Assessing Permafrost Degradation and Land Cover Changes (1986–2009) using Remote Sensing Data over Umiujaq, Sub‐Arctic Québec

Abstract

Recent land cover changes in the Umiujaq region of northern Québec, Canada, have been quantified in order to estimate changes in the extent of discontinuous permafrost that strongly affect the forest-tundra ecotone. Changes in the areas covered by different vegetation types, thermokarst lakes and degradation of lithalsas have been investigated over an area of 60 km 2 , extending from widespread discontinuous permafrost in the north to areas of scattered permafrost in the south, and from Hudson Bay in the west to the Lac Guillaume-Delisle graben 10 km further east. We used high-resolution remote sensing images (QuickBird 2004, GeoEye 2009) and four Landsat scenes (1986, 1990, 2001, 2008)

Remote sensing evaluation of High Arctic wetland depletion following permafrost disturbance by thermo-erosion gullying processes

“…Satellite data have been used increasingly in the Arctic for various geomorphological purposes such as mapping polygonal tundra landscape components (Skurikhin et al 2013), detecting degradation of ice wedges (Liljedahl et al 2016), assessing permafrost coast erosion (Obu et al 2016), understanding effects of flooding following storm (Lantz et al 2015), and monitoring permafrost thaw dynamics (Ulrich et al 2014;Beck et al 2015;Gün-ther et al 2015;Liu et al 2015;Saruulzaya et al 2016). Techniques such as InSAR (interferometric synthetic aperture radar) as well as airbone and terrestrial laser scanning have been used to document detailed topographical changes (Chen et al 2013;Hubbard et al 2013;Liu et al 2014;Wolfe et al 2014), thermokarst (Barnhart and Crosby 2013), active layer thickness (Gangodagamage et al 2014;Schaefer et al 2015;Widhalm et al 2017), and freeze-thaw cycles (Daout et al 2017).…”

Vertical movements of frost mounds in subarctic permafrost regions analyzed using geodetic survey and satellite interferometry

“…The lower overall dynamics at non-vegetated measurement points is not surprising since the records of the thaw depths during the same year (2010) indicate that nonvegetated areas had very shallow (5-60 cm) thaw depths in the summer (August) compared to areas covered with shrubs or trees, where the thaw depth was up to 200 m (Beck et al, 2015). This is due to the absence of any insulation during the winter (i.e., no insulating cover of either vegetation or snow), resulting in lower ground temperatures (e.g., Beck et al, 2015;Clebsch and Shanks, 1968;Mackay, 1974;Romanovsky and Osterkamp, 1995;Nelson et al, 1997).…”

“…This is due to the absence of any insulation during the winter (i.e., no insulating cover of either vegetation or snow), resulting in lower ground temperatures (e.g., Beck et al, 2015;Clebsch and Shanks, 1968;Mackay, 1974;Romanovsky and Osterkamp, 1995;Nelson et al, 1997). It can therefore be assumed that subsidence at these points starts much later than elsewhere.…”

Periphytic diatom community structure in thermokarst ecosystems of Nunavik (Québec, Canada)

“…These thermokarst ecosystems are critical places of rapid changes in energy and matter fluxes (Vonk et al 2015;Vincent et al 2017 and references therein) that transfer large quantities of organic carbon to the atmosphere in the form of greenhouse gases such as CO 2 and CH 4 (Walter et al 2006;Laurion et al 2010), although this may be offset by bacterial consumption processes (Crevecoeur et al 2015). As climate is the main driver of vegetation and aquatic ecosystem dynamics in these systems, increasing air temperatures can have a strong impact on lake spatiotemporal evolution and vegetation densification (Fallu and Pienitz 1999;Bouchard et al 2014;Beck et al 2015).…”