Mudanças de uso da terra e emissão de gases de efeito estufa na Amazônia Legal.

Abstract

The risks that global warming brings to humanity make it necessary to carry out studies that improve the understanding of how the various sectors built with greenhouse gas (GHG) emissions into the atmosphere. Here, we assess the effect of land-use change on GHG emissions associated with increased temperature and soil N input. In addition, we also surveyed the main GHG emission routes through a literature review. The results show that the evaluated systems (native forest - MN, intensive pasture - PI, extensive pasture -PE and agricultural - AG) when only due to land use behave as emitters of nitrous oxide (N2O) with an average of 107.67 μg N2O.g dry soil-1

and methane (CH4) consumers with an average of -146.5 μg CH4.g dry soil-1 , in addition, rising soil temperature also boosted emissions N2O, and the temperature of 45 °C generated a N2O production 42 and 22 times higher in the PE and AG systems respectively compared to the average of the MN system. Regarding methane at temperatures of 45 °C, it generated an increase in consumption with an average of -452 μg CH4.g of dry soil-1

, equivalent to 1.92 and 7.38 times the average transmission capacity compatible at temperatures of 25 and 35 °C respectively. The N input results surprised that the increase of N in the soil generated a higher N2O emission, in which doses of 180 and 270 Kg.N.ha-1

produced 5 times more than the

average of inputs of 0 and 90 Kg. N.ha-1

, as for CO2, the input of 180 Kg.N.ha-1

stood out the

most, with an average of 1094 μg CO2.g of dry soil-1

. Depending on the N input, the systems

behaved as methane consumers (average of -301 μg CH4.g of dry soil-1

), except for the intensive pasture system without N application. The emission behaviors found in incubations controlled are similar to behaviors observed in works extracted from the review, thus being possible, supporting the raised hypotheses.