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The Ecology of the Zone

n the Spruce–Willow–Birch Zone, conditions are harsh, Iwith bitterly cold, snowy winters and short cool summers. However, the pristine environment, wonder- ful scenery, and abundant wildlife make the zone ideal for a variety of recreational activities. Although the steep, mountainous terrain is unsuited to human habitation, resident wildlife are well adapted to its winter conditions. cover is sparse and comprised mostly of coniferous species, except on warmer slopes, where trem- bling often dominates. Other dominant vegeta- tion in the zone includes , especially scrub birch and several species of and grasses, primarily Altai fescue. Location Ecology The Spruce–Willow–Birch Zone occupies subalpine At lower elevations, the elevations in the northern third of the British Columbia landscape of the Spruce– interior. It extends north well into the Yukon and the Willow–Birch Zone is Mackenzie District of the Northwest Territories. mostly forested. The This is a mountainous area of old are primari- that includes the northern ly a mixture of white , the Cassiar spruce and subalpine . and northernmost Omineca In many of the valleys in and Skeena mountains, part this zone, the forest cover is of the St. Elias Mountains, made up of white spruce with Del Meidinger and much of the Stikine, variable amounts of lodge- Yukon, and Liard plateaus. pole and trembling Old forest of white spruce, sub- There are no significant aspen in the valley bottoms alpine fir, willows and scrub birch settlements in this and on lower slopes. zone, but several Higher on the active mining camps slopes, subalpine fir are located here. dominates the forest. Subalpine fir com- monly forms open forest and woodland Climate on steep, moist, cold, middle slopes, espe- The Spruce–Willow– cially on northern Birch Zone has the and eastern expo-

harshest climate of all sures, where it Del Meidinger the forested zones in often forms nearly Open forests, typical of much of the zone British Columbia, . Fuhr pure stands. second only to the Mountains near Atlin in winter Alpine Tundra. Winters here are long and cold, and summers are brief and cool. The mean annual temperature ranges between -0.7° and -3°C. Average temperatures remain above 10°C for only about a month in most parts of the zone and up to 3 months in some medium-elevation areas such as Muncho Lake in the drier, eastern portion. Moist Pacific air frequently causes sudden, often violent,

local storms during summer. The weather is more settled John Parminter in winter, but chinook winds sometimes disrupt the cold spells. Prescribed burning to enhance wildlife in the Tuchodi Valley Black spruce occurs infrequently on nutrient-poor sites at lower elevations. West of the Rocky Mountains, have had comparatively low impact in this zone. As a result, extensive seral stands of lodgepole pine are not common here, though they do occur in places such as the upper Jennings and Little Rancheria rivers. From the Rocky Mountains east, large-scale burning to enhance wildlife range has resulted in extensive young aspen stands and grasslands.

Muncho Lake

MoELP cover photo: Jim Pojar Balsam poplar is also uncommon throughout most of the zone, Wildlife but in Alsek-Tatshenshini it is widespread and often forms the he climate of the Spruce– timberline. Engelmann spruce, Willow–Birch Zone limits the birch, and tamarack are diversity of species in the zone. absent from the Spruce–Willow J. Pojar AlthoughT the high-elevation plateaus –Birch Zone. Scrub birch thickets amid grassy meadows and valleys provide critical summer -dominated ecosystems are range, most species abandon these widespread, ranging from swamps and fens to dry areas before the onset of winter. Only colluvial scrub. On some of the driest, poorest those animal species that go dormant sites, usually rapidly drained outwash or are capable of surviving the bitter deposits, an open woodland of lodgepole cold remain in the zone year round. pine, scrub birch, and ground lichens Winter residents include mountain occurs. Aspen stands are fairly common goats, which can survive the deep on drier sites along the major valleys. snow better than most ungulates At upper elevations, the landscape of because they retreat to steep, rocky this zone is essentially scrub/parkland winter ranges where snow accumu- that is dominated by fairly tall (1–4 m lates less than elsewhere. Stone sheep high) deciduous shrubs. These are inhabit areas of steep, south-facing primarily scrub birch and willows such grasslands, especially in areas where as grey-leaved willow, Barclay’s willow, less snow falls or the snow blows tea-leaved willow, Barratt’s willow, Alaska away. Rocky Mountain elk and mule willow, and woolly willow. In some areas, deer are found only in the Rocky groves of stunted aspen and balsam poplar occur at the timberline, usually on steep south slopes. It may be that deciduous shrubs dominate in this zone because they grow quickly F. Boas during the short, intense growing season, then shed their in late summer, thus avoiding the killing Grey-leaved willow autumn frosts. In some of the high, wide valleys where cold air masses settle, a non-forested mosaic of shrubfields, fens, and dry to moist grassland occupies the val- MoELP ley floor and lowermost slopes. The lower slopes have a skirt of Stone sheep forest, and above the interme- Ovis dalli stonei diate forested belts, shrubs dominate again. This “double Mountain foothills and east slopes, treeline” phenomenon is John Parminter where the snowfall is less than in most particularly well developed and Wide valley affected by cold air drainage areas of the zone. and caribou striking on the northern plateaus. Some of are abundant and widespread. these valleys also contain permafrost, especially above 1200–1400 m. Elsewhere Their best winter range is in the in the zone, pockets of permafrost occur sporadically, mainly on north slopes. valley bottoms, but, because of deep Wetlands in the Spruce– snow, they often abandon the zone Willow –Birch Zone are usually by mid-winter. the richer types, including white spruce and tall willow swamps, sedge fens, and Jim Pojar sedge marshes. Acid, nutri- ent-poor bogs are uncom- mon. Although subalpine grasslands occur frequently Jim Pojar in this zone, they are usually not extensive.

