|Norton, Urszula - SEPARATED POST-DOC|
|Stahl, Peter - UNIVERSITY OF WYOMING|
|Ingram, Lachlan - UNIVERSITY OF WYOMING|
Submitted to: American Society of Agronomy Abstracts
Publication Type: Proceedings
Publication Acceptance Date: May 15, 2004
Publication Date: November 15, 2004
Citation: Norton, U., Morgan, J.A., Mosier, A.R., Derner, J.D., Stahl, P., Ingram, L.J. 2004. Trace gas emissions and soil c and n transformations following moisture pulses in sagebrush: effects of invasive and native companion plant species. American Society of Agronomy Abstracts. Abstract 5328. Technical 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 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.