Changes in riparian forest cover from 1966 to 2017 along the Paraíba do Sul River between Jacareí and Queluz, São Paulo, Brazil

Abstract

This study is based on the assumption that beginning with the passage of the Forest Code in 1965, which was revised by the law of 2012, the Permanent Preservation Area (PPA) of Paraíba do Sul River, PSR, is currently recuperated and preserved. In this context, the objective of this study was to: 1) conduct a temporal survey with respect to the rate of change of gains and losses of forest cover during the years 1966, 1977 and 2017; and, 2) do a spatial analysis in relation to this rate of change. This study was conducted along the stretch of the PSR between the municipalities of Jacareí and Queluz. Maps were used from the Brazilian Institute of Geography and Statistics - IBGE (1964-1966), the Geographic and Cartographic Institute of the state of São Paulo – IGC-SP (1978) (IGC), and high resolution images from the Pléiades satellite (2017). For the spatial and temporal analyses of the study area, geoprocessing techniques were used to quantify the area occupied by forest in two: 100 m buffer strips of the PPA, and in buffer strips of 1,000m, starting from each bank of the river. With respect to forest cover, measurements of its total and average size, proportion, gain or loss, and distance between nearby fragments were made. The results indicate that, from the decade of the 1960s to 2017, forest cover grew from 5.3% to 21%, and from 2% to 13% in the strips of 100 and 1,000 meters, respectively. With respect to areas registered from 1960, there was a reduction of 691 hectares, principally of large areas of remaining forest. However, a portion of this forest area was still present in 2017, but most of this forest was in the area 1,000 m from the riverbanks. These results will aid in the planning for establishment of priority areas for conservation of the riparian forest of the PSR. Through analysis of distances between forest fragments, empty spaces devoid of forest cover were identified, and in some cases these spaces were indicated as priority areas for recuperation. The results are discussed in the context of public policies and the periods of economic development that were drivers of landscape changes in the Paraíba do Sul Valley in the São Paulo region. In conclusion, the results demonstrate that the riparian forest of the PSR has slowly recuperated but is still far from being in compliance with current Brazilian legislation. This study will be an important aid in compliance activities conducted by public authorities in permanent preservation areas in the São Paulo PSR. An ample and refined survey of consolidated and fallow areas is suggested so that mitigation and compensation activities can be proposed for the PSR riparian forest that will promote the conservation of the quality of its water and biodiversity resources.