Collaborative research: Restricted plasticity of canopy stomatal conductance: A conceptual basis for simpler models of forest transpiration

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0405306MacKayOur proposed project has significant intellectual merit because it explicitly addresses two keyproblems facing hydrology. The first problem concerns the opposing views of stomatal control ofwater fluxes, with one perspective assuming carbon assimilation control, and the other assumingan environmental control. Our conceptual model combines both of these perspectives in a unifiedmechanistic framework that combines both assimilation and water potential controls ontranspiration. The second problem addressed by our conceptual model is the tendency towardsfavoring complex and often mathematically ill-posed canopy models over simpler, verifiableones. We explicitly address this fundamental issue in hydrologic modeling by using a novel,object-oriented canopy model that can flexibly adjust its structure and mechanisms to the data itis provided. By adjusting model complexity spatially we will gain deep insights on speciesplasticity and restrictions thereof across spatial gradients, thus providing a rigorous approach totesting our conceptual model within our study site in northern Wisconsin.The knowledge gained from our proposed research has broad implications for land surfacemodeling efforts seeking to generate accurate predictions of global change effects on watercycling. By developing our conceptual model we will be able to provide a relatively simple, buttransportable and scientifically defensible model. Such models are essential foundations for thecreation and implementation of credible state, federal and international policies aimed atmitigating or otherwise adjusting to the consequences of anticipated global change. Theeducational emphasis of this project is multi-faceted. First, we will seek additional funding andother means of supporting, advising and training an integrated team of undergraduate studentsfrom the economically disadvantaged region of Northern Wisconsin, using this project as theprincipal context for their education in Forest Ecology at UW-Madison. Also, in connection withthe NSF Research Collaboration Network project entitled "Chequamegon Ecosystem-Atmosphere Study," for which Mackay is a core project participant, we will hold a nationallyadvertised workshop on multi-scale canopy flux measurements and modeling. The PIs willcontinue to recruit and hire minorities and other underrepresented students in our respectivefields.