Stop # 8. Schaeffer Mountain

As we approach Schaeffer Mountain (Chit Chechii or Chit Che Chii), on the east side of the Old Crow River and Burnt Hill farther downstream on the west side, areas where the forest and tundra have been burnt over become more apparent.

Fire Ecology

Fire is a common occurrence in the Old Crow Flats. Several fires have burned over parts of what is now Vuntut National Park (Figure 1.8). Historical and recent accounts tell of smoke from tundra fires in the Flats being so thick as to prevent normal travel and activities (e.g., International Boundary Commission 1918). Techlit Lake, between Timber and Black Fox Creeks, refers to peat that has caught fire and has been burning for an undetermined period. Techlit means "land that caught fire underground" (Yukon Geographical Place Names Board 1998).

The importance of fire in the boreal forest is well-recognized and the effect of fire on wildlife, vegetation, soils, and permafrost has been documented (Hettinger et al. 1973). The importance and effect of fires in tundra and other treeless areas is not as well known. Tundra fires are somewhat lighter and vegetation recovers relatively quickly, but slumping and thermal subsidence do occur after fires in the tundra areas (Hettinger et al. 1973).

Hettinger et al. (1973) examined burned areas in much of the lowland area between the Richardson Mountains and the Old Crow Range to evaluate the rate of secondary succession after fire. The dates of fires were determined from tree ring counts. The researchers found that secondary succession after fire varies with site conditions. In the forested parts of the study area, succession is from white birch to white spruce forests on drier, better-drained sites, and white spruce forests are the climax comunity on south-facing slopes. White spruce reproduction was well established at 40 years after fire and mature forests at about 140 years. The moss, Hylocomium splendens, was the dominant understory in most mature forest stands. Secondary succession on areas not well drained is toward black spruce forests which may deteriorate with time (more than 200 years) to dwarf shrub communities. On rolling hills and depressions, black spruce or low shrubs form the dominant climax community.

Burning results in a temporary lowering of the permafrost and checks natural succession towards a climax vegetation community (Strang 1973). The near surface ice content of the terrain undergoes a rapid change after a fire, resulting in subsidence. In about five years the surface again becomes stable (unless larger ice bodies were exposed by the subsidence), and the slow process of ice build-up and raising of the permafrost table begins. This process lasts about 70 years (Van Eyk and Zoltai 1975).

Dependent on fire intensity and soil conditions, the active layer depth increases by 10 to 15 cm after fire. Open evergreen and deciduous forest formations on upland and south slopes probably have the highest potential for carrying fire and for environmental change after fire (Hettinger et al.1973).

Under mature forests the ice content of near-surface permafrost is high, and most of this would melt if the organic layer is disturbed. Subsidence greater than 100 cm is to be expected if the mineral soil is also disturbed. Recently-burned areas (burned less than 50 years ago) would react to a lesser degree or not at all to the same level of disturbance in a mature forest, as they would have been recently subjected to a similar disturbance. The active layer in such burned areas is up to twice as thick as normal and relatively dry, especially on gentle slopes (Zoltai and Tarnocai 1974)

As part of an investigation of the effects of disturbance in permafrost terrain, Strang (1973) described a site near Old Crow where a discharge of sulphur-rich water from the bottom of a hill following burning caused significant damage. Vegetation was dead or dying in several long strips, and with continued water seepage, deep gullies were forming in the bare areas.

Obviously fires can drastically affect the ecology of both forest and tundra. Fires can have a widespread impact, such as on the winter range of the porcupine caribou, or a more specific impact, such as damage to trap-lines (Morlan 1973). Fires near the village of Old Crow have damaged forested areas and caused temporary abandonment of the community.