[Characteristics of Spatial and Temporal Variations of Multi-year Vegetation Cover in Different Climatic Zones of China and Their Topographic Effects].

Exploring the spatial and temporal dynamics of vegetation cover in different regions of China and its topographic effect is crucial for maintaining the ecological environment and preventing soil erosion. Based on the MODIS NDVI data from 2000 to 2023, the vegetation cover of China for 24 years was calculated by using the pixel binary model. The spatial and temporal trends of vegetation cover in different regions of China and the influence of topographic factors on the spatial distribution of vegetation cover were investigated by dividing the study area into seven typical climate zones. The results showed that： ① From 2000 to 2023, the vegetation cover in China showed a fluctuating upward trend, with a growth rate of 0.207%·a-1 and a basic pattern of "low in the northwest, high in the southeast, and spatially differentiated in the central part of the country." The proportion of areas with improved vegetation cover over the years was 46.7%, with a risk of continuous degradation in local areas. ② With the increase in altitude, the trend of vegetation cover changes in various climatic zones was not the same. With the increase in slope, the vegetation cover of the climatic zones showed a fluctuating upward trend, and the proportion of vegetation cover of different slope direction was relatively stable. ③ The vegetation cover in the same climatic zone had a significant difference in the response to the topographic factors, and the experiment showed that topographic factors had a significant influence on the vegetation cover. The experiment showed that the influence of terrain factors on vegetation cover was as follows： elevation > slope > slope direction. The study of the spatial differentiation of vegetation and the driving law of topography in typical climatic zones can provide scientific basis for the improvement of China's ecological environment.