Análise da dinâmica de uso e ocupação do solo e estrutura da paisagem da Bacia Hidrográfica do Rio Capivari, Bahia

Abstract

Anthropogenic activities are considered to be the major cause of landscape changes, entailing the fragmentation of the native vegetation and consequently causing biodiversity loss. Studying the land use and occupation dynamics while examining a river basin is very important due to its social, economical and environmental dimensions. Thus, the purpose of this paper is to obtain information about the biotic and abiotic environment of Capivari river basin (one of the most important sub-basins of Paraguaçu river) by mapping the land use and occupation of the area, emphasizing the native vegetation fragments which, through landscape metrics application, will give us information about its ecologic structure and function. Combining 1, 2, 3, 4, 5 and 7 bands of ETM+ LANDSAT 7 imagery and 2, 3, 4, 5, 6 and 7 bands of OLI LANDSAT 8 imagery, it was possible to create a supervised classification to obtain the land use and occupation map, through the maximum likelihood estimation method, resulting in 5 land use classes: native vegetation, exposed soil, agriculture, pasture and water. In order to analyze the Landscape structure, the Path Analyst tool was used to generate the landscape metrics: size, form, boundaries and density. The procedures were done using Arcgis software 10.2 version. The results showed that the greater class was agriculture with 35,24% and 27,24% for the years of 2000 and 2014, respectively, which represents the sugar cane crop culture at the beginning of Brazil’s colonization. The native vegetation class had the smallest difference between years, 1,6% due to the fragmentation of the area. As a consequence of the lack of vegetation, the exposed soil class increased from 17,35% in 2000 to 23,86% in 2014. The pasture, as well as the agriculture and the exposed soil classes had a increase of 5,21% among years. In general, the landscape structure analysis showed that although the fragments are rounded, most of them have a small size, therefore being vulnerable to the edge effect.