DEFORESTATION DYNAMICS IN MATO GROSSO, CENTRAL-WEST BRAZIL USING GIS AND NOAA/AVHRR DATA

摘要

Since the early 1980s, large scale and deep environmental alterations in the Amazon River Basin owing to land development, population inflow, and the consequent deforestation, have become a serious ecological problem in this region which is known to be, both climatologically and biogenetically, one of the most important ecosystem in the world. Mato Grosso has emerged as the Brazilian state with the highest deforestation rate, and with the most dynamic changes in vegetation and land covers. In this paper, we focused on the following two main objectives: (i) to quantitatively assess the extent of vegetation change over the past two decades for more accurate eco-climatic impact analysis, and (ii) to clarify the causes to these changes, with special focus to human factors, with Mato Grosso as our case study. 5-year Digital Vegetation Model (DVM) Maps, aggregated into Phases I and IV, were created for every five years during the 1981-2001 period, using the first components of the principal components analysis (PCA) of NOAA/AVHRR multi-spectral data (Channels 1, 2 and 4). Vegetation and land cover changes are characterized by broad destruction of primary forests in the north and large-scale savanization expanding from the south. Change rates are shown to be larger over non-inhabited areas (56percent) and far away from the main highways (52percent), than over the populated zones in the south (42percent), within 50km of the roads (44percent). This emphasizes not only the role of population density and road building in accelerating deforestation, but also the importance of navigable rivers, especially over the roadless areas in the north.