PNNL

Abstract

Plant functional traits regulate ecosystem carbon uptake, evapotranspiration and tree growth in response to climate change, yet data from tropical forests are limited. As tree mortality rates appear to be increasing in these vast and hyperdiverse forests, we assessed the relationships between plant functional traits and growth and mortality for common co-occurring trees in the Central Amazon. Seventeen trees with similar sizes but a range in wood density were assessed for 27 different functional parameters, including whole tree architecture, stem xylem anatomical and hydraulic traits and leaf traits. These traits of the individual trees were related to stand-level growth and mortality rates collected over 30 years from nearby permanent inventory plots. Wood density was inversely proportional to leaf size, foliar base cations, stem water content and sapwood proportion, and directly proportional to foliar nitrogen:phosphorus, in agreement with the fast-slow plant economics spectrum. Individuals with lower wood density had more acquisitive characteristics with greater hydraulic capacity and foliar nutrient concentrations, correlating with greater growth and mortality rates. Understanding the relationships among tree functional traits, and correlations to mortality provide insight into how tropical forests may respond to future stress from climate change.