Characterizing the hydrological function of treed bogs in the zone of discontinuous permafrost

• Main Author: Disher, Brenden
• Format: Text
• Language: English
• Published: Scholars Commons @ Laurier 2020
• Subjects: permafrost thaw; landscape transition; hydrology; cold regions; climate warming; Scotty Creek; Earth Sciences; Fort Simpson; Ice; Peat; Peat plateau; permafrost; taiga; Taiga plains
• Online Access: https://scholars.wlu.ca/etd/2261; https://scholars.wlu.ca/context/etd/article/3386/viewcontent/auto_convert.pdf

The loss of permafrost has produced a wholesale conversion from forest to wetland, and many studies have analyzed the effects of permafrost thaw-induced land cover change on the hydrology and ecology of landscapes within the Taiga Plains. The permafrost thaw driven areal shrinkage of forested plateaux and their replacement by treeless wetlands is well documented, and the co-occurrence of permafrost and black spruce forest cover is the basis for areal estimates of the former. However, field studies conducted at a peatland dominated landscape near Fort Simpson, NWT indicate that tree canopy may persist following the loss of permafrost and the gradual drying and succession of the previously treeless bog landscape. Such treed bogs are present on the borders of thawed plateaux and within larger and more established bog complexes. These features are typically characterized by stunted black spruce (Picea mariana), ground lichen (Cladonia spp.), and sphagnum hummocks (Sphagnum Spp). A total of four sites, each containing a bog, treed bog and peat plateau were chosen based on a supervised image classification completed within the basin. A geophysical investigation was completed to determine permafrost presence, depth of seasonal ice was measured along transects at each site, a series of wells were installed to measure hydrological response and discrete soil moisture measurements were taken immediately following snowmelt to characterize differences in moisture retention. Treed bogs are permafrost free features that intersect peat plateaux and bogs in terms of their hydrology. It is not clear whether these features represent a temporary state of succession for drier bogs, or if they will remain as permanent features on the landscape. Understanding the succession of northern landscapes due to climate warming provides an important step in predicting the trajectory of change in the north. This work provides new insights regarding the future of post-thaw landscapes within the Taiga Plains.