Soil carbon dioxide fluxes in northern semiarid grasslands

• Published in: Soil biology & biochemistry Vol. 34; no. 9; pp. 1235 - 1241
• Main Authors: Frank, A.B, Liebig, M.A, Hanson, J.D
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2002; New York, NY Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon cycling; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Prairie grasslands; Soil CO 2 flux; Soil respiration; Soil science; Great Plains of America; United States; North America; North Dakota; America; Prairie grasslands; Soil CO 2 flux; Soil respiration; Carbon cycling; Monocotyledones; Gas emission; Carbon dioxide; Bouteloua gracilis; Forecast model; Loamy soil; Gramineae; Semi arid zone; Air temperature; Angiospermae; Grassland soil; Silty soil; Biogeochemical cycle; Mollisols; Grazing; Carbon cycle; Soil water properties; Cyperaceae; Poa pratensis; Herbaceous plant; Spermatophyta; Carex; Fodder crop; Respiration; Soil temperature
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(02)00062-7

The high indigenous soil organic carbon content, root biomass, and microbial populations in prairie soils provide a source of carbon dioxide (CO 2) that is important in the carbon budget of grasslands. Soil chambers were used to measure soil CO 2 flux from a grazed mixed-grass prairie (GP), nongrazed mixed-grass prairie (NGP), and grazed western wheatgrass (WWG) [ Pascopyrum smithii (Rybd) Löve] grasslands in the Northern Great Plains, USA. Objectives were to quantify soil CO 2 fluxes for each site and to determine the contribution of soil temperature, soil water content, and air temperature to soil CO 2 flux. Soil CO 2 fluxes were measured on each site about every 21 d at 13:00 h during the 25 April–27 October growing period from 1996 to 2000 for NGP and GP and from 1996 to 1998 for WWG. Dormant period fluxes were measured on the GP from 28 October to 26 April from 1999 to 2001. In addition, five sequential daytime measurements were made on each site for 3 days each year. Fluxes were low in the spring and autumn and peaked concurrent with biomass in late June to mid-July. Maximum fluxes for these dissimilar managed grasslands averaged 5.8 g CO 2-C m −2 d −1 for NGP, 6.9 g CO 2-C m −2 d −1 for GP, and 6.1 g CO 2-C m −2 d −1 for WWG. Soil fluxes measured during the dormant period decreased to near zero during the months of December, January, and February and then increased rapidly in March as soil temperatures increased. Daily soil flux during the growing period averaged 3.5 g CO 2-C m −2 d −1 for NGP, 4.3 g CO 2-C m −2 d −1 for GP, and 4.0 g CO 2-C m −2 d −1 for WWG. Dormant period fluxes for the GP averaged 0.5 g CO 2-C m −2 d −1. Regression analysis indicated that soil temperature accounted for 65%, soil water content 5%, and air temperature 3% of flux variability. Growing period soil CO 2 flux over years averaged 728 g CO 2-C m −2 and dormant period CO 2 flux averaged 86 g CO 2-C m −2. A predictive relationship describing the response of soil CO 2 flux to changes in soil temperature was developed using the minimum, maximum, and optimum soil temperatures for soil CO 2 flux. The model provides an estimate of the important dormant period soil flux component in annual ecosystem carbon budgets.