A tropical rainforest clearing experiment by biomass burning in the state of Pará, Brazil

Results are described of a forest clearing experiment conducted in Tomé Acu, located approximately 250 km south of Belém, the capital of the Brazilian northern state of Pará. An area of 3 ha of virgin forest was cut in July 1994 and left to dry until October of the same year, when fire was set. Post burning was also performed 30 days after the main fire. The test location biomass content per hectare was measured by indirect methods using formulas with parameters of forest inventories. The carbon content of the several biomass compartments was determined in a CHN analyzer. The combustion completeness was estimated by selecting ten 2+2 m2 areas and 24 large trunks and examining their consumption rates by fire. The 2+2 m2 areas were used to determine the completeness of small parts of biomass (those whose characteristic diameters were lower than 10 cm) and the trunks to determine the efficiency of the larger parts (characteristic diameters larger than 10 cm). The overall process combustion completeness was estimated to be 20.1%. Considering that the combustion gases of carbon in open fires contain approximately 90% of CO2 and 10% of CO in volumetric basis, the emission rates of these gases by the burning process were estimated as 70.2 and 5.0 t ha-1, respectively.