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National Science Foundation (USA) 2009

Biotic alteration of soil hydrologic properties and feedback with vegetation dynamics in water limited ecosystems

Vegetation Water Limited


Titre  : Biotic alteration of soil hydrologic properties and feedback with vegetation dynamics in water limited ecosystems

Organismes NSF : Division of Earth Sciences (EAR)

Durée : October 1, 2009 - September 30, 2013

Heterogeneity of soil properties and associated structure exert major controls on the storage and fluxes of water through the surface soils and provide habitat and resources for life in the critical zone - that part of the terrestrial biosphere extending from the bottom of the root zone to the top of the canopy. Also, soil structure and properties are not fixed, but are altered dynamically, in part by the organisms that inhabit it. The importance of soil properties in controlling resource availability and primary production formed the basis of the ecological optimality hypothesis (Eagleson, 1978) that biological processes alter soil properties over time in such a way that increases ecosystem productivity, e.g., by increasing the permeability of fine soils, and/or increasing the retention capacity of sandy soils. This project aims to understand the role of biologic alterations of soil hydrologic properties on soil moisture fluxes and the feedback with associated vegetation dynamics in water limited ecosystems. The objective is to test the overarching hypothesis that alteration of the soil environment by inputs of soil organic matter and the development of macropores increases the access of plants to water and nutrients and thus reduces the need for plants to expend carbon to access those resources.
We will critically examine this hypothesis using a holistic ecohydrologic modeling framework, and will test model predictions of soil properties with observed field measurements in New Mexico and Arizona. The collection of chosen field sites, especially in Arizona, pairs granitic and schist-underlain catchments at three elevations representing desert shrub, oak woodland and ponderosa pine forest. Specifically, we will 1) develop understanding of biologically mediated alteration of soil properties in a small New Mexico watershed to establish a foundation for the interaction of ecohydrologic processes, 2) then incorporate biotic effects of soil properties into the CRS canopy-root-system model being developed as part of another NSF project (ATM 06-28687, PI Praveen Kumar), which has been validated in a number of humid sites, and which we now will validate using data from arid sites, including the New Mexico site, 3) generate predictions of hydrologic fluxes, vegetation dynamics and soil properties based on appropriate climate forcing and the new understanding gained, 4) validate these predictions using soil structure data and hydrologic data taken from sites located along several climo-topo-sequences, including one in the Catalina Mountains in Arizona, and 5) develop an interpretive framework using the concept of hydrologic regimes and available global data sets. The work will be conducted in partnership with the new NSF-funded Critical Zone Observatory at the University of Arizona (especially arid-land ecology specialists Travis Huxman, Scott Saleska and David Breshears).

Partenaires : Murugesu Sivapalan sivapala (Principal Investigator) Praveen Kumar (Co-Principal Investigator)

Financement : $384,244.00

Présentation (National Science Foundation)

Page publiée le 9 avril 2017, mise à jour le 7 novembre 2017