Permafrost and Ground Ice Conditions in the Ogilvie Mountains, Central Yukon

• Main Author: Frappier, Roxanne
• Other Authors: Lacelle, Denis
• Format: Thesis
• Language: English
• Published: Université d'Ottawa / University of Ottawa 2023
• Subjects: Permafrost; Climate change; Geomorphology; Ground ice; Remote sensing; Modeling; Arctic; Ogilvie; Ogilvie Mountains; Tombstone; Yukon; Ice; permafrost; wedge*
• Online Access: http://hdl.handle.net/10393/45076; https://doi.org/10.20381/ruor-29282

Permafrost is vulnerable to climate changes and the associated landscape changes that are enhanced by amplification processes and feedbacks unique to the Arctic. Permafrost degradation leads to important changes in terrestrial and aquatic ecosystems, and determining regions that are sensitive to permafrost degradation therefore represents an urgent issue. The Tombstone Territorial Park (TTP) and its surroundings (Ogilvie Mountains, central Yukon) represent one of those sensitive permafrost environment that should be monitored. The central Yukon is an enigmatic permafrost environment that reflects both Pleistocene and Holocene permafrost and climate conditions. The area is particularly intriguing because of the extensive presence of permafrost landforms that are more typical of areas much further north, especially ice-wedge (IW) polygons. It also represents a major transportation corridor linking multiple northern communities (Dempster Highway). Despite access along the road, and signs of permafrost degradation, there have been a limited number of studies addressing permafrost and ground ice conditions throughout the landscape. Consequently, this PhD thesis aims to characterize IW polygons, define the type and magnitude of landscape changes, and model permafrost distribution, conditions and sensitivity to climate changes in the study area. Characterization of IW polygons reveals that they occupy 2.6% of the TTP and preferentially develop in woody sedge peat, glaciofluvial and alluvial deposits along the lower reaches of the Blackstone and East Blackstone rivers on hillslopes of ≤1°. Vegetation type, surface wetness, and polygon spatial pattern are influenced by the development stage of ice-wedge polygons, while the size and angles of polygons seem independent of the development stage. A Landsat-based landscape change analysis of the TTP and surrounding region covering the 1986-2021 period shows that statistically significant spectral changes occurred in 24% of the study area, and most of these changes are ...