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Impacts of thawing permafrost at the Scotty Creek Research Station, NWT, Canada
Ryan
Connon, Wilfrid Laurier University, rfconnon@gmail.com
(Presenter)
Rapid climate warming in northwestern Canada has led to unprecedented rates of permafrost thaw. Near its southern edge, the occurrence of permafrost is often restricted to peatlands, where the large thermal offset between the ground surface and permafrost table preserves permafrost when mean annual temperatures approach, and sometimes exceed, 0°C. The Scotty Creek Research Station (SCRS; 61.3°N, 121.3°W) was established in 1999 to investigate the controls that permafrost exerts on hydrology and other ecosystem functions in peatland terrains underlain by permafrost. The SCRS is located in the headwaters of the Scotty Creek watershed (approximately 50 km south of Fort Simpson, NT). Here, permafrost exists solely beneath forested peat plateaus, which are interspersed with permafrost-free wetlands (channel fens and flat bogs), where saturated conditions typically limit the development of trees. Permafrost at the SCRS has been thawing rapidly over the past 60 years, and has changed the cycling and storage of water and solutes, transforming biophysical land cover units from forested, permafrost-cored peat plateaus to wetlands. A similar trend is observed using a space-for-time approach along a North-South transect from Northern BC to the SCRB. The processes that give rise to permafrost thaw are initiated by either climate warming or natural or anthropogenic disturbances. Within plateau systems, climate warming-induced thaw has led to the development of significant talik networks (perennially thawed regions in a permafrost environment) that allow for the perennial storage and transport of mass (water) and energy. The impact of these talik networks on the stability of underlying permafrost and the transport of water and solutes is not yet well understood. In the Northwest Territories, the most common natural disturbances are forest fires, a phenomenon that is becoming more frequent as the region warms. A relatively small fire occurred at the SCRS in 2014, and has been instrumented and monitored to assess the impacts on permafrost stability and changes to the physical structure of the near-surface peat. Anthropogenic disturbances in the region often take the form of linear cut lines used for either winter roads or seismic exploration. The density of these disturbances is approximately 7 times higher than the natural drainage density in the Scotty Creek basin, and involve the complete removal of the tree canopy, a process that leads to the degradation and loss of the underlying permafrost. Permafrost degradation along linear disturbances transforms these features into preferential flowpaths and may fundamentally change the hydrology of the basin. Data collected by the Arctic Boreal Vulnerability Experiment (ABoVE) will play an integral role in enhancing our understanding and improving our capacity to predict the impacts of thawing permafrost in peatlands in subarctic ecosystems. In addition to ongoing monitoring efforts, repeated thaw depth and soil moisture measurements were taken in a defined forest plot in the summer of 2017 to provide ground-truthing data for ABoVE missions. Associated Project(s): Poster Location ID: 14 Session Assigned: Permafrost and Hydrology
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