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United States Department of Agriculture (USDA) 2002


Carbon Cool Desert Rangelands

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


Identification : UTA00925

Pays : Etats Unis

Durée : Jul 1, 2002 à Jun 30, 2008

Mots clés : bromus tectorum agropyron desertorum juniperus osteosperma rangelands carbon dioxide atmosphere eddies covariance carbon carbon cycle storage cool deserts artemisia tridentata desert plants range management weather plant communities plant ecology annual grasses perennial grasses shrubs trees sequestrants seasonal variation plant ecosystems plant water relations water availability


Three objectives will be addressed in this work. The work will be based on comparisons among four ubiquitous Great Basin plant communities dominated by four different life forms (annual grass, perennial grass, shrub and tree). 1) Assess the seasonal and annual differences in carbon sequestering and water use among the four plant communities ; 2) Assess the importance of the timing of water availability on carbon uptake and net ecosystem carbon exchange within the four different communities ; and 3) Assess how conversion of rangeland to different vegetation communities will alter net ecosystem carbon exchange and affect the ability to manage these rangelands in line with the Kyoto Protocol.

Eddy flux measurements of CO2 and water vapor will be used to determine seasonal patterns for these gasses between the canopy and atmosphere, and to calculate annual net ecosystem exchange (NEE) for each community (Objective 1). Patterns of carbon sequestering and water use from these eddy flux measurements will be evaluated in response to pulses of resources (water, nutrients) during spring, summer and fall (Objective 2). New and existing measurements will be used to parameterize a plant-community level simulation model of CO2 and water fluxes to better understand the role of plants and microbial community in the dynamics of these gasses. This bottom up modeling approach is designed to provide more mechanistic description of seasonal dynamics of CO2 and water vapor and annual NEE. Eddy-flux measurements and simulation results will be used to compare CO2 and water vapor NEE among the four communities and assess how management for specific communities might affect regional NEE for CO2 (Objective 3). These simulations will permit assessing differences among years for temperature and rainfall, and evaluating potential changes in climate (increased temperatures, more summer "monsoon" rainfall).

Présentation : USDA

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