Acessibilidade / Reportar erro

Spatial analysis of forest fragments in the Itapemirim River Basin, ES

The objectives of this study were to map and analyze the structure of forest landscape in a representative area of Itapemirim river basin, ES, through indexes of landscape ecology. The mapping of forest fragments was obtained using image interpretation techniques on a scale of 1:1500 of the ortho-image-mosaic of the year 2007. For the ecology metrics calculation, the extension Patch Analyst was used within the computational application ArcGIS 9.3. In general, 3285 forest fragments were found in all the area, representing 17% of the forest covering. The mapped fragments were divided into size classes, considering as small those fragments smaller than 5 ha, average fragments have size between 5 and 50 ha, and large fragments are larger than 50 ha. The small fragments were found in greater number (2,236), followed by average fragments (749), and finally the large fragments, comprising only 100 spots. The number of fragments of each size class has an inverse relationship with the contribution in area of the same class within the forest fragmentation. Quantitative characterizations through landscape metrics were made with groups of area index, density and size, shape, proximity and central area, which was obtained from different simulations of edge effect (20, 40, 60, 80, 100, 140 and 200 m). For all the indexes there were differences on size classes of forest fragments. Most of the basin forest fragments are small, less than 5 h, and the distance of edge 100 meters completely eliminates the central area of these fragments. Although large fragments present the most irregular shapes, they have a higher index central area even under the effect of the greater distance of the edge effect.

Forest Fragmentation; Geographic Information Systems; Indexes of Landscape Ecology


Sociedade de Investigações Florestais Universidade Federal de Viçosa, CEP: 36570-900 - Viçosa - Minas Gerais - Brazil, Tel: (55 31) 3612-3959 - Viçosa - MG - Brazil
E-mail: rarvore@sif.org.br