Altai fescue grassland in foreground, and wetland in valley, Spatzizi Plateau Moose Alces alces Mark Nyhof

Common Raven Ken Bowen Corvus corax Grizzly bear Ursus arctos Open stands of lodgepole pine, such as those in the upper reaches of the Turnagain and Jennings rivers, provide impor- are common in wetlands and shallow lakes, tant winter range for caribou, which paw or nuzzle through and moose wade through these areas in summer to the snow to get at the ground lichens. Hardy birds, such as find aquatic vegetation and escape biting insects. Common Raven, Gray Jay, and Chickadee eke out a Other representative species that use Spruce–Willow– winter existence by foraging or carion. There are no Birch wetlands include the Northern Harrier, Mallard, reptiles in the zone, but a few amphibians—the , frog, and spotted frog—survive by burrowing in the mud and hibernating away the winter. With the coming of spring, the zone explodes with life. Because of the abundance of wildlife in summer, the Spruce–Willow–Birch Zone is often called the “Serengeti of the North.” Mountain goat, sheep, moose, caribou, and elk are all common, along with wolves and bears. Grizzly bear are more abundant than black bear in this zone. Open coniferous forests are the most common habitat in Illustration: Mark Nyhof this zone. Bird life includes , Common Wolverine Raven, Gray Jay, Boreal Chickadee, Red-breasted Nuthatch, Gulo gulo Three-toed Woodpecker, Ruby-crowned Kinglet, and Golden-crowned Kinglet. Small include red , wolverine, and marten. Open, shrubby and grassy valley bottoms are important summer range for moose and caribou. The , White-tailed Ptarmigan, Gyrfalcon, Wilson’s Warbler, and arctic ground squirrel also inhabit these sites in summer.

Gray wolf Canis lupus

Mark Nyhof Ken Bowen Arctic ground squirrel Spermophilus parryii , Gyrfalcon, Common Raven, Blue Grouse, Say’s Phoebe, and arctic ground squirrel. A wide diversity of species inhabits the extensive young seral stands of this zone, including moose, , lynx, , Dark- eyed Junco, American Robin, Mark Nyhof Wilson’s Warbler, Kestrel, Northern Pintail Townsend’s Solitaire, - Anas acuta rumped Warbler, and . Northern Pintail, Bufflehead, Arctic Tern, Floodplains and riparian California Gull, Red-necked Phalarope, Red- are more important for throated Loon, Yellow Warbler, and Common moose, because they produce Ken Bowen Yellow-throat. such good browse. Although South-facing slopes of younger forests and these areas are not extensive, they Arctic Tern grasslands are very important habitats in the also provide habitat for the Northern Waterthrush, Sterna paradisaea Spruce–Willow–Birch Zone. These areas have American Redstart, and Ruffed Grouse. shallower snow depths and a warmer local The Muskwa River area has a large population climate and are used in early winter and spring of plains bison, a non-native species that was by Stone sheep, Dall sheep, mountain goat, and introduced here in the 1970s. moose. Other characteristic species include the

Mark Nyhof

Mark Nyhof Yellow Warbler Dall sheep Dendroica petechia Ovis dalli dalli Resources The Spruce–Willow–Birch Zone has no forest harvesting or agriculture. Most people who live here are guide outfitters who assist people from around the world to hunt big . Many people from neighbouring zones come here for outdoor activities such as hunting, horseback riding, hiking, camping, back-country MoELP skiing, rafting, canoeing, Spatzizi MoELP and snowmobiling. Spatzizi River ALPINE TUNDRA

SPRUCE–WILLOW–BIRCH

BOREAL WHITE AND BLACK SPRUCE

SUB–BOREAL PINE – SPRUCE

SUB–BOREAL SPRUCE

MOUNTAIN HEMLOCK

ENGELMANN SPRUCE – SUBALPINE FIR

MONTANE SPRUCE

BUNCHGRASS

PONDEROSA PINE

INTERIOR DOUGLAS–FIR

COASTAL DOUGLAS–FIR

INTERIOR CEDAR – HEMLOCK

COASTAL WESTERN HEMLOCK

he Spruce–Willow–Birch Zone is one of four- teen biogeoclimatic or ecological zones within T British Columbia. These zones are large geo- graphic areas that share a similar climate within the province. Brochures in this series explore each zone.

Ministry of Forests For further information contact: December 1998 Detail on British Columbia’s Biogeoclimatic Zones is available in: B.C. Ministry of Forests Research Ecosystems of British Columbia P.O. Box 9519 Stn Prov Govt Special Report Series #6 Victoria, B.C. V8W 9C2 D. Meidinger and J. Pojar Ministry of Forests Research Branch, Victoria, B.C.

Text: Judith Alldritt McDowell Technical Editors: Jim Pojar, Craig DeLong, and Del Meidinger Image Co-ordination: Linda Bedard Design and Layout: Soren Henrich

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