Geotecnologias aplicadas ao uso e cobertura do solo e à composição florística da microbacia do Rio da Cruz-PB.

Abstract

Natural resources are exploited by man and the impacts of these disorderly actions are perceptible in ecosystems. In general, the vegetation present in the river basins is exposed to the various types of anthropic action. The effects are found in the reduction of water abstraction, causing the impoverishment of the flora and fauna biodiversity, productivity and scenic beauty, especially in the semi-arid region of Northeast Brazil, where water is a determining factor. Despite the existence of the Forest Code and its importance, the riparian forests of water basins and micro-basins are increasingly being exploited in violation of the Forest Code. Geographic Information Systems (SIG) and Remote Sensing (SR) techniques are important for the management of natural resources, since they can assist in the planning, monitoring and mapping of land use and land cover. In the semi-arid region of northeastern Brazil, geotechnologies can be used to detect the landscapes and facilitate the implementation of appropriate management techniques. The objective of this work was to characterize the soil use and cover of the Rio da Cruz water basin, to study the floristic composition of the arboreal and herbaceous components and to verify the degree of occupation of the banks of two stretches of Rio da Cruz (PB). The soil use and cover of the microbasin were classified using satellite images of the years 2001, 2009 and 2017, in the rainy and dry periods. The floristic composition of the arboreal and herbaceous strata of each year was determined by plot marking and walking techniques, respectively. The classification of the images of the watershed of the Rio da Cruz resulted in seven classes: Arboreal Caatinga, Arboreal Shrub Caatinga, Anthropized Caatinga, Pastures and Agriculture, Rock Outcrops, Bodies of Water and Buildings. A reduction of the Arboreal Caatinga and increase in the other classes of Caatinga and in the Pastures and Agriculture when comparing the years and periods of 2001 and 2017 was observed. The applied techniques are relevant for classification of the use and soil cover of the semi-arid region in conditions of precipitation regular, but in years of higher precipitation the tree vegetation is overestimated and may make it difficult to identify the targets, especially in the rainy season. It was verified the existence of few arboreal individuals and wide use of the Rio da Cruz margins for agroforestry activities, indicating the need to enforce the Forest Code and the adoption of mitigating measures to mitigate the impacts caused by anthropic action.