Análise temporal da cobertura vegetal de um fragmento da RPPN Seringal Triunfo, Ferreira Gomes - Amapá

Abstract

The construction of dams became necessary for national development, the Amazon region, for having a great hydro-energetic potential, was also used for the construction of these projects. River Araguari's hydrographic basin has three hydroelectric dams (Coaracy Nunes, Ferreira Gomes and Cachoeira Caldeirão) built in its middle course, in the municipality of Ferreira Gomes, however the construction generated several problems, such as loss of territoriality, difficulties in subsistence of villages and the environment modification. However, in 1998, there was the enactment of the Seringal Triunfo National Heritage Private Reserve, which aims to conserve biodiversity. Therefore, there is a need for studies aimed at improving the knowledge of vegetation cover, which have occurred since the enactment of the RPPN. In this sense, the present study sought to understand whether there were changes in the vegetation cover in the RPPN from 2000 to 2015, after its approval and with the construction of UHE Ferreira Gomes and Cachoeira Caldeirão. For this, remote sensing data were used. Twelve images obtained from the TM/Landsat-5, ETM+/Landsat 7 and OLI/Landsat-8 satellites were used, delimiting the study area with the creation of two polygons (buffer), one located within the RPPN and another adjacent with approximately the same size. Digital processing techniques were applied to these images with the aid of pixel counting software. The Normalized Difference Vegetation Index (NDVI) was calculated, making it possible to obtain the median. The obtained results show that the image processing allowed differentiate its constituent elements (vegetal cover and exposed soil). The calculation of the NDVI medians, for the scenes between the years 2000 to 2015, in the area located within the RPPN ranged from 0,37 to 0,64 and the medians of the adjacent area ranged from 0,29 to 0,63, thus, the statistical analysis showed no relationship with the years (F1,10 = 0,02 and P = 0,87), indicating that during the analyzed period there was a stability in the vegetation cover, the same occurred for the adjacent area (F1,10 = 0,11 and P = 0,74). This stability in the area of the RPPN may be related to the role it plays in nature conservation and in the adjacent area to the stagnation of population growth in the municipality. The use of images from remote sensors proved to be a very valuable tool for the present research, even without carrying out an on-site visit, it was possible to calculate the NDVI. Therefore, it is recommended for future work to analyze the NDVI from years prior to 2000, that is, years prior to the approval of the RPPN, as well as on-site visits, for the validation of the components observed in the NDVI, for the NDVI classification to the studied locality.