Poster Title	Exploring interactions between soil-plant hydrodynamics and vegetation demography within ELM-FATES
First Author	Jennifer Holm
Topic	BGC, Land/Energy model development, E3SM evaluation
Affiliation	Land/Energy NGD; ELM-FATES; LBNL
Link to document

Title

Exploring interactions between soil-plant hydrodynamics and vegetation demography within ELM-FATES

Authors

Jennifer Holm (LBNL), William Riley (Unlicensed) (LBNL), Ryan Knox (LBNL), Daniel Ricciuto (ORNL), Khachik Sargsyan (Sandia)

Abstract

High-latitude forests are known to be vulnerable to permafrost thawing, increased disturbances, and shift in forest cover type to potentially more deciduous as a result of climatic warming. These forest changes can have strong feedbacks to regional and global climate, water and carbon cycling, and carbon sink strengths. For example, soil inundation with thawing can lead to decreases in ecosystem productivity in boreal forests, and strongly influences the vegetation composition via plant competition and survival during wetland expansion, shifting ecosystems into carbon sinks. To be able to accurately predict and model these complex ecological processes we are using a new demographic vegetation model (FATES; Functionally-Assembled Terrestrial Ecosystem Simulator) that is coupled to ELMv1, the land surface model in the global Earth System Model - E3SM. A new continuous soil-root-plant plant hydraulic scheme has been included within FATES, allowing dynamic plant mortality and growth from water stress and changes in subsurface drainage. We use FATES-Hydro to quantify the impacts on water cycling (e.g., water use efficiency, latent heat, soil water storage) and carbon fluxes (NEE) under transitions between boreal evergreen and deciduous trees, and upland and wetland habitats.

As a first step to evaluate climate warming-vegetation interactions, we performed a parameter sensitivity analysis using a Latin hypercube approach to sample the parameter space of 15 main vegetation parameters, over a 100-member ensemble run. In addition, leaf and wood allometry parameters for boreal plants have been updated based on observational data from the BAAD Database. Initial tests of FATES at a boreal Alaska site found strong biomass and plant mortality sensitivity to soil moisture availability in deciduous trees and shrubs, but not evergreen (i.e., spruce) trees. Further testing of the newly developed plant hydraulic scheme (FATES-Hydro) allows us to simulate the impacts of warming and soil moisture changes on boreal evergreen and deciduous tree cover, and ultimately shifts in carbon source vs. sink.

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