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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. D16, PAGES 17,877–17,887, 2001

Biomass fire consumption and carbon release rates of rainforestclearing experiments conducted in northern Mato Grosso, Brazil

João A. Carvalho Jr.

Fernando S. Costa

Carlos A. Gurgel Veras

David V. Sandberg

Ernesto C. Alvarado

Ralf Gielow

Aguinaldo M. Serra Jr.

José C. Santos

Abstract

Biomass consumption and carbon release rates during the process of forest clearing by fire in five test plots are presented and discussed. The experiments were conducted at the Caiabi Farm, near the town of Alta Floresta, state of Mato Grosso, Brazil, in five square plots of 1 ha each, designated A, B, C, D, and E, with different locations and timing of fire. Plot A was located in the interface with a pasture, with three edges bordering on the forest, and was cut and burned in 1997. Plots B, C, D, and E were located inside the forest. Plot B was cut and burned in 1997. Plot C was inside a deforested 9-ha area, which was cut and burned in 1998. Plot D was inside a deforested 4-ha area, which was cut in 1998 and burned in 1999. Plot E was inside a deforested 4-ha area, which was cut and burned in 1999. Biomass consumption was 22.7%, 19.5%, 47.5%, 61.5%, and 41.8%, for A, B, C, D, and E, respectively. The effects of an extended curing period and of increasing the deforested area surrounding the plots could be clearly observed. The consumption, for areas cut and burned during the same year, tended toward a value of nearly 50% when presented as a function of the total area burned. The aboveground biomass of the test site and the amount of carbon before the fire were 496 Mg ha⁻¹ and 138 Mg ha⁻¹, respectively. Considering that the biomass that remains unburned keeps about the same average carbon content of fresh biomass, which is supported by the fact that the unburned material consists mainly of large logs, and considering the value of 50% for consumption, the amount of carbon released to the atmosphere as gases was 69 Mg ha⁻¹. The amounts of CO₂ and CO released to the atmosphere by the burning process were then estimated as 228 Mg ha⁻¹ and 15.9 Mg ha⁻¹, respectively. Observations on fire propagation and general features of the slash burnings in the test areas complete the paper.

Received 8 September 2000; accepted 29 November 2000.

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Citation: Carvalho, J. A., Jr., F. S. Costa, C. A. Gurgel Veras, D. V. Sandberg, E. C. Alvarado, R. Gielow, A. M. Serra Jr., and J. C. Santos (2001), Biomass fire consumption and carbon release rates of rainforestclearing experiments conducted in northern Mato Grosso, Brazil, J. Geophys. Res., 106(D16), 17,877–17,887.

Copyright 2001 by the American Geophysical Union.