Trees & Shrubs

Alaska Birch

The Alaska birch is a small tree, which resembles the white birch. Its bark peels off in papery layers, but not as readily as that of white birch. The leaf of this birch is almost triangular.

The Alaska birch is found throughout the Northwest Territories. It inhabits bogs and poorly drained soils. The birch commonly grows in pure stands or with other wet area species such as black spruce or tamarack.

Alpine Fir

The Alpine fir is a high-altitude tree with a narrow, spire-like crown and branches sweeping nearly to the ground. Where it grows at tree line in the mountains, it may be stunted, contorted and form a dense, matted growth.

The alpine fir closely resembles the more eastern balsam fir. The bark is smooth, grey and covered with resin blisters when young, later becoming scaly.

Balsam Poplar

The balsam poplar belongs to the same family as the trembling aspen. The bark is smooth and greenish-brown on young trees, becoming thick and furrowed as the tree ages. Its name was derived from the fragrant, resinous buds. The flowers form drooping catkins that hang from branches in the spring. The male and female catkins occur in separate trees. In the spring, the poplar discharges many cottony seeds, which are carried by the wind.

The balsam poplar is a wide ranging tree. It grows throughout the entire forested region of the Northwest Territories. Balsam poplar commonly co-exists with white spruce, sometimes along north-flowing rivers beyond the treeline. This poplar grows best in moist, rich, low-lying ground, such as river valleys and flood plains. The largest poplars of the Northwest Territories can be found along the Liard River south of Nahanni Butte to the British Columbia border.

A fast-growing, short-lived tree, the balsam poplar cannot tolerate shade. Wide-spreading, shallow root systems support balsam poplars that easily propagate by root suckers. In this way, poplars can easily regenerate in cut-over or burned areas.

The buds of the balsam poplar are eaten by grouse. Moose browse on the twigs and foliage. The bark is eaten by beaver, hares and porcupine.

Black Spruce

The black spruce is a slow-growing evergreen. It has drooping, up-turned branches. On many trees, the top branches form a dense, club-like crown because of cone clipping by squirrels combined with very slow branch growth. Along the treeline, the black spruce has a stunted growth.

The needles are stiff and four-sided. The cones are dark brown in colour, egg-shaped and hang from the branches. The cones can remain on the branches for several years.

The black spruce is the most widespread of the trees of the Northwest Territories. It occurs throughout the entire forested area. It grows on many different soils, but grows especially well in wet, boggy conditions.

Dwarf Birch

The dwarf birch is a bushy shrub with many branches that are densely covered with small, round leaves. The leaves are dark green with a shiny surface, and have rounded teeth on the margins. The flowers are borne on slightly hairy catkins.

The dwarf birch inhabits the low-arctic tundra and boreal forest across most of the Northwest Territories. It grows mainly on acidic rocks or peat bogs where it commonly forms thickets. It is generally associated with willow and other shrubs.

Green Alder

The green alder is a bushy shrub that forms dense thickets in some areas. The alder is common in all of the forested parts of western Northwest Territories. It grows well in low moist sites and along rivers and creeks. It may also be found along some rivers in the treeless tundra.

The bark of the green alder is smooth, reddish-brown or grey. The catkins develop before the leaf buds open in the spring. The fruit consists of small cone-like catkins on long stalks with several in a cluster. They are green, turning brown and woody at maturity.

Alders can be easily distinguished from other native tree species by the buds on a twig. The buds grow on a stalk that is attached to the twig while on other tree species the buds are attached directly to the twig.

Jack Pine

The jack pine is a ragged-looking evergreen. It has short needles that grow in pairs. The cones are curved inwards and generally arranged in pairs on the branches. They usually remain closed and persist on the tree until opened by the heat of a forest fire, or sometimes, by the heat of the sun. This pine is a pioneer species that readily regenerates in burned-over, sandy sites.

The jack pine is the most northerly of Canadian pines. It grows in areas south and around Great Slave Lake and extends north and west to the Mackenzie River valley. It is best developed on sandy soils growing in pure stands or mixed with spruce, aspen and birch. On poor soils or rocky sites, the tree is stunted and often twisted. The jack pine is closely related to and readily hybridizes with the lodgepole pine.

Lodgepole Pine

The lodgepole pine is a tall, slender evergreen with a straight trunk. It is very similar to the jack pine and readily hybridizes with it in areas where both species exist.

