Geomorphological controls over carbon distribution in permafrost soils: the case of the Narsajuaq river valley, Nunavik (Canada)

Soils in the northern circumpolar region play a central role in the global carbon cycle because the release of carbon through permafrost thaw and geomorphological disturbances can potentially cause a feedback on climate. However, large uncertainties in estimates of permafrost carbon stocks remain, m...

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Bibliographic Details
Published in:Arctic Science
Main Authors: Samuel Gagnon, Michel Allard
Format: Article in Journal/Newspaper
Language:English
French
Published: Canadian Science Publishing 2020
Subjects:
geo
Online Access:https://doi.org/10.1139/as-2019-0026
https://doaj.org/article/6d2dcb2b68b14ba1bb321a16aff71025
Description
Summary:Soils in the northern circumpolar region play a central role in the global carbon cycle because the release of carbon through permafrost thaw and geomorphological disturbances can potentially cause a feedback on climate. However, large uncertainties in estimates of permafrost carbon stocks remain, mainly because of wide gaps in the spatial coverage of soil carbon sampling sites and the large mapping polygons used to upscale data. By combining mapping of landforms and knowledge of surficial geology to upscale soil carbon content measurements, we provide an assessment of soil total carbon content in the region of the Narsajuaq river valley (Nunavik, Canada) to generate the first high-resolution soil carbon estimate confirmed by field measurements in Nunavik. We estimate that the Narsajuaq river valley and the surrounding uplands have a weighted average of 3.4 kg C m−2 (0–100 cm), with 73% of the total carbon content stored in the top 30 cm. The results also indicate that the valley is a carbon hotspot in the region, containing 76% of the total carbon content (0–100 cm) of the study area. Although soil carbon estimates will always require field sampling, the geomorphological mapping approach can significantly improve carbon content estimates and provide better inputs for models.