The taiga, also called the boreal forest or snow forest, is a type of land area covered mostly by forests with cone-shaped trees like pines, spruces, and larches.

The taiga is the largest land area of its kind in the world. In North America, it covers most of inland Canada, Alaska, and parts of the northern United States. In Eurasia, it covers most of Sweden, Finland, much of Russia from the western region of Karelia to the Pacific Ocean (including much of Siberia), parts of Norway, some areas of the Scottish Highlands, some lowland and coastal parts of Iceland, and parts of northern Kazakhstan, northern Mongolia, and northern Japan on the island of Hokkaido.

The main types of trees in the taiga depend on the length of the growing season and summer temperatures. In North America, the taiga is mostly spruce. In Scandinavia and Finland, the taiga has a mix of spruce, pine, and birch. In Russia, the taiga includes spruce, pine, and larch, depending on the region. In Eastern Siberia, the taiga is mostly a large forest of larch trees.

The taiga as it exists today is a relatively new land area, forming only about 12,000 years ago during the Holocene epoch. Before that, the land was covered by mammoth steppe or ice sheets in Eurasia, such as the Scandinavian Ice Sheet, and in North America, such as the Laurentide Ice Sheet.

At high elevations, the taiga changes into a type of cold, treeless area called alpine tundra through a process called Krummholz. However, the taiga is not only found in high areas. Unlike subalpine forests, most of the taiga is located in lowland areas.

Climate change is a danger to the taiga. There is debate about how carbon dioxide absorbed or released by the taiga should be counted in carbon accounting.

Name and terminology

The word "taiga" comes from the Russian word "tayga" (тайга), which was used in the past in Russia and other northern parts of Eurasia to describe large areas covered with forests. The Russian word is thought to have come from Turkic or Mongolic languages, where similar words describe forested or empty land with trees. In English, "taiga" is often used the same way as "boreal forest," but the two terms are sometimes used differently depending on the region.

In North American writing, "boreal forest" is usually used to describe the large, worldwide area of coniferous forests that circle the Earth. "Taiga" is sometimes used to describe the colder, northern parts of this area that are near the tundra. However, in Russian and Eurasian writing, "taiga" generally refers to the entire boreal forest area without dividing it into northern and southern parts. The choice of which term to use in scientific or geographic writing depends on the region and the field of study.

Climate and geography

The taiga covers 17 million square kilometers (6.6 million square miles), or 11.5% of Earth’s land area. It is the second-largest biome after deserts and dry shrublands. The largest taiga areas are in Russia and Canada. In Sweden, taiga is found in the Norrland region.

After ice caps and tundra, taiga has the lowest average annual temperatures of any land biome. Temperatures usually range from −5 to 5 °C (23 to 41 °F). In northern taiga regions, winter temperatures can be colder than in tundra areas. In parts of eastern Siberia and interior Alaska-Yukon, the average annual temperature drops to −10 °C (14 °F). The coldest temperatures ever recorded in the Northern Hemisphere were in the taiga of northeastern Russia.

Taiga has a subarctic climate with large temperature differences between seasons. A typical winter day might be −20 °C (−4 °F), while a summer day averages 18 °C (64 °F). However, the long, cold winter is the most common feature. This climate is classified as Dfc, Dwc, Dsc, Dfd, and Dwd in the Köppen system. These classifications mean summers are short (1–3 months) with average temperatures above 10 °C (50 °F), while winters last 5–7 months with temperatures below freezing.

In Siberian taiga, the coldest month averages between −6 °C (21 °F) and −50 °C (−58 °F). Some areas near the ocean have milder winters, and in the south and west of the taiga, summers are longer and fall into humid continental climates (Dfb, Dwb).

When the average annual temperature reaches about 3 °C (37 °F), taiga transitions into temperate mixed forests. Permafrost (frozen ground) is common in areas where temperatures stay below freezing. In Dfd and Dwd climate zones, continuous permafrost limits tree growth to shallow-rooted species like Siberian larch.

The growing season, when taiga plants begin to grow, is usually slightly longer than the summer season. Some sources say the typical growing season lasts about 130 days. In Canada and Scandinavia, the growing season is often measured by the time when the average daily temperature is +5 °C (41 °F) or higher. In the Taiga Plains of Canada, the growing season ranges from 80 to 150 days, and in the Taiga Shield, it ranges from 100 to 140 days.

