Abstract: Aims In order to accurately assess the impact of drought events on the function of forest carbon sinks, this paper explores the occurrence and persistence of the drought legacy effect at different altitude gradients based on tree radial growth data. Methods In this paper, we take Picea schrenkiana as the dominant tree species in the Ili River Basin in the western Tianshan Mountains of Xinjiang, quantify the drought legacy effect of Picea schrenkiana at different elevations (2100, 2300 and 2500 m a.s.l.) by using ARIMA.We compared and analysed the differences in the duration and degree of the drought legacy effect of Picea schrenkiana at different altitudes, and revealed the changing law of the drought legacy effect of Picea schrenkiana at different altitudes and its driving factors. Important findings The results showed that (1) the radial growth of Picea schrenkiana at all three elevations was significantly positively correlated with the precipitation and PDSI of last year's growing season, suggesting that drought stress strongly limited the radial growth of trees. (2) With the increase of elevation, the duration of drought legacy decreased. The drought legacy effect of Picea schrenkiana existed for 2 years at low elevation, but only existed for 1 year at middle and high elevation. The recovery and resilience of Picea schrenkiana to drought events at low elevation were lower than those at medium and high elevation（P＜0.05）..(3) The effect of drought legacy and the cumulative drought legacy are low elevation＞middle elevation＞high elevation,and the drought legacy effect of each elevation was the greatest in the first year after the end of drought.After several drought disturbances, the cumulative drought legacy effect and the percentage of trees with drought legacy effect showed a tendency of decreasing and then increasing.Therefore, the recovery and resilience of trees to drought events and the frequency of droughts are all important factors that contribute to the elevation differences of the Picea schrenkiana drought legacy in western Tianshan.

Key words: drought legacy, Picea schrenkiana, drought event, elevation gradient, western Tianshan, Ecological resilience, radial growth