Hydraulic architecture explains species moisture dependency but not mortality rates across a tropical rainfall gradient

作者：Alexandria L. Pivovaroff, Brett T. Wolfe, Nate G. McDowell, Bradley Christoffersen, Stuart J. Davies, L. Turin Dickman, Charlotte Grossiord, Riley Leff, Alistair Rogers, Shawn Serbin, S. Joseph Wright‬, Jin Wu, Chonggang Xu, Jeffrey Q. Chambers · 发表于：Biotropica · 年份：2021 · DOI：10.1111/btp.12964 · 被引用次数：17 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Forest ecology and management

Abstract Intensified droughts are affecting tropical forests across the globe. However, the underlying mechanisms of tree drought response and mortality are poorly understood. Hydraulic traits and especially hydraulic safety margins (HSMs), that is, the extent to which plants buffer themselves from thresholds of water stress, provide insights into species‐specific drought vulnerability. We investigated hydraulic traits during an intense drought triggered by the 2015–2016 El Niño on 27 canopy tree species across three tropical forest sites with differing precipitation. We capitalized on the drought event as a time when plant water status might approach or exceed thresholds of water stress. We investigated the degree to which these traits varied across the rainfall gradient, as well as relationships among hydraulic traits and species‐specific optimal moisture and mortality rates. There were no differences among sites for any measured trait. There was strong coordination among traits, with a network analysis revealing two major groups of coordinated traits. In one group, there were water potentials, turgor loss point, sapwood capacitance and density, HSMs, and mortality rate. In the second group, there was leaf mass per area, leaf dry matter content, hydraulic architecture (leaf area to sapwood area ratio), and species‐specific optimal moisture. These results demonstrated that while species with greater safety from turgor loss had lower mortality rates, hydraulic architecture wa...