The Taiga Biome Essay Research Paper Between

The Taiga Biome Essay, Research Paper

Between the tundra to the north and the deciduous forest to the south lies the vast expanse of the taiga, also known as the coniferous or boreal forest; the largest biome in the world and the second largest forest in the world, with only the great Siberian forest exceeding it in size. This cold-climate biome supports a dense belt of coniferous, or cone-bearing, trees extending all across North America, Europe and Asia at high altitudes. In North America, the taiga is located mainly in Canada and Alaska. In Europe, it lies in Sweden, Finland, Norway, and extends from Russia into Asia and down to Mongolia and China. Special adaptations by the plants and animals allow this biome to flourish despite the sub-zero temperatures in winter and wildfires in summer.

Rainfall is moderately high and spread throughout the year, and snow blankets the ground during the winter. With low temperatures normal throughout most of the year, little water is evaporated by the sun. Lakes, ponds, and bogs are highly abundant, especially in glacially carved areas where water is allowed to pool. The average temperature in the taiga is below freezing for six months of the year. The temperatures in the taiga can dip to a low of 54.C below zero (-65.F) during these months, but the average summer temperature rises to 15.C (60.F), warm enough to support the growth of trees.

Trees in this area use lots of energy to grow leaves in the spring. Some trees would not have enough energy to survive after growing their leaves. The coniferous trees have adapted by keeping their needles, which are modified leaves, year-round. That way, when the sun returns in the spring, the trees are already collecting vital sunlight instead of growing new leaves. The trees that grow there must face long periods of cold and drought, winds, and very poor soils. The soil is not only thin in depth, scraped away by the movements of glaciers, but also very acidic. This acidity comes from the pine needles themselves as they decompose on the forest floor. The trees fill their needles with chemicals to repel grazing animals such as deer and moose. The chemicals in the decomposing leaves form black humus and seep down through the layers of soil leaching valuable minerals and nutrients to below the root zone. The absence of earth churning invertebrates, like earthworms, means the soil becomes hard and compacted. The conifers do have an ally however: certain kinds of fungi live among the root hairs of the trees. The fungi are able to decompose the leaf litter and make the nutrients available to the trees, and the trees contribute carbohydrates in return.

Conifers have several adaptations that make them well suited to their northern environment. Their needles are thin and waxy protecting them from becoming dried out, and the deep green color helps them absorb the maximum warmth from the sun. Their branches are flexible and down drooping to prevent breakage by heavy snowfalls, and because they retain their needles year-round they are ready for food-production (photosynthesizing) as soon as the sunlight is adequate.

The most common evergreens in the taiga are the spruce, balsam fir, and pine. Other types include hemlock, cedar, redwood, and juniper, which can be found at varying latitudes. Just as latitude influences species, so also does altitude. In the northern Rocky Mountains the lower slopes may be dominated by ponderosa and sugar pine. At about 4,000 feet Douglas fir and white fir appear, and above 9,000 feet alpine fir and whitebark pine can be found. In the southern Rockies a most unusual pine is found, the bristlecone pine. Some of these gnarled and stunted trees are as much as 4,000 years old and they are generally found above the 10,000 foot mark, where the soil and the climate are very inhospitable to all but the toughest survivors.

Evergreens can survive in areas that are far too cold or dry for deciduous trees due to their effective conservation of moisture. However, in some places there is sufficient rainfall for deciduous growth, conifers are able to take over because of another set of adaptations that allow them to not only survive but also benefit from the occurrence of fire. Pines have a pulpy bark that does not easily burn and protects the inner layers of the tree from heat. The buds are protected by a cloak of long needles that burn, but not nearly as fast as other leaves, and with less heat-generation. Other adaptations to fire include cones that only release their seeds when dried and split open by the heat. The needles that the pines shed decay very slowly but are very flammable, so wildfire spreads over the ground quickly killing competing plants, harmful insects and fungi, and releasing the nutrients tied up in the fallen needles to the pine-tree roots.

Fire in a forest is not necessarily a bad thing. Fire has been used by nature to clear away shrubby growth, return nutrients to the soil, open clearings in dense forests to allow new growth that can provide wildlife with new food sources, and allow heat-sensitive cones and seeds to germinate. In forests that have been allowed to burn periodically the large healthy trees have little damage done to them and most wildlife is able to outrun or burrow in long enough to make it. It is when human intervention attempts to protect a forest from fire that a great deal of deadwood and low shrub mat