Other sources define the growing season by the number of frost-free days. In southwest Yukon, there are 80–120 frost-free days. In the closed canopy boreal forest of Kenozersky National Park, Russia, there are about 108 frost-free days on average.

The longest growing seasons occur in coastal areas of Scandinavia and Finland, where the closed boreal forest can have 145–180 frost-free days. The shortest growing seasons are in the northern taiga-tundra boundary, where the growing season lasts only 50–70 days, and the warmest month averages 10 °C (50 °F) or less.

High latitudes mean the sun stays low in the sky, so less solar energy reaches the taiga compared to southern regions. However, summers have very long days, with the sun staying above the horizon for nearly 20 hours or even 24 hours in some areas. Winters have very short days, with as little as 6 hours of daylight or none, depending on the location. Areas within the Arctic Circle experience the midnight sun in summer and polar night in winter.

The taiga has low annual precipitation, usually 200–750 mm (7.9–29.5 in), with most falling as rain in summer and some as snow or fog. Snow can cover the ground for up to nine months in northern taiga regions.

Fog is common in low-lying areas, especially after Arctic seas thaw. This fog reduces sunlight reaching plants even during long summer days. Because evaporation is low, precipitation exceeds evaporation, supporting dense vegetation like tall trees. This explains why the taiga has more biomass per square meter than the Steppe biome, where evaporation exceeds precipitation, limiting plant growth to mostly grasses.

The taiga generally extends south of the 10 °C (50 °F) July isotherm, occasionally as far north as the 9 °C (48 °F) isotherm. The southern boundary varies depending on rainfall. In areas with very low rainfall, taiga may be replaced by forest steppe south of the 15 °C (59 °F) July isotherm. More typically, taiga extends south to the 18 °C (64 °F) July isotherm, and in regions with higher rainfall, like eastern Siberia and Outer Manchuria, it reaches the 20 °C (68 °F) July isotherm.

Warmer areas of the taiga have more species, including trees like Korean pine, Jezo spruce, and Manchurian fir. In some coastal regions of North America and Asia, the taiga merges with temperate rainforests where oak and hornbeam grow alongside conifers, birch, and poplar.

Much of the taiga in Europe and North America (except Alaska) was once covered by glaciers. As glaciers melted, they left depressions that filled with water, forming lakes and bogs like muskeg soil.

• The taiga near Verkhoyansk, Russia (67°N), has the coldest winter temperatures in the Northern Hemisphere. Despite this, summers are warm, with an average daily high of 22 °C (72 °F) in July.
• Lakes and water bodies are common in the taiga. Helvetinjärvi National Park, Finland, is located in the closed canopy taiga (mid-boreal to south-boreal) with a mean annual temperature of 4 °C (39 °F).

Soils

Taiga soil is often young and has few nutrients. It lacks the deep, rich layers found in temperate deciduous forests. The cold climate slows soil development and makes it harder for plants to use the soil's nutrients. Fewer deciduous trees, which drop large amounts of leaves each year, and fewer grazing animals, which add manure to the soil, also contribute to this. The boreal forest has a high number of soil organisms, similar to tropical rainforests.

In the cool, moist climate, fallen leaves and moss can stay on the forest floor for a long time. This limits how much organic material is added to the soil. Acids from evergreen needles wash away soil nutrients, forming a type of soil called spodosol or podzol. The acidic forest floor often only supports lichens and mosses. In forest clearings or areas with more boreal deciduous trees, more herbs and berries grow, and the soil becomes deeper.

Flora

North America and Eurasia were once connected by the Bering land bridge, allowing many animal and plant species, mostly animals, to move between the two landmasses. These species are found in the taiga biome (see Circumboreal Region). Some species differ by region, with each genus having several species that live in different parts of the taiga. The taiga also has small-leaved deciduous trees, such as birch, alder, willow, and poplar. These trees grow in areas with milder winters.

The Dahurian larch can survive the coldest winters in the Northern Hemisphere, found in eastern Siberia. In the southern parts of the taiga, trees like oak, maple, elm, and lime may grow among conifers, with a gradual shift into temperate, mixed forests, such as the eastern forest-boreal transition in eastern Canada. In drier areas of continents, boreal forests may change into temperate grasslands.

