Altitude Patterns of Leaf Carbon Isotope Composition in a Subtropical Monsoon Forest

Variations in leaf and stem traits across two elevations in subtropical forests

Understanding the variations in plant traits across elevations may provide valuable insights into the species structure and function of forests and their responses to climate change. To explore the patterns of trait variation across elevations, we analysed 14 leaf and stem traits associated with resource acquisition and stress tolerance in Schima superba Gardner & Champion, Castanopsis chinensis (Sprengel) Hance, and Pinus massoniana Lambert trees at two elevations in a subtropical forest in southern China. Wood density increased, whereas crown width, leaf water potential at 0700 hours (Ψ L-0700 ), and leaf δ 18 O decreased in high-elevation plants. Vessel diameter, daily maximum sap flux density, leaf δ 13 C, and leaf C and N concentrations per unit mass were comparable across elevations. We found species-specific variations in specific leaf area, midday leaf water potential, and leaf P concentration across elevations. Decreasing crown width with increasing elevation was associated with decreasing leaf δ 18 O and Ψ L-0700 , suggesting that higher stomatal conductance may moderate the loss of carbon assimilation. We elucidated the adaptive strategies of plants in response to environmental change, and showed that physiological traits varied in coordination with structural traits. Future studies incorporating multi-dimensional trait analyses can improve our understanding of the responses of forest ecosystems to climate change and global warming.