Diagnóstico e riscos ambientais relacionados à fragmentação de áreas naturais e semi-naturais da paisagem. Estudo de caso: município de Araraquara, SP

Abstract

The study of the landscape dynamics involving the modifications of the land use and its relationships with the physical, biological, socioeconomic and political aspect, represents an essential condition in the definition of viable strategies in the environmental planning. In this context, it was carried out the study of the landscape dynamics of the municipal district of Araraquara with base in the spatial modifications of the land cover, in the perspective to obtain information to subsidize the formulation of public politics and conservation strategies for the local landscape. The methodological procedure involved the the environmental diagnosis of the current soil use current, with emphasis in the loss of the environmental quality of the local landscape resulting from the fragmentation and loss of the natural land cover. Based on an image LandSat 7 and in the use of the software SIG IDRISI Version 32 and MapInfo Professional Version 7.5 thematic letters of the study area were elaborated related to the road net, to the classification of the soil use and the qualitative and quantitative condition of the fragmentation of the natural and semi-natural vegetation. Each fragment (just the largest than 1 ha) received a specific code (ID) and then, calculated your area, perimeter, border area, interior border area and type of land cover. Through the thematic letter of the soil use it was accomplished the environmental quality analysis of the 10 landscape management units in the study area. The environmental diagnosis of the landscape was made with base in the use of vulnerability environmental indexes related to the water resources and natural and semi-natural vegetation components, in your different aspects of area, form and distance among the fragments. It was identified 13 types of soil use classified in 6 classes of land cover identified as: natural and semi-natural areas, silviculture, agricultural, urban and suburban areas, mining and aquatic environment. The types of natural and semi-natural vegetation were represented by the vegetation of Savannah, Cerradão, Seasonal Semidecidual Forest, Alluvial Seasonal Forest (riparian forest), Swamps and flooded areas and Vegetation of hillside areas and tops of hills, and represent about 10.59% (10,725.82 ha) of the total area of Araraquara municipal district. The class agricultural areas constituted the predominant type of soil use with an area of 71,465.87 ha, representing about 70.56% of the total area of the municipal district of Araraquara. Most of the fragments (192) of natural and semi-natural vegetation present smaller area than 10 ha, evidencing a high degree of landscape fragmentation resulting from the local development pressure. Four fragments, considered as "Source Areas", particularly important in terms of the extension area, of the circular format and, mainly for its values of interior border area, should be considered priority in terms of strategies for the recovery and conservation of the land cover and for the maintenance and protection of the environmental quality of the water resources in the municipal district area. The Vulnerability Environmental Index of the landscape of the municipal district of Araraquara reflects a scenery strongly committed by the economical development supported by the sugar-cane expansion, resulting in biodiversity and habitats loss due to the qualitative and quantitative condition of the fragmentation of the natural and semi-natural vegetation, and in the compromising of the water resources quality in face to the current impacts of the soil use. The disturbances in the landscape resulting from the soil uses (deforestation, mining activities, agriculture, urbanization and rod net infrastructure) were the key-process that allowed to compose the landscape environmental diagnosis of the municipal district of Araraquara, for the interval of time of this study.