often herbs, shrubs, and deciduous trees such as aspen and willow. Although these plants may dominate the region for a long time, conifers such as white spruce and black spruce often overtake them. In other places, conifers such as lodge-pole pine and black spruce may reseed and dominate an area directly after afire, bypassing the deciduous stage. Because upland forests have many fires, the landscape is a mosaic of stands of various types and ages.
climate and Terrain
Winters in this zone are long and extremely cold. The summer growing season is warm, but short. The zone receives relatively little precipitation and the least snowfall of all northern zones. Pockets of permafrost (permanently frozen ground) are common in peat lands in the northern areas. Trees and most other plants grow slowly in the cold climate and dead plants decompose slowly. The topography of the zone varies from the mostly flat and low-lying Alberta Plateau in the northeast, tithe rolling Rocky Mountain foothills and the rugged mountains of British Columbia’s northwest.
The Boreal White and Black Spruce Zone is a mixture of two main ecosystems: upland forests and muskeg. Upland forests are most common in better-drained parts of the Alberta Plateau in the east and in mountainous parts of the zone in the west. Muskeg is most extensive on the poorly-drained northeastern lowlands. The zone contains several different upland forest types. The most common types are mixed stands of trembling aspen and white spruce and mixed stands of lodge pole pine and black spruce. Open lodge-pole pine and lichen forests occupy drier sites, whereas wetter sites give rise to communities of dense black spruce and moss. White spruce and balsam poplar flourish in rich, well-drained river bottoms, which contain the most productive forests of the zone.
E ecosystems
The term “muskeg” describes the peat land combination of bogs and nutrient-poor fens that cover extensive parts of northeast British Columbia. The most common trees in this ecosystem are stunted black spruce and tamarack. Muskeg occurs over deep layers of peat, and per-mafrost can be found here. The Boreal White and Black Spruce Zone con-tains several other minor but important ecosystems: in the northeast, nutrient-rich swamps and fens are dominated by tamarack, sedges, and brown mosses; boreal grassland and scrub communities occupy steep, south-facing slopes; and small
but productive marsh and shal-low-lake ecosystems are found throughout the zone.
Sub boreal Pine Spruce
Climate
The Coast Mountains cast a strong rain shadow over the Sub-Boreal Pine–Spruce Zone. As a result, winters and summers are both dry, with a mean annual precipitation of only 335–580mm. Skies are mostly clear and humidity is low. The resulting lack of moisture is a principal factor in limiting growth. Because the zone lies at relatively high elevations, winters are cold and temperatures remain cool in summer. Night-time frosts, caused by the rapid loss of heat through re radiation into the dry, often cloudless night-time sky, are common in all months. The short, cool growing
season and relatively dry soils are reflected in slow tree growth and an abundance of plants that can tolerate frequent frosts and drought.
Ecosystems
The Sub-Boreal Pine–Spruce Zone consists of two principal ecosystems – lodge pole pine forests and wetlands. Lodge pole pine is by far the most common tree species here. In fact, it is the only tree species in many extensive forest stands in the high and very dry southwestern part of the zone. In this area, lodge pole pine not only dominates the forest canopy, it is the only tree species in the under story, which indicates that it is the climax tree species here. This seldom occurs in North America. Other forest ecosystems, though much less extensive than lodge pole pine forests, add
important diversity to the Sub-Boreal Pine–Spruce landscape. Stands of white spruce or hybrid white-Engelmann spruce occur on moist sites throughout the zone, but they are
usually small and located primarily around the edges of non-forested wetlands and adjacent to streams. In wetter parts of the zone to the north and east, white spruce is occasionally found in the canopy of mature pine stands. It is also common in the under story. Trembling aspen is
a common seral species throughout the zone, but, like spruce, it usually dominates in small stands, primarily in moist are as such as the borders of wetlands and streams. Douglas-fir, black spruce, and black cottonwood occur occasionally on specific sites. For example, Douglas-fir grows on some warm, south-facing slopes near the boundary with the Interior Douglas-fir Zone, and black spruce appears in northern parts of the zone in cold valley bottoms and wetlands. The floodplains of some rivers contain stands of black cotton wood. In the very dry southwestern parts of the zone, the pine forest undergrowth consists largely of kinnikinnick, common juniper, soopolallie, pine-grass, and lichens. On especially dry sites, even pine grass is often either absent or very sparse, and only kinnikinnick, common juniper, and lichens form the undergrowth.
