Characterizing the influence of depth and glacial drift on microbial community diversity and potential carbon-cycling enzyme activity in permafrost soils

• Main Author: Bakke, Dana Victoria
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2024
• Subjects: Extracellular enzyme activity; Microbial diversity; Permafrost soils; permafrost; Tundra; Alaska
• Online Access: https://scholars.unh.edu/thesis/1821; https://scholars.unh.edu/context/thesis/article/2862/viewcontent/Bakke_unh_0141N_11702.pdf

Microbial communities in permafrost soils play an important role in breaking down organic matter and cycling nutrients. Despite difficult environmental conditions including below-freezing temperatures, yearly freeze-thaw cycles, and short growing seasons, these microbial communities remain active year-round. To better understand the microbial community diversity and potential activity across environmental gradients in northern Alaska, I sequenced the microbial community and measured the potential enzyme activity of three carbon-cycling enzymes at 5-centimeter increments in 60-centimeter soil cores spanning active layer and permafrost at three moist acidic tundra sites located on landscapes with different glacial histories in northern Alaska. I found that microbial community diversity was not driven by glacial drift, but decreased significantly with depth. There was higher hydrolytic enzyme activity per gram dry soil in soil horizons with higher carbon availability, regardless of microbial diversity, and oxidative enzyme activity per gram dry soil did not vary significantly with carbon availability, soil horizon, or glacial drift. This suggests that microbial communities are able to produce hydrolytic enzymes proportionally to the available soil carbon in active layer and permafrost soil horizons, regardless of the decline of microbial community diversity with depth.