Jordan Marie Beer, Yifeng Wang, Robert Way, Anika Forget, Victoria Colyn

Palsas and peat plateaus in subarctic peatlands are some of the southernmost lowland permafrost landforms in the Northern Hemisphere. Peatland permafrost along the Labrador Sea coastline in northeastern Canada has remained largely understudied and uncharacterised, despite the importance of these landforms for wildlife, carbon stores, and Indigenous land users. In this study, we derived geomorphological and resiliency indices for peatland permafrost landforms at 20 wetland complexes, spanning a latitudinal gradient from Blanc-Sablon, QC (51.4°N) to Nain, NL (56.5°N). Orthomosaics and three-dimensional point clouds were created for each site using high-resolution UAV-based surveys and structure-from-motion photogrammetry. Analyses revealed that peatland permafrost landforms along the Labrador Sea coastline are characterised by short heights (maximum height: 3.65 m, average height: 0.49 m), with lichen and dwarf shrub cover, making them more similar to features in northern Europe than western Canada. Palsas and peat plateaus ranged in size from 49 m2 to 14,233 m2, with a median feature size of 259 m2 across all sites. Peatland permafrost in the region exhibits high levels of fragmentation, with most study sites (90%) exhibiting low or very low thaw resiliency. Results from this study indicate that peatland permafrost in many parts of Labrador are vulnerable to degradational processes with potential negative consequences for species with high cultural value to Labrador Inuit and Innu.