The trait-rate linkage: How well do structural and hydraulic traits predict interspecific differences in response to drought?
Abstract
In species-rich and structurally complex ecosystems such as tropical forests, coexisting species exhibit a wide range of responses to drought. Droughts can cause interspecific divergence in growth, mortality, and thus fitness, at longer timescales. Quantifying real-time physiological response to drought and screening for traits predictive of those responses is critical for a mechanistic understanding of how such fitness differences ensue. To address this challenge, we collocated in-situ measurements of tree hydraulic function (leaf water potential and xylem sap flux) along with rigorous quantification of plant functional traits in four tropical forests in Central and South America experiencing the same climatically driven drought (the 2015-2016 El Niño-Southern Oscillation). We found a broad range of hydraulic responses to drought along the iso-to-anisohydric continuum, with water flux responses ranging from steady state to near-complete cessation of sap flux during drought. We tested and found that: 1) leaf phenological habit is a first-order predictor of sap flux drought sensitivity, 2) sap flux sensitivity to soil moisture increases with increasing degrees of isohydry (i.e., water potential and fluxes are causally linked), 3) some, but not all hydraulic traits predict where species align along a functional response continuum of sap flux responses or iso-aniso hydry, and 4) tree size is important modulator of these responses. We highlight how these responses provide critical benchmarks for coupled plant hydraulic-demographic vegetation models, such as FATES-Hydro, for predicting forest responses to droughts.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B51A..06C
- Keywords:
-
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0466 Modeling;
- BIOGEOSCIENCES;
- 0476 Plant ecology;
- BIOGEOSCIENCES