Pantropical moist forests are converging towards a middle leaf longevity

Leaf longevity is a fundamental plant trait that largely explains ecosystem functional dynamics in global pantropical moist forests. However, the signs, magnitudes, and mechanisms of the spatiotemporal variations in leaf longevity with ongoing climate change are still lacking. Using both ground measurements and gridded leaf age-dependent leaf area index data, we map the continental-scale variability of annual mean leaf longevity across pantropical moist forests over 2001–2023. We find a biome-dependent and converging trend in leaf longevity under climate change. In Amazon and tropical Asia with long leaf longevity (> ~1.8 years), leaf longevity decreases due to rising temperature and intensified atmospheric dryness. In contrast, an increasing trend is observed in Congo and subtropical Asia where forests have short leaf longevity (<~1.8 years). These responses cause a convergence of pantropical short and long leaf longevity into a middle longevity range, with maximization of plant functional traits, photosynthesis, and species evenness, which are expected to better resist climate variability. Our study provides emerging evidence for large-scale structural and functional adaptions across pantropical moist forests and is helpful for predicting climate-driven risks to ecosystem stability. The longevity of leaves determines the overall duration of photosynthesis for plants. This study suggests that climate change drives leaf longevity convergence toward intermediate ranges, which, by altering leaf traits and enhancing photosynthetic capacity, strengthens ecosystem stability and is closely linked to vegetation diversity.