LAUSR

Addressing intraspecific variability of functional traits helps understand how climate change might influence the distribution of organismal traits across environments, but is notably understudied in the Amazon, especially for plant-hydraulic traits that are often used to project drought responses. We quantified intraspecific trait variability of leaf mass per area (LMA), wood density (WD) and hydraulic traits (xylem embolism resistance) for two dominant central-Amazonian tree species, along gradients of water and light availability, while accounting for tree age and height. Intraspecific variability in hydraulic traits (e.g., P50) was high, with within-species variability comparable to the whole-community variation. Hydraulic-trait variation was modulated mostly by the hydrological environment, with higher embolism resistance of trees growing on deep water table plateaus, as compared to shallow water table valleys. Intraspecific variability of LMA and WD was mostly modulated by intrinsic factors and light. The different environmental and intrinsic drivers of variation among and within-individuals lead to an uncoupled coordination among carbon acquisition/conservation and water use traits. Our findings suggest multivariate ecological strategies driving tropical tree distributions even within species, and reflect differential within-population sensitivities along environmental gradients. Therefore, intraspecific trait variability must be considered for accurate predictions of climate-change responses of tropical forests.