Legacy effect of extreme wetness events on subsequent tree growth evidenced by water use source shifts in a semi-arid region of North China

Key message Extreme wetness changed the pattern of tree water uptake and improved tree water status at the beginning of the growing season in the subsequent year. Improved understanding of tree and ecosystem responses to precipitation changes is paramount for their conservation and management. However, not much is known about the influence of extremely high rainfall periods on forest ecosystems. In this study, tree stem growth, water use uptake, leaf water potential, and leaf water use efficiency of Pinus tabulaeformis plantations were assessed to investigate the legacy effects of extreme wetness events on subsequent tree growth in a semi-arid region of North China. The soil water content in 20–40 cm and 40–80 cm soil layers was higher than that in 0–10 cm and 10–20 cm layers after an extreme wetness event in 2018, and the high soil water content lasted until July 2019. This consequently increased the ratio of tree water uptake from middle and deep soil layers, and improved tree water status at the beginning of the growing season, which can be explained by strong stem growth increase observed in 2019. These findings reveal regional forest dynamics under increased precipitation pattern variability, and play a vital role in providing adaptive forest management strategies in semi-arid regions of North China.