Small Mammals of the Muskwa-Kechika
Management Area
Table of Contents

STUDY AREA DESCRIPTION

I. General
The MKMA has a diverse physiography and climate (Fig. 1). Northern limits of the MKMA are the Liard River. The western limits are in the Stikine Ranges (see Holland 1964) of the Cassiar Mountains east of Dease Lake. The major watershed in this portion of the MKMA is the Turnagain River. From the Cassiar Mountains, the MKMA boundary extends eastward across the Kechika River in the Rocky Mountain Trench into the Muskwa Ranges of the northern Rocky Mountains. Southern limits in the Rocky Mountains are east of the Ospika River and north of the Ospika Arm of Williston Lake near Laurier Pass and the Graham River. Major watersheds on the eastern slope of the Rocky Mountain portion of the MKMA include: the Sikanni Chief, Prophet, Muskwa, and Toad Rivers. No communities or settlements occur with the boundaries of the MKMA. Fort Nelson on the Alaska highway and Dease Lake on the Stewart Cassiar highway are the closest communities. The only highway that traverses the MKMA is the Alaska Highway.

II. Ecological unit boundaries
Three ecoprovinces and 11 associated ecosections are represented in the MKMA (Table 1; Fig. 2). The greater part (about 88%) of the MKMA lies in the Northern Boreal Mountains Ecoprovince which is generally made up of areas of mountains and high plateaus separated by wide valleys and lowlands (Demarchi 1996). The regional climate is dominated by prevailing westerly winds that bring Pacific air over the St. Elias Mountains and Boundary Ranges. The moisture content of the coastal air is greatly reduced when it reaches the area, giving rise to very dry conditions where rain shadow effects are strong. Precipitation, provided by summer time convective showers and winter frontal systems, is distributed evenly throughout the year. Arctic air masses frequently dominate the region in winter and spring, and the varied topography leads to complex patterns of surface heating and cooling and cold air drainage in the valleys (Demarchi 1996). The remaining portion of the MKMA is split roughly equally between the northern fringe of the Sub-Boreal Interior and eastern edge of the Taiga Plains ecoprovinces.

The Boreal Mountains and Plateaus ecoregion in the Northern Boreal Mountains Ecoprovince is an area of complex lowlands, plateaus, and rugged mountains. The Cassiar Ranges ecosection has the highest and most rugged mountains in the ecoregion, while the Kechika Mountains ecosection is in the rain shadow created by these mountains. The Northern Canadian Rocky Mountains ecoregion is dominated by high, rugged mountains and rounded foothills separated by wide valleys.

Much of the Sub-Boreal Interior Ecoprovince is in a rain shadow (particularly the Peace Foothills ecosection) and precipitation is delivered roughly evenly by summer showers and winter frontal systems. The Misinchinka Ranges ecosection that makes up the southeastern tip of the MKMA is an exception to this, as moist Pacific air often stall over the rugged mountains in the area. The southern end of the ecoprovince is near the typical southern limit of the Arctic air mass in January (Demarchi 1996).

The Taiga Plains ecoprovince is mainly a large lowland extending into the upper Mackenzie River Basin that has been dissected below the Alberta Plateau surface by the Liard River and its tributaries (Demarchi 1996). The climate is continental and cold, dense Arctic air flows unimpeded from the north, often covering the area in winter and spring. In summer, the location of the area between the Pacific and Arctic air masses leads to long periods of cloud cover and unstable weather. In colder or wetter years some soils may remain frozen year round (Demarchi 1996).

