ALTERAÇÕES NA PAISAGEM E COMPOSIÇÃO FLORÍSTICA DE MATAS CILIARES NA ILHA DE SÃO LUÍS, MARANHÃO

Abstract

The island of São Luís, like other coastal areas in the world, is economically attractive and has a pattern of occupation and land use dictated by population growth. The vegetation, which is directly affected, presents itself in different typologies in intensely urbanized and anthropized areas. Among the vegetation types are the riparian forests, present along water courses, important for water resources, therefore categorized, according to the Forest Code, as Permanent Preservation Areas - APPs. This work aims to survey the current composition and the changes suffered in the original vegetation of the riparian forest of the Pimenta River. Vegetation sampling was performed by the method of plots in dimensions of 10mx20m (200m²). The plots were identified by means of numbered plates, with date and place. Along 21 sample plots in the riverside strip, plant species, number of individuals, height, Circumference at the Heigth of the Chest, successional stages of vegetation and other environmental and botanical characteristics were recorded. Within the possibilities of access and work, the characterization of the Pimenta River along its length was carried out, in relation to its current vegetation, its conformation, alterations and state of conservation of its riparian forest. In addition to the current floristic composition surveyed by sampling, species that are indicators of vegetation conservation and indicators of environmental changes were defined. Through the GIS environment - Geographic Information System - thematic maps were produced through the MDE-Digital Elevation Model, derived from the image, Shuttle Radar Topography Mission (SRTM) from the year 2000, with a spatial resolution of 30m. A single source of the Rio Pimenta was located, classified as disturbed in its floristic composition, water flow and general state of the environment. On its banks, the Pimenta River is competing for space with human constructions and occupations. The general floristic composition presents 70% of species not expected for environments conserved in gallery forest vegetation. In number, per group of individuals of secondary species, the progress in the alteration of these environments is evident. The number of individuals of invasive species along the banks of the river is worrying. Regarding the representative plant families of the species present, in greater number those of the Palmae family. Adult individuals were recorded in greater occurrence than adults in the upper course region, although juveniles are even more numerous in the lower course of the river, where the changes are more severe, evidencing nature's effort to regenerate the vegetation cover.