Stress triggers tree-growth rebound in global forests

Abstract

Plants maintain their health through various ecological processes, among which resilience to external stresses has received increasing attention in recent years. By analyzing tree-ring data from 1762 sites, encompassing a total of 1,623,006 weak stresses (mean-2sd ≤ tree ring indices (TRI) < mean-sd) and 320,345 strong stresses (TRI < mean-2sd), we observed a significant growth increase following stresses for a subset of trees. We found that the growth increase was not a consequence of post-stress climate but an inherent property of trees’ response to stresses that could be called “rebound effect”. Across all the 16 genera studied, a similar proportion of trees, 26.23 % and 25.73 %, exhibits rebound effect in the first year after weak and strong stresses, respectively. The amplitudes of growth rebound, measured as the difference between the mean of ring-width indices in the rebounding year and the subsequent eight years, are 0.242 and 0.266 after weak and strong stresses, respectively. Conifers generally rebound at a higher proportion but to a lesser amplitude than broadleaves. Furthermore, a higher proportion and greater amplitude of rebound were observed in trees having longer age and slower growth. Our findings provide a new perspective of tree resilience to disturbances and shed insights into the processes of forest recovery after growth suppressions.