FETCH3: A Tree-Level Hydrodynamic Modeling Approach for Examining
Species-Specific Stomatal Regulation at AmeriFlux Sites
Abstract
Improving the representation of plant hydraulic behavior in vegetation
and land-surface models is critical for improving our predictions of the
impacts of drought stress on ecosystem carbon and water fluxes.
Species-specific hydraulic traits play an important role in determining
the response of ecosystem carbon and water fluxes to water stress. Here,
we present plans for the development of the Finite-difference
Ecosystem-scale Tree Crown Hydrodynamics model version 3 (FETCH3), a
tree hydrodynamic model which builds upon its predecessors FETCH and
FETCH2. FETCH3 simulates water transport through the soil, roots, and
xylem as flow through porous media. The model resolves water potentials
along the vertical dimension, and stomatal response is linked to xylem
water potential. The tree-level model is scaled to the plot scale based
on the species composition and canopy structure of the plot, allowing
the model to be validated using both tree-level observations (sap flux)
and plot-level observations (eddy covariance). We will collect data from
multiple sites that have both sap flux and eddy covariance measurements
for analysis. The Predictive Ecosystem Analyzer (PEcAn) will be used for
optimization of the hydraulic parameters in FETCH3 for different plant
types in multiple sites. We plan to use this new modeling framework to
examine the interactions among water stress, species-specific hydraulic
strategies, and stomatal regulation across different species and
ecosystem types.