South of the tundra, in the areas near 60º latitude, the second biome that corresponds to cold ecological zones is located and is the most extensive on the planet: the taiga or boreal forest.The taiga is an enormous green strip over 1,500 kilometers wide that is only present in the northern hemisphere, which includes important sectors of America, Europe and Asia. It is characterized for having shorter winters than the tundra, but way more rigorous, as well as presenting a characteristic type of tree: conifers, flowerless plants with seeds capable of withstanding life’s cold conditions.
Another determinant factor is the lack of water because it doesn’t rain much and normally the hydro resources that are present remain frozen due to the low temperatures. The northern part of the taiga is an area of the Earth’s surface that used to be totally covered by the ice from the glaciations. This cold surface eroded the terrain, originating rounded elevations and important depressions. Later and gradually after the thawing, the landscape was covered by trees, while the lower zones of the terrain received the waters coming from the thawing, forming important lakes, which nowadays freeze every winter and serve as a path for some animals.
Climatic conditions
This zone of high latitudes is characterized for having a cold, humid climate that goes through intense variations between the two main seasons: winter and summer. Although the colder season is a bit shorter than the tundra’s (it lasts around eight months), many times it is more rigorous, reaching temperatures of -40ºC.
The summer season is quite cool, with an average temperature of 19ºC, which favors the thawing of frozen surfaces and makes the normal movement of some animals more difficult. Once again, the proximity of the oceans in regard to the land explains the more favorable conditions present at the coast compared to those at the interior of the continent. Although precipitation is spread throughout the year, they are scarce, reaching a maximum of 500 millimeters a year. Water remains cold during any months, which makes capturing it hard for the present vegetation. Another feature that identifies this region is its humidity, quite high, which conditions the existing type of soil and the formation of peatlands.
Soil
Just like the tundra, a great part of the taiga’s soil is covered by an important layer of permafrost, which conditions its humidity and scarce drainage. In addition, it freezes it and reduces its depth and the availability of nutrients. The typical soil of the taiga is podsol, an unfertile, acidic soil with a reddish color that is common base of all pine forests.
Generally, the iron lodged in the superficial layer of the soil is dragged towards deeper horizons, becoming more and more red because that is where important amounts of iron oxide are finally deposited. Low temperatures inhibit the action of bacteria, so decomposition is quite slow. This normal process is also affected by the ground’s great acidity, which prevents the normal development and action of some decomposer organisms, like worms.
Vegetation
Compared to the tundra, the taiga has a few characteristics that benefit the development of an important vegetal diversity. The variations of slopes, orientation, topography, drainage and the less extreme qualities of permafrost enable the development of great coniferous forests (species that make up the order Coniferae, belonging to the class Coniferopsida within the Pinophyta division), which form a real green belt in the area.
The typical conifers of this type of biome have high, straight trunks, with a central axis and branches arranged in an orderly fashion. A characteristic that enables them to inhabit and withstand cold environments is the shape of their leaves.
Generally, they are narrow and flat in the shape of needles or similar to scales, which allow them to withstand the intense winds. In addition, these leaves have a thick outer layer (called cuticle), thanks to which they can withstand extreme temperatures, and they have sunken stomas (small pores located on their surface) that conserve water better.Almost all conifers are perennial, meaning; they maintain their leaves year-round, which allows them to perform the process of photosynthesis quickly, as soon as the environmental conditions are favorable.
Their reproduction method is quite peculiar because they do so through cones, which carry female or male cells. Fertilization takes place when the female cones receive male pollen, generally through the wind. In Europe, the boreal forest is dominated by Red firs, the Scots or wild pine and the birch, while in Siberia the dominant trees are the Siberian spruce, the rocky Siberian pine and the Siberian larch.
The North American taiga is made up of four genders of conifer, with the Black spruce and the Swiss pine (Pinus cembra) dominating the landscape.There is usually a scarce development of bushes, grasses or of trees smaller than the conifer, as they block the passage of sunlight to the lower areas. Usually, only some herbs, woody brushes, moss and lichen (undergrowth) grow under this dense shadow.
Fauna
The behaviors of many of the animals that live in the taiga are similar to those that inhabit the tundra: they hibernate or migrate in order to survive the extreme winters. Among the principle mammals, standouts are otters, stoats, skunks, martens, beavers, bears, wolves, reindeer and moose.
The herbivore with the greatest presence in these latitudes is once again the Caribou (Rangifer tarandus), who dominates these icy surfaces by taking advantage of the greater abundance of vegetables like grasses, rushes and lichen.Among the characteristic birds of the place we find the Great Horned Owl (Bubo virginianus), the Barn Owl (Tyto alba), the Capercaille (Tetrao urogallos), the Hazel grouse (Tetrastes bonaisa), the Red Crossbill (Loxia curvirostra) and the Linnet (Acanthis cannabina), among others.
Man of them prepare for the crude winter by storing food, mainly conifer seeds. An example of this conduct is Clark’s Nutcracker (Nucifraga columbiana), an inhabitant of the boreal forests of North America that is capable of collecting nearly 4,000 seeds each fall, which it keeps in the bark of trees or in some holes in the ground.
This far-sighted action is joined by a great memory: this bird is capable of remembering the exact spot where it deposited most of its reserves, which will last approximately eight or nine months.Insects also abound in this sector, the most characteristic being the Larch sawfly (Pristiphora erichsonii), the European pine sawfly (Neodiprion sertifer) and the Spruce budworm (Choristoneura fumiferana).
Not only do the latter have an ecological function by being part of the food chain (they are a feast for the many insectivore birds that arrive in summer), but the irregular increase of their populations condition the appearance of real plagues that destroy great extensions of the forests. A key organic adaptation of the animal species that live in the tundra is that, in their majority, they present short appendixes (like ears, tails or snouts) to avoid losing heat through them.
Man and taiga: gradual intervention
Compared to other ecological regions, the taiga has not suffered human intervention so strongly. Low temperatures and soils that grant few benefits agriculturally have protected this area. However, two important interventions have affected and hindered its normal development: the exploitation of forest resources and the commerce of a few animals’ skins.
As we mentioned earlier, conifers dominate the landscape of the taiga, being the most important source of wood in the world. Unfortunately, man has used these resources indiscriminately, performing scarce efforts for the recovery and regeneration of these forests.
However, some reforestation initiatives are also hindering vegetal diversity, because after the aggressive use of forest resources mono-cultivations of conifers are developed that hinder the presence of some typical species. Another problem brought on by cutting down trees is the inevitable advance towards the south of the nearest biome, the tundra.
Added to this are the problems caused by the overgrazing of some species, like the reindeer, as well as the exploitation of important mineral deposits from which gold, coal, gas and oil are extracted.
