| Summary: | Specialization: Microbiology and Biotechnology Degree: Master of Science Abstract: Anthropogenic climate change and increasing industrial activity is impacting Northern Canada and accelerating permafrost thaw. While research into the impact of permafrost thaw on microbial community dynamics is burgeoning, there has been little investigation into how human activities alter the resident microbial communities of permafrost. To examine the effect of anthropogenically-induced permafrost thaw on living microbial communities, I surveyed a site where permafrost thaw was induced by stripping the area’s vegetation and topsoil in preparation for gold mining near Dominion Creek, Yukon, Canada. I analysed a set of permafrost cores, as well as surface soil samples, across a disturbance gradient from undisturbed forest active layer to disturbed soils, composed of recently thawed permafrost, to a newly formed thermokarst pond. I identified three distinct community groupings within the dataset: (1) undisturbed active layer, (2) lower active layer, disturbed active layer, and disturbed permafrost, and (3) intact permafrost. These groupings indicate that disturbance alters the microbial community of surface soils. Biotic interactions drove differences across these groupings, while within group variation was controlled primarily by pH. This study suggests a strong microbial community response to anthropogenic permafrost disturbance under field conditions and that this response occurs prior to shifts in the measured soil edaphic parameters. Both anthropogenic and natural disturbances to permafrost may induce significant microbial community changes, impacting carbon budgets and carbon feedback in permafrost-affected soils.
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