There are two main types of taiga. The southern part is a closed canopy forest, with many closely spaced trees and mossy ground. In open areas, shrubs and wildflowers like fireweed and lupine are common. The other type is lichen woodland or sparse taiga, where trees are farther apart and lichen covers the ground. This type is common in the northernmost taiga, where trees grow more slowly and are often stunted, with black spruce having uneven growth on the windward side.

In Canada, Scandinavia, and Finland, the boreal forest is divided into three subzones: the high boreal (northern taiga), the middle boreal (closed forest), and the southern boreal, which has a closed canopy with some temperate, deciduous trees like maple, elm, and oak. The southern boreal forest has the longest and warmest growing season. In some areas, such as Scandinavia and western Russia, this subzone is used for farming.

The boreal forest has many berry species. Some, like wild strawberry and partridgeberry, grow only in the southern and middle closed-boreal forest. Others, like cranberry and cloudberry, grow in most parts of the taiga. Some berries, such as bilberry, bunchberry, and lingonberry, grow in both the taiga and the southern regions of the tundra.

The taiga is mostly covered by coniferous trees, such as larch, spruce, fir, and pine. The mix of trees varies by geography and climate. For example, the Eastern Canadian forests are dominated by balsam fir, while the Eastern Canadian Shield taiga is mostly black spruce and tamarack larch.

Evergreen trees like spruce, fir, and pine have adaptations for cold winters. Larch, which is very cold-tolerant, is deciduous. Taiga trees have shallow roots to grow in thin soil and change their biochemistry seasonally to resist freezing, a process called "hardening." Their narrow, cone-shaped form and drooping limbs help shed snow.

Because the sun is low for much of the year, plants struggle to make energy through photosynthesis. Evergreen trees keep their leaves year-round, allowing them to photosynthesize in late winter and spring when light is available but temperatures are too low for new growth. Their needles reduce water loss and absorb more sunlight. Although water is not a major issue, frozen ground in winter prevents roots from absorbing water, causing desiccation for evergreens in late winter.

While the taiga is mostly coniferous, some broadleaf trees like birch, aspen, willow, and rowan also grow. Small herbaceous plants, such as ferns and ramps, grow near the ground. Wildfires, which occur every 20 to 200 years, clear tree canopies and allow sunlight to reach the forest floor. Some species, like jack pine, depend on fire to open their cones and spread seeds. Fungi like morels also grow after fires. Grasses grow in sunny patches, and mosses and lichens thrive on damp ground and tree trunks. Compared to other biomes, the taiga has low plant diversity.

Coniferous trees dominate the taiga, with only four main genera: evergreen spruce, fir, and pine, and deciduous larch. In North America, one or two species of fir and spruce are common. In Scandinavia and western Russia, Scots pine is widespread. In the Russian Far East and Mongolia, larch is dominant. In western Siberia, the taiga is rich in spruce and Scots pine, while in eastern Siberia, larch is dominant. In southern Siberia, birch and Populus tremula grow alongside conifers.

• Conifer cones and morel mushrooms grow after a fire in a boreal forest.
• Moss (Ptilium crista-castrensis) covers the floor of the taiga.

Fauna

The boreal forest, also called the taiga, has many animals that are specially adapted to its tough climate. Canada's boreal forest includes 85 species of mammals, 130 species of fish, and about 32,000 species of insects. Insects are important because they help pollinate plants, break down dead plants and animals, and are part of the food chain. Many birds, rodents, and small meat-eating mammals eat insects during the summer.

The cold winters and short summers make the taiga a difficult place for reptiles and amphibians, which need the environment to help control their body heat. Only a few species live in the boreal forest, such as the red-sided garter snake, common European adder, blue-spotted salamander, northern two-lined salamander, Siberian salamander, wood frog, northern leopard frog, boreal chorus frog, American toad, and Canadian toad. Most of these animals hibernate underground during winter.

Fish in the taiga must survive in cold water and live under ice-covered water. Species in the taiga include Alaska blackfish, northern pike, walleye, longnose sucker, white sucker, several species of cisco, lake whitefish, round whitefish, pygmy whitefish, Arctic lamprey, several grayling species, brook trout (including sea-run brook trout in the Hudson Bay area), chum salmon, Siberian taimen, lenok, and lake chub.

