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

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 globe. 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 climates. 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 unclear. 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-back and may help focus restoration efforts on species that increase the resistance and resilience of forests to climate change.