Recession of Permafrost in a Cultivated Soil of Interior Alaska

Classification of Permafrost Soils

“…Depending on the severity of disturbance (e.g., intensity of burn), or the overlapping of disturbances, the cycle can be entered or interrupted at any stage. This cyclic relationship between vegetation, soils, and permafrost in the subarctic is well documented in the literature (Kallio and Rieger, 1969;Viereck and Schandelmeier, 1980;Ping, 1987). Management is directed, in some cases, at preserving the permafrost level, and, in others, at lowering it.…”

Physical and biological feedbacks of deforestation

“…Simultaneous measurements of soil temperature at an adjacent clear‐cut versus forested site showed that following the removal of forest vegetation, soil temperatures can increase during the summer months by 5°C [ Machimura et al , 2005]. Similarly, Kallio and Rieger [1969] noted an increase in seasonal soil temperatures after removal of the forest canopy and observed for the first 3 years after clearing that soil temperatures at 0.2 m depth were 5.2 and 14.1°C over the course of the growing season and −6.0 and −4.4°C during winter, for the forest and deforested area, respectively. The increase in soil temperature can lead to a more rapid decomposition of the litter layer at the surface, which reduces the depth to active layer (i.e., the surficial layer above permafrost which thaws during summer and freezes again in winter) and can also lead to a rise in the active layer toward the surface.…”

Human Land-Use and Soil Change

“…Once the thermal equilibrium is disrupted, increased thawing can result (Brown 1997). Near Fairbanks Alaska, clearing of an area of natural boreal forest vegetation and removal of the 10-cm-thick surface organic layer resulted in a drop in the permafrost table from 1 to 5 m (Kallio and Rieger 1969). When ground ice melts, the surface topography is changed and increased melting can lead to major ground disturbances known as thermokarst (Fig.…”