| 10 Apr 2026
Greater variability in environmental stress favours trees that prioritise storage of carbohydrate reserves over growth: a modelling analysis
Abstract. Trees use reserves of non-structural carbohydrates (NSC) to help them survive and recover from stress periods. However, accumulation of reserves is at the expense of growth, resulting in a growth-storage trade-off. Tree species may pursue different storage strategies to optimise fitness in environments with differing degrees of stress, but it is not clear which storage strategies provide a competitive advantage in which environments.
We use a forest gap model to explore competitive outcomes among idealised tree species with different combinations of two carbon storage-related traits: carbon utilisation rate (fast-slow spectrum) and switch time from growth to storage (risky-safe spectrum). We investigate the competitive success of alternative growth vs storage strategies in simplified environments which have a non-specific annual stress period. We vary stress intensity (the mean stress duration) and stress stochasticity (the variance of stress duration) to determine the effect of increased stress on composition outcomes.
Community composition shifted from growth-prioritising strategies to storage-prioritising strategies with increasing stress intensity and stochasticity. The major driver of this shift in community composition was increased mortality, due to depletion of carbon reserves, in species with growth-prioritising strategies.
Our results demonstrate that considering carbon storage strategies can provide new insights into tree survival and adaptation of tree communities to increasing stress caused by climate change.
This manuscript addresses the ecologically important trade-off between carbon allocation to growth and to non-structural carbohydrate storage. The authors extend the plant trait-, size- and patch-structured forest model with an active non-structural-carbohydrate (NSC) storage pool. Carbon-allocation strategy is represented by two traits: the timing of the switch from growth to storage and the rate at which stored carbon is utilised for growth. Four idealised strategies (Fast-Risky, Fast-Safe, Slow-Risky, and Slow-Safe) are allowed to compete in 100-year simulations across eight environmental treatments, combining two mean annual stress durations with four levels of stress stochasticity. The extended model also incorporates storage-dependent mortality, productivity-dependent mortality, and an allometric recalibration mechanism that allows plants to restore imbalances among tissues following stress. The main results show that seasonal stress favours slower carbon-utilisation strategies, whereas risk-taking strategies are more advantageous in the absence of stress because of their longer growing periods. Overall, the study provides a useful modelling perspective on how carbon storage strategies may mediate tree survival, competitive interactions, and forest community responses under climate change, particularly as droughts, heatwaves, and other extreme events become more variable and severe. My general comments are provided below.
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