What is it about?
Trees store carbon not only in wood but also as nonstructural carbohydrates (NSC), mainly soluble sugars and starch. These carbon reserves help trees survive drought, heat, and other environmental stresses by supporting metabolism, maintaining water balance, and fueling recovery after stress. However, tree species differ greatly in how much sugar and starch they store, even when they grow side by side in the same forest. Until now, it has remained unclear whether these differences are mainly driven by the environment or by the biological characteristics of the species themselves. To answer this question, we analyzed data from 281 woody species growing in 102 forest communities around the world. By comparing each species with the average of its local community, we removed much of the influence of climate and site conditions, allowing us to identify the intrinsic factors that shape carbon storage strategies. We found that closely related species tend to store carbon in similar ways, and that key plant traits—including stomatal regulation, photosynthetic capacity, leaf characteristics, and wood density—consistently explain how species allocate carbon to soluble sugars and starch. Importantly, sugars and starch showed opposite relationships with several traits, reflecting their different biological functions: sugars mainly support rapid physiological responses, whereas starch serves as a longer-term carbon reserve.
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Why is it important?
Forests play a critical role in regulating the global carbon cycle, yet predicting how different tree species will respond to increasing droughts and climate extremes remains one of the biggest challenges in ecology. Our study provides a simple trait-based framework for understanding why some tree species maintain different carbohydrate storage strategies than others. Rather than focusing only on environmental conditions, we show that species' evolutionary history and functional traits strongly influence how carbon is stored. Because the traits identified in this study are already widely measured across global forest monitoring networks, our findings can be readily incorporated into ecological research and vegetation models. This will improve predictions of forest carbon allocation, resilience, and survival under future climate change, helping scientists better understand which forests are most vulnerable and why.
Perspectives
Our study provides a foundation for linking plant functional traits to carbohydrate storage across the world's forests. Because the key traits identified here are among the most widely measured in plants, the relationships revealed in this study can be readily incorporated into ecological research and vegetation models without requiring extensive new measurements. Future research can build on this framework by exploring how carbohydrate reserves interact with hydraulic function, nutrient availability, and changing climate over time. Integrating these processes into ecosystem and Earth system models will improve our ability to predict forest growth, resilience, and mortality, ultimately leading to more reliable projections of the future global carbon cycle.
Weibin Li
Lanzhou University
Read the Original
This page is a summary of: Divergent trait controls on soluble sugars and starch underlie global strategies of tree carbohydrate storage, Proceedings of the National Academy of Sciences, July 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2605066123.
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