British Columbia: Forests

The Catt-Trax2 Team — Fri, 12 Jan 2007 15:30:20 -0800

Montane forests occupy the southern and central interior of British Columbia. They are dry because they exist in the rain shadow of the coastal mountains of the province. These forests are dominated by two tree species ponderosa pine and Douglas-fir. In winter, the snow covers the grassy ground for two or three months. In summer, it is usually hot and dry but not quite as hot and dry as the grasslands.

Interior Douglas-fir forests

The interior Douglas-fir is slightly different from coastal Douglas-fir. It can be distinguished by its bluish needles and is more shade- and cold-tolerant. Interior Douglas-fir forests provide the best nesting site for large birds such as hawks, ravens and owls. Interior Douglas-firs also have very thick bark, which protects it from fire.

Typically, pure Douglas-fir forests have an open canopy due to fires. Natural stands of interior Douglas-fir forests are home to Douglas-fir, lodgepole pine, and ponderosa pine. Shrubs include birch-leaved spirea and soopolallie, prickly rose, snowberry, Saskatoon, black gooseberry, black twinberry. Herbs and grasses include pinegrass, bluebunch wheatgrass, showy aster and yarrow. Mosses are red-stemmed feathermoss, and wavy-leaved moss.

In some wetter areas, the western larch takes over the forest after fires. Nevertheless, they slowly become dominated by Douglas-fir. The most unique birds in this zone are Williamson’s sapsucker (the rarest Canadian woodpecker), northern pygmy-owl, and the western tanager.

Ponderosa pine forests

These occupy the valley bottoms above the Bunchgrass zone and beneath the interior Douglas-fir zone. They are characterized by very hot, sunny summers and cool winters with light snow cover. Elevation ranges from 335 to 900 m. The ponderosa pine can be identified by its large woody, egg-shaped cones and long needles. The ponderosa pine’s interesting climatic adaptation is its taproot which is over fifty centimeters long! Most of the forests are covered with scattered ponderosa pine roots.

In summer, the ponderosa pine forests are fragrant with the scent of vanilla. These forests are dominated by bluebunch wheatgrass and big sagebrush on the hillsides where the soils are too hot for ponderosa pine seeds to develop. In very dry parts of the zone, ponderosa pine forms early seral stands on zonal sites but is eventually replaced by Douglas-fir. In fact, the vegetation often consists of a mosaic of forest and grassland. Mature stands of ponderosa pine forest are home to the following species:

ponderosa pine
Douglas-fir
trembling aspen
black cottonwood
rabbit-brush
big sagebrush
common snowberry
roses
red-osier dogwood
Douglas maple
tall Oregon-grape
bluebunch wheatgrass
star-flowered false Solomon’s-seal
Canada violet

Ponderosa pine forests are also home to unique birds such as the:

pygmy nuthatch
white-headed woodpecker
Lewis’s woodpecker
western tanager
mountain chickadee

Pygmy nuthatches are often seen in large groups of twenty to fifty birds. The Lewis's woodpecker has a bright pink belly and always found in the stands of large ponderosa pine, Douglas-fir or cottonwood close to grasslands.

Mammals of these forests include:

Rocky Mountain elk
mule deer
white-tailed deer
bighorn sheep
yellow-pine chipmunk
least chipmunk (found locally in the Selkirk Mountains)

Reptiles of the ponderosa pine forest include:

northern alligator lizard
rubber boa (the only Canadian Boa)
garter snake
yellow-pine chipmunk

Larch forests

The western larch is restricted to the south eastern part of the zone, where it frequently occurs after fire. It is the most fire-resistant and fire-adapted tree in the montane forest. Fire plays an important role in helping to establish the species throughout its range.

Western larch has many adaptations that enhance its ability to either survive fire or to quickly colonize recently burned areas. While seedlings, saplings, and poles are somewhat susceptible to fire, trees that are 150 to 200 years old or older are able to survive all but the most severe fires. Western larch has very thick bark that protects its cambium from overheating. The tree’s characteristic high, open crown and ability to self-prune its lower branches minimize ladder fuels and risk of crown fire. Its deep roots are protected from surface and ground fires. Western larch seedlings rapidly outgrow competitors.

Glasslands

A combination of soil, topographic conditions, and fire history has led to the development of large grassland communities in parts of the montane forest. Grasslands occur throughout the ponderosa pine forests.

Wetlands

Non-forested wetlands are common in the montane forests. Plants characteristic of these wetlands include

Cattail (Typha latifolia)
Great bulrush (Scirpus lacustris)
sedge fens of Carex aquatilis, C. rostrata, and C. lasiocarpa
saline meadows dominated by alkali saltgrass (Distichlis stricta)

Many of the fens include a tall or low shrub canopy of willows and sometimes Betula glandulosa.

Fire and adaptation

Forest fires have a big influence on the montane forest ecosystem. They are divided into two main types: low-intensity fires and high-intensity fires. Low-intensity fires burn low on the forest floor, killing small trees, shrubs and dry grass but leaving large, live trees to create an open, park-like forests of Douglas-fir or ponderosa pine. High-intensity fires, which can destroy stands, kill almost everything in their path.

Some montane forest species, such as ponderosa pine, western larch, ceanothus, saskatoon, and bluebunch wheatgrass, are fire-adapted species. That is, over many centuries, they have evolved strategies that help them to maintain populations on sites where fires commonly occur. Other vegetation, such as Douglas-fir, is not as well adapted. Historically, frequent fires tended to reduce the abundance of young Douglas-fir because their thin bark and low-hanging branches make them vulnerable to fire.

Wildfires have also played an important role in maintaining grasslands in the Montane forests. Without regular grassfires, trees take root in open grassy areas and, over time, grasslands become overgrown with trees. Today, wildfires are suppressed, and there is evidence that forests are taking over areas once occupied by grasslands.

References

Wildlife Habitat Relationships in B.C.’s Columbia Basin
Grasslands Conservation Council of British Columbia
Environment Canada
Selkirk College
BC Forest Information
Government of British Columbia, Ministry of Environment

MontainForests.net
Forest Service of British Columbia

Richard Cannings and Sydney Cannings, 2004, Natural History of British Columbia. Greystone Books. Vancouver, B.C.
Dei Meidinger and Jim Pojar. 1991. Ecosystems of British Columbia. Research Branch, Ministry of Forests. Victoria, B.C.

Catt-Trax 2 - Forests