Dinâmica de alterações na paisagem à luz do novo código Florestal: estudo de caso da Bacia Hidrográfica do Rio Santa Maria - RS

Abstract

The past 50 years have been marked by changes in ecosystems caused by man, in a fast and extensive way when compared to any equivalent time interval in History. These actions led to several changes in biological systems. As a legal instrument for the protection and recovery of native flora and fauna, in our country we have the Forest Code Legislation. With the revising of this legislation, in 2012, the New Forest Code was approved (Law No. 12,651 / 12), replacing the former one of 1965 (Law No. 4,771 / 65). The occurrence of Pampa as a biome in Brazil is restricted to the state of Rio Grande do Sul, where it occupies about 63% of its territory and has continuity in the neighboring countries of Uruguay and Argentina. As geoprocessing is an important tool for the analysis of the use and occupation in geographic spaces, it allows the verification of these uses with less cost and time for an area of concern. Orbital sensors widely used in the study of natural resources are Thematic Mapper (TM), on board the Landsat 5 satellite, and Operational Land Imager (OLI), on board the Landsat 8 satellite, which appear for nearly 30 years of terrestrial surface data. In order to try to understand the consequences of the changes caused in the landscape by the New Forest Code Legislation and if there were really notable changes in the landscape, the present research was developed in the hydrographic basin of Rio Santa Maria, located southwest of the State of Rio Grande do Sul. The research was conducted by using Landsat 5 satellite images, referring to the years 1984, 1996, 2008 and 2011, and from Landsat 8, referring to the years 2015 and 2019. Using the QGIS software and the Semi-Automatic Classification Plugin (SCP), supervised classification of land cover and use was carried out, with the differentiation among classes of forest / tree vegetation, agriculture, exposed soil, water and fields. With the reports of the areas of the classifications carried out, comparative tables were elaborated and changes in the landscape were evaluated, contextualizing the impact of the implementation of the new environmental law, validated from the year 2012. It is understood that the studied area shows conformity concerning to the item “attendance limit of 20% of RL ”according to the New Forest Code Legislation, as the classes of land use representative of the natural vegetation of the Pampa biome compose a percentage above from that one required for the classification. However, this does not mean that all rural properties have the minimum percentage of RL required by law. Changes in land use have been shown to vary according to economic opportunities, showing that different crops vary according to their economic favoring.