Local and nonlocal topographic controls on landscape ecohydrology

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The overarching goal of this research is the statistical quantification of the relative importance of local vs. nonlocal geomorphologic controls on landscape metabolism in complex topographies differing in hydroclimatic forcing and geologic age, and the quantification of their degree of nonlinearity and threshold effects. The research is guided by the hypothesis that the relative importance of local and nonlocal topographic effects on landscape metabolism shifts according to hydroclimatic conditions. Moreover, the conditions for such shifts change with the landscape age and the related surface smoothing processes, which modify the relative importance of tails vs. mode of the distributions of topographic properties (aspect, slope, contributing area, etc.). The research will provide a theoretical description of landscapes using statistical field theories, and analyze local and nonlocal controls on CN cycles (radiation, soil features, vegetation cover, and soil moisture dynamics). Finally it will couple local and nonlocal controls to biogeochemical dynamics, extending previous stochastic soil moisture and biogeochemistry models to include spatially random components. The fundamental environmental processes controlling vegetation and soil nutrient dynamics and the related carbon and nitrogen fluxes (also called landscape metabolism) are related to the land energy and water budgets. This research analyzes such processes and quantifies how they differ in space and time, as a function of the local and nonlocal landscape features, such as slope, orientation and drainage area. This proposal will pave the way to a more fundamental understanding of the laws for carbon, nitrogen, and water fluxes at different spatial scales over complex landscapes such as river basins and mountain regions. The project will be instrumental for the quantification of the land surface conditions for global climate models, especially in the contexts of variation in climatic and land-use scenarios.