Integration of remotely sensed and ancillary data to assess the impacts of shifting cultivation / Integração de dados de detecção remota com dados complementares para a avaliação dos impates da agricultura de corte e queima

Abstract

Annual emissions of CO 2 from biomass burning in shifting cultivation systems in Brazil were estimated as the product of area burned, aboveground biomass, combustion completeness and emission factor. The total area of shifting cultivation was derived from the Global Land Cover 2000 map for South America, while the area cleared and burnt annually was obtained by multiplying the total area by the rotation cycle of shifting cultivation, calculated using cropping and fallow lengths reported in the literature. Aboveground biomass accumulation was estimated as a function of the duration and mean temperature of the growing season, soil texture type and length of the fallow period. Published combustion completeness and emission factor values were used. Two scenarios were set using minimum and maximum fallow lengths and emissions calculated. Results revealed that a reduction of emissions in shifting cultivation systems is not easily achieved by extending the length of the fallow period. Results also showed a good agreement between the spatial distribution of shifting cultivation in Brazil, obtained with remote sensing, and the location of studies describing fallow and cropping periods practiced in shifting cultivation systems.Key words: Shifting cultivation; biomass burning; atmospheric emissions; tropical forests; remote sensing. ResumoAs emissões anuais de CO 2 provenientes da queima de biomassa em sistemas de agricultura de corte e queima no Brasil foram estimadas como o produto da área queimada, da biomassa acima do solo, do fator de combustão e do fator de emissão. A área total afetada por este tipo de agricultura foi obtida a partir do mapa Global Land Cover 2000 da América do Sul, enquanto a área cortada e queimada anualmente foi obtida multiplicando a área total pelo ciclo de rotação, calculado Palavras-chave: Agricultura de corte e queima; queima de biomassa; emissões atmosféricas; florestas tropicais; sensoriamento remoto.