Extreme weather events are becoming more frequent. Understanding how forest ecosystems respond to such disturbances is essential for developing adaptive management strategies. However, knowledge regarding the post-disturbance growth recovery of trees in subtropical forests, and the factors driving this process, remain limited.

In a study published in Forest Ecology and Management, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences investigated the impact of extreme snow disasters on the growth recovery of tree species and revealed the driving mechanisms in subtropical evergreen broad-leaved forests.

Based on tree-ring width chronologies and long-term monitoring data from permanent plots, researchers analyzed post-disturbance growth recovery and resilience in four most prevalent broad-leaved species (Stewartia pteropetiolata, Schima noronhea, Machilus yunnanensis and Machilus gamblei) in the Ailao Mountain subtropical evergreen forest, following an extreme snow event in 2015.

Researchers found that immediately after the snow disaster, the radial growth of all four species declined sharply, however, the recovery capacity varied remarkably among species. Over 50% of individuals of Stewartia pteropetiolata and Machilus yunnanensis bounced back to pre-disturbance growth rates within just one year. In contrast, Schima noronhea and Machilus gamblei required up to four years for a full recovery.

“The variation in recovery time indicates the complex interplay within forest ecosystems after a disturbance. However, across all species, competition release stands out as the most critical driver for resilience,” explained FAN Zexin, the corresponding author of this study.

Researchers quantified "competition release" which occurs when damage or death of neighboring trees reduces competition for essential resources like light, water, and nutrients. Dendrochronological analysis combined with long-term forest census data showed that this release is the key factor governing both the speed and degree of a tree’s growth recovery, outweighing the influence of tree age or size.

"Our study underscores that competition release following extreme snowfall can accelerate tree-growth recovery. It provides a scientific basis for adaptive forest management in subtropical regions as global warming continues,” said FAN.