Trait coordination reveals the fast–slow plant economics spectrum along the vertical canopy profile in central Amazonian forests

Abstract Understanding how environmental drivers affect tree functioning is essential to improve predictions of tropical forests' response to climate change. While functional traits directly influence tree performance, our understanding of how canopy environments shape their coordination and variation along the vertical forest profile remains limited. We quantified annual growth rates in terms of above‐ground biomass (AGB), the maximum efficiency of photosystem II (Fv/Fm) and six tree functional traits related to water transport (xylem density and Huber value), leaf morphology (leaf size, angle and stomatal density) and photosynthesis (specific leaf area) along the vertical forest profile in an old‐growth central Amazonian forest. To investigate the influence of canopy environments and ontogenetic stages on the variation of these traits, we divided the forest into three vertical strata defined by height from the ground (S1: 0–20 m; S2: 20–40 m; S3: >40 m).