Dinâmica espaço-temporal de incêndios florestais e avaliação multiespectral de queimas prescritas no Pantanal

Abstract

The Pantanal is the largest wetland area in the world, recognized by UNESCO as a natural heritage of humanity and biosphere reserve, of great ecosystem importance and habitat for a wide variety of fauna and flora, being a highly water-dependent ecosystem due to the flood pulse. Forest fires are growing problems that cause impacts on the biome, due to the increase in frequency and intensity, and these events are mainly associated with anthropogenic actions of land transformation and aggravated by climate change. The general objective of this research was to use data obtained by orbital sensors and integrated into Remotely Piloted Aircraft Systems (RPAS) to perform a spatial analysis of forest fires and an assessment of prescribed burning in the Pantanal biome, with the purpose of generating contributions to Integrated Fire Management in the region. In the first analysis of historical series and fire dynamics in the Pantanal, satellite images and spatial data were used to understand fire behavior and its spatial patterns in the biome. For this, data from the monitoring of land use and land cover in Brazil (MapBiomas) were used for the mapping of areas affected by fire, as well as data on hotspots and climatic variables of precipitation and "El Niño -Southern Oscillation”. The satellite images allowed an overview of the areas affected by fire, identifying the affected areas and the spatial patterns of autocorrelation of hotspots and temporal variations of fires. There is a linear behavior with the loss of natural cover, being mainly affected by fire the areas of grassland and savannah vegetation. Fire behavior is related to precipitation patterns and when driven by extreme weather events it aggravates the impact on vegetation. Spatial autocorrelation patterns can be influenced by several factors, such as climate, land use and environmental conditions. For the second analysis, the effects of prescribed burning were evaluated in focal plots in the SESC Pantanal Natural Heritage Reserve. Periods of the year 2021 were analyzed, being: early (July), modal (September) and late (October), in three macrohabitats (M1: Natural grassland flooded with Combretum spp. proliferation, M2: Natural grassland of seasonal wetlands and M3: Natural grassland flooded with Vochysia divergens proliferation). The MicaSense Altum high spatial/spectral resolution camera coupled to a multirotor RPAS was used for data acquisition. The controlled use of fire in the burns made it possible to reduce the load of combustible material and the spectral and thermal analysis facilitated the recording of information and measurements of high precision, fast and indirect, based on the post-fire spectral response, allowing to determine the degree of severity of the burns and the effect on the vegetation, where it was evidenced low level of disturbance on areas with greater tree cover and lower load of combustible material, revealing the potential of this equipment and achieving the objective of prescribed burning. The research results indicated that the combination of satellite images and RPAS data is an effective tool for the diagnosis and monitoring of forest fires, in addition to serving as technical support for the conduct and analysis of prescribed burning in the Pantanal.