Dinâmica de uso e cobertura da terra em floresta tropical seca no sertão pernambucano

Abstract

In view of the increasing degradation that the Caatinga suffers in recent years, mainly in Pernambucano, this work aimed to map the disturbance in dry tropical forest using medium resolution images in the city of Salgueiro-PE. For this, images of LANDSAT 5 satellite were used in the 1998 and 2008 periods, and LANDSAT 8 to 2018. All scenes were georeferenced by the Datum SIRGAS 2000 and the bands used were 5, 4 and 3 for LANDSAT 5 , and the bands 6, 5 and 4 for LANDSAT 8, generating the classification of six classes (forests, agriculture, exposed soil, water bodies, riparian forest and infrastructure) using the QGIS software and the Semi-Automatic Classification Plugin (SCP). The accuracy of the maps was verified by the Kappa coefficient. The three-year maps were crosschecked to quantify remaining forest, forest expansion and deforestation. The Kappa index found for 1998 was 0.72, for 2008 and 2018 it was above 0.8, indicating very good accuracy for 1998 and excellent for 2008 and 2018. In these 20 years, classes that declined in size were forests, exposed soil, bodies of water and infrastructure, being a perimeter of 48.2 km², 84.9 km², 9.4 km² and 16.7 km², respectively. While agriculture and riparian forest increased 81.0 km² and 78.1 km², respectively. The decrease of the exposed soil is due, mainly, to a period of extreme drought in 1998, where there was only rainfall in the first two months. The decrease of the forests is due to several factors, such as population increase, vegetal extraction in the region, an industrial pole of red ceramics and the transformations of the Caatinga in agricultural areas. When observed the changes that occurred in the classes in these 20 years, the remaining forest was 438.1 km², the forest expansion of 181.1 km² and the deforestation of 229.5 km², indicating a good regeneration capacity of the forests and a damaging process of deforestation in this municipality. Therefore, it is concluded that Salgueiro underwent intense anthropic actions harmful to vegetation during 1998 and 2018, provoking deforestation, which provides socioeconomic and environmental problems, thus showing the urgent need for efficient public action.