Page 210 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 9. Long-term warming effects on permafrost soil microbial communities
Figure 3. Taxonomic composition of a) the bacterial community at phylum level and b) the archaeal community at phylum level, with major methanogens at order level for the active layer (AL), transition layer (TL), and permafrost (PF). For each layer, the two bars illustrate the original sample at the left and the incubated sample at the right. All lineages with relative abundance below 1% were grouped into “others”.
Taxonomic shifts within the archaeal population
The shift in the taxonomic profile is also reflected in the archaeal community structure on the phylum-level (Fig. 3b) and on the family-level shown as fold changes (Fig. 4b). Pronounced fold-changes were observed in Bathyarchaeia and Woesearchaeia with overall increases of 7.0% and 11.4%, respectively, after long-term thaw exposure. A complete overview of the archaeal community changes at phylum level for all layers is given in Supplementary Table S2. The relative abundance of methanogenic archaea decreased after over the five years warming scenario (average decrease of 40.8%, 13.4% and 19.9% for AL, TL, and PF, respectively), but members related to the hydrogenotrophic Rice Cluster II lineage methanogens showed a clear 18-fold increase in PF at the end of the incubation (1.2% to 21.8%). In addition, also hydrogenotrophic Methanomicrobiales showed a substantial increase (9.1% to 24.5%), at least in TL, which is reflected in the fold-increase in Methanoregulaceae (Fig. 4b). The relative abundance of Methanosarcinales and Methanobacteriales declined in all layers. Methanosarcinaceae-specific sequences were only detected in the original AL and the obligate acetoclastic Methanosaetaceae decreased in all samples upon incubation.
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