Linking Greenhouse Gas Production to Microbial Communities in High Arctic Polar Desert Soils.

The greenhouse gases CO₂, CH₄, and N₂O are produced and consumed by soil microorganisms.  Production and consumption of one GHG may occur within the same soil profile, for example oxidation of CH₄ in near-surface aerobic soil overlying a deeper, anaerobic soil layer where CH₄ is released. Understanding these processes requires knowledge of microbial community ecology, because the organisms responsible for both production and consumption respond to both abiotic (soil water, oxygen, pH, nutrient availability) and biotic (competition, symbiosis, predation) factors. Within functional guilds such as ammonia-oxidizers, different phylotypes will be more or less represented in different environments, with consequences for overall rates of GHG production or consumption and thus consequences for total GHG flux to overlying atmosphere.

I have employed DNA-microarrays to survey the community composition of soils of the Canadian High Arctic, polar desert soils that have previously been shown to be active in GHG production, consumption, and efflux to atmosphere. These cold, nutrient-poor soils include a number of unusual features, including production/consumption overlying structures for CH₄ and highly variable N₂O productions. Community composition of ammonia-oxidizers and methane-oxidizers reveals dominance of ammonia-oxidation by Archaea, rather than Bacteria, and considerable diversity of high-affinity methane-oxidizing Bacteria.