Methanogen diversity and community composition in peatlands of the central to northern Appalachian Mountain region, North America

Abstract

Methanogenic archaea are ubiquitous in peat soils; however, their diversity and distributions within and among peatland ecosystems are not well known. We used comprehensive clone libraries of 16S rRNA gene sequences to investigate spatial patterns in diversity (richness, evenness of taxa) and composition (taxonomic, phylogenetic) of the methanogenic community in six peatlands arrayed 775 km from eastern Ontario, Canada to West Virginia, USA. Five sites were Sphagnum (moss) and shrub dominated; one site was sedge dominated; and, potential rates of methane (CH 4 ) production ranged from 15 to 450 nmol/g day. The gradient allowed us to examine influences of site conditions, site history, and climate on community composition. The region had representatives of methanogens from four taxonomic orders. We observed 29 operationally defined units (OTUs) based on [97% sequence identity. One OTU accounted for 43% of all clones, whereas 15 OTUs were rare with \1% of the total number of clones. The number of OTUs per site ranged from 4 to 21, and statistical analysis suggested diversity of 4-43 per site. Eighteen of the OTUs were endemic to one site; albeit, most endemics occurred in the sedge dominated site. One OTU was cosmopolitan, occurring in all six sites. We found a positive relationship between methanogen diversity and rates of CH 4 production per site (Pearson r = 0.93). Turnover in community composition between sites was weakly related to geographic distance between sites, whereas variation in soil pH and annual temperature played larger roles. About 50% of the variation in community composition was unexplained by distance, pH, mean climate, and site age. We conclude that methanogen diversity in peatlands of the central Appalachian region is shaped by present-day environmental conditions, suggesting an influence of impending climatic and environmental changes.

Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia

“…The two sites on about the same latitude, SM and LV (Table 1) showed similar abundance, activity and diversity of methanogens, while all these characteristics were lower at the high latitude DS site. This is in accordance with the discussion forwarded by Yavitt et al (2011) for the diversity variation found among North American peatbogs, i.e. the diversity variation may be related to geographical distances.…”

“…the diversity variation may be related to geographical distances. The distance between the two southern bogs was within the range for those observed with similar diversities by Yavitt et al (2011), while the northern site is separated by about 1000 km from the LI and SM sites in the present study (Table 1). In a parallel study (Robroek et al, 2014), investigating the plant composition and ecological functions, observed that the plant species richness and plant diversity variation were similar for the southern sites (LV and SM) but differed from the northern site (DS).…”

“…The abundance of methanogens differs between areas with high and low water table, however, the variation in the methanogenic community composition among peatlands is mainly explained by peat pH and temperature, where the hydrogenotrophic pathway has been found to be dominant at acidic peat pH and low temperature (Kotsyurbenko et al, 2007;Yavitt et al, 2011). There is no consensus on the effects of peat edaphic variables on the methanogenic community composition, which rather seems to depend on the peatland type investigated and the scope of the study.…”

“…In addition, these microhabitats are characterized by a different set of peat mosses and accompanying vascular plants (Saarnio et al, 1997;Rydin and Jeglum, 2006;Robroek et al, 2009) which ultimately control the quantity and quality of the organic matter available for microbial decomposition (Kettunen and Kaitala, 1996;Galand et al, 2003;Andersen et al, 2013;Jassey et al, 2013). In short, the composition of the methanogenic archaeal communities in peatlands shows a tight link with the microtopography in the peatland (Galand et al, 2003;Yavitt et al, 2011). Hence, understanding the spatial distribution of the methanogenic population along the lawn-hummock topography may reveal further insight into the regulation of the methane formation capacity linked to the carbon balance of peatlands.…”

Methanogens in the Environment: An Insight of Methane Yield and Impact on Global Climate Change

“…Therefore in earlier there was a proof for niche adaptation in methanogens (Yavitt et al, 2012) and methanotrophs (Kumaresan et al, 2011;Nazaries et al, 2011). But after that, Reim and colleagues (2012) detected vertical niche differentiation in gamma proteobacterial methanotrophs inside the first three milli metres of water saturated soils.…”