After four years of decreases on the burnings index, Brazil had to deal again with high levels of fire activities during the 1995 dry season. According to the information obtained from the NOAA AVHRR satellite sensor the average total number of fires detected between 1991 and 1994 had dropped by 23% each year. During the five dry months of 1995 the total number of detected fires reached 367,000. That means a 70% increase, if compared with 1994’s numbers.
The distribution of the main fire concentrations also changed. During the last four years the fires had followed almost the same pattern throughout the dry season, in a high correlation with the dislocation of the Intertropical Convergence Zone (ITCZ) and the occurrence of rainfall. The regions where the rainfall stops first, burning activities also start first. Whenever out of season rainfalls occur, there are no burnings. From 1991 to 1994, June and July were the months of medium fire concentrations in Southern Brazil, predominating in Paraná, Santa Catarina and Sao Paulo. From August on, the burnings rapidly progressed into Central Brazil, spreading smoke over Mato Grosso do Sul, Mato Grosso, Goiás, Tocantins and West Bahia. Then the major fire concentrations moved North, towards the Amazon region (Pará, Amazonia, Acre, Rondônia), and to the East (Maranhao, Piauí), ending October with the first burnings in Northeastern Brazil, at the semi-desert region called The Drought Polygon (Bahía, Pernambuco, Rio Grande do Norte, Paraíba, Ceará).
This year, June and July started with the highest concentrations of fire points ever registered, and many of them were localized in the Amazon Region. These months’ indexes almost doubled, if compared with the average of previous records. In August there was a 34% increase above the average of previous years. But in September and October the fire numbers kept the same level of previous years.
The main reason for this change of patterns and standards was economic. Since 1991, less investment money was available for farmers, cattle ranchers and agriculturists. They have reduced, therefore, their planted areas and did not open new farming lands. In 1995, the situation changed, with the success of the Plano Reál. Its economic measures drastically reduced inflation and stabilized the Brazilian economy. Farmers, cattle ranchers and agriculturists reinvested in plantations and pasture renovations. The abandoned areas were again prepared and fire was again used as the cheapest and easiest tool to control weeds and accelerate grass sprouting. New areas were also opened, on a smaller scale.
The climate also favoured the fires, especially in the Amazon Basin. This year, the dry season started first and lasted longer in the Amazon states. Consequently, agriculturists had more time to prepare their lands and set fire. At Rondônia State, for example, the satellites detected concentrations of fire from early June until late November! Usually, the burnings detected in that state last only from August to September/early October.
It is important to bear in mind that Brazilian fires are very different from those in the natural vegetation of the Mediterranean basin, from wildfires in California’s chaparral, and forest and tundra fires in Alaska. The untouched rainforests – either at the Amazon Basin and at the Brazilian Atlantic Coast – do not burn by accident, nor even if someone sets fire to them. They are too humid to burn by themselves. They only catch fire after a severe and long drought and if disturbed or cut down. Therefore, almost all fires detected on forested areas are associated with either deforestation or post-deforestation burning. When converting forest into other land-use systems, trees are first cut down. After several months of drying, trunks and branches are burned. It takes an average of eight years until all the wood is burned. So, fire is used as a tool to clean up the land, and the hotspots are not representing wildfires. Fire is also used to eliminate weeds, plagues and leftovers of plantations, to accelerate the pastures sprouting and even to make harvesting easier, as well as a fast fertilization process. And those are the causing that high number of fires detected each winter in Brazil. That’s why burnings cannot necessarily be used as a deforestation indicator: if it is true that the fire is commonly set on deforested areas, it is also true that deforested areas are not always burned and it is specially true that fires are also set on a lot of other areas, not necessarily deforested, like Cerrados, grasslands, and traditional agricultural lands. More reliable deforestation indicators were developed in studies by the National Space Research Institute (INPE), with Landsat TM and Spot data (called PRODES). At the end of December 1995, INPE will release the new deforestation numbers, based on 1992 and 1994 satellite images. The 1995 numbers shall be available by June 1996.