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The Prairie Heating and Carbon Dioxide Enrichment (PHACE) experiment was created in 2006 to learn how future environmental conditions will influence mixed-grass prairie. Mixed-grass prairie is the largest remaining grassland ecosystem in North America, and is integral to both agricultural productivity and conservation of biological diversity in the western United States.

PHACE Sampling

Click here for a video describing the experiment and early results.




Augustine DJ, DM Blumenthal, TL Springer, DR LeCain, SA Gunter, JD Derner. 2018. Elevated CO2 induces substantial and persistent declines in forage digestibility and protein content irrespective of warming in mixed-grass prairie. Ecological Applications 28:721-735.

Blumenthal DM, KE Mueller, JA Kray, DR LeCain, E Pendall, S Duke, TJ Zelikova, FA Dijkstra, DG Williams, JA Morgan. Warming and elevated CO2 interact to alter seasonality and reduce variability of soil water in a semi-arid grassland. In press, Ecosystems:

Sorokin, Y, TJ Zelikova, D Blumenthal, DG Williams, E Pendall.  2017. Seasonally contrasting responses of evapotranspiration to warming and elevated CO2 in a semi-arid grassland. Ecohydrology DOI10.1002/eco.1880.

Nelson, L, DM Blumenthal, DG Williams, E Pendall. 2017. Digging into the roots of belowground carbon cycling following seven years of Prairie Heating and CO2 Enrichment (PHACE), Wyoming, USASoil Biology and Biogeochemistry 115:169-177.

Hines, J, S Pabst, KE Mueller, DM Blumenthal, S Cesarz, N Eisenhauer. 2017. Soil-mediated effects of global change on plants communities depend on plant growth form. In press, Ecosphere 8(11):e01996. 10.1002/ecs2.1996

Blumenthal, D.M., J.A. Kray, W. Ortmans, L.H. Ziska, E. Pendall. Cheatgrass is favored by warming but not CO2 enrichment in a semi-arid grassland.  Global Change Biology, doi: 10.1111/gcb.13278

Ryan, E., K. Ogle, D. Peltier, A.P. Walker, M.G. De Kauwe, B.E. Medlyn, D.G. Williams, W. Parton, S. Asao, B. Guenet, A.B. Harper, X. Lu, K.A. Luus, S. Zaehle, S. Shu, C. Werner, J. Xia, E. Pendall (2017). Gross primary production responses to warming, elevated CO2, and irrigation: quantifying the drivers of ecosystem physiology in a semiarid grassland. Global Change Biology 23:3092-3106, doi: 10.1111/gcb.13602

Derner, J.D., Briske, D., Reeves, M., Brown-Brandl, T.M., Meehan, M., Blumenthal, D.M., Travis, W., Augustine, D.J., Wilmer, H.N., Scasta, J. 2017. Vulnerability of grazing and confined livestock in the Northern Great Plains to projected mid- and late- 21st century climate. Climatic Change. DOI:10.1007/s10584-017-2029-6.

Mueller, K. E., D. M. Blumenthal, E. Pendall, Y. Carrillo, F. A. Dijkstra, D. G. Williams, R. F. Follett and J. A. Morgan. 2016. Impacts of warming and elevated CO2 on a semi-arid grassland are non-additive, shift with precipitation, and reverse over time. Ecology Letters, 19: 956–966.

Click here for a complete list of publications.



Identifying plants

Our objective is to predict the consequences of global change for plant and microbial communities and ecosystem processes. Responses of particular interest include plant metabolism, production, quality, diversity and community composition (invasive species, functional groups); microbial community composition and function; greenhouse gas sequestration and emission; and cycling of water, nitrogen and phosphorus. Read more... 



The core PHACE experiment includes five replications of the following treatments: (1) control (ambient conditions), (2) elevated CO2, (3) warming, and (4) elevated CO2 plus warming. Elevated CO2 treatments use free air CO2 enrichment technology to increase atmospheric CO2 to 600 ppm. Warming treatments use ceramic heaters to increase temperatures 1.5o C during the day and 3o C at night. Additional treatments use irrigation to separate water-mediated effects from direct effects of elevated CO2, and to learn how the seasonality of precipitation influences mixed-grass prairie. Read more about the experimental design...

Arial photo of PHACE



Installing frame

In 2005-2006, below-ground infrastructure for the PHACE plots was put in place, including hydrologic isolation of soils within plots, and installation of tubes for monitoring soil moisture and plant roots. The elevated CO2 and warming treatments began in spring 2006 and spring 2007, respectively. These treatments have been very effective in controlling environmental conditions. See Morgan et al. 2011, and associated supplementary material for details. See images of PHACE construction...




This project is a collaboration between the United States Department of Agriculture-Agricultural Research Service, the University of Wyoming, Colorado State University, the University of Sydney, Arizona State University, and the Institute for BioMeteorology (CNR, Italia). See a full list of researchers here.





Funding for this work is provided by the US Department of Agriculture-Agricultural Research Service Climate Change, Soils & Emissions Program, the US Department of Agriculture-Cooperative State Research, Education, and Extension Service Soil Processes Program (grant no. 2008-35107-18655), the US Department of Energy's Office of Science (Biological and Environmental Research) through the Western Regional Center of the National Institute for Climatic Change Research at Northern Arizona University, and the National Science Foundation (DEB no. 1021559).


Dr. Dana Blumenthal
Telephone: 970-492-7122
Fax: 970-492-7160
Postal address: 1701 Centre Ave, Fort Collins, CO 80526