Implications of Global Change for Semi-Arid Rangelands
Rangeland Resources Research
2013 Annual Report
1a.Objectives (from AD-416):
Evaluate how warming and increasing atmospheric CO2 concentration affect the structure and functioning of Great Plains grasslands through their affects on primary production, N and C cycling, water relations, and plant community dynamics.
1b.Approach (from AD-416):
Stable Isoptope Lab/University of Wyoming (SILUW) and ARS will collaborate in planning and conducting cooperative global change research at the High Plains Grasslands Research Station (HPGRS) to investigate how global change influences ecosystem functioning through evaluating the combined effects of rising atmospheric CO2 and temperature on C and N cycling, plant/soil water relations, weed invasions and plant community ecology. Research will be conducted under realistic field conditions in a native, semi-arid grassland in which ambient CO2 is increased from present-day levels of 390 ppm to 600 ppm and temperatures increased 1.5/3 C day/night. These altered environmental conditions are predicted to develop in Wyoming over the second half of the century.
Collaborators at the University of Wyoming are working with ARS to increase our understanding of how plants and soils respond to global warming, rising atmospheric carbon dioxide (CO2), and altered precipitation, as part of a comprehensive research project predicting how western rangelands will respond to climate change. We are in the 8th year of the Prairie Heating and CO2 Enrichment (PHACE) experiment, being conducted at the USDA-ARS High Plains Grassland Research Station in Cheyenne, WY. Research through this cooperative agreement on the PHACE experiment focused on obtaining a more thorough understanding of below-ground global change responses through extensive sampling during the final growing season of the experiment. New sub-studies included effects of elevated CO2 and warming on.
1)root architecture and chemistry of key rangeland species;.
2)microbial carbon use efficiency and effects on nitrogen availability; rhizosphere N fixation; root crown biomass and chemistry; soil nematodes; and mycorrhizae. This work complements ongoing studies at PHACE to determine how elevated CO2 and warming influence the cycling of key resources: water, nitrogen and carbon. In addition, a sub-experiment started in FY 2012, to examine success of restoration under different climate conditions was continued. The work follows emergence and establishment of grass and forb species of different biogeographic origins across the northern and southern mixed-grass prairies in North America. Three graduate students are contributing to this research. The PHACE experimental treatments will be terminated in September 2013. Above and below ground biomass and soils will be harvested for analysis and disturbed plots will be restored. To ensure accountability of funds utilized, the ADODR and his staff hold meetings every 6 months with collaborators to discuss research and site issues; staff of both groups communicates regularly on experimental protocols, site management, and presentation of results. The group continues to coordinate on modeling and data base management efforts so the results of this work can be extrapolated by modeling projects involving project scientists and potential future collaborators.