Individual asynchrony promotes population‐level tree growth stability

Abstract Community‐level stability is widely considered to increase with species richness and asynchrony. However, it is not well understood to what extent population‐level stability may be regulated by population size and within‐population asynchrony among individuals. Using a large set of global tree‐ring data, we quantified the effects of population size and within‐population tree growth asynchrony on the temporal stability of population‐level tree growth rate. We also examined the relationship between the global distributions of within‐population tree growth asynchrony and population‐level tree growth stability. The results showed that population‐level tree growth stability asymptotically increased with population size and quickly levelled off at an average population size of 26. After population size was controlled, population‐level tree growth stability increased with within‐population tree growth asynchrony ( R 2 = 0.54). Globally, population‐level tree growth stability was 52% higher than individual‐level tree growth stability on average. This percentage varied considerably across climate zones and was highest in the Tropical zone (84%) due to its highest within‐population asynchrony, while lowest in the Dry zone (34%) due to its lowest asynchrony. Synthesis . Our results indicate that individual asynchrony plays a primary role in stabilizing population‐level tree growth rate, followed by population size. This finding highlights the importance of individual‐level differences in alleviating environmental stresses on forest growth.