Shifts of methanogenic communities in response to permafrost thaw results in rising methane emissions and soil property changes

Abstract

Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number. The mcrA gene clone libraries analyses indicate that Methanocellales/Rice Cluster I was predominant both in the original permafrost and in the thawed permafrost. However, only species belonging to Methanosarcinales showed higher transcriptional activities in the thawed permafrost, indicating a shift of methanogens from hydrogenotrophic to partly acetoclastic methane-generating metabolic processes. In addition, data also show the soil texture and features change as a result of microbial reproduction and activity induced by this permafrost thaw. Those data indicate that microbial ecology under warming permafrost has potential impacts on ecosystem and methane emissions.

Increasing Organic Carbon Biolability With Depth in Yedoma Permafrost: Ramifications for Future Climate Change

“…Prior to the establishment of stable CH 4 ‐producing microbial communities, GHG emissions from thawed permafrost OC are dominated by CO 2 (Knoblauch et al, ; Schädel et al, ); however, following the establishment of these communities over longer times, permafrost OC mineralized under anaerobic conditions has the potential to emit equal quantities of CO 2 and CH 4 (Knoblauch et al, ). Methanogens of the taxa Methanosarcinales , which we detected at all our sampled depths (Figure b), have been previously associated with rapid increases in number and subsequent CH 4 emissions following permafrost thaw (Wei et al, ). Therefore, the detection of methanogens at all sampled depths in the VC permafrost tunnel suggests that in situ microbial communities in this yedoma profile, including deep yedoma, are equipped to metabolize OM into CH 4 following thaw.…”

“…Prior characterization of microbial communities in deep yedoma permafrost suggests active microbial metabolic processes in permafrost soils, but low microbial biomass and diversity (Mackelprang et al, 2017;Wagner et al, 2007). Following thaw, suitable conditions could allow for the activation of microbial communities, including methanogens, and subsequent GHG production (Knoblauch et al, 2018;Mackelprang et al, 2011;Wei et al, 2018). However, microbial communities in deep permafrost remain a relatively unknown component, and we cannot currently predict how microbes will use permafrost OC following thaw (Graham et al, 2012;Malard & Pearce, 2018).…”

Microbiological Study of Yamal Lakes: A Key to Understanding the Evolution of Gas Emission Craters

“…A quarter of all archaea in the sediments of background lakes belonged to hydrogenotrophic methanogens of the genus Methanoregula and acetoclastic Methanosarcina and Methanosaeta; both groups have been commonly detected in various thermokarst lakes [29][30][31]. In general, all four known pathways for methane production (hydrogenotrophic, aceticlastic, methylotrophic, and methyl-reducing) were previously reported for permafrost-related environments, including lakes [28][29][30][31][32][33]. The low concentration of the heavy isotope in methane carbon in both bottom water and sediments (−71 /−89 ) indicated the definitely biogenic origin of this gas [34,35].…”

Carbon dynamics in forest fire affected permafrost soils

“…The soil moisture conditions after fire are governed by permafrost thaw, increased evaporation caused by the increased soil temperatures (Bond-Lamberty et al 2009) and on the other hand by reduced transpiration as the vegetation is at least partly burned. In waterlogged permafrost soil, the thawing ice may further advance the anoxic conditions (Wei et al 2018). The fluxes might also be affected by the increased diffusion of gases caused by the higher soil temperatures (Kim and Tanaka 2003), although this increase would be quite small and possibly decreased if soil water content increases.…”

“…Sometimes permafrost soils have also been noted to become sources of CH4 because of permafrost thaw (Kim and Tanaka, 2003). Permafrost soils are often prone to CH4 production, as the soils may be waterlogged due to permafrost surface that restricts drainage (Schuur et al 2015), further reinforced by permafrost thaw (Wei et al 2018). Therefore, the CH4 stored and produced in permafrost peatlands and soils has raised concerns about permafrost thaw resulting in positive feedback to climate warming via increased CH4 emissions (Christensen et al 2004;Smith et al 2004;Wei et al 2018).…”