Abstract: Vegetation plays a crucial role in ecosystem functioning by linking energy flow and material cycling. Understanding vegetation dynamics and their responses to climate is essential for ecosystem conservation. Based on normalized difference vegetation index (NDVI), precipitation, and temperature data of the Jinsha River Basin from 2001 to 2022, we used Mann-Kendall trend test and Sen's slope analysis to analyze the temporal and spatial variations of vegetation cover, while applied partial correlation analysis to explore the lagged responses of vegetation to temperature and precipitation and the lag differences across the responses of different land types. Results showed that vegetation coverage in the basin improved overall from 2001 to 2022, with the increasing rate of NDVI being 0.002·(10 a)^-1. There were significant spatial variations of vegetation changes, with 25.4% of the area showing improvement. The mean NDVI negatively correlated with altitude (correlation coefficient was -0.76). The basin's climate condition exhibited drier and warmer trends. NDVI showed a one-month lagged response to precipitation and a no-lagged response to temperature. Vegetation coverage in cultivated land and shrubland increased, while that in grassland and forest remained stable. The changes in grassland coverage had the strongest correlation with both precipitation and temperature, while forest coverage had the lowest correlation. Land types exhibited varying lag times in their response to the variations of precipitation and temperature. The lag time of precipitation response for cultivated land, grassland, and shrubland was one month, while forest showed an immediate response. The cultivated land and forest showed immediate response to temperature, while grassland and shrublands had significant differences in lag time. These findings would offer scientific basis for ecological protection and resource management in the basin and provide methodological insights for examining vegetation dynamics in other regions.

Key words: Jinsha River Basin, normalized difference vegetation index, land type, climate factor