ARS | Publication request: SIX YEARS OF CO2 FLUX MEASUREMENTS FOR A GRAZED MIXED-GRASS PRAIRIE.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 2, 2002
Publication Date: October 1, 2002
Citation: Frank, A.B. 2002. Six years of co2 flux measurements for a grazed mixed-grass prairie.. Meeting Abstract.

Technical Abstract: Carbon dioxide fluxes were measured over a moderately grazed mixed-grass prairie site using the CO2 Bowen ratio/energy balance technique. Fluxes were measured from 24 April to 26 October from 1996 through 2001 at Mandan, ND. The site is mostly cool season grass species with a complement of warm season grasses. Long-term annual precipitation averages 404 mm. Average CO2 fluxes for the 175 day period from 24 April to 26 October for the six years was 103 g CO2-C m-2. Yearly fluxes ranged from 75 g CO2-C m-2 in 1996 to 154 g CO2-C m-2 in 2001. Dormant season fluxes measured with soil chambers in 1999 averaged -0.4 g CO2-C m-2 d-1 or an average of 76 g CO2-C m-2 for the entire dormant season. When using -0.4 g CO2-C m-2 d-1 for the dormant season flux the six year average carbon sequestration rate was 27 g CO2-C m-2 yr-1. The period of peak fluxes occurred from late-June to mid-July and coincided well with periods of peak standing biomass. These results suggest that Northern Great Plains mixed-grass prairie grasslands can function as a small sink for atmospheric CO2 even when defoliated at a moderate grazing intensity. Discussion will include the significance of dormant period C fluxes, the seasonality of biomass accumulation and leaf area, and their relationship to C uptake.