[1] Earlier work showed that Amazonian biomass burning produces both lofted and initially unlofted emissions in large amounts. A mobile, Fourier transform infrared spectrometer (FTIR) measured the unlofted emissions of 17 trace gases from residual smoldering combustion (RSC) of logs as part of the Tropical Forest and Fire Emissions Experiment (TROFFEE) during the 2004 Amazonian dry season. The RSC emissions were highly variable and the few earlier RSC measurements lay near the high end of combustion efficiency observed in this study. Fuel consumption by RSC was $5% of total for a planned deforestation fire. Much regional RSC probably occurs in the residual woody debris burned during pasture maintenance fires. RSC could increase estimated total fire emissions for the Amazon region by 20-50% for several important VOC. FTIR emissions measurements of burning dung (in a pasture) showed high emission ratios for acetic acid and ammonia to CO (6.6 ± 3.4% and 8.9 ± 2.1%). Large emissions of nitrogen containing trace gases from burning dung and crop waste could mean that biomass burning in India produces more particle mass than previously assumed. Measurements of late-stage kiln emissions suggested that VOC/CO may increase as carbonization is extended. A cook stove emitted many VOC and NH 3 far outside the range observed for open wood cooking fires. Enclosed/vented cooking stoves may change the chemistry of the smoke that is emitted.

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.

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Fire characteristics in tropical ecosystems are poorly documented quantitatively in the literature. This paper describes an understorey fire propagating across the edges of a biomass burn of a cleared primary forest. The experiment was carried out in 2001 in the Amazon forest near Alta Floresta, state of Mato Grosso, Brazil, as part of biomass burning experiments conducted in the same area since 1997. The vegetation of a 200 × 200-m2 forested area was clear-cut in early June and burned in late August. The understorey fire that escaped from the main burn was monitored across the four sides of the land clearing area. Flame-front spread varied between 0.14 and 0.35 m min–1. Maximum flame height was about 30 cm and typical flame depth was 10 to 15 cm. Tree mortality was investigated in 2003 in four areas adjacent to the biomass burning experiment. A total of 210 trees were counted in the four areas, 29.5% were dead as a consequence of the understorey fire that had occurred 2 years before. This fire-caused mortality is evidence of the synergistic effect between slash burning, tree mortality and future fire vulnerability on the forest–land clearing interfaces.