The taiga is mainly home to large plant-eating mammals, such as Alces alces (moose) and some subspecies of Rangifer tarandus (reindeer in Eurasia; caribou in North America). Some southern parts of the boreal forest have other deer species, like maral, elk, Sitka black-tailed deer, and roe deer. Some southern herds of muskoxen live in the taiga of Russia's Far East and North America. The Amur-Kamchatka region of far eastern Russia also has snow sheep, wild boar, long-tailed goral, and the Russian relative of the American bighorn sheep. The largest animal in the taiga is the wood bison of northern Canada/Alaska. Some American plains bison have been introduced into the Russian Far East as part of a project called Pleistocene Park, along with Przewalski's horse.

Small mammals in the taiga include rodents like beavers, squirrels, chipmunks, marmots, lemmings, North American porcupines, and voles. A few lagomorph species, such as pikas, snowshoe hares, and mountain hares, also live there. These animals have adapted to survive the harsh winters in their areas. Some larger mammals, like bears, eat a lot during the summer to gain weight and then hibernate in the winter. Other animals have thick fur or feathers to stay warm.

Predatory mammals in the taiga must travel long distances to find scattered prey or eat plants and other foods, such as raccoons. Mammalian predators include Canada lynx, Eurasian lynx, stoats, Siberian weasels, least weasels, sables, American martens, North American river otters, European otters, American minks, wolverines, Asian badgers, fishers, timber wolves, Mongolian wolves, coyotes, red foxes, Arctic foxes, grizzly bears, American black bears, Asiatic black bears, Ussuri brown bears, polar bears (in small areas of the northern taiga), Siberian tigers, and Amur leopards.

Over 300 bird species nest in the taiga. Birds like the Siberian thrush, white-throated sparrow, and black-throated green warbler migrate to the taiga to use the long summer days and plenty of insects near bogs and lakes. Of the 300 bird species that summer in the taiga, only 30 stay during winter. These are usually birds that eat dead animals or large birds of prey that hunt mammals, such as golden eagles, rough-legged buzzards (also called rough-legged hawks), Steller's sea eagles (in coastal northeastern Russia-Japan), great gray owls, snowy owls, barred owls, great horned owls, crows, and ravens. The only other winter adaptation is seed-eating birds, which include several species of grouse, capercaillie, and crossbills.

Fire

Fire has played a major role in shaping the types of trees and how forests grow in the boreal forest, which covers much of Canada. Fire is the main way that forests are renewed in many parts of this region. The pattern of fires in an ecosystem is called its fire regime, which has three parts: (1) the type and strength of fires, such as crown fires (fires that burn through tree tops) or severe and light surface fires, (2) the typical size of important fires, and (3) how often fires happen in specific areas. The average time it takes for an area to burn completely in a fire regime is called its fire rotation or fire cycle. However, as noted by Heinselman (1981), different areas within a forest may have different fire return times. Some places may not burn for many years, while others may burn more than once during the same time period.

The most common fire pattern in the boreal forest involves large, high-intensity crown fires or severe surface fires that can cover more than 10,000 hectares (100 square kilometers) and sometimes over 400,000 hectares (4,000 square kilometers). These fires destroy entire forest stands. In drier areas of western Canada and Alaska, fire rotations average 50–100 years, while in wetter areas of eastern Canada, they may take 200 years or longer. Fire cycles are also longer near the tree line in subarctic spruce-lichen woodlands. The longest fire cycles, possibly 300 years, are likely found in western boreal floodplain white spruce areas.

Amiro et al. (2001) calculated that the average fire cycle in the Canadian boreal forest (including taiga) from 1980 to 1999 was 126 years. Scientists predict more frequent fires in western Canada, but some parts of eastern Canada may see fewer fires in the future due to increased rainfall in a warmer climate.

In the southern boreal forest, the pattern of mature trees changes depending on the area. In eastern Canada, balsam fir is dominant on well-drained soil, while in central and western areas, white spruce becomes more common. Black spruce and tamarack grow on peat-rich soil, and jack pine is found on dry areas except in the far east, where it is absent. Fire has a strong influence on the types of plants that grow in different areas. In the east, black spruce, paper birch, and jack pine are more common than balsam fir. In the west, aspen, jack pine, black spruce, and birch are more likely to grow than white spruce. Scientists have found charcoal in soil layers, which has helped them understand past forest conditions, such as in areas near Ennadai Lake in the Northwest Territories.

