Caracterização espacial dos fragmentos florestais em Recife/PE.

Abstract

The growth of cities and the consequent increase in the population density bring forth changes in the natural environment reflected directly into the urban landscape. The existence of fragments of natural habitats in cities reverberates positively both in human life and in preserving ecosystems. Thereby, Landscape Ecology and its metrics aim to analyze spatial structures to understand potential dynamics and landscape structures, subsidizing urban planning and development. This way, this work aims to characterize the spatial distribution of forest fragments and their preservation and ecological relations in Recife-PE, Brazil. The land cover classification, performed from photointerpretation, was obtained from the Recife City Hall database, from the 2013 orthophoto map. The land cover classification went through analysis, reaching an accuracy of 0,88 according to the Kappa index's determination. All the forest features with at least 15m width and length were considered fragments. The fragments were divided into size classes <0,1ha; 0,1 to 1ha, 1,01 to 10ha; 10,01 to 100ha and >100ha. The total area metrics, number, median and average size of the patches were analyzed with the Patch Analyst extension for ArcGIS. It was also analyzed the fragment area by political-administrative regions (RPA) to identify the RPA's with the lower tree covering, and the edge effect's spatial influence from every 10 meters of 20 to 100m of the border was also analyzed. Besides, the proximity index between fragments went through analysis with the V-LATE extension and the relations of the size classes of the fragments with the Recife City Conservation Units with the tool Near Table. Recife showed 39,58% of its area covered with forestry fragments, in which 6,50% are smaller than 1ha, while the class >100ha contains 74,37% of the fragments' area. The three first classes suffer approximately 70% of influence from the edge effect by 20m, and the class >100ha maintains itself 43,75% without being affected by 100m. The proximity indexes determine that Recife's vegetation, in general, is connected, with few fragments in total isolation. However, there are some RPA with trees covering lower than 30%. The incidence of forest fragments in Conservation Units (UC) grows gradually together with the size classes, so that all the fragments with more than 100ha are located in UC or are directly connected to them. It was noticed three significant areas that are not included in UC and should receive government attention and that tiny fragments should be expanded to improve the connection and establishment of species. The RPA 01, 02 and 06 should receive more attention in this process, seeing that they do not have the proper tree covering.