Linking methane flux and microbial diversity in Amazon soils across forests-to-pasture conversion: a multidisciplinary approach

Abstract

The Amazon basin constitutes 40% of the world's rainforest, participating in global climate regulation and atmospheric gases fluxes including methane (CH4). However, more than 15% of the Amazonian forest has been converted to agricultural use, of which 80% is pastures. The Amazon soils are also important sinks of atmospheric CH4, but the forest-to-pasture conversions turn then in net emission sources. This phenomenon occurs due to transformations of the methanotrophic and methanogenic microbial communities driving methane cycle, likely associated with alterations in physicochemical properties of the soil, although these relationships remain unclear. This internship would be part of our doctorate plan at CENA-USP (FAPESP fellowship 2016/24695-6), under the supervision of Prof. Dr. Siu Mui Tsai, focused on the characterization of the structural and functional transformations of the methane-cycling microbial communities, across the land-use change of forests to pastures. For this purpose, a multidimensional study will be conducted, including CH4 fluxes measurement, CH4 stable-isotope ratios (of C and H), and soil physicochemical properties characterization, coupled with high-throughput amplicon sequencing of 16S rRNA gene from bacteria and archaea, and bioinformatic data analysis. The dataset will be generated from samples (soil and gases) collected in areas of forest and pastures at the Tapajós National Forest, in the Eastern Amazon (Brazilian State of Pará). The sampling will be performed during the rainy and dry seasons, and soil profiles (0, 10, 20, 30, 40 cm) will be considered. Yet, this multi-dimensional analysis of the microbial methane cycle requires a multidisciplinary approach, therefore this internship proposal at the School of Environmental Sciences, University of Guelph (Ontario, Canada) is based on the broad experience of working together achieved by the Laboratory of Greenhouse Gases (Prof. Dr. Claudia Wagner-Riddle Lab) and the Soil Microbial Ecology Laboratory (Prof. Dr. Kari Dunfield Lab). In addition, this work will initiate the collaboration between our research teams in Brazil and Canada, as a platform for future research involving temperate and tropical ecosystems. (AU)