Thermorkarsting

Thermokarsting is a localized thawing of ice-rich soil that results in formation of a depression at the ground surface and eventual erosion (Walker et al. 1987a). Thermokarsting is a natural process that initiates the lake phase in the thaw lake cycle and influences plant distribution in the region (Walker 1985). The ecological effects of thermokarsting usually include increased thaw depths and soil temperatures, which enhance organic-matter decomposition and nutrient release. Increased nutrient availability increases primary productivity and may change plant species composition (Chapin et al. 1980, Ebersole and Webber 1983). Although thermokarsting is a natural process, it can be initiated by small disturbances to vegetative cover and soil moisture, including a variety of oilfield activities (Brown and Grave 1979; Lawson 1986; Walker et al. 1987a, 1987b).