Altitudinal differentiation of forest resilience to drought in a dryland mountain

Abstract

Drought is the major climate disaster experienced by dryland mountains. However, the altitudinal differentiation of forest resilience to drought and its dominant climate factors in dryland mountains is largely unknown, which is crucial to predict whether the primary forests will collapse under future global warming. In this study, we selected the leaf area index (LAI) and the standardized precipitation evapotranspiration index (SPEI), fitted forest resilience curves based on drought intensity and recovery time, calculated the curve area to define resilience along elevation zones in Qilian Mountains from 1982 to 2020, and analysed the characteristics of resilience altitudinal differentiation and dominant factors. The results showed that the humid characteristics and trends towards humidification in forests were more significant at higher elevations. Forests in the elevation range of 2600–3900 m exhibited faster recovery rates and greater resilience to drought than those in 1700–2600 m. This altitudinal differentiation was related to precipitation non-monotonically. Meanwhile, potential evapotranspiration and cloud cover were the most important climate factors for resilience temporal changes in different altitude zones. The findings of this study confirm the importance of the altitudinal perspective in studies of the dryland mountain evolution under future global change conditions.