Spatio-temporal dynamics of the active microbiota on the methane cycling in an Amazonian soil after forest-to-pasture conversion

Abstract

The Amazon watershed constitutes 40% of the world's rainforest, participating in global climate regulation and atmospheric gas-flow, including greenhouse gases (CO2, CH4, N2O). More than 15% of the Amazonian forest have been converted into agricultural and livestock areas, especially about 80% are occupied with pasture. The forest-to-pasture conversion have impacted on the soil microbiota and its relationships with the climate. This work aims to evaluate the impact of forest-to-pasture conversion in the dynamics of consumption and production of CH4 by the active microbiota of an Amazonian soil. For this purpose, biogeochemical, molecular and isotopic methods will be combined for the characterization of methanogenic (acetoclastic and hydrogenotrophic) and methanotrophic microbial communities, and their relationships with CH4 flow. It is proposed a spatial (biogeographic) and temporal (seasonal rainfall) approach in soils under primary forest, and converted to pastures of different ages in the Brazilian Western Amazon. Auto chamber for CH4 flux measurement, connected to a quantum cascade laser spectrometer (real-time isotopic analysis), along with massive DNA sequencing will provide unprecedent data for Amazonian soils, which will be combined using bioinformatics and statistical methods. It is expected that the results of this study will elucidate in more detail the role of microbial communities involved in the production and consumption of CH4 in soils under different uses in the Amazon region, integrating molecular and isotopic analyzes. These results may support new management strategies in tropical soils such as those from Amazonia, seeking for mitigation of CH4 emissions. (AU)