Uso de dinâmica de sistemas para simulação de remoções de gases do efeito estufa em floresta de eucalipto

Abstract

This study aimed to develop a model of environmental management for monitoring and evaluation of net removals of greenhouse gases (GHG) by sinks. The determination of these removals is given by detailing the calculation of removals of carbon by forests, deducted GHG emissions occurring within and without the geographic boundaries of the project and the GHG removals by baseline. System Dynamics was used and evaluated as simulation technique for the carbon credits quantification from projects of the Clean Development Mechanism (CDM), which revealed itself adequate for the results obtained and its sensitivity to regional characteristics, reflected in the evaluation performed. By using the System Dynamics growth forests of eight regions in the state of Minas Gerais in Brazil has been modeled, with different soil and climatic characteristics dissimilar, evidencing its efficiency as simulation technique. The model was sensitive to regional characteristics, where the difference in forest inventories at the end of a cycle of 30 years with cutting rotations of 7 years was 45.1% among the regions best and worst result. It has been found that the cutting rotations are not always cause a larger stock of sequestered CO2 accumulated, it is possible to obtain a gain of 21.0%. Further GHG emissions occurring within the geographic boundaries of the project were modeled, detailing the four sources of emissions: fuel burning, biomass loss in site preparation and conversion to reforestation, biomass burning due to accidental fires, and N2O emissions by the application of nitrogen (fertilization). It was found that emissions from fuel burning is the largest contributor to GHG emissions occurring within the geographic boundaries of the project. The modeling of GHG emissions occurring outside the geographic boundaries of the project (Leakage) involves the burning of fuels and displacement of economic activities that were based on the land prior to project implementation. The burning of fuel occurs in the transport of seedlings, fertilizer, labor, wood harvested outside the project area, and the inspection and monitoring of field activities. By the simulations, it was found that these emissions are insignificant. The final simulations execute the accounting of net GHG removals around the reforestation project. For the simulated conditions is large balance of carbon credits being found for one of the study areas, with rotating cutting seven years, a final balance of 69,061,720 units of carbon credits. The results showed that the cutting rotations adopted by the company do not result in higher sales of carbon credits.