Net Carbon Fluxes Over Burned and Unburned Native Tallgrass Prairie |
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| Authors: | Dale J Bremer Jay M Ham |
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| Institution: | 1. Associate Professor, Department of Horticulture, Forestry and Recreation Resources, 2021 Throckmorton Hall, Kansas State University, Manhattan, KS 66506, USA;2. Professor, Department of Soil and Crop Sciences, C107 Plant Sciences Building, Colorado State University, Fort Collins, CO 80523, USA.;1. Assistant Professor, State Key Laboratory of Grassland Agroecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.;2. Associate Professor, Agriculture and Ecology Research Department, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China.;3. Visiting Scholar, School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA.;4. Professor, School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA.;1. PhD student, BioSciences Graduate Program, Universidad de Sonora (DICTUS), Blvd. L.D. Colosio y Reforma, Hermosillo, Sonora 83000, México;2. Research Professor Department Investigaciones Científicas Tecnológicas, Universidad de Sonora (DICTUS), Blvd. L.D. Colosio y Reforma, Hermosillo, Sonora 83000, México;3. Research Professor, Department Agricultura y Ganadería, Universidad de Sonora, Blvd. L. Encinas y Rosales, Hermosillo, Sonora 83000, México;4. Research Professor, División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica A. C., Camino a la Presa San José 2055, San Luis Potosí, S.L.P. 78216, Mexico;5. Research Professor Ecology and Evolutionary Biology, Center for Environmental Biology, University of California—Irvine, Irvine, CA 92629, USA.;1. Research Scientist, USDA-ARS Eastern Oregon Agricultural Research Center, Burns, OR 97720, USA;2. Research Leader, USDA-ARS Eastern Oregon Agricultural Research Center, Burns, OR 97720, USA;1. Professor, Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada;2. Research Scientist, Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1, Canada;3. Graduate Student, Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada;4. Provincial Rangeland Specialist, Alberta Sustainable Resource Development, Lands Division, Pincher Creek, AB, T0K 1W0 Canada;1. Research Ecologist, USDA-ARS, Rangeland Resources Research Unit, Cheyenne, WY 82009/Fort Collins, CO, 80526 USA;2. Research Leader and Rangeland Scientist, USDA-ARS, Rangeland Resources Research Unit, Cheyenne, WY 82009/Fort Collins, CO, 80526 USA;1. Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, 97333, USA;2. Department of Fisheries and Wildlife, Hermiston Agricultural Research and Extension Center, Oregon State University, Hermiston, OR 97838, USA;3. Bee Biology and Systematics Laboratory, Utah State University, Logan, UT 84322, USA |
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| Abstract: | Prescribed burning of aboveground biomass in tallgrass prairie is common and may influence dynamics and magnitudes of carbon (C) movement between the surface and atmosphere. Carbon dioxide (CO2) fluxes were measured for 2 yr using conditional sampling systems on two adjacent watersheds in an ungrazed tallgrass prairie near Manhattan, Kansas. One watershed was burned annually (BA) and the other biennially (BB). Leaf and soil CO2 fluxes were measured in the source area. Net ecosystem exchange (NEE) of CO2 reached a maximum daily gain of 26.4 g CO2·m?2·d?1 (flux toward surface is positive) in July 1998 (year when both sites were burned and precipitation was above normal); gains were similar between sites in 1998. The maximum daily NEE loss of CO2 was ?21.8 g CO2·m?2·d?1 from BA in September 1997 (year when only BA was burned and precipitation was below normal). When data were integrated over the two years, both sites were net sources of atmospheric CO2; NEE was ?389 g C·m?2·2 yr?1 on BA and ?195 g C·m?2·2 yr?1 on BB. Burning increased canopy size and photosynthesis, but the greater photosynthesis was offset by corresponding increases in respiration (from canopy and soil). Carbon losses from fire represented 6–10% of annual CO2 emissions (bulk came from soil and canopy respiration). Data suggest that annual burning promotes C loss compared to less-frequently burned tallgrass prairie where prairie is not grazed by ungulates. Greater precipitation in 1998 caused large increases in biomass and a more positive growing season NEE, indicating that C sequestration appears more likely when precipitation is high. Because C inputs (photosynthesis) and losses (canopy and soil respiration) were large, small measurement or modeling errors could confound attempts to determine if the ecosystems are long-term CO2 sources or sinks. |
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