minor. Therefore, errors in this regard are of less concern in our investigation.  
Certainly, the vegetation recovery period after drought varies across different climatic regions. In our study, a gradual decrease in the vegetation recovery period was observed as we transitioned from arid to humid climates (Figures 9 and 10). This is consistent with findings by [PERSON] et al., who investigated meteorological and agricultural droughts in northwestern China. They reported differences in drought resilience across various climate zones and vegetation types and highlighted that vegetation recovery is closely linked to the specific sensitivities and unique characteristics of the local drought environment [94]. This observation aligns closely with our study results. This phenomenon could be attributed to the limited water supply in arid regions, where moisture constraints are more severe during drought, thereby hindering vegetation growth and metabolism [95; 96]. Prolonged drought can lead to soil moisture deficits, soil erosion, and nutrient loss [97; 98]. Even after drought ends and rainfall replenishes moisture, the soil requires ample time to recover to its original levels [99]. The survival strategies of vegetation during drought differ from those under well-watered conditions, and when the environmental conditions shift between dry and wet conditions, vegetation needs time to adjust its water balance and survival strategies, including its community structure [100]. Conversely, regions with humid climates receive sufficient precipitation and have strong soil water storage capacity, allowing them to retain some moisture even during drought periods [101]. Typically, humid areas have suitable temperatures and greater vegetation diversity, causing them to be better adapted to wetter environments [102; 103]. After drought ends, these characteristics provide better growth conditions for vegetation, promoting photosynthesis and metabolism and thus accelerating the vegetation recovery process.