Montane Cordillera Ecozone

Changing Forest Landscape Conditions

The subalpine forests of this ecozone are considered healthy.

Fire suppression and ecological change: Fire suppression is essential to protect lives and property throughout much of this ecozone. It is also essential to protect commercially valuable timber. This activity has resulted in some ecological change not characteristic of the fire-dominated ecosystems before active fire suppression. For example, successional patterns are being altered in lodgepole pine stands. These stands are growing to older ages, increasing the risk of mountain pine beetle attack (Safranyik 1995).

As well, in the absence of recurring fires, ground fuel throughout the montane forests accumulates over time. Consequently, the fire hazard increases, including the risk of a major wildfire event (Harding 1994).

Armillaria root rot: Forest practices such as harvesting, thinning, and spacing have altered the normal dynamics of Armillaria root rot disease in many stands (Morrison et al. 1991). Harvesting in stands where Armillaria is present at moderate to high levels, significantly increases the amount of fungus in the soil and dramatically increases the amount of mortality caused by this disease over the next rotation. Thus, the ecological role of Armillaria is changed from an organism in equilibrium with its host and causing little damage, to one that aggressively attacks and kills its host. Age-class structures and species that are relatively tolerant of the disease emerge and become dominant.

Changing Biodiversity

Old-growth ponderosa pine: Old-growth ponderosa pine stands are maintained by frequent low-intensity, naturally occurring, surface fires that burn brush and prevent maturation of the more shade-tolerant Douglas-fir. Effective fire suppression, combined with selective harvesting of these pines, have contributed to a very dense regeneration of almost pure Douglas-fir in these stands. The sustainability of ponderosa pine ecosystems, already severely fragmented by non-forest land uses, is further threatened by these forest management practices (Harding 1994).

Changing Atmospheric Environment

Local air pollution: Localized damage to forests from sulfur and other emissions of pollutants has occurred from point sources such as smelting operations. Mapping of recent heavy metal and sulfur deposition indicates that dispersion of pollutants remains local, due to a combination of emission characteristics and topography (Enns and Duncan 1998).