Draft, Remedial Measures Primer Pilot Version 1.0

SOUTHERN INTERIOR FOREST

There are four main forest zones.

1. Pondersoa Pine zone (open forest)

The smallest of the four forest range zones, it occupies lower slopes and outwash terraces, forming a narrow fringe along the upper edge of the grassland zone. It is limited to the southern interior, not extending north of latitude 51. Tree stands are relatively open and support well developed ground cover. It is permanently suited for livestock grazing and usually found on sites with inherently low timber production.

Principal forage plants include bluebunch wheatgrass, junegrass and rough fescue or Idaho fescue. A wide variety of herbs is also present.

From a grazing standpoint the ponderosa pine zone is similar to the grasslands at lower elevations. Spring and fall are the principal times of use.

Ground squirrels often become a serious problem, frequently destroying the greater part of the perennial herbaceous vegetation thus encouraging the growth of annuals.

Effects of grazing

Species that increase with heavy grazing are Sandberg’s bluegrass, Columbia needlegrass, needle-and-thread, and pussytoes. The most characteristic annual species that invade are downy brome, six-weeks fescue and bluebur.

Effects of longterm rest

It is estimated to take 20 to 40 years for overgrazed ranges in the rough fescue and ponderosa pine zones to recover to excellent condition when fully rested. The main plants to increase with protection are bluebunch wheatgrass and rough fescue. The main species to decrease were Sandberg’s bluegrass, pussytoes, and rabbitbrush.

Long periods of complete rest are not usually an economically acceptable form of range rehabilitation. One alternative is to graze only during the season that is least damaging to the herbage i.e. moderate fall or winter grazing.

2. Douglas-fir zone

This is the most extensive grazing zone of British Columbia and supplies most of the forest grazing. It lies between the open forest of the ponderosa pine zone and the dense forest of the subalpine fir zone.

The principal herbaceous species is pinegrass, providing 40-50% of the forage. Grasses of secondary importance are Bromus sp., Stipa sp., and Carex sp. The cover, vigour and forage yield varies greatly, depending on the density and nature of the tree canopy. Grazing in this zone is largely restricted to summer (mid-June through September). This zone provides a period of rest for the grassland types.

Locally the climate is affected greatly by topographic differences. Elevation is the major factor, producing vertical zonation of climate, soils, and vegetation. Periodic fires have replaced Douglas-fir, the climax dominant, with lodgepole pine and trembling aspen over extensive areas.

A. Pseudotsuga menziesii-Calamagrostis rubescens (Douglas-fir-Pinegrass)

Herbaceous cover is dominated by pinegrass. This perennial grass provides about 70% of the herbage yield. The main forbs are timber milkvetch, peavine, aster, twinflower, and lupine which can provide valuable forage. Although not abundant, Canada buffaloberry, rose, meadowsweet and willow are the most common shrubs.

B. Pinus contorta-Calamagrostis rubescens (Lodgepole pine-Pinegrass)

This is the most common seral community that develops after burning. Pinegrass is the dominant plant in the understorey. Snowberry is the dominant shrub on drier sites and Canada buffaloberry on the more mesic sites.

C. Populus tremuloides-Calamagrostis rubescens (Trembling aspen-Pinegrass)

A seral community that develops after burning. Like the other plant communities, pinegrass is the dominant plant in the understorey.

D. Pinus contorta-Populus tremuloides-Calamagrostis rubescens (Lodgepole pine-Trembling aspen-Pinegrass)

Pinegrass is the dominant plant with vetch, arnica and violets all occurring in considerable amounts.

Effects of Grazing

Pinegrass is consistently the dominant species in the understorey of the climax forest and seral plant communities, and it is a good indicator of the Pseudotsuga menziesii zone. This perennial grass declines under heavy grazing. Several other species preferred by cattle decline in abundance and vigour under heavy grazing. The plants most affected include aster, vetch, peavine and Indian paintbrush.

3. Montane Spruce Zone

At climax, white spruce and Englemann spruce are the dominant trees, but much of the zone is covered by seral stands of lodgepole pine or trembling aspen. Pinegrass is the principal forage species. Mature forests provide virtually no forage value, but once harvested, sites can produce forage for 10 to 15 years (cutblocks). This zone is important summer range for wildlife

4. Englemann spruce - Subalpine fir zone

Livestock grazing is limited to numerous natural meadows and scattered forest openings. The more open cover type occurring near timberline and areas that have been burned. The period of use is usually short and restricted to mid-summer.

Forage production is low because of the dense tree and shrub cover, except for a few years after logging or fire. The shrub cover is valuable browse for moose and deer. Aesthetic and recreation values are high.