Saturday, 11 August 2012


As you hike up the mountain the trees gradually get smaller and farther apart. There are more sunny openings with wildflowers and views. Eventually, if you climb high enough the trees disappear altogether, and the ridges are occupied by low-growing shrubs. This transition occurs at about the 1800 metre level, and has been called the timberline. It is the zone where the snow stays so long into the summer that the growing season is too short for trees to survive. Only shrubs and herbaceous plants are able to live there. The snows do not melt until July and they come again in October. The plants that live here must leaf out, flower, and produce seeds in a period of three months, as they are snow-covered for three quarters of the year. This is the high country of alpine meadows and heather-covered summits. The bare rocks contrast sharply with the brilliant colors of the wildflowers. This is the country that enchants both the naturalist and the hiker. It is an environment which is rugged and delicate at the same time.

The lake in this photo is at 1900 metre elevation.
Photo by Kelly Sekhon

The low elevation forest along the coast is often referred to as the rainforest, because of the high rainfall levels. The higher elevation forest has been called the snow forest, as snow has more influence here than rain. Although snow cover lasts into the summer or late spring, the growing season is still long enough for trees to develop. As you hike through this upper forest, however, there are signs and indications that you are approaching the high country. Some of these indicators are the changes in the species of trees themselves. Even if you do not know the names of these trees, you will still see that they are different from the familiar trees near sea level. Those familiar trees are gradually replaced by others which are more adapted to the long winters and harsher conditions. Redcedar (Thuja plicata) is replaced by yellow cedar (Chamaecyparis nootkatensis). Western hemlock (Tsuga heterophylla) gives way to mountain hemlock (Tsuga mertensiana), and Douglas fir (Pseudotsuga menziesii), which is not actually a true fir, is superseded by amabilis fir (Abies amabilis). The low elevation forest, because its most common tree is the western hemlock, is called the Western Hemlock Zone, and the high forest which is dominated by mountain hemlock is called the Mountain Hemlock Zone. 

There are a number of features about the Mountain Hemlock Zone which tell you that you have reached the high elevation forest even before the trees begin to thin out. The thick snow  cover lasts well into the summer, at which time it becomes very hard and treacherous, especially on steep slopes. At such times it is advisable to have an ice axe and know how to do a self arrest. Another hazard on these slopes are deep tree wells. The snow melts away from the sides of the tree trunks. The trunks are dark and absorb heat, and there is also a small amount of heat released by the trunks themselves. In early summer the larger trees are surrounded by these deep vertical shafts. Another reason for carrying an ice axe. Once the snow has melted another characteristic of the trunks becomes visible. The tree itself may be vertical, but the base usually curves downhill. This twist was produced when the tree was young and small. For the large trees that was centuries ago. The weight of the snow bends small trees. It is only when they are older that they can become tall and straight, but the evidence of the long ago formative years remains. 

As the growing season becomes less and less, the trees get smaller and smaller, and farther apart. This means that sunlight can reach the ground, and is not blocked by the needles on the trees. If there is enough moisture herbaceous plants are able to grow, and they do so in great profusion. These are the subalpine meadows, and in July they present a panorama of colors. They  have little time to flower and set seed, and so they do so rapidly, and with a blaze of glory. With so many flowers it would seem that there must be an equally large number of seedlings. But like so many other things in life, this is an illusion. There are many seeds, but very few seedlings. Unlike the plants at lower elevations, the harsh conditions of the high country allow only a miniscule number of these seeds to be successful. As you hike through the meadows, look and see how many seedlings you can see. Usually there are none at all! 

The meadows bloom in two waves. First there are the plants that are the most cold resistant. These flower close to the melting snow. As the soil warms the second wave comes into bloom. By this time the early ones are already in seed. Some of the first shoots actually push their way through the melting snow, although usually there is a brown zone of dead vegetation immediately adjacent to the snowbanks, and outside this is the green zone of emerging shoots. The first flowers to appear are the yellow snowlilies (Erythronium grandiflorum), the little white spring beauties (Claytonia lanceolata), and the white flowered western anemone (Anemone occidentalis). The later stage is dominated by flowers such as the blue flowered lupins (Lupinus arcticus), and the orange flowered paintbrushes (Castilleja miniata).

The meadowlands grow where there is rich soil, and abundant seepage. If you leave the meadows and hike onto the rocky, dry ridges you find a much more hostile environment. Rain or snow melt runs rapidly off these sites, carrying nutrients with it. This moisture and dissolved minerals runs down slope to the lush herbaceous plants below. There is a striking difference between the dominant vegetation of the rocky sites and the moist, deep soil slopes below. The ridges belong to small shrubs with tiny needle-like leaves. These are the heathers (Ericaceae). Heathers are adapted to live in such extreme environments. Their roots contain efficient microscopic fungi that help them gather water and nutrients in such sites. Their leaves are like tiny coniferous tree needles. They are small, evergreen, and narrow, and have thick surfaces which resist water loss. The shrubs themselves are short and close to the ground, so that they are covered by a blanket of protective snow in the winter. Because they grow close together they are able to lessen the effects of desiccating winds. There are two common heather species on these ridges, the pink mountain heather (Phyllodoce empetriformis), and the white heather (Cassiope mertensiana). The pink flowered species tends to grow at lower elevations than the white one. Its leaves look like the needles on many conifer trees. The white one is adapted to more extreme sites where the snow lingers longer. Its leaves are shorter and pressed close to the stem, like scale leaves on cedars. This is an adaptation to the more rigorous conditions at these higher altitude ridges. 

Where the trees give way to the meadows or ridges, you may notice that they present some unusual growth forms. In the meadows there may be a few tree islands. These are spots where the snow leaves a little earlier, and the growing season is just long enough for tree seedlings to get started. They usually occupy little hillocks where the sun can heat the ground a little more. Once one tree gets started it produces some protection against the wind, and also lessens the accumulation of snow, and so other trees can get started. In this way a small grove develops after several centuries. On the ridges trees are often dwarfed, and grow densely packed together. This growth form is called krummholz, meaning crooked wood. During the winter these sites are bitterly cold and windy. Any buds or needles projecting above the snow surface are killed, but those protected by the covering of snow are able to survive. Therefore, the trees cannot grow upwards, but they can grow sideways. Hiking along such ridges is difficult because of the impenetrable shrubby barrier.  

One feature you cannot fail to notice on the alpine rocks are the lichens. Even if you are not consciously aware of them, they still form part of the subconscious impression of what a high mountain ridge looks like. The dry surfaces of such rocks are very inhospitable for living things, but many lichens are specially adapted for living is such places, especially the ones that form thin crusts. The splotches on the rocks are usually lichens, not mineral coatings. Although they may not appear so on casual observation, they are alive, growing and reproducing. Their growth rate, however, is very, very slow. Most of the year they are covered by snow, and most of the time when they are not covered by snow, they are dried out by the sun. It is only during or shortly after rainy periods that they can actually grow. These splotches can come in a number of different shades and colors, and are more complex than they seem. They are simple ecosystems composed of two different organisms. Most of the lichen is composed of fungus threads, and among these threads are microscopic green plant cells - algae. The plant cells gather sunlight the way all plants do. They use this energy to combine water and carbon dioxide into sugars. The fungus part then uses some of the sugar to build its own cells. 

Some of the lichen species seen on rocks above the timberline.
Photo by Kelly Sekhon

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