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

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. In this work, 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. Thesemore » results demonstrated that while species with greater safety from turgor loss had lower mortality rates, hydraulic architecture was the only trait that explained species’ moisture dependency. Species with a greater leaf area to sapwood area ratio were associated with drier sites and reduced their transpirational demand during the dry season via deciduousness.« less

Authors:

Pivovaroff, Alexandria L.  ^[1];

• Search DOE PAGES for author "Pivovaroff, Alexandria L."
• Search DOE PAGES for ORCID "0000-0002-3104-1900"

Wolfe, Brett T. ^[2]; McDowell, Nate ^[1]; Christoffersen, Bradley ^[3]; Davies, Stuart ^[4]; Dickman, L. Turin  ^[5];

• Search DOE PAGES for author "Dickman, L. Turin"
• Search DOE PAGES for ORCID "0000-0003-3876-7058"

Grossiord, Charlotte ^[6]; Leff, Riley T. ^[1]; Rogers, Alistair  ^[7];

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• Search DOE PAGES for ORCID "0000-0001-9262-7430"

Serbin, Shawn P. ^[7]; Wright, S. Joseph  ^[4];

• Search DOE PAGES for author "Wright, S. Joseph"
• Search DOE PAGES for ORCID "0000-0003-4260-5676"

Wu, Jin ^[8]; Xu, Chonggang  ^[5];

• Search DOE PAGES for author "Xu, Chonggang"
• Search DOE PAGES for ORCID "0000-0002-0937-5744"

Chambers, Jeffrey Q. ^[9]

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+ Show Author Affiliations

1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. Smithsonian Tropical Research Institute, Balboa (Republic of Panama); ; Louisiana State Univ., Baton Rouge, LA (United States)
3. University of Texas Rio Grande Valley, Brownsville, TX (United States)
4. Smithsonian Tropical Research Institute, Balboa (Republic of Panama)
5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
6. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne (Switzerland); Ecole Polytechnique Federale Lausanne (Switzerland)
7. Brookhaven National Lab. (BNL), Upton, NY (United States)
8. Brookhaven National Lab. (BNL), Upton, NY (United States); Univ. of Hong Kong (Hong Kong)
9. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

Sun Jun 13 00:00:00 EDT 2021

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); Swiss National Science Foundation (SNF); USDA; National Institute of Food and Agriculture (NIFA); National Science Foundation (NSF); Forest Global Earth Observatory; Smithsonian Tropical Research Institute; John D. and Catherine T. MacArthur Foundation; Mellon Foundation; Small World Institute Fund

OSTI Identifier:

1804377

Alternate Identifier(s):

OSTI ID: 1773128

Report Number(s):

LA-UR-21-22555; BNL-221193-2021-JAAM
Journal ID: ISSN 0006-3606

Grant/Contract Number:  

89233218CNA000001; SC0012704; 1046113; DEB-00753102; DEB-0129874; DEB-0346488; DEB-0425651; DEB-0640386; DEB-9615226; DEB-9909347

Resource Type:

Accepted Manuscript

Journal Name:

Biotropica

Additional Journal Information:

Journal Volume: 53; Journal Issue: 4; Journal ID: ISSN 0006-3606

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; biological science; earth sciences; drought; El Niño; hydraulic safety margins; leaf mass per area; sapwood capacitance; tropical forest; turgor loss point; water potential; El Nino