A tropical rain-forest clearing experiment by biomass burning in the stateof Para, Brazil

Results are described of a forest clearing experiment conducted in Tome Acu , located approximately 250 km south of Belem, the capital of the Brazilian northern state of Para. An area of 3 ha of virgin forest was cut in July 1 994 and Weft 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 b iomass compartments was determined in a CHN analyzer. The combustion comple teness was estimated by selecting ten 2 x 2 m(2) areas and 24 large trunks and examining their consumption rates by fire. The 2 x 2 m(2) areas were us ed to determine the completeness of small parts of biomass (those whose cha racteristic diameters were lower than 10 cm) and the trunks to determine th e efficiency of the larger parts (characteristic diameters larger than 10 c m). The overall process combustion completeness was estimated to be 20.1%. Considering that the combustion gases of carbon in open fires contain appro ximately 90% of CO2 and 10% of CO in volumetric basis, the emission rates o f these gases by the burning process were estimated as 70.2 and 5.0 t ha(-1 ), respectively. (C) 1999 Published by Elsevier Science Ltd. All rights res erved.