Variação espaço-temporal da produtividade primária líquida da caatiga

Abstract

The Brazilian semiarid region is represented by the Caatinga, which occupies approximately 10% of the national territory. The Caatinga has been identified as one of the most important wildlife regions in the world, containing the greatest biodiversity among dry forests. The objective of this study was to evaluate the impacts of land use change on the Net Primary Production (NPP) of the Caatinga, through remote sensing data. The Normalized Difference Vegetation Index (NDVI) data were obtained from the Google Earth Engine platform. The NPP was estimated using the methodology of Montheith (1977) and extracted from the GEE database, which was determined by MODIS. To assess the impacts of land use change on the NPP, two land use maps for the years 2001 and 2022, respectively, derived from MapBiomas, were analyzed. It was observed that the lowest NDVI values were between the years 2010 to 2015, periods of great droughts. The highest NPP value was recorded in 2011, which subsequently decreased, reaching its lowest value in 2013. It was possible to observe how climate variables, temperature and precipitation influenced NPP over the years. Precipitation is a fundamental climate variable for determining the health of vegetation. Based on the survey derived from MapBiomas and its classifications, it is noted that the forest area suffered a significant loss, going from an area of 494,093.1 km² to 465,531.5 km² in the second period, thus impacting the amount of carbon sequestered, with a value of 400 TgC in the first period and 377 TgC in the second, thus suffering a reduction in carbon sequestration. An increase of 0.1% in water bodies was also observed in the second period, since it was a period of the La Niña phenomenon. It is well known that the Caatinga has been suffering from land use and occupation, and it is necessary for the competent authorities to create mitigating policies in order to preserve this biome.