Journal Article

Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics

Baraloto, Christopher, Pacific Northwest National Laboratory (PNNL), Smithsonian Conservation Biology Institute, Wolfe, Brett, SILVA (SILVA) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Université de Lorraine (UL), Asbjornsen, Heidi, Swenson, Nathan, Los Alamos National Laboratory (LANL), Wei, Liang, Stahl, Clement, Czech University of Life Sciences Prague (CZU), Aparecido, Luiza Maria T, School of Geosciences [Edinburgh] ; The University of Edinburgh, Grossiord, Charlotte, Miller, Gretchen, M, Chambers, Jeffrey, Trotsiuk, Volodymyr, ANR-10-LABX-0025,CEBA,CEnter of the study of Biodiversity in Amazonia, Christoffersen, Bradley, Xu, Chonggang, Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD

2019

Overview

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.

• Publisher: Springer Verlag,CCSD,Springer Science + Business Media,Springer Berlin Heidelberg,Springer,Springer Nature B.V
• Subject: Annual precipitation / atmospheric precipitation / Biodiversity / Biodiversity and Ecology / Biomedical and Life Sciences / Botanics / Climate / Climate change / Climate variability / Drought / Droughts / Ecology / Ecology, environment / Economics / Ecosystems / environmental factors / ENVIRONMENTAL SCIENCES / Evaporation / evaporative demand / evapotranspiration / Fluctuations / Flux / Forests / Global warming / Hydrologic cycle / Hydrological cycle / Hydrology/Water Resources / Laws, regulations and rules / leaf mass / Life Sciences / Neotropics / PHYSIOLOGICAL ECOLOGY – ORIGINAL RESEARCH / plant functional traits / plant response / Plant Sciences / Plant species / Plant Transpiration / Power plants / Precipitation / sap flow / Specific gravity / Systematics, Phylogenetics and taxonomy / Transpiration / Trees / Tropical climate / Tropical environment / Tropical environments / Tropical forests / tropical plants / tropics / Vapor Pressure / vapor pressure deficit / Vapour pressure / Vegetal Biology / Water / Water exchange / Water use / Wood
• ISBN: 0004937757000