Tree growth response to the 2022 compound drought and heatwave on the eastern Qinghai-Tibetan Plateau

Abstract

With global climate warming, compound extreme climate events, combining droughts and heatwaves are increasing in frequency and intensity. In 2022, the eastern Qinghai-Tibetan Plateau experienced a once-in-a-century compound drought and heatwave, which probably had a profound impact on tree growth. To assess the extent of this impact, we investigated Minjiang fir (Abies fargesii var. faxoniana) at different growth stages (seedling, sapling, and mature tree) and elevations (low, middle, and high). We found that there was no significant change in the diameter class structure of the Minjiang fir population after the 2022 heatwave–drought, although the mortality rate increased insignificantly. The event significantly promoted the height growth of seedlings and saplings and the radial growth of mature trees at low elevations in 2022. It significantly suppressed the growth of branches in seedlings and saplings across all elevations. There was a unimodal effect on tree growth of the event that varied with elevation, and the sensitivity of tree growth to the event declined from seedlings to mature stages. This study enhances our understanding of the response dyssynchrony of tree growth to unstable states in the subalpine region. This study is helpful in planning the protection and utilization of forest resources in the climate-sensitive area of the Qinghai-Tibetan Plateau, which is exposed to increasingly frequent extreme events.