Impact of Linear Disturbances on a Discontinuous Permafrost Peatland Environment

• Main Author: Braverman, Michael
• Format: Text
• Language: English
• Published: Scholars Commons @ Laurier 2017
• Subjects: Permafrost; peatlands; seismic lines; disturbance; thaw; Hydrology; Canada; Ice; Peat; Peat plateau; permafrost; Subarctic
• Online Access: https://scholars.wlu.ca/etd/1915; https://scholars.wlu.ca/context/etd/article/3025/viewcontent/Impact_of_Linear_Disturbances_on_a_Discontinuous_Permafrost_Peatland_Environment.pdf

Permafrost is ground that remains at or below 0°C for at least two consecutive years (PIWP, 2012). In the continuous permafrost zone its thickness may exceed 300 m, in lower latitudes, permafrost thickness is progressively decreasing, its occurrence becomes discontinuous and eventually sporadic (PIWP, 2012). At the southern fringe of permafrost in northwestern Canada, just about few meters. In subarctic peatlands permafrost is one of the main elements governing the hydrological processes. Being very thin and with temperature just fractions of the degree below 0oC, it is very vulnerable to any changes in soil temperature and water content. Permafrost in peatlands is found exclusively under peat plateaus, which are elevated 1-2 m over fens and bogs that do not contain perennially frozen ground. In this environment the peat plateaus act as natural frozen dams between such water bodies as fens and bogs. If the surface of a peat plateau is disturbed naturally, as by forest fires, or artificially, as by human activity, the function of the peat plateau as a frozen dam is diminished with the permafrost thaw. The effects of ground surface disturbance propagates through the water, ice, soil and vegetation components of peatland ecosystems (Woo, 2011). Permafrost degradation can occur from the top due to the changes in ground surface conditions, from the sides by heat conduction and convection from the surrounding permafrost free terrains and from the bottom due to the geothermal heat flux. The combination of two or more of these scenarios can lead to rapid permafrost thaw and its complete disappearance.While climate warming is the main natural cause of permafrost degradation in the zones of discontinuous permafrost, economic development of natural resources resulting in considerable ground surface disturbance can also lead to permafrost thaw. Vegetation has a profound effect on the energy balance at ground level. For example, in winter time trees intercept large amounts of snow, creating conditions for deeper freezing of ...