Taiga Biome & Boreal Forests: Features, Extent, Soil, Ecosystem and Wildfires

Taiga is also known as Boreal Forest. Taiga is earth’s largest terrestrial biome, covering 29% of World’s Forest cover and is characterized by coniferous forests.

Extent of Taiga Biome

Taiga Biome covers in North America most of inland Canada and Alaska as well as parts of the extreme northern continental United States; and in most of Sweden, Finland, inland and northern Norway, much of Russia (Siberia), northern Kazakhstan, northern Mongolia, and northern Japan (Hokkaidō Island).

Largest areas under Taiga are located in Russia and Canada. Please note that there is no Taiga on Southern hemisphere.

Key Features of Taiga Biome

Taiga accounts for lowest annual average temperatures after the tundra and permanent ice caps. Here we note that the extreme minimums temperatures of Taiga are typically lower than those of the tundra. In Tundra it is around -50°C, in Taiga it has been recorded -68°C at Verkhoyanks in Siberia.

In winter, there are long periods of frozen Ice on Polar Tundra, yet the nearby Arctic Ocean contains enough heat to tweak the temperature a little bit. This is the reason that lowest reliably recorded temperatures in the Northern Hemisphere were recorded in the taiga of north-eastern Russia. The soil in Taiga is young with little development and profile. This is mainly because of the fact that cold hinders the development of soil. The taiga soil is also poor in nutrients.

Soil Features in Taiga Biome

The Taiga soil is poor in nutrients in comparison to the temperate deciduous forests. This is because the fallen leaves and moss can remain on the forest floor, without decomposing for a long time in the cool, moist climate. This would result in poor organic contribution to the soil. Further, the Taiga soil is acidic due to the falling pine needles. Since the soil is acidic, the acidity aids in the decomposition of the mineral components and the minerals are washed away in the lower horizons. This leaching of the minerals makes them inaccessible to the tree roots. This causes infertility of the soil.

The leaching of the nutrients, along with the permeability of the soil gives Taiga a light colored eluvial soil horizon leached of most base forming cations such as Calcium. Since the soil is acidic due to the falling pine needles, the forest floor has only lichens and some moss growing on it.

However, diversity of soil organisms in the boreal forest (southern Taiga) is high, comparable to the tropical rainforest. The Taiga soils are dominated by the microscopic fungi. These microscopic fungi play an important role in the decomposition of the dead phytomass. So, the above mentioned infertility is compensated by the activity of the microorganisms in the upper soil horizons. In summary the soil of the Taiga Biome and Boreal forests is

• Young with little development
• Poor in Nutrients
• Rich with Soil organisms in comparison to Tropical Forests
• Acidic due to fallen leaves

Flora of Taiga Biome

Taiga is spread over both Asia and North America. Both of them were connected by the 1600 kilometres wide Bering land bridge at various times during the Pleistocene ice ages in the Geological history. (It connected Alaska to Siberia). So, due to this reason, a number of animal and plant species were able to colonize both continents and are distributed throughout the taiga biome that spreads in both of them like Tundra.

The forests of the taiga are largely coniferous, dominated by larch, spruce, fir, and pine. There are also some small-leaved deciduous trees like birch, alder, willow, and poplar; mostly in areas escaping the most extreme winter cold. Southernmost parts of the taiga has trees such as oak, maple, elm, and tilia scattered among the conifers, and there is usually a gradual transition into a temperate mixed forest. The Southern Taiga is a closed canopy forest consisting closely spaced trees with mossy ground cover. It also has shrubs and wildflowers such as the fireweed. Wherever the trees are located at a father space, land is covered by lichens and mosses. These lichens and mosses are more common in the northernmost taiga. In northernmost taiga the forest cover is not only more sparse, but often stunted in growth.

The trees are coniferous which an adaptation to cold harsh climate is. Most of the species of Taiga such as spruce, fir, and pine are Evergreen. This is because the sun is low in the horizon for most of the year; it is difficult for plants to generate energy from photosynthesis.  The trees do not lose their leaves seasonally and are able to photosynthesize with their older leaves in late winter and spring when light is good but temperatures are still too low for new growth to commence. The leaves are needle shaped to curb loss of water and with dark green color to increase absorption of sunlight.

However, Larch, which seems to be most cold-tolerant, is deciduous. The roots of Taiga Trees are shallow, which is basically to take advantage of the young thin soils. The conical shape and downward-drooping limbs help them shed snow. Further, there are also some broadleaf plants found in Taiga. Examples are birch, aspen, willow, and rowan.

Taiga Environment Challenges

The Taiga is being destroyed everyday by both humans and nature. Nature causes forest fires with lighting, diseased by parasites or herbicides, and spruce trees that grow on top thick moss are frequently blown over by strong winds. Large-scale clear cutting, plantation forestry, introduction of exotic tree species, soil scarification, ditching, and use of pesticides or herbicides have led to habitat loss. Large-scale industrial forestry, or logging, is the greatest important threat effecting the boreal forest. Other threats to the Taiga are oil and gas exploration, road building, mining, human triggered forest fire, and climate change. Animals of the Taiga are being hunted and trapped for their fur which decreases their population greatly. Hydroelectric power has ruined the water system. Many fish have mercury poisoning. The Taiga is being destroyed equal to that of the rainforest.

Wildfires in Taiga Biome

One of the most important environmental factors that affect the Taiga Forests is Wildfires. Wildfires have been an integral part of the Taiga environment for several thousand years.  The main natural reason of the wildfires in Taiga is lightening strikes. However, the spread of the fire is dependent on weather, soil conditions, topography and the amount of dry organic matter (fuel) on the soil surface. The combination of these factors forms the fire regime, which is characterized by the intensity, pattern of distribution and type of fire (i.e. ground or crown fire).

By knowing a specific site’s forest type, habitat and local climate, it is possible to determine the natural frequency of fire, which can vary from just a few years to hundreds of years. For example, wildfires develop more often in forests under a more continental climate (e.g. in Eastern Siberia) and in drier habitats with sandy soils (e.g. on the fluvial-glacial plains of Western Siberia).

Plant Adaptations to Wildfires

Where fires occur more frequently, plant communities often have special ecological mechanisms to make them more resistant or even adapted to fire. For example the older trees of the Taiga Zones have thicker bark. There are some plants in which the seed cones open just after a wildfire (.g. Jack Pine, an excellent adoption to pioneer the development of new trees.

Advantage Wildfires

Due to heavy and thick bark, and due to the canopy made by the trees, usually, the wildfire would burn away the upper canopy of the trees and let sunlight reach the ground. New plants will grow and provide food for animals that once could not live there because there were only evergreen trees. This is how even wildfires add in development of new forests in Taiga environment. Many smaller herbaceous plants that grow closer to the ground may survive in the Crown wildfires that eliminate only the canopies. The periodic wildfires clear out the tree canopies, allowing sunlight to invigorate new growth on the forest floor. That is why the wildfires have become a necessary part of the life cycle in the taiga.