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TitleActive layer variability and change in the Mackenzie Valley, Northwest Territories between 1991-2014: an ecoregional assessment
AuthorGaribaldi, M C; Bonnaventure, P P; Smith, S LORCID logo; Duchesne, CORCID logo
SourceArctic, Antarctic and Alpine Research vol. 54, no. 1, 2022 p. 274-293,
Alt SeriesNatural Resources Canada, Contribution Series 20210224
PublisherTaylor & Francis
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut; Northwest Territories; Yukon
NTS95I; 95J; 95K; 95L; 95M; 95N; 95O; 95P; 105I; 105J; 105K; 105L; 105M; 105N; 105O; 105P; 96; 106; 97A; 97B; 97C; 97D; 107A; 107B; 107C; 107D
Lat/Long WENS-136.0000 -120.0000 70.0000 62.0000
Subjectsenvironmental geology; Science and Technology; Nature and Environment; permafrost; freezing ground; Mackenzie Valley; Ecology
Illustrationslocation maps; tables; photographs; plots; graphs
ProgramClimate Change Geoscience Permafrost
Released2022 08 02
AbstractActive layer thicknesses (ALTs) from sites along a transect through the Mackenzie Valley, Northwest Territories, Canada, were analyzed to explore variation in thickness within and between ecoregions. At an ecoregional scale the relation between ALT, latitude, freezing and thawing degree-days, and snowfall were examined to determine the presence of trends. Site-specific variables including dominant vegetation and substrate were explored to explain spatial variability in ALT within ecoregions. Generally, average ALT increases moving southward through the comprising ecoregions (68 cm to 126 cm), following the increase in air temperature. Spatial variability in ALT within ecoregions was greater than that between ecoregions (up to 145 cm), which may be attributed to site-specific conditions (vegetation and snow cover). Most notable, sites with shrubs had thicker than average active layers likely because of increased snow retention leading to warmer overall ground conditions. Despite a warming trend in air temperatures, only one northern ecoregion showed a corresponding thickening trend in ALT. Sites located in southern ecoregions with mature forests showed limited response to changes in air temperature. For these locations, disturbance, specifically changes in thermally protective vegetation cover, rather than changing air temperature could potentially have a larger impact on ALT into the future.
Summary(Plain Language Summary, not published)
Active layer thickness data have been analyzed along with climate information for a transect in the Mackenzie Valley Northwest Territories. The results of the analysis have been used to characterize active layer conditions within ecoregions and their response to changes in climate. Most previous studies only considered the role of summer conditions in determining active layer thickness but this study found that winter conditions including air temperature and snow cover are also important. The results of the study improve our knowledge of the relation between active layer thickness, climate and ecoregion characteristics which allows us to make better assessments of how the active layer will respond to a changing climate.

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