Atlantic Forest Gross Primary Productivity Dynamics: Remote Sensing and Micrometeorological Perspective

Abstract

The Atlantic Forest, a biodiversity hotspot and critical carbon sink, is under threat from deforestation and fragmentation. This study evaluates gross primary productivity (GPP) in the Itatiaia National Park (PNI), one of Brazil's oldest conservation units, using 19 years of Moderate Resolution Imaging Spectroradiometer remote sensing data (2001–2020) and 3 years of micrometeorological tower data (2018–2020). GPP was estimated through models integrating vegetation indices (Enhanced Vegetation Index [EVI] and Normalized Difference Vegetation Index) and photosynthetically active radiation (PAR), and validated against FLUXNET data. Seasonal analysis revealed higher GPP values during the rainy season, peaking at 8.07 g C m⁻² day⁻¹ in September, while agricultural areas exhibited the highest GPP, with annual averages above 9.00 g C m⁻² day⁻¹. Temporal trends indicated a decline in GPP across all land use classes, with the most pronounced reduction in vegetative refuges (Z_mk = −1.65, P < 0.10). Among the models tested, the GPP equation using EVI and PAR yielded the highest accuracy (R² = 0.49, d = 0.89, standard error of estimate = 1.91). The study highlights the effectiveness of remote sensing and micrometeorological data in monitoring ecosystem health and underscores the role of conservation units in carbon sequestration. These findings support integrating protected areas into carbon market initiatives, emphasizing their value for biodiversity conservation and climate change mitigation.