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Soil surface CO2 fluxes and the carbon budget of a grasslandMeasurements of soil surface CO2 fluxes are reported for three sites within the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) area, and simple empirical equations are fit to the data to provide predictions of soil fluxes from environmental observations. A prototype soil chamber, used to make the flux measurements, is described and tested by comparing CO2 flux measurements to a 40-L chamber, a 1-m/cu chamber, and eddy correlation. Results suggest that flux measurements with the prototype chamber are consistent with measurements by other methods to within about 20 percent. A simple empirical equation based on 10-cm soil temperature, 0- to 10-cm soil volumetric water content, and leaf area index predicts the soil surface CO2 flux with a rms error of 1.2 micro-mol sq m/s for all three sites. Further evidence supports using this equation to evaluate soil surface CO2 during the 1987 FIFE experiment. The soil surface CO2 fluxes when averaged over 24 hours are comparable to daily gross canopy photosynthetic rates. For 6 days of data the net daily accumulation of carbon is about 0.6 g CO2 sq m/d; this is only a few percent of the daily gross accumulation of carbon by photosynthesis. As the soil became drier in 1989, the net accumulation of carbon by the prairie increased, suggesting that the soil flux is more sensitive to temperature and drought than the photosynthetic fluxes.
Document ID
19930036620
Document Type
Reprint (Version printed in journal)
Authors
Norman, J. M. (Wisconsin Univ. Madison, United States)
Garcia, R. (NASA Headquarters Washington, DC United States)
Verma, S. B. (Nebraska Univ. Lincoln, United States)
Date Acquired
August 15, 2013
Publication Date
November 30, 1992
Publication Information
Publication: Journal of Geophysical Research
Volume: 97
Issue: D17
ISSN: 0148-0227
Subject Category
EARTH RESOURCES AND REMOTE SENSING
Funding Number(s)
CONTRACT_GRANT: NAG5-890
CONTRACT_GRANT: NAGW-1469
Distribution Limits
Public
Copyright
Other