III. Biogeoclimatic unit boundaries
Three biogeoclimatic zones and 10 associated subzones are represented in the MKMA (Table 2, Fig. 3). The Engelmann Spruce Subalpine Fir (ESSF) zone has a cold, moist, snowy continental climate. Average temperature is below 0oC for 5 to 7 months annually and above 10oC for 0 to 2 months (Meidinger and Pojar 1991). The mean annual precipitation within the zone ranges from 400 to 500 mm in drier areas to a maximum of about 2200 mm in wetter areas. About 50-70% of the precipitation falls as snow, and maximum snowpack accumulations range from about 1 to 4 metres. There is continuous forest cover at the middle to lower elevations and subalpine parkland at upper elevations in the zone. Engelmann spruce and subalpine fir are the dominant climax tree species in the zone, and lodgepole pine is a widespread serial species after fire. Deciduous tree species are rare in the ESSF (Meidinger and Pojar 1991). The moist very cold (mv) subzone is found in two variants (2 and 4) in the MKMA. This subzone is characterized by an ericaceous shrub layer, sparse herb cover, and relatively dense moss layer. Long, cold, snowy winters, wet, cool summers, and steep topography are factors which influence the assemblage of wildlife species found in the ESSF. Conifer forest is the most common habitat in the zone, and there are extensive areas of both old-growth/mature forests as well as young seral forests (Meidinger and Pojar 1991).

The Boreal Black and White Spruce (BWBS) zone in the region is located on an extension of the Alberta Plateau. The zone has a northern continental climate characterized by frequent arctic air mass outbreaks, very cold, long winters, and a short growing season. The average temperature is below 0oC for 5 to 7 months per year, and above 10oC for about 2 to 4 months per year. The mean annual precipitation ranges between 330 and 570 mm; about 35 -70 % falls as snow. White spruce, trembling aspen, lodgepole pine, black spruce, balsam poplar larch, subalpine fir and paper birch are the major tree species found in the BWBS. The wet cool (wk) and dry cool (dk) subzones are found in two variants, while the moist warm (mw) and moist very cold (mv) subzones are found in one variant in the MK.

The BWBSdk is located below the Spruce-Willow-Birch (SWB) or Engelmann Fir-Subalpine Fir ESSF zone and is dominated by white spruce and lodgepole pine. The BWBSmw generally covers the rolling topography between 350 and 1100 m. The dominant tree species are white spruce and trembling aspen. The BWBSwk is found on lower to middle slopes at elevations between 900 and 1399 m, above the BWBSmw and below the SWB and ESSF. The forest is dominated by white spruce or lodgepole pine.

The Spruce-Willow-Birch (SWB) zone is the most northerly subalpine zone in British Columbia, extending from about 57 o N to about 70 o N (Meidinger and Pojar 1991). In the study area the SWB is found at middle elevations ranging between 900 and 1500 m. The SWB is typically the subalpine zone above the BWBS, a position comparable to the ESSF further south. The climate is an interior subalpine type with mean annual temperature ranging between -0.7 and -3oC, and averages above 10oC for 1 to 3 months. Winter cold spells can be broken by chinook winds. The mean annual precipitation ranges between 460-700 mm, with 35-60% falling as snow. Lower elevations in the SWB are usually forested, with white spruce and subalpine fir as the dominate tree species. Pine and aspen are common in valley bottoms and lower slopes but subalpine fir dominates at higher elevations, particularly on northern and eastern exposures. Balsam poplar, Engelmann spruce, paper birch, and larch are all absent from the SWB (Meidinger and Pojar 1991).

The Alpine Tundra (AT) zone occurs on high mountains throughout the province, generally above 2250 m in the southeast, above 1650 m in the southwest, above 1400 m in the northeast (typical in the MKMA), and above 1000 m in the northwest (Meidinger and Pojar 1991). The alpine climate is cold, windy, and snowy. Average temperature is below 0oC for 7 to 11 months per year, and frost can occur at any time. Mean annual precipitation ranges between 700 and 3000 mm, of which 70-80% falls as snow. The alpine zone is by definition treeless, although subalpine fir, Engelmann spruce, and white spruce are often found in stunted (krumholz) form. The vegetation is dominated by shrubs, herbs, bryophytes, and lichens, but most of the landscape is composed of rock, ice, and snow (Meidinger and Pojar 1991).

IV. Protected areas
There are 17 provincial parks and protected areas in the MKMA (Table 3). No national parks occur within the MKMA. The provincial protected areas range from 2 to 665135 ha in area with the total protected area about 1.1 million ha. The Northern Rocky Mountains protected area makes up nearly 60% of the total protected areas within the MKMA. Contiguous with Stone Mountain Provincial Park and Kwadacha Wilderness (Fig. 4), it represents the largest area of connected protected areas. Other protected areas within the MKMA are small and isolated.