Trace Gas Emissions, and Soil C and N Transformations Following Moisture Pulses in High Desert Community: Differences between Invasive and Native Plant Species. (5328)
Authors:
U. Norton* - USDA ARS
A.R. Mosier - USDA ARS, Ft. Collins CO P.D. Stahl - Univ. of Wyoming, Laramie WY J.D. Derner - USDA ARS, Cheyenne WY J.A. Morgan - USDA ARS, Ft. Collins CO
Abstract:
Simulating water pulses is an important tool for understanding biogeochemical processes in semi arid environments. Global change triggered shifts in plant species composition exert significant control over belowground C and N transformations. They also affect the ecosystem resiliency and its ability to withstand exotic weed invasion. We monitored effects of water additions on trace gas emissions and soil C and N in sagebrush soils, both canopy and shrub interspace, on sites dominated by either native bunchgrass, western wheatgrass, or an exotic annual, cheatgrass. Our results indicate that long-term cheatgrass establishment affects not only soil under its own thatch, but also soil under shrubs within cheatgrass stand. Overall, soil total N and total organic C on cheatgrass sites were lower than these of western wheatgrass. Trace gas measurements of non-wetted soils showed greater N2O and smaller CH4 fluxes compared to western wheatgrass sites. Upon water pulse, cheatgrass soils demonstrated greater CO2 production rates, relative to pre-wet conditions, greater N2O flux per unit soil total N, and more rapid microbial biomass C and dissolved organic C response compared to western wheatgrass. Possible mechanisms include faster turnover of microbial biomass and greater nitrification potential of
cheatgrass soils.
Speaker Information: Urszula Norton, USDA ARS, High Plains Grassland Research Station 8209 Hildreth Road, Cheyenne, WY 82009; Phone: (307) 772-2433 x 126; E-mail: [email protected]
Session Information: Monday, November 1, 2004, 1:00 PM-3:00 PM Presentation Start: 1:00 PM (Poster Board Number: 2818) Keywords: trace gas; soil C and N; cheatgrass; water pulse