Environmental analysis of an urban forest fragment, Alvorada municipality, Rio Grande do Sul, Brazil

Abstract

This study was developed in a forest fragment named “Cinturão Verde”, in an urban area of Alvorada municipality, Rio Grande do Sul State. It is an area with irregular topography and illegal habitations, with consequent problems related to garbage deposition, sewerage and deforestation. The objective of this study was to characterize social and environmentally the local human population and to identify the influence of urbanization over this time. From the prodution of land use images, five sample stations were demarcated along Nunes creek. Water quality characterization of the creek, floristic and phytophysionomy composition and richness and abundance of birds and arthropods were sampled during October and November 2003, with a characterization of local human population concerning its sociocultural and environmental perception about the forest fragment. Regarding chemical and biological water analysis, results indicated high eutrophization degree due, probably, to lack of basic sanitation. Despite the impacts, the forest fragment still presents some biotical integrity, reflected by the representativity of the considered groups. It was verified, for example, that 14.8% of bird species contribute to seed dispersion of 67% of tree species. However, we evidenced loss of forested area due to urbanization. Trails and garbage deposition in the forest decrease undestory area, restricting its natural regeneration. Results obtained from the environmental perception analysis indicated lack of integration of the local human population with the forest fragment. The increase of local insecurity was the main negative aspect pointed, but inhabitants wished a suitable recreation area. The long term sustainability of this forest fragment will occur through a conection with other near forested areas. Also, it is important for conservation area to stimulate environment educational programs to sensitize the people about the value of the local environment.