4.3

Carbon dioxide fluxes over a tallgrass prairie in central Texas

William A. Dugas, Texas Agricultural Experiment Station, Temple, TX

Net ecosystem carbon dioxide (CO₂) fluxes were measured using the Bowen ratio/energy balance method from 1993 through 1999 in a tallgrass prairie in Temple, TX, U.S.A. The prairie was burned on 22 Feb. 1995. Averaged over the seven years, daily fluxes were negative (CO₂ loss) from 1 January to about 10 April (day 100) and from late summer or early fall until 31 December. In 1995, maximum daily CO₂ flux (55 g m^-2 d^-1) was considerably greater than pre fire flux maxima and the duration of positive fluxes was longest of all years. Annual CO₂ fluxes varied from -0.2 to 3.9 kg m^-2 y^-1 (-0.05 to 1.1 kg C m^-2 y^-1), were greatest in 1995, and were greater after the fire, except in 1998 when there was a severe summer drought. These results show this grassland community was a greater C sink after the fire and precipitation totals affected annual CO₂ fluxes.

Session 4, ARS Network
Tuesday, 21 May 2002, 8:30 AM-11:15 AM

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