Journal ArticleDOI
Interannual variability in net CO2 exchange of a native tallgrass prairie
TLDR
In this paper, year-round eddy covariance flux measurements were made in a native tallgrass prairie in north-central Oklahoma, USA during 1997-2000 to quantify carbon exchange and its interannual variability.Abstract:
Year-round eddy covariance flux measurements were made in a native tallgrass prairie in north-central Oklahoma, USA during 1997–2000 to quantify carbon exchange and its interannual variability. This prairie is dominated by warm season C4 grasses. The soil is a relatively shallow silty clay loam underlined with a heavy clay layer and a limestone bedrock. During the study period, the prairie was burned in the spring of each year, and was not grazed. In 1997 there was adequate soil moisture through the growing season, but 1998 had two extended periods of substantially low soil moisture (with concurrent high air temperatures and vapor pressure deficits), one early and one later in the growing season. There was also moisture stress in 1999, but it was less severe and occurred later in the season. The annual net ecosystem CO2 exchange, NEE (before including carbon loss during the burn) was 274, 46 and 124 g C m−2 yr−1 in 1997, 1998, and 1999, respectively (flux toward the surface is positive), and the associated variation seemed to mirror the severity of moisture stress. We also examined integrated values of NEE during different periods (e.g. day/night; growing season/senescence). Annually integrated carbon dioxide uptake during the daytime showed the greatest variability from year to year, and was primarily linked to the severity of moisture stress. Carbon loss during nighttime was a significant part of the annual daytime NEE, and was fairly stable from year to year. When carbon loss during the burn (estimated from pre- and post-burn biomass samples) was incorporated in the annual NEE, the prairie was found to be approximately carbon neutral (i.e. net carbon uptake/release was near zero) in years with no moisture stress (1997) or with some stress late in the season (1999). During a year with severe moisture stress early in the season (1998), the prairie was a net source of carbon. It appears that moisture stress (severity as well as timing of occurrence) was a dominating factor regulating the annual carbon exchange of the prairie.read more
Citations
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Journal ArticleDOI
Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California
Liukang Xu,Dennis D. Baldocchi +1 more
TL;DR: In this paper, the authors used the eddy covariance method to measure the flux of CO 2 (F{sub c, flux toward the surface is negative) over a Mediterranean, annual grassland in California, USA for two years.
Journal ArticleDOI
Annual carbon dioxide exchange in irrigated and rainfed maize-based agroecosystems
Shashi B. Verma,Achim Dobermann,Kenneth G. Cassman,Daniel T. Walters,Johannes M. H. Knops,Timothy J. Arkebauer,Andrew E. Suyker,George Burba,Brigid Amos,Haishun Yang,Daniel Ginting,Kenneth G. Hubbard,Anatoly A. Gitelson,Elizabeth A. Walter-Shea +13 more
TL;DR: In this article, the authors quantified CO2 exchange in maize-soybean agroecosystems employing year-round tower eddy covariance flux systems and measurements of soil C stocks, CO2 fluxes from the soil surface, plant biomass, and litter decomposition.
Journal ArticleDOI
Full accounting of the greenhouse gas (CO2, N2O, CH4) budget of nine European grassland sites
Jean-François Soussana,Vincent Allard,Kim Pilegaard,Per Ambus,C. Amman,Claire Campbell,Eric Ceschia,John Clifton-Brown,Szilárd Czóbel,R. Domingues,Christophe Flechard,Jürg Fuhrer,Arjan Hensen,László Horváth,Michael P. Jones,G. Kasper,Cécile Martin,Zoltán Nagy,Albrecht Neftel,Antonio Raschi,Silvia Baronti,Robert M. Rees,Ute Skiba,P. Stefani,Giovanni Manca,Mark A. Sutton,Zoltán Tuba,Riccardo Valentini +27 more
TL;DR: Soussana et al. as discussed by the authors presented a full accounting of the greenhouse gas (CO2, N2O, CH4) budget of nine European grassland sites.
Journal ArticleDOI
Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California
TL;DR: In this article, the authors measured CO2 fluxes over and under an oak-grass savanna and over a proximate grassland in California using the eddy covariance technique.
Journal ArticleDOI
Relationship between gross primary production and chlorophyll content in crops: Implications for the synoptic monitoring of vegetation productivity
Anatoly A. Gitelson,Andrés Viña,Andrés Viña,Shashi B. Verma,Donald C. Rundquist,Timothy J. Arkebauer,Galina P. Keydan,Bryan Leavitt,Veronica S. Ciganda,George Burba,George Burba,Andrew E. Suyker +11 more
TL;DR: In this article, the authors used an independent data set for irrigated and rainfed maize showed robustness of the technique; RMSE of GPP prediction was less than 0.27 mg CO2/m 2 s.
References
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Journal ArticleDOI
Correction of flux measurements for density effects due to heat and water vapour transfer
TL;DR: In this article, the basic relationships are discussed in the context of vertical transfer in the lower atmosphere, and the required corrections to the measured flux are derived, where the correction to measurements of water vapour flux will often be only a few per cent but will sometimes exceed 10 percent.
Journal ArticleDOI
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Journal ArticleDOI
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Journal ArticleDOI
Respiration as the main determinant of carbon balance in European forests
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TL;DR: Data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, confirm that many European forest ecosystems act as carbon sinks and indicate that, in general, ecosystem respiration determines netcosystem carbon exchange.
Journal ArticleDOI
Measurements of carbon sequestration by long‐term eddy covariance: methods and a critical evaluation of accuracy
TL;DR: In this paper, the turbulent exchanges of CO2 and water vapour between an aggrading deciduous forest in the north-eastern United States (Harvard Forest) and the atmosphere were measured from 1990 to 1994 using the eddy covariance technique.
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