Abstract
AbstractSeasonal floodplains in the Amazon basin are important sources of methane (CH4), while upland forests are known for their sink capacity. Climate change effects, including shifts in rainfall patterns and rising temperatures, may alter the functionality of soil microbial communities, leading to uncertain changes in CH4 cycling dynamics. To investigate the microbial feedback under climate change scenarios, we performed a microcosm experiment using soils from two floodplains (i.e., Amazonas and Tapajós rivers) and one upland forest. We employed a two-factorial experimental design comprising flooding (with non-flooded control) and temperature (at 27 °C and 30 °C, representing a 3 °C increase) as variables. We assessed prokaryotic community dynamics over 30 days using 16S rRNA gene sequencing and qPCR. These data were integrated with chemical properties, CH4 fluxes, and isotopic values and signatures. In the floodplains, temperature changes did not significantly affect the overall microbial composition and CH4 fluxes. CH4 emissions and uptake in response to flooding and non-flooding conditions, respectively, were observed in the floodplain soils. By contrast, in the upland forest, the higher temperature caused a sink-to-source shift under flooding conditions and reduced CH4 sink capability under dry conditions. The upland soil microbial communities also changed in response to increased temperature, with a higher percentage of specialist microbes observed. Floodplains showed higher total and relative abundances of methanogenic and methanotrophic microbes compared to forest soils. Isotopic data from some flooded samples from the Amazonas river floodplain indicated CH4 oxidation metabolism. This floodplain also showed a high relative abundance of aerobic and anaerobic CH4 oxidizing Bacteria and Archaea. Taken together, our data indicate that CH4 cycle dynamics and microbial communities in Amazonian floodplain and upland forest soils may respond differently to climate change effects. We also highlight the potential role of CH4 oxidation pathways in mitigating CH4 emissions in Amazonian floodplains.
Funder
Fundação de Amparo à Pesquisa do Estado de São Paulo
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Publisher
Springer Science and Business Media LLC
Reference98 articles.
1. Alvares CA, Stape JL, Sentelhas PC, Gonçalves JLM, Sparovek G. Köppen’s climate classification map for Brazil. Meteorol Z. 2013;22(6):711–28.
2. Alvarez DO, de Souza LF, Mendes LW, de Moraes MT, Tosi M, Venturini AM, et al. Shifts in functional traits and interactions patterns of soil methane-cycling communities following forest-to-pasture conversion in the Amazon Basin. Mol Ecol. 2023;6:66.
3. Apprill A, McNally S, Parsons R, Weber L. Minor revision to V4 region SSU rRNA 806R gene primer greatly increases detection of SAR11 bacterioplankton. Aquat Microb Ecol. 2015;75(2):129–37.
4. Basso LS, Marani L, Gatti LV, Miller JB, Gloor M, Melack J, et al. Amazon methane budget derived from multi-year airborne observations highlights regional variations in emissions. Commun Earth Environ. 2021;2(1):246.
5. Bento MDS, Barros DJ, Araújo MGDS, Da Róz R, Carvalho GA, do Carmo JB, et al. Active methane processing microbes and the disproportionate role of NC10 phylum in methane mitigation in Amazonian floodplains. Biogeochemistry. 2021;156:293–317.