Dinâmica da paisagem na microbacia hidrográfica do Rio Mojuí, Oeste do Estado do Pará

Abstract

Currently, conservation issues have been discussed with great emphasis by society in general, especially on the Amazon landscape. Within this context is Mojuí River watershed, located in the cities of Santarém and Belterra, in the state of Pará. This comes under constant exploration of natural resources, mainly due to conversion of forest areas into agricultural areas, mainly for soybeans cultivation. The aim of this study was to characterize and quantify mapping , semi -scale detail , the areas of vegetation cover classes and land use in the period of 11 years as use of LANDSAT , orbit / points 227/62 , TM bands 3 , 4:05 , for the years 1999 , 2005 and 2010 , the landscape dynamics in the region . The selection of images was determined considering the similar climatic period, with the same lighting conditions and cloud cover. The boundaries of the basin were established by dividers that form the topographic area that drains to a specific point. Based on the data obtained in the field survey and with the support of photointerpretation the scenes of the sensors in the years established by research, has defined a thematic caption for vegetation classification and land use in the basin, identified seven forms of vegetation and land use in the catchment area of the basin. We defined the following classes of land cover: Rain Forest , Secondary Succession , Alluvial Rain Forest , Grassland , Degraded Grassland , Agriculture and Water Bodies . During the research it was observed that the Mojuí river watershed has lost 221.73 km² of natural vegetation cover (dense ombrophilous forest, alluvial dense ombrophilous forest). Until 1999 the dense ombrophilous forest class was the largest present at the watershed, however from 2005 on the agricultural class became the largest at that location, with an increase of approximately 518.11% of the initial research area. When the results were analyzed more specifically, it is highlighted that the agricultural area suffered a strong expansion during the time of the research, at the expense of other areas. The exception was the agricultural advance over the classes alluvial dense ombrophilous forest and waterbody, as theses classes are protected by law and unapropriated for mechanized agriculture.

A bacia hidrográfica do Rio Mojuí, localizada nos municípios de Santarém e Belterra, no estado do Pará, vem sofrendo constantes explorações dos seus recursos naturais, principalmente devido à conversão de áreas com florestas em áreas agrícolas, principalmente para cultivo da soja. O objetivo deste trabalho foi caracterizar mapear e quantificar, em escala de semi detalhe, as áreas das classes de cobertura vegetal e uso da terra no período de 11 anos, como uso de imagens LANDSAT, órbita/ pontos 227/62, bandas TM 3, 4 e 5, referentes aos anos de 1999, 2005 e 2010, a dinâmica da paisagem na região. Baseando- se nos dados obtidos no levantamento de campo e com o suporte da fotointerpretação das cenas dos sensores nos anos estabelecidos pela pesquisa, foi definida uma legenda temática para classificação da vegetação e uso do solo na bacia, sendo identificadas seteformas de coberturas vegetais e uso do solo na área de abrangência da bacia: Floresta Ombrófila Densa, Sucessão Secundária, Floresta Ombrófila Densa Aluvial, Pastagem, Pastagem Degradada, Agricultura e Corpos D’água. No intervalo da pesquisa foi observado que a bacia hidrográfica do Rio Mojuí perdeu 221,73 km² de coberturas vegetais naturais (Floresta Ombrófila Densa, Floresta Ombrófila Densa Aluvial) e que em 2005 a classe agricultura tornou-se a classe de maior expressão na bacia, com um aumento de aproximados 518,11% da área inicial da pesquisa.