Ministry of Environment Ecology

Northwestern Wildlife Capability Atlas

Introduction

This atlas represents an analysis of wildlife values for the northwestern portion of British Columbia. The wildlife resources for the northwestern portion of the province are unique, varied and abundant. Many species such as Stone Sheep, Caribou and Mountain Goat achieve population highs within the project area. The occurrence of each species corresponds to land form, climate and species immigration as represented by various Ecosection units. In some cases predator-prey systems, such as Wolf, Caribou, Moose and Grizzly Bear, transcend individual Ecosections. Such systems are dependent on large, intact wilderness areas to function naturally. This project evaluated eleven species of big game that inhabit the northwest portion of British Columbia - Bison, Black Bear, Caribou, Elk, Grizzly Bear, Moose, Mountain Goat, Mule Deer, Thinhorn Sheep, (Dall and Stone Sheep), White-Tailed Deer and Wolf.

Although prospecting, mining and corridor development have been conducted in the region for the past century (and lately logging), most of the area is in a natural state. Several large Provincial Parks and Protected Areas occur in the area : Atlin, Denetiah, Gladys Lake Ecological Reserve, Mount Edziza, Spatsizi Plateau Wilderness, Stikine River, Tatlatui, Tatshenshini-Alsek Wilderness. And even though the large asbestos mine at Cassiar has closed and the town removed, and an extension of the British Columbia Railway from Fort St. James north to the Yukon was abandoned in the mid 1970’s, development pressures, and resource exploitation interest persists. The Stewart Highway is paved, and there are two highways that cross the northwest portion of the project area that lead from the Yukon, across the Alaska Panhandle to sea-ports.

Methods Applied

The distribution and abundance for each of the eleven highlighted species were rated against the provincial standard for each species. The mapping was based on the capability of the ecosystems to produce each species. The classification methods applied here at an overview level are consistent with definitions developed for more detailed mapping set by the Wildlife Interpretations Subcommittee (1997). Ratings of wild ungulates (elk, moose, caribou. etc.) Follow those set in the Northeastern British Columbia Wildlife Biophysical Project (Demarchi and Demarchi 1994), and for grizzly bears, were set by Hamilton et al. 1997. The ratings and mapping for ungulates were conducted by two regional wildlife and habitat experts, with extensive knowledge of the wildlife in this region, they were assisted by a wildlife biologist with extensive knowledge of the provinces wildlife and habitats. Ratings and mapping for grizzly bears were developed as part of a provincial map base by two provincial wildlife biologists with extensive knowledge of the provinces grizzly bears and habitats. The grizzly bear ratings have been reviewed by regional wildlife experts. The black bear ratings and map were developed by a provincial expert as a function of grizzly bear habitats. In all cases, there were four steps to the wildlife evaluation portion of the project:

1. Examining the potential of each Ecosection in the project area to support each of the eleven highlighted species;
2. Rating the potential of each biogeoclimatic Subzone/Variant within each Ecosection to support each of the eleven highlighted species;
3. Comparisons of rated values to those of either the Northeast Wildlife Biophysical Project or the Provincial Grizzly Bear Habitat Suitability Ratings Project;
4. Synthesis of all wildlife values, irrespective of species composition or use made of the habitat, onto one map.

The mapping of each ecosection, that is, Ecosection/Biogeoclimatic Subzone/Variants, was based on 1:250,000 mapping conducted by the former Ministry of Environment, Lands and Parks and the Ministry of Forests. For presentation purposes the maps have been reduced to 1:2,000,000.

Ecoregion Classification

The Ecoregion Classification is used to stratify British Columbia’s ecosystem complexity into discrete Geographical units at different levels. The two highest levels, Ecodomain and Ecodivision, are very broad and place British Columbia globally. The three lowest levels, Ecoprovince, Ecoregion and Ecosection are progressively more detailed and narrow in scope and relate segments of the province to one another. They are used to describe areas of similar climate, physiography, hydrology, vegetation and wildlife potential.

The Northwestern British Columbia Wildlife Biophysical Project area contains portions of three Ecodomains, three Ecodivisions, three Ecoprovinces, ten Ecoregions and twenty-three Ecosections. The project area extends across the Coast and Mountains Ecoprovince on the west, the Sub-Boreal Interior Ecoprovince in the south and the Northern Boreal Mountains Ecoprovince in the middle, north and east. All areas are generally under the influence of Arctic conditions for most or part of the winter and early spring months (even the coastal units). In the summer and fall Pacific westerlies bring moisture via storm tracts across northern British Columbia and the southern Yukon, via the Gulf of Alaska. Precipitation on these northern plateaus and mountains is generally evenly distributed throughout the year, due to surface heating of streams and lakes and the movement of Pacific air masses across the region. (For more information see Demarchi 1995 and Demarchi et al. 1990).

Biogeoclimatic Classification

Within each Ecoregion, climatic zones occur where specific soils, plant and animal communities and aquatic systems develop because of the interaction of climate with the land surface and surficial materials. These zones are defined within the Biogeoclimatic Ecosystem Classification system. There is a hierarchy of units, with the Biogeoclimatic Subzone being the basic unit. Subzones are grouped into zones to represent broadly similar types of climatic parameters over large geographical areas, or they can be divided into variants based on considerable geographic variation in plant community expression.

The Northwestern British Columbia Wildlife Biophysical Project area contains portions of eight Biogeoclimatic zones, represented by 15 Subzones and 20 Variants. The majority of plant communities relate to the cold, boreal climates, or northern mountain environments, with the exception of the Coastal Western Hemlock, Mountain Hemlock, and Interior Cedar - Hemlock zones that are rain forest environments. Forests are dominated by white spruce, lodgepole pine, trembling aspen and balsam poplar. On the low poorly drained portions of the Liard Plain, Teslin Basin and Stikine Plateau for example, extensive muskeg wetlands, black spruce, Labrador tea and sphagnum dominate the landscape. In the mountains alpine tundra, heath, altai fescue, and stunted willow are abundant, but non-vegetated rock occurs at higher elevations, and glaciers occur on the highest portions of the Alsek, Icefield and Boundary Ranges. (For more information see Meidinger and Pojar 1991, Ministry of Forests 1995).