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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #113823
Title: MEASURING CARBON FLUXES OVER NORTHERN GREAT PLAINS RANGELANDS

Author
item Haferkamp, Marshall
item Heitschmidt, Rodney

Submitted to: Research Update for Fort Keogh Livestock and Range Research Laboratory
Publication Type: Other
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Citation: HAFERKAMP, M.R., HEITSCHMIDT, R.K. MEASURING CARBON FLUXES OVER NORTHERN GREAT PLAINS RANGELANDS. RESEARCH UPDATE FOR FORT KEOGH LIVESTOCK AND RANGE RESEARCH LABORATORY. p. A.2.1-2. 1999.

Interpretive Summary: The role of various ecosystems in regulating atmospheric carbon dioxide levels is a critical issue in global climate change research. Although rangelands cover a vast area, more than 40% of the land area in the world and 150 million acres in the Northern Great Plains, few have estimated their potential role as a sink for atmospheric carbon. Goals of these studies were to: 1) quantify rangeland ecosystem contributions to regulating atmospheric gases; and 2) better estimate impacts of livestock grazing rangelands. Two studies were conducted at Fort Keogh. Carbon dioxide flux at a landscape level was monitored with a Bowen- Ration system in the first study. Effects of seasonal grazing on carbon dioxide flux was estimated in the second study. Treatments imposed on replicated plots were: no grazing, grazed in mid-May, and grazed in mid- July. From mid-April to mid-November (weather permitting) at about 30- day intervals, data were collected for standing crop, leaf area on clipped and nonclipped plots, soil organic matter, root mass to an 11.8 inch soil depth, within-day variation in carbon dioxide concentration above 10.8 square feet of rangeland, and carbon dioxide evolved from bare soil. Field measurements begun in 1996 were completed in 1998, and lab measurements are in progress. Data from two replications of ungrazed plots in 1996 and 1997, show sequestration and release of carbon dioxide are very dependent upon environment (precipitation and temperature) as well as the growth stage of plants. Information from these studies should provide improved estimates of the contribution of Northern Great Plains ranges and associated grazing practices to carbon dioxide flux and ultimately global warming.

Technical Abstract: The role of various ecosystems in regulating atmospheric carbon dioxide levels is a critical issue in global climate change research. Although rangelands cover a vast area, more than 40% of the land area in the world and 150 million acres in the Northern Great Plains, few have estimated their potential role as a sink for atmospheric carbon. Goals of these studies were to: 1) quantify rangeland ecosystem contributions to regulating atmospheric gases; and 2) better estimate impacts of livestock grazing rangelands. Two studies were conducted at Fort Keogh. Carbon dioxide flux at a landscape level was monitored with a Bowen- Ration system in the first study. Effects of seasonal grazing on carbon dioxide flux was estimated in the second study. Treatments imposed on replicated plots were: no grazing, grazed in mid-May, and grazed in mid- July. From mid-April to mid-November (weather permitting) at about 30- day intervals, data were collected for standing crop, leaf area on clipped and nonclipped plots, soil organic matter, root mass to an 11.8 inch soil depth, within-day variation in carbon dioxide concentration above 10.8 square feet of rangeland, and carbon dioxide evolved from bare soil. Field measurements begun in 1996 were completed in 1998, and lab measurements are in progress. Data from two replications of ungrazed plots in 1996 and 1997, show sequestration and release of carbon dioxide are very dependent upon environment (precipitation and temperature) as well as the growth stage of plants. Information from these studies should provide improved estimates of the contribution of Northern Great Plains ranges and associated grazing practices to carbon dioxide flux and ultimately global warming.