Active layer variability and change in the Mackenzie Valley, Northwest Territories between 1991-2014: An ecoregional assessment

Active 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 sn...

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Bibliographic Details
Published in:Arctic, Antarctic, and Alpine Research
Main Authors: Madeleine C. Garibaldi, Philip P. Bonnaventure, Sharon L. Smith, Caroline Duchesne
Format: Article in Journal/Newspaper
Language:English
Published: Taylor & Francis Group 2022
Subjects:
permafrost
active layer
ecoregion
Mackenzie Valley
Environmental sciences
GE1-350
Ecology
QH540-549.5
Canada
Northwest Territories
Antarctic and Alpine Research
Arctic
Online Access:https://doi.org/10.1080/15230430.2022.2097156
https://doaj.org/article/d9598ae2fbea4e82be99a74a304573cb
Description
Summary:Active 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.

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