Thaw Depth Progression in Response to Vehicle Disturbance
Steve RewaIntroduction: Off road vehicle (ORV) traffic has been extensive and necessary in Arctic regions. With a lack of vast roadway networks, transportation has been relatively costly and inefficient, particularly in summer (Rickard and Brown 1974). It is estimated, that by 1977, the most widespread cause of surface disturbance was use of tracked vehicles (Van Cleve 1977; Milchunas et al. 2000). With a strong cultural heritage based on a subsistence lifestyle, hunting and fishing are central to the lives of many Inupiat people. ORV's are used to a great extent in the daily lives of both native Inupiat people as well as non-native settlers.
Because the soils of tundra systems generally have high moisture contents, they are easily compressed by the weight of many ORVs, leaving distinct ruts. Pressure by ORV traffic can also affect the thermal regime of the soil causing a change in the depth of the ice rich permafrost layer that underlies tundra soils. The combination of these two effects can lead to a trenching effect as the ruts fill with water and succumb to the freeze/thaw cycle. This leads to a positive feedback situation where damage is compounded until thermokarst occurs and the ground surface crumbles and collapses.
Little is known about the long-term effects of these impacts, therefore it is the intent of this study to document these lingering effects by examination of a 25-year-old vehicle trail. I hypothesize that the permafrost layer of the soil will have a different thaw response in areas covered by old trails.
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