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Development of a Novel Hydrodynamic Approach for Modeling Whole-plant Transpiration

Mirfenderesgi, Golnazalsadat
http://rave.ohiolink.edu/etdc/view?acc_num=osu1502375927541919

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Civil Engineering.
The Finite-difference Ecosystem-scale Tree-Crown Hydrodynamics model (FETCH2) is a novel tree-scale hydrodynamic model of transpiration. The FETCH2 model employs a finite difference numerical methodology and a simplified single-beam conduit system and simulates water flow through the tree as a continuum of porous media conduits. It explicitly resolves xylem water potential throughout the tree’s vertical extent (from root to shoot). Empirical equations relate water potential within the stem to stomatal conductance of the leaves at each height throughout the crown. While highly simplified, this approach brings additional realism to the simulation of transpiration by linking stomatal responses to stem water potential rather than directly to soil moisture, as is currently the case in the majority of land-surface models. FETCH2 accounts for plant hydraulic traits, such as the degree of anisohydric/isohydric response of stomata, maximal xylem conductivity, vertical distribution of leaf area, rooting depth, and maximal and minimal stem water content. We used FETCH2 along with sap flow and eddy covariance data sets to conduct an analysis of the inter-genera variation of hydraulic strategies and their effects on diurnal and seasonal transpiration dynamics. We define these strategies through the parameters that describe the genus-level transpiration and xylem conductivity responses to changes in stem water potential. Using a virtual experiment, we showed that the model was able to capture the effect of hydraulic strategies such as isohydric/anisohydric behavior on stomatal conductance under different soil-water availability conditions. Our evaluation revealed that FETCH2 considerably improved the simulation of ecosystem transpiration and latent heat flux than more conventional models. Whole-plant hydraulic performance depends on the integrated function of complexes of traits, such as embolism resistance and xylem anatomy, stomatal closure mechanisms, hydraulic architecture, and root properties. The diversity of such traits produces a wide range of response strategies to both short-term variation of environmental conditions and long-term changes to climate and hydrological cycles which affect water availability. FETCH2 resolves plant functional traits at the root, stem and leaf levels and simulates the integrated plant-level transpiration, provided hydraulic traits and environmental forcing. This framework may be helpful in studying the influence of each suits of plant hydraulic traits independently and assess how the different trait groups interact with each other to form viable hydraulic strategies for different environmental conditions. We define a multi-dimensional hydraulic “strategy space” by considering a broad continuum of hydraulic traits at each of the leaf, stem, and root levels, and test the consequences of different strategies under a range of environmental conditions in a research forest in Northern Michigan, USA. We evaluated the degree to which simulated trees suffer hydraulic failure due to cavitation resulting in loss of xylem conductivity or carbon starvation through leaf-water-potential-driven reduction of stomatal conductance. Finally we concluded that incorporation of the plant functional traits into FETCH2 allows us to simulate the dissimilar water use patterns of species with contrasting hydraulic strategies. This will improve predictions of transpiration, growth, and mortality, and consequently simulations of the surface energy budget and the global carbon and water balances.
Gil Bohrer (Advisor)
Peter S Curtis (Committee Member)
Ethan Kubatko (Committee Member)
Andrew A May (Committee Member)
183 p.
Environmental Engineering; Hydrology

Recommended Citations

Citations

  • Mirfenderesgi, G. (2017). Development of a Novel Hydrodynamic Approach for Modeling Whole-plant Transpiration [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502375927541919

    APA Style (7th edition)

  • Mirfenderesgi, Golnazalsadat. Development of a Novel Hydrodynamic Approach for Modeling Whole-plant Transpiration . 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1502375927541919.

    MLA Style (8th edition)

  • Mirfenderesgi, Golnazalsadat. "Development of a Novel Hydrodynamic Approach for Modeling Whole-plant Transpiration ." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502375927541919

    Chicago Manual of Style (17th edition)

osu1502375927541919
343
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This open access ETD is published by The Ohio State University and OhioLINK.