Produtividade primária bruta para áreas de cana-de-açúcar e cerrado na bacia hidrográfica do Mogi-Guaçu-SP.

Abstract

The forests play an important role in the mitigation of climate change by acting as large carbon sinks through their primary productivity. The gross primary productivity corresponds to the total carbon fixed by the vegetation through the photosynthesis process. In this way, the objective of this work was to evaluate the carbon fixation capacity in the Mogi-Guaçu river basin, especially in the cerrado and sugar cane areas in the municipality of Santa Rita do Passa Quatro - SP, based on estimates made by means of remote sensing techniques and validate the results according to measurements performed by the Eddy Coariance method. For the gross primary productivity determination, the radiation and energy balances were determined using TM - Landsat 5 and OLI / TIRS - Landsat 8 images using the SEBAL methodology, for further comparison with the gross primary productivity of the product MOD17A2H and the estimated by the eddy covariance method. Images were selected without clouds in the years 2005 and 2015, and measurements of the CO2 flux obtained in two micrometeorological towers installed in the area of sugarcane and Cerradão were used. The Landsat images provided greater agreement between the gross primary productivity data in relation to those obtained in the micrometeorological towers, unlike the values generated with the MOD17A2H. The seasonality of the gross primary productivity shows good correspondence with the rainfall data recorded in the study area. The cerrado has behaved as a carbon sink throughout the year, even with below-average precipitation, which it evidences the need for preservation of this biome.