TY - JOUR
T1 - Carbon, water, and heat flux responses to experimental burning and drought in a tallgrass prairie
AU - Fischer, Marc L.
AU - Torn, Margaret S.
AU - Billesbach, David P.
AU - Doyle, Geoffrey
AU - Northup, Brian
AU - Biraud, Sebastien C.
N1 - Funding Information:
The authors gratefully acknowledge Dr. Herman Mayeaux, former director of the USDA Grazing Lands Research Laboratory, for his vision and assistance in designing and initiating the experiment. We also thank the USDA at El Reno, OK and Patrick Dowell of the USDOE ARM Southern Great Plains ACRF facility for collecting biomass samples and maintaining the instrumentation deployed for this research. This research was supported by the USDA and the Office of Biological and Environmental Research of the U.S. Department of Energy under grant or contract number DE-AC02-05CH11231 as part of the Atmospheric Radiation Measurement Program.
PY - 2012/12/15
Y1 - 2012/12/15
N2 - Drought and fire are common disturbances to grassland ecosystems. We report two years of eddy covariance ecosystem-atmosphere fluxes and biometric variables measured in nearby burned and unburned pastures in the US Southern Great Plains. Over the course of the experiment, annual precipitation (∼600mmyr-1) was lower than the long term mean (∼860mmyr-1). Soil moisture decreased from productive conditions in March 2005 dry, unproductive conditions during the growing season starting in March 2006. Just prior to the burn in early March 2005, burned and unburned pastures contained 520±60 and 360±40gCm-2 of total above ground biomass (AGB) and litter, respectively. The fire removed approximately 200gCm-2 of litter and biomass. In the 2005 growing season following the burn, maximum green AGB was 450±60 and 270±40gCm-2, with corresponding cumulative annual net ecosystem carbon exchange (NEE) of -330 and -150gCm-2 for the burned and unburned pastures, respectively. In contrast to NEE, cumulative mean sensible heat and water fluxes were approximately equal in both pastures during the growing season, suggesting either an increase in water use efficiency or a decrease in evaporation in the burned relative to the unburned pasture. In the 2006 growing season, dry conditions decreased carbon uptake and latent heat, and increased sensible heat fluxes. Peak AGB was reduced to 210±30gCm-2 and 140±30gCm-2 in the burned and unburned pastures, respectively, while NEE was near zero. These results suggest that the lack of precipitation was responsible for most of the interannual variation in carbon exchange for these un-irrigated prairie pastures.
AB - Drought and fire are common disturbances to grassland ecosystems. We report two years of eddy covariance ecosystem-atmosphere fluxes and biometric variables measured in nearby burned and unburned pastures in the US Southern Great Plains. Over the course of the experiment, annual precipitation (∼600mmyr-1) was lower than the long term mean (∼860mmyr-1). Soil moisture decreased from productive conditions in March 2005 dry, unproductive conditions during the growing season starting in March 2006. Just prior to the burn in early March 2005, burned and unburned pastures contained 520±60 and 360±40gCm-2 of total above ground biomass (AGB) and litter, respectively. The fire removed approximately 200gCm-2 of litter and biomass. In the 2005 growing season following the burn, maximum green AGB was 450±60 and 270±40gCm-2, with corresponding cumulative annual net ecosystem carbon exchange (NEE) of -330 and -150gCm-2 for the burned and unburned pastures, respectively. In contrast to NEE, cumulative mean sensible heat and water fluxes were approximately equal in both pastures during the growing season, suggesting either an increase in water use efficiency or a decrease in evaporation in the burned relative to the unburned pasture. In the 2006 growing season, dry conditions decreased carbon uptake and latent heat, and increased sensible heat fluxes. Peak AGB was reduced to 210±30gCm-2 and 140±30gCm-2 in the burned and unburned pastures, respectively, while NEE was near zero. These results suggest that the lack of precipitation was responsible for most of the interannual variation in carbon exchange for these un-irrigated prairie pastures.
KW - Carbon exchange
KW - Eddy covariance
KW - Fire
KW - Grassland
KW - Prairie
KW - Water stress
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U2 - 10.1016/j.agrformet.2012.07.011
DO - 10.1016/j.agrformet.2012.07.011
M3 - Article
AN - SCOPUS:84866158704
SN - 0168-1923
VL - 166-167
SP - 169
EP - 174
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
ER -