Sub Boreal Spruce Zone
Climate
Because of its northern interior location, the Sub-Boreal Spruce Zone has a continental climate with characteristic extremes of temperature. Summers are short but warm and moist, with day-time temperatures that occasionally reach into the 30s. Winters can be severe, with extended periods below -10°C and extremes that can reach-40°C or colder. Though drier than the coast, the Sub-Boreal Spruce Zone is wetter than areas such as Williams Lake to the south. Most of the zone is under snow for four to five months, from November to March. In summer, frequent thunderstorms sweep through the area, creating a fire hazard which is somewhat moderated by the moist climate.
Ecosystems
Seen from an air-plane, the terrain in the Sub-Boreal Spruce Zone appears as a vast, rolling landscape covered with dense coniferous forests. The upland forests of the Sub-Boreal Spruce Zone contain a distinctive combination of tree species. Here, the dominant coniferous species are hybrid white spruce, sub-alpine fir, and occasionally, black spruce, along with lodge pole pine, a pioneer species in the drier parts of the zone. Douglas-fir also occurs on dry, warm, rich sites. Together with the moist climate, deep snows, and heavier precipitation, this combination of species results in a highly productive forest with a distinctive under story that includes abundant lilies, ferns, blueberries, and Devil’s club.
trembling aspen, which regenerates primarily from underground roots, is a common pioneer deciduous species on moist to dry birch is another pioneer species Forests of black cottonwood of spruce occur occasionally on of major streams and rivers. well-drained sites, the shrub huckleberry, thimbleberry, high-bush- and Sitka alder under spruce and sub-alpine Spruce and fir also appear as shrubs under huckleberry, velvet-leaved blueberry, and kinnikinnick frequent many drier sites under lodge pole pine. Black gooseberry, black twinberry, bunchberry, thimbleberry, Devil’s club, oak fern, and Queen’s cup are among the shrubs and herbs that occur in wetter areas, usually under a canopy of spruce and sub-alpine fir.
Mountain Hemlock Zone
Climate
The Mountain Hemlock Zone has short, cool summers and long, cool, and wet winters, which are typical of a maritime mountain climate. This is one of Canada’s wettest ecological zones. It receives up to 5000mm of precipitation every year from the numerous Pacific weather systems that sweep over the coastal mountains. With up to 70 percent of this precipitation falling as snow, the area has a deep snow cover form any months of the year. Because the deep snow pack melts so slowly, the zone has a relatively short growing season.
Ecosystems
Vegetation within the Mountain Hemlock Zone is strongly influenced by elevation. Because at higher elevations temperatures are colder, the growing season is shorter, and snows are deeper, trees grow better at the lower elevations. Mountain hemlock, Amabilis fir, and sometimes yellow-cedar are typical of lower-elevation forests. Western hemlock and western red cedar are less common but often form an important part of the tree canopy. In the southern part of the zone, Douglas-fir and western white pine may also occur in lower-elevation forests; in the north, Sitka spruce is often present. These forests often have dense shrub growth under the tree canopy. Oval-leaved blueberry, Alaska blue-berry, black huckleberry, false azalea, and white-flowered rhododendron are the most common shrubs. Typically, these forests also have abundant regeneration of amabilis fir in the under story. The forest floor is usually covered with a thick and diverse carpet of mosses. Dry forests occur intermittently at low elevations, and tend to have amore open tree canopy dominated by mountain hemlock. On these dry sites, Copper Bush is a common shrub. Occasionally, lodge pole pine grows on very dry sites, but it can also grow on wet sites. On wetter and richer sites, amabilis fir and yellow-cedar are dominant. Bog forests inhabit very wet sites at lower elevations within the zone. Yellow-cedar and mountain hemlock form an irregular and open canopy in these bogs, while skunk cabbage and Indian hellebore are characteristic under story plants.
Englemen Spruce Sub alpine fir
Climate
Cold and snowy conditions prevail for five to seven months of the year in the Engelmann Spruce – Sub alpine Fir Zone, where snow packs as deep as two to three meters are common. Snows are heaviest in the wetter parts of the zone: for example, in the area of the northern Selkirks and along the Coast Mountains. In the drier areas, where snowfalls are relatively light, soils usually freeze early and remain frozen for several months. In sub alpine parkland, at the highest elevations of the zone, snows are heavy and can stay on the ground until July. Not only are winters long and cold, summers are short and cool, with mean monthly temperatures above 10 • • C for up to two months of the year.
