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The Alpine Tundra Zone occurs on mountains throughout British Columbia, but especially along the Coast Mountains, in the north of the province

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Introduction

The Alpine Tundra Zone occurs on mountains throughout British Columbia, but especially along the Coast Mountains, in the north of the province, and in the southeast corner. It also extends beyond the borders of British Columbia to the north, east, and south. In southeastern British Columbia, alpine elevations start at about 2250 m, in the southwest at 1600 m, in the northeast at about 1500 m, and in the northwest at about 1500 to 1000 m. with limited areas of continuous vegetation cover. Soils are typically shallow and derived from weathered bedrock. Since cold retards the process of weathering, soils develop slowly in this zone. Occasional areas of permafrost also occur here. Terrain At the high altitudes typical of this zone, the terrain is often steep and rugged, with tall cliffs and rocky, snow-capped peaks. Much of the landscape is rock, ice, and snow, but some areas have stretches of flatter, gently rolling terrain, probably smoothed by glacial action. Glaciers also scoured out valleys and shaped steep cliffs and valley walls. When they melted, glaciers left a variety of special alpine landforms such as basin-like cirques. Talus slopes occur where gravity has caused frost-shattered fragments of rock to slide or fall down the slope. In alpine regions, the physical environment dictates the vegetation. Whether the terrain is gentle or extremely rough, the smallest differences in the microenvironment are important. In the open and windy places typical of the alpine tundra, even a few centimeters difference in topography have a pronounced effect on factors that influence plants - soil temperature, depth of thaw, exposure to wind, and drifting snow. The result is a complex mosaic of vegetation and soil types. At the middle and lower elevations of the zone, depending on the topography, there is a mix of patchy or patterned vegetation, along with limited areas of continuous vegetation cover. Soils are typically shallow and derived from weathered bedrock.

Middle

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.

Conclusion

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. ?? ??

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