Increased soil moisture intensifies the impacts of forest-to-pasture conversion on methane emissions and methane-cycling communities in the Eastern Amazon

Andressa M Venturini; Naissa M S Dias; Júlia B Gontijo; Caio A Yoshiura; Fabiana S Paula; Kyle M Meyer; Fernanda M Nakamura; Aline G da França; Clovis D Borges; Jos Barlow; Erika Berenguer; Klaus Nüsslein; Jorge L M Rodrigues; Brendan J M Bohannan; Siu M Tsai

doi:10.1016/j.envres.2022.113139

Increased soil moisture intensifies the impacts of forest-to-pasture conversion on methane emissions and methane-cycling communities in the Eastern Amazon

Environ Res. 2022 Sep;212(Pt A):113139. doi: 10.1016/j.envres.2022.113139. Epub 2022 Mar 23.

Authors

Affiliations

¹ Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, 13416-000, Brazil; Princeton Institute for International and Regional Studies, Princeton University, Princeton, NJ, 08544, USA. Electronic address: andressa.venturini@alumni.usp.br.
² Environmental Biogeochemistry Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, 13416-000, Brazil.
³ Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, 13416-000, Brazil.
⁴ Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, 13416-000, Brazil; Department of Biological Oceanography, Oceanographic Institute, University of São Paulo, São Paulo, SP, 05508-120, Brazil.
⁵ Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403, USA; Department of Integrative Biology, University of California - Berkeley, Berkeley, CA, 94720, USA.
⁶ Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
⁷ Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK; Environmental Change Institute, University of Oxford, Oxford, OX1 3QY, UK.
⁸ Department of Microbiology, University of Massachusetts, Amherst, MA, 01003, USA.
⁹ Department of Land, Air, and Water Resources, University of California - Davis, Davis, CA, 95616, USA.
¹⁰ Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403, USA.

PMID: 35337832
DOI: 10.1016/j.envres.2022.113139

Abstract

Climatic changes are altering precipitation patterns in the Amazon and may influence soil methane (CH₄) fluxes due to the differential responses of methanogenic and methanotrophic microorganisms. However, it remains unclear if these climate feedbacks can amplify land-use-related impacts on the CH₄ cycle. To better predict the responses of soil CH₄-cycling microorganisms and emissions under altered moisture levels in the Eastern Brazilian Amazon, we performed a 30-day microcosm experiment manipulating the moisture content (original moisture; 60%, 80%, and 100% of field capacity - FC) of forest and pasture soils. Gas samples were collected periodically for gas chromatography analysis, and methanogenic archaeal and methanotrophic bacterial communities were assessed using quantitative PCR and metagenomics. Positive and negative daily CH₄ fluxes were observed for forest and pasture, indicating that these soils can act as both CH₄ sources and sinks. Cumulative emissions and the abundance of methanogenesis-related genes and taxonomic groups were affected by land use, moisture, and their interaction. Pasture soils at 100% FC had the highest abundance of methanogens and CH₄ emissions, 22 times higher than forest soils under the same treatment. Higher ratios of methanogens to methanotrophs were found in pasture than in forest soils, even at field capacity conditions. Land use and moisture were significant factors influencing the composition of methanogenic and methanotrophic communities. The diversity and evenness of methanogens did not change throughout the experiment. In contrast, methanotrophs exhibited the highest diversity and evenness in pasture soils at 100% FC. Taken together, our results suggest that increased moisture exacerbates soil CH₄ emissions and microbial responses driven by land-use change in the Amazon. This is the first report on the microbial CH₄ cycle in Amazonian upland soils that combined one-month gas measurements with advanced molecular methods.

Keywords: Climate change; Land-use change; Metagenomics; Methanogens; Methanotrophs; Microbial ecology.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Climate
Forests
Methane* / analysis
Soil Microbiology
Soil* / chemistry

Substances

Soil
Methane