Ecosystems
Forests of Engelmann spruce and sub alpine fir cover the land in the lower and middle elevations of this zone. Since spruce typically lives longer than fir, it usually dominates the forest canopy in mature stands. Sub alpine fir is abundant in the under story. However, at high elevations in the zone and in some of the wetter parts of the zone, sub alpine fir often dominates. In the sub alpine parklands that occur at higher elevations, the landscape is dotted with scattered islands of fir trees mixed in with areas of heath, meadow, and grassland. On the heath, mountain-heathers dominate, usually on wet sites where snow remains into the summer. At the higher elevations, wind is an important factor in the formation of krummholz, bushy clumps of prostrate conifers that grow near the tree line in areas where deep snow accumulates. Krummholz trees put up long leaders that
become dry and rough from exposure to driving wind and ice crystals. In drier parts of the zone, trees occur primarily in places where soils are deeper and where snow accumulates and provides moisture for the growing season and pro-tection from winter winds. In these areas and in areas that have been disturbed by fire, lodge pole pine is often the main species.
Montane Spruce zone
Ecology
The unique combination of species that characterizes the Montane Spruce Zone reflects its transitional nature. The zone has floristic affinities to the zones that occur above and below it. Canopy species such as sub alpine fir and under story species such as grouse berry, black huckleberry, and Utah honeysuckle indicate the Montane Spruce Zone’s connection with the Engelmann Spruce–Sub alpine Fir Zone, while the occurrence of Douglas-fir, pine grass, and soapberry reflects its close association with the Interior Douglas-fir and Sub-Boreal Pine–Spruce zones. The spruce of the Montane Spruce Zone forests also reflects the zone’s transitional nature —it is a hybrid between the characteristically high-elevation Engelmann spruce and the lower-elevation, more northerly white spruce. One of the most distinctive features of this zone is the presence of extensive seral stands of lodge pole pine. These forests dominate the Montane Spruce landscape, and most stands display the even-aged, even-sized canopies that follow wildfires. Frequent stand-replacing fires have had a pervasive influence on this zone. This was especially apparent in southeastern British Columbia in 1985 and in south-central British Columbia in 1998, when mushroom-shaped smoke plumes climbed 5000 m into the sky from fires centered on the Montane Spruce Zone.
Climate
The climate of the Montane Spruce Zone is generally cool, with cold winters and short, dry summers. The climate is largely the result of the zone’s high elevations and its location in the strong rain shadow of the Coast and Selkirk mountains. The average temperature gets above 10°C for only 2–4 months of the year. For 5 months of the year, average temperatures stay below 0°C, and night-time below-freezing temperatures are possible, even during the growing season. Precipitation is relatively low. It varies between 300 and 900 mm a year, much of it as snow in the winter. The snow pack usually averages between 60 and 100 cm. May and June are often the wettest months of the growing season; however, summers tend to be dry, and lack of moisture in the growing season can be a problem in some areas. The extended period of drought in summer often leads to large, stand-destroying fires such as those that occurred in 1998.
Bunch Grass zone
Climate
Situated in the rain shadow of the Coast and Cascade mountains, the Bunchgrass Zone
includes some of British Columbia’s warmest and driest areas. Summer temperatures range from warm to hot, becoming progressively cooler to the north and west, and winters are moderately cold. Peak periods of precipitation occur in early winter and again in June, but, overall, precipitation is low. Peak snow pack is seldom greater than 50 cm, and many sites are without snow for most of the winter, especially on southern aspects and wind-exposed sites. Soils typically regain moisture during the winter and spring when temperatures are cooler and evaporation is less intense. However, because of low precipitation and high evaporation rates during the summer, upland soils typically remain moist for only a short period during the growing season. By late June, drought conditions prevail in most of the zone’s upland sites.
Ecosystems
On most upland sites, summer droughts are too severe for trees to become established. As a consequence, grasses form the dominant vegetation cover. Drought-tolerant shrubs and forbs are also common. Widely spaced bunchgrasses, particularly blue bunch wheat grass, are characteristic of the native, undisturbed vegetation. Other common grasses include needle-and-thread grass, June grass, and Sandberg’s bluegrass. Big sagebrush ecosystems (also called shrub-steppes) often dominate in the lower elevations of the zone. Rabbit-brush is also common in the zone but is seldom dominant. Many of the plants that occur here are typical of the Great Basin region of the western United States and reach their northern limits in this zone. Where sites have been disturbed by overgrazing or other activities, native species such as prickly-pear cactus, low pussy toes,
needle-and-thread grass, and pasture sage often become dominant.
