Incêndios florestais em Roraima: estimativa da área impactada e destino do carbono afetado (2000-2010)

Abstract

Forest fires act as source of greenhouse gas emissions contributing to global warming and climate change. Carbon is the base of the main gases causing greenhouse effect, and it is present in forest biomass. Brazil has the largest tropical forest in the world, the Amazon. However, the quantification of greenhouse gas emissions by forest fires is difficult to measure, and there are few studies in Amazon region. Roraima is one of the Amazonian States that has a known history of fires, which enables their quantification. The objective of this study was to understand the spatio-temporal dynamics of carbon affected by forest fires occurred in Roraima among 2000-2010. In this sense, the work verified (i) the area impacted by fires in the period; (ii) the relationship between the area impacted and climatic events (El Niño, La Niña and normal years); (iii) the forest types more affected by fires and (iv) the fate of carbon affected by fires. Were used mosaics of LANDSAT TM/ETM+composed of eight scenes each one by sampled year. The date of the scenes was preferably chosen between April and May, months that correspond to the end of the dry season in Roraima. Each mosaic was surveyed visually on a work scale of 1:50,000. It was adopted an inspection protocol along the main federal highways (BR 174, BR 210 and BR 401) to verify deforestation (i) in colonization areas, and (ii) on the border of savannas in contact with the forest. The areas burned in a given year were manually drawn after a system of checkpoints between the previous and subsequent year of construction to avoid build wrong polygon. To verification of forest types impacted, was used the vegetation map of the Programme for Conservation and Sustainable Use of Brazilian Biological Diversity, (PROBio). To calculate the fate of carbon affected were used studies on carbon stock and biomass of forest types in Roraima.