The needles of this pine are in bundles of two, and are spirally twisted. The cones stay closed and remain on the tree for many years. Like the jack pine, the cones of the lodgepole are "serotinous", and they require the heat of a forest fire to break the resin seal on the scales to release the seeds.

The tree occurs in the southwest corner of the Northwest Territories, south of Fort Simpson and up towards the lower slopes of the Mackenzie Mountains. It grows on a variety of sites, but its best growth occurs on well-drained loamy soils.

Lodgepole pine stands provide good habitat for spruce grouse, while its seeds are eaten by red squirrels, and its bark by porcupines.

Tamarack

The tamarack belongs the larch family. These trees are the only conifers that lose their needles in winter. The needles turn yellow in late autumn and are shed, then grown again in spring. These soft, flexible needles are arranged on the branches in clusters of 10 to 20.

The cones grow upright on the branches and stay on the trees over winter and through the following summer. Male and female cones occur on the same tree.

Tamaracks are found throughout most of the forested areas in the Northwest Territories. It is a tree of cold, wet places, occurring in sphagnum bogs and swamps. It grows with black spruce in open muskeg, and aspen and birch on better drained soils.

Trembling Aspen

The leaves of the trembling aspen give this tree its name. They have a flattened leaf stalk and flutter in a slight breeze. In the fall, the leaves turn brilliant yellow, contrasting with the green conifers. The bark is smooth and greenish-white with a waxy appearance, becoming rough and furrowed with age. The flowers form drooping catkins before the leaves appear in the spring. The flowers produce small tufted seeds.

The trembling aspen exists throughout most of the forested area in the Northwest Territories. It grows on almost all soils, but grows best in well-drained loams. It is a rapidly growing tree, quickly invading areas after forest fires or logging by sending root suckers up from its extensive root system. As a young tree, it grows in pure aspen stands. Since it is quite intolerant of shade, it is usually succeeded by more shade tolerant conifers.

Aspen is the chief food of the beaver. It also provides browse for moose and hares and cover for grouse.

White Birch

The white birch is known for its white, paper-like bark that peels easily into large sheets. The bark on young trunks is thin, smooth and reddish-brown before becoming white. This tree is also called paper birch and canoe birch because of its former use in making baskets and birch-bark canoes.

The flowers cluster in small, green, hanging catkins with the female and male flowers occurring on the same tree. These mature into cone-like catkins consisting of many small, three-lobed scales each of which bears a tiny, flat nutlet with a thin wing on each side.

White birch are distributed throughout most of the forested area in the Northwest Territories. They grow in a variety of places, but favour well drained sandy loams. They are intolerant of shade, so they grow in forest clearings and are one of the first trees to colonize burned or logged areas. This birch can reproduce quickly by developing sprouts around the base of the trunk.

Many animals feed on the white birch. Moose browse on the twigs in winter, while grouse and ptarmigan eat the buds. Small birds and rodents eat the seeds.

White Spruce

The white spruce is a dense evergreen with branches extending to the ground concealing a tapered trunk covered in thin scaly bark. Although the white spruce is tolerant of shade, its lower branches are shed in dense stands where there is little light.

The stiff, prickly needles are four-sided, unlike the flat ones of firs. The cones are long and slender and hang down from the ends of branches. Male and female cones grow on the same tree. The female cones mature in one season, opening in the autumn to release the seeds and falling off the branches in winter or spring.

The white spruce is found throughout the forested area of the Northwest Territories in a variety of soils. It grows best on well drained, but moist, silty soil. Large white spruce trees can be found in the Liard River area south of Nahanni Butte. The tree is commonly associated with aspen and white birch.

Willow

Over 40 different kinds of willow grow across the Northwest Territories. Willows are easily separated from other native broad-leaved trees, but it is difficult to distinguish between the various species themselves. Most are low-growing shrubs that occasionally form dense thickets.

The leaves are long and narrow, and pointed at both ends. They are arranged alternately on the twigs. Male and female flowers are on different shrubs, and form catkins that usually appear in the spring before the leaves emerge.

Willows generally grow along streams or in low places where the soil is moist. They are one of the few woody plants to survive in treeless tundra regions.

Willows provide browse for caribou, muskoxen and hares. The buds are a principal winter food for ptarmigan. The flexible twigs of some willows are used to make baskets.