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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.

The Brazilian Legal Amazon is an extensive territory (5,088,668.25 km2) in which different factors (environmental and social) influence the fire dynamics of the region. This study aims to explain the seasonal patterns of meteorological variables, fire, land use, and carbon emissions and their inter-relationships, focusing on years of El Nino–Southern Oscillation (ENSO) occurrence. For this purpose, we used data from fire foci and burned area obtained by the Moderate Resolution Imaging Spectroradiometer sensor and meteorological variables from Reanalysis 2. The kernel density was applied to the fire foci, and Spearman correlation coefficient between the foci and the other variables (fire foci, burned area, carbon emissions, evapotranspiration, wind speed, relative air humidity, rainfall, soil moisture, maximum temperature, minimum temperature, and mean air temperature) and Mann Kendall test for soybean, corn and sugarcane crops were performed. The years considered as La Nina were those with the highest fire foci, burned area, and carbon emissions. Our results show that even in periods considered as low fire risk, forests may be vulnerable to fires due to interaction with other variables. Furthermore, we found a tendency to increase the area planted with soybean, maize, and sugarcane, which may lead to more deforested areas in the region if there is no support from public policies. The uncertainty of the Legal Amazon's behavior towards climate change, combined with possible setbacks in Brazilian environmental policy due to the current government, highlights the importance of studies that encompass several factors such as this one.

The use of uncontrolled fire by human beings associated with climate conditions favorable to burning has caused social, economic and environmental damage in different parts of the world. The objective of the present study was to evaluate the variations in the occurrence of fire in Southern Region of Brazil caused by the seasonal characteristics of the years. We also sought to highlight the vegetation coverings most affected by fires within each year assessed and among the different ENSO events. Fire products from the MODIS were associated with meteorological elements and vegetation cover data, in addition to evaluating Carbon emission data made available by GFED. The correlation between the meteorological elements and fire was obtained by Spearman's non-parametric approach. Additionally, Mann Kendall's statistical test was performed with the harvested area extensions of three temporary agricultural crops (Maize, Soybean and Sugarcane) over 28 years. Fire in Southern Brazil correlates mainly with reduced rainfall and relative air humidity together with increased atmospheric pressure and increased wind speed. The periods under the effect of the cold phase of the phenomenon (La Nina) presented 26% to 114% more fire foci than those under the hot phase (El Nino). La Ninas also showed 7% to 77% more burned area than El Ninos. La Nina events emitted more carbon into the atmosphere than El Nino, and the greatest difference was observed between La Nina 2007/2008 (1.51 Tg) and El Nino 2015 (0.65 Tg). The vegetation covers most affected by the fire were those related to agricultural activity. Mann Kendall's statistics indicated that Sugarcane, an agricultural crop with flammable straw, showed a tendency to expand in the state of Parana between 1990 and 2018. Intra and inter-annual atmospheric variations and the mosaic of different vegetation covers determined the fire pattern in the study area over the period studied.