Seminar: Chenna Sun

Non-structural carbohydrates (NSCs) serve as critical energy sources and metabolic substrates for plant growth, development, and survival, particularly under stressful environmental conditions. Despite their significance, substantial gaps remain in our understanding of how NSCs are allocated among functional pools—such as storage, growth, and defense—and how this allocation varies with functional traits in tropical forests, which are increasingly subject to frequent droughts. To address these gaps, we integrated seasonal drought conditions with canopy crane sampling to investigate changes in carbon reserves across leaves in 18 dominant tree species within a tropical forest in southwest China. These species were selected to encompass a range of canopy positions and hydraulic strategies. We found that: (1) most tropical trees accumulate starch in the leaves during the wet season and convert it into soluble sugars in the dry season to support osmotic regulation and maintain other essential physiological functions under water stress. (2) most anisohydric trees tend to allocate more carbon to structural growth but less to storage compared to isohydric trees in the dry season; understory trees invest more carbon to structural growth rather than storage compared to most canopy trees in the wet season; (3) canopy position and leaf water potential jointly modulate patterns of leaf carbon allocation. These findings contribute to a deeper understanding of NSC dynamics in trees and offer valuable insights into the adaptive strategies tropical tree species adopt to survive seasonal drought conditions.