Exploring the spatio-temporal variations and influencing factors of vegetation cover in Yunnan Province

Yunnan Province has abundant species resources but fragile ecosystems, and the ecological vulnerability is closely related to vegetation cover. Hence, based on the normalized difference vegetation index (NDVI) from the MOD13Q1 dataset for 2000—2022, this study dynamically monitored the spatio-temporal variations of vegetation using the maximum value composite (MVC), Theil-Sen median trend analysis, and Mann-Kendall significance test. Moreover, this study delved into the response of vegetation to factors like topography, climate change, and land cover through correlation analysis. The results show that: ① From 2000 to 2022, the overall vegetation coverage of Yunnan Province was relatively high, with average annual NDVI values ranging from 0.74 to 0.90, showing a fluctuating upward trend. Of the whole area, 91.17% exhibited an increasing vegetation coverage trend, with the fastest growth rate seen in northeastern Yunnan; ② Regional differences were observed in vegetation cover, which was higher in southeastern and southwestern Yunnan compared to northwestern, central, and northeastern Yunnan; ③ The NDVI values of Yunnan Province were relatively stable below the altitude of 3 900 m, and decreased with increasing altitude in the case of over 3 900 m; ④ The NDVI values were the lowest with slopes below 3°, and with an increase in slope, they increased first and then decreased; ⑤ The planar slope aspect displayed the lowest NDVI values, and other slope aspects showed minimal impact on vegetation growth; ⑥ From 2000 to 2022, the vegetation cover in central, southeastern, and northeastern Yunnan was positively correlated with precipitation, suggesting that precipitation in these areas was favorable for vegetation growth. However, the vegetation cover in southwestern and northwestern Yunnan showed a negative correlation with precipitation. Additionally, the vegetation cover in the whole region and various areas was positively correlated with temperature, suggesting that temperature is beneficial to vegetation growth. The results of this study will provide a scientific basis for strengthening ecological environment construction and ecological management in Yunnan Province.