The Boreal forest represents the largest extension that exists in the Planet Earth’s coniferous (covering about 10% of the surface). For this condition, it is also named Northern Coniferous Forest. It extends from North America, Europe and Asia. This biome is represented by four types: the forest-tundra ecotone (lichens and mosses), the open boreal forest (lichen and spruce), the main boreal forest (spruce, pine, birch and aspen) and mixed-boreal forest ecotone (in which typical bodies interspersed coniferous forests).
In Boreal forests, the ground is often covered with snow so the soil is frozen, which means that the trees have low water. The coniferous that tolerate these conditions are primarily adapted to dryness. Larch (Larix laricina – Pinaceae), with deciduous leaves needle-shaped, is the common tree in the forest. It is estimated that even if there are only few species of trees throughout the forest, home to thousands of species of mycorrhizal fungi that grow on its land.
In general the trees in the Boreal forest are almost exclusively evergreen with needle leaves. Thin needles are grouped, allowing them to shed snow and block the wind. They have a waxy coating that helps to prevent water losses, and contain a heavy sap and sugared that prevents freezing during the winter. These conifer stands on eastern white pine (Pinus strobus – Pinaceae), which has long needles leaves and hard. They feed on fallen leaves with the help of fungi.
Large networks surface of the roots of these trees are surrounded by layers of these fungi. Extending upward, fungi decompose the needles , releasing chemicals that can be absorbed by trees. The fungi benefit by receiving other nutrients, they can not produce, directly from the tree roots. Some boreal trees such as the genus Populus (White Spruce, Black Spruce and Balsam Fir), have the highest ranks of global distribution among the tree species.
The Aspen trees (Populus tremuloides – Salicaceae) are among the few trees broadleaf which is located in Boreal forests. The fungi and mosses represent the only plants that grow under the trees in the coniferous forest, while lichens like Cladonia coccifera and Cladonia bellidiflora which prefer acid soils, grow in the glades. A typical example is the fungus Hydnum auriscalpium.
The life in the Boreal forest is very hard for the animals during the winter, so birds tend to migrate to warmer latitudes, while many other animals hibernate The greater part of life in these forests is hidden. Large animal species occur in relatively low amounts, and during the winter there can be areas which resemble a “empty” forest . The number and types of animals living in the Boreal forests are influenced by the use of needles leaves.
These forests can not maintain a large number of vegetarian species more than in the southern regions, they eat the softer leaves and more digestible broadleaf trees The needles are indigestible to most animals, from caribou and small rodents to most birds. Other birds and small mammals are also fed from seeds, and often stored for later use.
Some mammals, like the Lemine rodents (or lemmings) can eat as many seeds that in some years there are very few to germinate. Every few years, after an unusually hot summer or after the trees have had time to store enough energy, it produces an unusually large crop of seeds, thereby ensuring enough seeds remaining after the mammals and birds have eaten.
The animals that eat seeds are also very helpful to the trees, scattering inadvertently the seeds in large areas, allowing the trees to expand their ranges. The seeds, which are produced in large quantities in the cones of the “evergreen” trees are those which sustain the animals in the Boreal forest. The ‘cross-peak’or ‘crossbill’ (Loxia spp), a kind of finch, developed a beak that allows the easier removal of seeds from cones.
To conserve heat, mammals living in the boreal forest tend to be large: the moose (Moose alces) [the largest of the deer], wolverines (Gulo gulo) [the largest of the weasel], as well as the largest species of ptarmigan (Lagopus spp. – Tetraonidae). In addition to these very large and conspicuous animals, many of the mammals in these forests are or rodents, including porcupines and squirrels, and small insectivores such as moles. Some common birds are jackdaws and crows, in addition to the grouse and crossbills.
Large flocks of birds migrate to the boreal forests during the summer. The types of jackrabbit can be extremely numerous in the boreal forest, although their populations change dramatically from one year to another, related to the amount of available food, in turn, the populations of carnivores such as lynx, vary with the number of jackrabbits.Both types of animals are well adapted to the particular characteristics of boreal areas: the skin of the jackrabbit is brown in the summer but changes color with the seasons and is white in the winter so is confused with the snow, the lynx has claws very wide allowing it to run over the snow, allowing to hunt jackrabbits. Jackrabbits feed on bark and leaves.
During the winter, all the world’s boreal forests look very similar. Many common species are found on different continents, and other closely related species have a similar appearance. However, during the summer change the nature of the forest and many animals migrate from the south to feed there, eating lemmings, larvae, seeds and others that appear in large numbers during the short warm season in the region.
The most characteristic animals of the boreal forest are brown bear, wolf, fox, weasel, reindeer, deer, elk, owls, hawks, beavers, squirrels, arboreal porcupine.
Among the birds that eat conifer stand the parrot crossbill, common crossbill, common crossbill striped. The insects that eat conifer: Track, mesopolobus spermotrophus, weevil (Hylobius dwellings), the genus beetle (SPB). In the line of sap-sucking, moose, marmots, hares. From the insectivores: Woodpecker, Kirtland picafollas, saithe crafty Brambling, bats, shrew. Among the carnivores, brown bear, lynx, weasel, mink, marten, wolverine and among birds of prey: Owl, owl, osprey, peregrine falcons and goshawks.
Adaptations of the fauna: Among the adaptations of endothermic vertebrates (“Hot blood”) to conserve heat in low temperatures are found large size, low surface to volume relation and short appendages (ears, noses, legs, tail) compared with similar to species of lower latitudes.Birds and mammals have a well-developed insulation feathers or skin that is often thicker in the winter than in the summer. There are a variety of different strategies to avoid the winter season, including migration (in birds) and hibernation (in some mammals). Some ground mammals that are active during the winter change the color to white in that season.
The storage of food is well developed, particularly conifer seeds, which are produced plenty and are accessible to specialists with appropriate peak or adaptations of the teeth (for example, cross peak between birds and crossbills, red squirrels in mammals) The populations of some species characteristics are typically cyclical growth and decline, predators follow the prey cycles.
By Lenin Cardozo – Mariana Jaramillo / ANCA24 Canada