HR: 0800h
AN: B51C-0963 [Abstracts]
TI: Trace Gas Emissions and Soil C and N Transformations Following Moisture Pulses in Sagebrush: Effects of
Invasive and Native Companion Plant Species
AU: * Norton, U
EM: urszula@goldrush.com
AF: USDA/ARS High Plains Grassland Research Station, 8216 Hildreth Road, Cheyenn, WY 82009
United States
AU: Morgan, J A
EM: Jack.Morgan@npa.ars.usda.gov
AF: USDA/ARS High Plains Grassland Research Station, 8216 Hildreth Road, Cheyenn, WY 82009
United States
AU: Mosier, A R
EM: arvin.mosier@ars.usda.gov
AF: USDA/ARS Natural Resources Research Center, 2150 Centre Avenue, Bldg. D. Suite 100, Ft. Collins, CO
80526
United States
AU: Derner, J D
EM: Justin.Derner@npa.ars.usda.gov
AF: USDA/ARS High Plains Grassland Research Station, 8216 Hildreth Road, Cheyenn, WY 82009
United States
AB:
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 soil 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.
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting