|Milchunas, Daniel - COLORADO STATE UNIV|
|Pendall, Elise - UNIVERSITY OF WYOMING|
|Parton, William - COLORADO STATE UNIV|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2006
Publication Date: February 6, 2007
Citation: Morgan, J.A., Milchunas, D., Pendall, E., Parton, W.J., Derner, J.D. 2007. Enhanced forage production resulting from rising atmospheric carbon dioxide may not be good news for rangelands. Fourth USDA Greenhouse Gas conference. Baltimore, MD. February, 2007. CDROM. Technical Abstract: Significant progress has been made in understanding the separate effects of elevated atmospheric CO2 and warming on native grassland ecology, although little information is available on the combined influences of these two important global change factors. Further, despite speculation concerning the potential effect of global change on weed invasion, few experiments have specifically addressed this question. Previous research conducted on shortgrass steppe indicates that both elevated CO2 and warming can induce important changes in nutrient cycling, water relations and species shifts. However, the links between biogeochemical responses to global change and species shifts have yet to be convincingly established. The new multi-factor High Plains Global Change Experiment is a field experiment for subjecting a northern mixed-grass prairie, with and without introduced weeds, to elevated CO2 and warming. Herein we report on the design, operation and performance of this new experiment which combines Free Air CO2 Enrichment (FACE) technology with a newly-designed ceramic heater system. A novel feature of this project is a feed-back temperature control system which allows excellent control of separate day/night canopy temperatures. DAYCENT model projections of the experimental conditions suggest that increased CO2 (ambient plus 200 'l l-1 CO2) and temperature (ambient plus 1.5 °C daytime and 3.0 °C nighttime) treatments for the next five years will alter soil water and nutrient cycling, imposing strong indirect effects on ecosystem productivity. We expect that interactions among drivers plus feedback effects will dominate ecosystem responses of this native, semi-arid grassland to combined warming and CO2 enrichment.