Ponderosa Pone Zone
Ecosystems
The vegetation in this zone often consists of a mosaic of forests and grass-land. Ponderosa pine, which dominates most forests in this zone, is also called yellow pine and is best known for its characteristic vanilla-scented, cinnamon-colored bark made up of jigsaw-puzzle- shaped scales. The thick bark helps make the tree resistant to surface fires. Stands are often open and park-like, with a ponderosa pine canopy and an under story of blue-bunch wheat grass, rough fescue, and arrow-leaved balsamroot. Other dominant species in this landscape include Saskatoon, pasture sage, lemon weed, and yarrow. Tree regeneration, in natural conditions, is uncommon in the under story, and there are few, if any, shrubs. Additional plant species can include silky lupine, orange arnica, rosy puss toes, Rocky Mountain fescue, Idaho fescue, slender hawks beard, timber milk-vetch, June grass, and cheat grass. Ponderosa pine bark
Climate
The Ponderosa Pine Zone is the driest of the forested zones in British Columbia, and in summer it is also one of the warmest. In July, mean temperatures range from 17 to 22° C. The low precipitation of 250–450 mm per year is a result of the strong rain-shadow cast over this area by the Coast and Purcell Mountains. Most precipitation falls in winter, with December and January being the wettest months. Winters are cool, with a light, intermittent snow cover. The snow pack varies from 0 to up to 50 cm and may come and go throughout the winter. The growing season is relatively long, with a continuous frost-free period of 125–175 days. This makes the area suitable for agricultural purposes, provided there is water for irrigation.
Interior Douglas Fir
Climate
The Coast, Cascade, and Columbia mountains cast a rain-shadow over the Interior Douglas-fir Zone. Warm and dry in the short summer season and cool in winter, the climate is driest at lower elevations in the Okanagan-Similkameen, Lytton-Lillooet, Chilcotin, and Kamloops areas and wettest in areas close to the Columbia and southern Coast mountains. The ecology of the area reflects the shortage of moisture in much of this zone. Plants such as pine grass flourish here because they can survive on little moisture during the growing season.
Ecosystems
A diverse and interesting array of ecosystems occurs within the Interior Douglas-fir Zone. Forests dominated by Douglas-fir trees of all ages and sizes with a grassy under story in which pine grass is most common are typical in this zone. On hotter and drier sites, grassland and open ponderosa pine forest predominate, while dense, closed-canopy spruce forests occur on wetter and cooler sites such as in riparian areas. Lodge pole pine is common at higher elevations or where there has been recent fire. Extensive grassland communities, commonly called the “upper grass-lands,” occur throughout drier parts of the zone. Blue bunch wheat grass, June grass, and fescues are prominent grasses in these communities. These grasses also occur on very hot and dry sites such as upper, south-facing slopes and ridges where ponderosa pine forms open, park-like forests. Wetlands are found in depressions and around open water. Marshes with cattails, sedges, and bulrushes ring the open water with shrubby willows and birches in nearby swamps. The prominent red stems of
red-osier dogwood stand out along stream banks in winter after the leaves have fallen. A unique wetland ecosystem found in this zone consists of saline meadows dominated by salt grasses.
Coastal Douglas Fir zone
Environment
This small corner of the province enjoys perhaps the finest climate in Canada. Sheltered by the rain shadow of the Vancouver Island and Olympic mountains and warmed by air from the Pacific, the area basks in a Mediterranean-like environment of warm, sunny summers and mild, wet winters. Unlike more exposed coastal areas such as the west coast of Vancouver Island, this zone experiences long dry summers, which are a major factor in its ecology.
Ecosystems
Here the majestic Douglas-fir reigns supreme, occurring in a wide range of sites from dry rock outcrops to moist valley bottoms. In upland Douglas-fir forests, salal and Oregon grape are common under story plants; in rock outcrop areas, arbutus, Garry oak, and occasionally lodge pole pine grow alongside Douglas-fir. Wild rose, snowberry, and ocean spray are well adapted to these open, dry ecosystems. In moister forest areas, Douglas-fir, grand fir, western red cedar, big leaf maple, and western flowering dog-wood flourish together with under story plants such as sword fern, salmonberry, and trillium. Skunk cabbage and red alder are typical of wet swampy areas, along with Indian plum, salmonberry, and red elderberry.
