Sistemas agroflorestais: uma abordagem sobre mudanças de uso e cobertura da terra e estimativa de carbono, no município de Tomé-Açu, Pará.

Abstract

The study of the biomass estimate in SAF resulting from land use and land cover changes is relevant to reduce the uncertainties regarding the estimates of carbon emissions and removals and to understand how they act in the environmental processes. This work aims to estimate the carbon stock in above-ground biomass in SAFs resulting from land useand land cover changes, in the municipality of Tomé-Açú, Pará. The interpretation and classification of the images were carried out by class discrimination. The polygons were classified into 6 ranges of size of the areas. The mapping results were edited and thematic letters were prepared.Classes of land use and land cover were quantified and mapped based on visual interpretation, application of Random Forest, quantification of area for comparisons between the mappings of the years 1990, 2000, 2010 and 2018. Additionally, an inventory was made in SAFs, regression analyzes were carried out between the biomass data of the inventory and SR, followed by spatialization of biomass for the SAFs. For the period between 1985 and 2018, the expansion of deforestation resulted in a loss of forest of approximately 298 thousand ha, with 57% of the area of the municipality. In all years, high values of polygons were observed in the range <6.25 ha and low values in the range> 50 ha. Small fragments (<6,25 ha) accounted for 15% of all deforestation, while large fragments (> 50 ha) accounted for 45%. The SAF1 class was observed to have a slight growth with 7,049 ha (1,4%) in 1990, for the year 2018 it presented 9,148 ha (1,8%). The SAF2 class had its area progressively reducedfrom 16,803ha (3,3%) in 1990, to 10,508ha (2%) in 2018. For all periods, the SAF 1 and SAF 2 classes showed persistence of less than 8%.For both SAF 1 and SAF 2, a large part of the increase was due to the advance on the areas of VS, forest and pasture. The three equations resulting from the regression analysis of SR data with inventory showed the same trend. . The total value of the carbon stock in SAFs of Tomé-açu was 41,982.52 MgC for NDWI, 42,534.28 MgC for TSAVI x NDWI and 43,094.75 MgC for B5 x NDWI. It is concluded that the analyzed period presented differences both in the temporal analysis, as in the patterns of distribution of deforestation, indicating a strong future potential for forest loss. The classification of images through GEE proved to bevalid for monitoring changes in classes of use and coverage, including SAFs. The SAFs' spectral responses follow different patterns from other types of vegetation and are altered according to the variation of biomass. The NDWI vegetation index showed greater efficiency in the prediction of above-ground biomass of SAFs.