Occurrence of fire foci under different land uses in the State of Amazonas during the 2005 drought

The objective of this work is to evaluate the occurrence of fire foci during the severe drought that occurred in 2005 in the State of Amazonas. The study was conducted in the State of Amazonas, which is inserted in the northern region of Brazil. The main types of vegetation are Igapo Forest, Varzea Forest and Terra Firme Forest. Kernel density was used to spatialize fire foci to quantify them in seven classes of land use and cover (forest, pasture, exposed soil, urban area, pastoral agroforestry system, agroforestry system and agriculture). Through the regression analysis, the relation among the number of fire foci and four meteorological variables was obtained: rainfall, evapotranspiration, relative humidity and average air temperature. Forest and pasture classes were those with the highest number of fire foci corresponding, respectively, to 58 and 37% of the total number of foci. This can be explained by the greater representativeness of these classes in the State and by the high degree of soil exposure in the case of pasture. The number of fire foci was higher in the dry season, covering approximately 85% of the total fire foci. The variable that had the greatest influence on the occurrence of fire foci in the dry season was evapotranspiration. The study puts on alert the vulnerability of the State of Amazonas to the occurrence of fires and may also suggest actions to mitigate carbon emissions and biomass stock. Research like this one may provide subsidies to region’s managers in an attempt to preserve forest areas and a greater controlling in priority areas considered very high.