(published 1998)
Habitat Atlas for Wildlife at Risk
Forest Ecosystems

The South Okanagan and Similkameen valleys have a diverse array of forests covering almost 44 percent of the land area, from the lower treeline, where ponderosa pines are scattered among the sagebrushes, up to the alpine treeline, where mats of stunted spruce and fir are twisted by cold mountain winds. Between these two limits are relatively dry ponderosa pine and Douglas-fir forests, somewhat wetter western larch forests at middle elevations on the eastern side of the valley, and cool, moist Engelmann spruce and subalpine fir forests on the ridge tops and high plateaus.

This atlas is confined largely to forests in the South Okanagan below approximately 1200 metres in elevation. These low elevation forests are dominated by ponderosa pine and Douglas-fir. These are relatively dry forests, characterized by an open, park-like structure with grassy understories. Indeed, the ground cover of ponderosa pine forests is very similar to that found in the adjacent grasslands and shrublands.

Forestry & Fire Management

Since the turn of the century, South Okanagan forests have been harvested with increasing intensity. This harvest has changed the structure of the forests. Old growth forests were likely the dominant successional stage before the turn of the century, but now make up only 23 percent of the forests in the area.

Harvesting methods have changed significantly since the early 1900s. Early logging operations removed large ponderosa pine and Douglas-fir, leaving many mature trees and dead snags, resulting in a forest that retained most of its old-growth characteristics. While low elevation logging still uses selection methods, most or all snags are removed, resulting in a forest that cannot be used by many species that require dead trees for nesting, roosting or feeding. Old, large ponderosa pines, which are associated with a number of endangered and threatened bird species, became seriously depleted early in this century.

Selective logging practices and fire suppression have resulted in a dramatic change in the structure of low elevation forests in the South Okanagan, from open, park-like forests with scattered large trees to the present dense stands of younger trees. With these changes in practices and structure comes a change in fire regime. Fires were once more frequent, smaller and cooler, but now are less frequent, larger and more intense. The formerly common, low-intensity fires are called stand-maintaining fires, since they maintain an overstory of large, well-spaced trees while clearing out shrubs, small trees and other vegetation.

Fire suppression policies over the last 50 years have dramatically altered the fire return frequency, and most sites have not been burned at all during that period. Many areas are now characterized by a dense understory of shrubs and small, regenerating trees. This dense growth excludes many plant and animal species that require the open, grassy understory typical of the natural forest.

Threats:

• Removal of dead standing snags used as nest holes.
• Low elevation forests may disappear with increase residential and subdivision development on forested slopes.
• Old growth trees, used as roosting, nesting and denning habitat for birds and mammals, are subject to logging pressure.
• Increased forest density has lowered habitat quality for some species.

Wildlife at Risk for which Forest habitat is critical: