[Attribution Analysis of Vegetation Variation in the Southwest Alpine Canyon Area of China Considering Climate...

The ecosystem in the Southwest Alpine Canyon Area of China is fragile and sensitive to climate change. Studying the time effect of vegetation growth in response to climate change in this area is helpful to accurately understand the relationship between climate and vegetation and can provide an important scientific basis for regional ecosystem management. Based on the enhanced vegetation index （EVI） of the growing season from 2001 to 2023， the pixel-by-pixel trend analysis， time-lag and time-cumulative effect analysis， and multiple regression residual analysis system were used to explore the characteristics of vegetation dynamic change and its climate response mechanism. The results showed that： ① From 2001 to 2023， the EVI in the growing season of the study area showed a significant upward trend at a rate of 0.001 1 a^-1 （P<0.001）. Spatially， EVI showed a pattern of high in the south and low in the north and decreased rapidly with the increase in altitude. The rising area of EVI accounted for 80.49%， of which the significant rising area accounted for 24.15%， which was concentrated in the northwest of Yunnan-Kweichow Plateau. The area of EVI decreased significantly， accounting for 1.31%， which was scattered in the valley plain area. ② The response of vegetation growth to precipitation and temperature changes showed a significant cumulative effect， and the affected areas accounted for 70.61% and 45.05% of the study area， respectively. The effects of temperature and precipitation on vegetation growth lagged by 0.26 and 0.31 months on average and accumulated by 0.66 and 1.36 months on average. The lag period and cumulative period of precipitation affecting vegetation growth were longer than that of temperature， and vegetation growth was more sensitive to temperature changes. ③ The average explanatory power of climate change on EVI changes increased by 6.68%， 7.97%， and 8.16%， respectively， when considering both time delay and cumulative effects， compared with those without considering time effect， only considering time delay effect， and only considering cumulative effect. ④ Climate change and human activities jointly drove EVI changes， with the contribution rates of 44.61% and 55.39%， respectively. Among them， the change of EVI in the alpine zone was mainly positively affected by climate change， while the change of EVI in the middle and low mountain valley zone and the middle mountain zone was mainly positively affected by human activities.