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United States Department of Agriculture (USDA) 2007

FUNCTIONAL CONSTRAINTS IN MICROSCALE CARBON AND NITROGEN CYCLING BY BIOLOGICAL SOIL CRUSTS

Carbon Nitrogen Biological Soil Crusts

United States Department of Agriculture (USDA) Research, Education & Economics Information System (REEIS)

Titre : FUNCTIONAL CONSTRAINTS IN MICROSCALE CARBON AND NITROGEN CYCLING BY BIOLOGICAL SOIL CRUSTS

Identification : ARZR-2007-03214

Pays : Etats Unis

Durée : Aug 1, 2007 à Jul 31, 2011

Domaine : Soil, Plant, Water, Nutrient Relationships ; Conservation of Biological Diversity ; Management of Range Resources ; Desert and semidesert shrub land and shinnery ; Rangelands, other ; Pinyon-juniper ;

Partenaire : ARIZONA STATE UNIVERSITY TEMPE,AZ

Objectifs
During the tenure of this grant we aim at attaining 4 major objectives. First, to determine the extent, over climatic provinces in Western rangelands, of a break in the N cycle, characteristic of Colorado Plateau crusts, and upon which intense C and N exports heavily hinge. This will allow to scale up predictive models to the continental scale. Second, to determine the precise biological agency of reactions in the biogeochemical pathways of nitrogen. Establishing this link between microbial community structure and function will improve our ability to predict functional changes that have to do with climatically driven or anthropogenically mediated variations in organismal distribution. Third, to determine the precise biological agency of key steps in organic carbon mineralization pathways, as they relate to ecosystem services in fertility and soil erodibility. Fourth, to determine the influence of pore-clogging by polymeric carbon on the hydrological character of crusts and their mode and range of C and N export.

Descriptif
We will use a combination of microbiological, micro-chemical, molecular and soil science techniques, to attain a mechanistic and predictive understanding of functional clockwork of soil crust communities. Standard biogeochemical incubation techniques will be used to determine rates of N and C transformations in the field. Cultivation independent molecular analyses, such as stable isotope probing will be combined with microscale determinations of geochemical transformations of relevant analytes, in order to establish the precise agency and location of individual microbial types. Biochemical analyses coupled to rheological determinations will be used in the assessment of hydrological effects of soil crusts.

Présentation : USDA

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