Gross primary productivity by remote sensing in the Serra das Confusões National Park, Piauí, Brazil

Abstract

The increase in anthropogenic CO2 emissions has raised the Earth's surface temperature in an anomalous and unprecedented way. Among the activities that contribute most to these increased emissions is the burning of fossil fuels and the change in land use. Part of these emissions are absorbed by terrestrial ecosystems, potentially productive and important carbon sinks (C) among them, we can mention the seasonally dry tropical forests (SDTF), which are found mainly in the Caatinga biome. Although little explored, the role they play in the global carbon (C) cycle is not negligible. Therefore, this research aimed to evaluate the seasonal behavior of biophysical variables and their effect on gross primary productivity (GPP) in a Conservation Unit in the Caatinga biome. The study area is located in the Conservation Unit (UC) of the Serra das Confusões National Park, located in the southwest region of the state of Piauí. Data for the years 2010–2020 were obtained from the MODIS sensor, which is inserted in the Terra satellite. Data on air temperature, precipitation, relative humidity and global solar radiation were obtained from the National Institute of Meteorology. According to the results obtained, the dynamics of GPP is modulated by the seasonal distribution of precipitation, presenting an average value of 5.53 gC m−2 day−1 in the months of higher precipitation and 1.43 gC m−2 day−1 in the period of lower precipitation. Additionally, precipitation also exerts a strong influence on vegetation status, as observed from the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Leaf Area Index (LAI) the maximum values observed during the rainy season, reflecting directly on the radiative and water components. However, even subjected to adverse environmental conditions, the potential of the area as a sink for C. Thus, in a future scenario of projected climate changes, and considering the vulnerability of these ecosystems, studies that evaluate the seasonal behavior of its structure and functioning is of fundamental importance for the knowledge of its resilience mechanisms and also as a contribution to the implementation of public policies that promote the conservation of the ecosystem.