Drought survival of tropical tree seedlings enhanced by non-structural carbohydrate levels

Widespread forest die-back due to the increasing frequency and intensity of drought in many parts of the planet is focusing attention on the mechanisms of tree drought resistance. This study provides direct experimental evidence that greater non-structural carbohydrate concentrations before drought help maintain hydraulic function and thereby prolong drought tolerance in seedlings of ten tropical tree species. Plants in most biomes are thought to be living at their hydraulic limits, and alterations to precipitation patterns consistent with climate change trends are causing die-back in forests across the globe1,2,3,4. However, within- and among-species variation in plant traits that promote persistence and adaptation under these new rainfall regimes may reduce mortality in these changing climates5,6. Storage of non-structural carbohydrates (NSCs) is posited as an important trait for resistance and resilience of forests to climate-change-induced drought, but the underlying mechanisms remain unclear7,8,9,10. Here we demonstrate a positive relationship between NSCs and drought survival by manipulating NSC concentrations within seedlings of ten tropical tree species. Seedlings experimentally enriched in NSCs showed higher stem water potentials and sustained NSCs during drought. NSC use for maintenance of osmoregulation and hydraulic function therefore seems to underlie improved drought resistance. That drought mortality is delayed by higher NSC concentrations has implications for predicting the impacts of climate change on forest die-back2,4 and may help focus restoration efforts on species that increase the resistance and resilience of forests to climate change.