A one-dimensional model of water flow in soil-plant systems based on plant architecture

Abstract

The estimation of root water uptake and water flow in plants is crucial to quantify transpiration and hence the water exchange between land surface and atmosphere. In particular the soil water extraction by plant roots which provides the water supply of plants is a highly dynamic and non-linear process interacting with soil transport processes that are mainly determined by the natural soil variability at different scales. To better consider this root-soil interaction we extended and further developed a finite element tree hydrodynamics model based on the one-dimensional (1D) porous media equation. This is achieved by including in addition to the explicit three- dimensional (3D) architectural representation of the tree crown a corresponding 3D characterisation of the root system. This 1D xylem water flow model was then coupled to a soil water flow model derived also from the 1D porous media equation. We apply the new model to conduct sensitivity analysis of root water uptake and transpiration dynamics and compare the results to simulation results obtained by using a 3D model of soil water flow and root water uptake. Based on data from lysimeter experiments with young European beech trees (Fagus silvatica L.) is shown, that the model is able to correctly describe transpiration and soil water flow. In conclusion, compared to a fully 3D model the 1D porous media approach provides a computationally efficient alternative, able to reproduce the main mechanisms of plant hydro-dynamics including root water uptake from soil.

Species‐specific transpiration responses to intermediate disturbance in a northern hardwood forest

“…Understanding the mechanisms that shape plot level transpiration and how they influence forests' response to disturbance will help modelers eliminate errors and better capture changes to water and C fluxes as forests are shaped by natural succession and other disturbances, as well as climate and land-use change. The incorporation of advanced hydrodynamic models for hydraulic functional-type-specific stomatal parameterization (e.g., Finite Elements Tree-Crown Hydrodynamic model (FETCH) [Bohrer et al, 2005] or Expert-N [Janott et al, 2011]) could help resolve these differences and improve the quality of simulated ET by land surface models, in general, and particularly in forests undergoing intermediate disturbance. …”

“…This finding supported our fourth hypothesis, that predisturbance and postdisturbance transpiration are distinct in such a manner that adjustment on the basis of LAI alone is not sufficient to adequately represent disturbance in land surface models. Additionally, the PM model residual analysis demonstrated significant interactions of soil water potential with species and size, and analysis of hysteresis revealed significant interactions between soil water potential and tree size indicating that improving the representation of the mechanisms by which soil moisture affects stomatal conductance, and species or hydraulic functional-type parameterization could improve model performance [Bohrer et al, 2005;Grant et al, 2006;Janott et al, 2011;Weng and Luo, 2008]. There was a significant decline in transpiration postdisturbance, beyond the extent that is predicted by the differences in atmospheric forcings and LAI, and the hysteresis analysis revealed important differences between species behavior in disturbed and undisturbed plots.…”

Contrasting Hydraulic Strategies during Dry Soil Conditions in Quercus rubra and Acer rubrum in a Sandy Site in Michigan

“…Current land-surface and ecosystem models will, therefore, not be able to predict such interactions between hydraulic strategy, forest composition and climate change. Species-specific stomatal conductance parameterizations (e.g., [42,43]) and/or tree-level hydrodynamic models using mechanistic water transport principles or parameterization for tree-level water storage and multiple resistance levels, such as the Finite-Elements Tree-Crown Hydrodynamics (FETCH) [44], SPA [45] and Expert-N [46] may be able to fulfill this need.…”

Rootstock control of scion response to water stress in grapevine

“…However, the effect of rootstock/scion interaction on plant adaptation to stress is still very much debated (Gambetta et al, 2012). Since drought conditions affect water transport from the soil through the plant into the atmosphere in a soil-plant-air continuum that is interconnected by a continuous film of water, measuring its influence on plant water transport requires considering both water extraction at the soil-root interface and water release at the leaf-air interface (Janott et al, 2011). Although the key role played by both rootstock and scion is acknowledged their relative contribution and differences obtained by specific combination of genotypes require some further analysis.…”