Environmental Indicators in Forest Fragments From Urban Watersheds

Abstract

Accelerated urbanization in Brazil promoted the rapid growth of cities and, in most cases, was not based on adequate land use planning. The result was the intense fragmentation of the landscape, causing the destruction and fragmentation of forest habitats, which were restricted to small and isolated remnants. In this sense, the present study promoted an analysis of the environmental quality of vegetation fragments in the sub-basins of Ribeirão Anhumas, Campinas, São Paulo, Brazil by calculating and interpreting the circularity index (CI), in order to define the format of the fragments, connectivity/ isolation and the use and occupation of the environment as well as area and location, in order to promote the diagnosis and identification of priority areas for the implementation of restoration and environmental management actions. It was identified, therefore, that the remaining vegetation of the upper, middle and lower sub-basins is divided between small and medium unconnected fragments of which 56.2% and 24.2% presented an elongated and moderately elongated shape, respectively, and, therefore, high susceptibility to external interference and edge effects. On the other hand, high urbanization evidenced mainly in the high-level limits forest management projects, since the fragments are surrounded by built areas.

Environmental quality in urban forests in campinas – Sãpaulo State/Brazil

“…Using these indicators, the Environmental Quality Index was calculated by summing the weighted values associated with the indicators, for each remnant and according to their classification (Table 2) and fragments [31].…”

“…Thus, it was identified that in the upper, Figure 5: Resultados relativos à distância do vizinho mais próximo e conectividade. middle and lower regions, respectively, 66.7%, 83.3% and 88.0% of the fragments present connectivity [31].…”

“…It is worth remembering that the circularity index analyzes the similarity of the shape of the fragment to a circular shape that, given its regularity, guarantees greater distance from the edges in relation to the center; therefore, values closer to 1 indicate, a priori, greater protection to the nuclear areas of the fragments. Thus, more than 50% of the fragments in each region of the river basin can be classified as moderately elongated, according to reference [31] and presented in Fig. 3c.…”

“…It is also emphasized that the association between reduced area and irregular shape is one of the main causes for the decrease of the nuclear area in the forest fragments [8]. In this way, these are essential indicators for the management and monitoring of forest fragments, especially those under high pressure, such as urban remnants [31]. Sampaio [5] Table 3: Criterion for classification of the environmental quality.…”

“…This classification includes deforested and/or degraded areas, streets, exposed soil, buildings, etc. Changes in land use and occupation, especially for uses of major modifications such as urbanization, can promote disturbances in forest ecosystems, as well as interfere with the intensity of fragmentation, the remaining vegetation cover and the size of the fragments [31].…”