Saanich
Ecosystems
The Coastal Douglas-fir Zone is also home to a unique and sensitive group of ecosystems known collectively as saanich, meaning “place of fertile soil” in the language of the local aboriginal people. Most common on southeast Vancouver Island and the Gulf Islands, the saanich complex includes seaside parkland, dry forest, rock outcrop, and wetland habitats and contains many rare plants. Two common trees here, Garry oak and arbutus, are found nowhere else in Canada. Garry oak parkland is perhaps the most unusual ecosystem in the saanich group. In dry sites with deep soils, Garry oaks form an open tree cover above a carpet of grasses and colorful spring
flowers, including blue camas, shooting star, Easter lily, chocolate lily, and satin flower. These habitats may also harbor rare, endangered plants such as golden Indian paintbrush and deltoid balsamroot.
Where Rivers Meet the Sea
Estuaries, where rivers and streams flow into the sea, are highly productive and important ecosystems, providing habitat for a wide variety of life. The nutrient-rich, protected waters of estuaries are an ideal environment for over wintering birds, for example, and serve as excellent nurseries for young fish.
Interior Cedar Hemlock Zone
Climate
The Interior Cedar–Hemlock Zone owes its long, warm summers and cool, wet winters to the predominance of easterly-flowing air masses. Although in most of the zone summers are relatively dry, the slow-melting snow pack helps keep soil moisture levels high during the summer. In general, warm moist conditions prevail in southeast parts of the zone (commonly called the Interior Wet Belt) while the northwest is cooler and wetter.
Forests and Other Ecosystems
Wetlands make up only a small part of the zone. They are generally confined to valley bottoms, where marshes form along lakes and streams (riparian areas). Widely spaced red cedar, hemlock, spruce, and an under story of skunk cabbage dominate in small swamps. Devil’s club and large ferns grow along stream edges and seepage sites. Small bogs are found in some upland areas. Willows, sedges, and other characteristic wetland plants may dominate in non-forested or sparsely treed ecosystems. Productive coniferous forests cover most of the Interior Cedar– Hemlock Zone. Western red-cedar or western hemlock characterize these forests, but there are more tree species here than in any other ecological zone in the province. Ponderosa pine, Douglas-fir, western larch, lodge pole pine, and western white pine all grow here. Two deciduous trees— trembling aspen and paper birch—grow in drier parts of the zone, while sub-alpine fir and spruce thrive in wetter and cooler areas. Western yew grows mostly in southern parts of the zone.
O ld Forests
Old forests predominate in wetter parts of the zone, where fires are infrequent. Here, trees grow to great sizes and ages, rivaling the giant trees on the British Columbia coast. Forests in this zone contain many standing dead trees (called snags) and large accumulations of fallen logs and other woody debris. These features of old forests pro- vide valuable habitat for a wide variety of life forms, from seedlings and fungi to birds and bears.
Coastal Western Hemlock Zone
Temperate Rainforests
Coniferous forests predominate in the Coastal Western Hemlock Zone. Commonly called “temperate rain-forests” because of the mild, wet climate in which they grow, these forests are complex and often highly productive ecosystems. British Columbia’s temper-ate rainforests are among the most impressive in the world. They are home to trees of great age and massive proportions. Temperate rain-forests grow in moderate climates, where temperature varies relatively little from summer to winter, and where there is an abundance of rainfall. About half of the world’s temperate rainforests are found on North America’s west coast. Others are found in Norway, New Zealand, Tasmania, and southern Chile.
Environment
Mountains and ocean dominate the Coastal Western Hemlock Zone, creating the coastal climate and ecology. The Coast Mountains form a barrier between warm air flowing in from the Pacific and the continental air masses of the province’s interior. As Pacific air pushes over the mountain barrier, it drops much of its moisture as rain or snow, producing one of the wettest climates in Canada. The mild Pacific Ocean moderates temperatures, resulting in cool summers and mild winters. Because of the wet climate, nutrients are quickly leached out of the mineral soil. Many of the nutrients are held in the soil by organic matter such as humus and rotting wood, and in the vegetation itself.
wind in the Forest
Wind is a common form of natural disturbance in this zone, especially on the exposed outer coast,
where storms are often accompanied by strong winds. By blowing down one tree or small patches of trees, wind disturbance creates openings or gaps in the forest canopy. These gaps allow light to penetrate to the forest floor, stimulating the growth of shrubs and tree seedlings. More rarely, larger patches are partially or completely blown down and the recovery cycle occurs on a larger scale.