Suscetibilidade da vegetação ao fogo no sul do amazonas sob condições meteorológicas atípicas durante a seca de 2005

Abstract

Weather conditions play an important role in the behavior of fires both in agricultural and pasture management and in forest wildfires in Amazonia. In severe drought years, the fires used for the management of land can escape from human control and burn large areas of vegetation. Meteorological parameters and hotspot locations were used to evaluate the susceptibility of the vegetation to fire in the southern portion of the state of Amazonas in a year without drought (2004) and a year with severe drought (2005). The number of cells susceptible to fire was 84% higher in 2005 (72%) compared with 2004 (39%). In 2005, the number of cells with hotspots increased by 66% and the number of hotspots by 121%. In 2004, 65% of the hotspots occurred in locations with 40 and 90 mm precipitation, 96% with an average temperature of 26 to 28 º C, and 89% with less than 65% humidity. In 2005, 83% of the hotspots occurred when rainfall was less than 70 mm, 96% with average temperature between 24 and 28 º C and 99% with air humidity below 65%. The meteorological parameters differed between years but not between areas with and without hotspots (PC1 = 84%). There was a higher amplitude variation in these meteorological parameters in the severe drought year, providing hotter and drier weather, thus increasing the susceptibility of vegetation to fire.