Two types of evidence support the idea that fire has always been an important part of the boreal forest: (1) direct observations and fire records, and (2) indirect clues, such as the effects of fire and remaining signs like charcoal. The mix of different forest areas in the boreal forest, with clear boundaries between similar stands, shows how fire has shaped the landscape. Most boreal forests are less than 100 years old, and only a few areas with no fire activity have white spruce stands older than 250 years.

Many boreal tree species have traits that help them survive and grow after fires, showing their long connection to fire. Seven of the ten most common trees in the boreal forest—jack pine, lodgepole pine, aspen, balsam poplar, paper birch, tamarack, and black spruce—are good at quickly growing in open areas after fires. White spruce can also grow in new areas but is less able to spread seeds year-round compared to black spruce and pines. Balsam fir and alpine fir are not as well adapted to fire because their cones fall apart when mature, leaving no seeds.

The oldest forests in the northwest boreal region, some over 300 years old, are pure stands of white spruce growing on moist floodplains. These areas experience fewer fires than nearby uplands covered by pine, black spruce, and aspen. In contrast, in the Cordilleran region, fires are most frequent in valley bottoms, with younger pine and broadleaf forests below and older spruce-fir forests on slopes above. Without fire, the boreal forest would become more uniform, with long-lived white spruce gradually replacing other tree species like pine, aspen, balsam poplar, and birch, except in peatland areas.

Climate change

During the last quarter of the twentieth century, the area near the Earth's poles where boreal forests grow experienced some of the largest temperature increases on Earth. Winter temperatures rose more than summer temperatures. In summer, the lowest daily temperatures increased more than the highest daily temperatures. The number of days with extremely cold temperatures (e.g., −20 to −40 °C; −4 to −40 °F) has decreased unevenly but steadily across most of the boreal region. This has helped tree-damaging insects survive better. In Fairbanks, Alaska, the number of days without frost has increased from 60 to 90 days in the early 1900s to about 120 days by the early 2000s.

Some scientists think that boreal environments have only a few long-term stable states: a treeless tundra or steppe, a forest with more than 75% tree cover, or an open woodland with about 20% to 45% tree cover. If climate change continues, some taiga forests might shift into one of these woodland states or even into a treeless steppe. At the same time, warming tundra areas might become suitable for trees to grow.

Studies from the early 2010s found that western Canadian boreal forests lost many trees due to drought since the 1960s. This trend was weak or absent in eastern forests but strong in western coniferous forests. However, a 2016 study found no overall trend in Canadian boreal forests between 1950 and 2012. Some southern forests grew better, while northern forests grew less, but these patterns were not strong enough to confirm the earlier findings.

A 2018 analysis using satellite data confirmed that western Canadian forests are drying and losing trees, while eastern forests are greening. It also found that much of the earlier forest loss linked to climate change was actually a delayed effect of human activities like logging. Later research showed that even in forests where total tree growth did not change, there was a shift toward deciduous trees that tolerate drought better. Another satellite study found that areas with fewer trees became greener as temperatures rose, but areas with more trees experienced more tree death due to stress.

Most studies on boreal forest changes have focused on Canada, but similar patterns have been seen in other countries. In central Alaska and parts of far eastern Russia, summer warming has increased drought stress and reduced tree growth in dry areas. In Siberia, the taiga is changing from larch trees that shed needles to evergreen conifers as the climate warms. This shift may speed up warming because evergreen trees absorb more sunlight. In Alaska, white spruce growth is slower in warmer summers, but trees on the coldest edges of the forest are growing faster. Birch trees in central Alaska are also stressed by dry summers.

Studies on future forest changes show that a 2 °C temperature rise could increase growth of seven main tree species in eastern Canadian forests by about 13%, but water availability is more important than temperature. If warming reaches 4 °C without more rain, growth would decline. A 2019 study found that forest plots used to study climate change often have less competition between trees than typical forests, and in areas with strong competition, warming had little effect on growth.

In central boreal forests, climate change only helped trees grow when competition was low. A 2021 study found that boreal forests in Canada are more affected by climate change than other forest types and predicted that most eastern Canadian boreal forests would reach a tipping point around 2080 under a high-emission scenario. Another 2021 study projected a 15% global increase in boreal forest biomass by the end of the century under a moderate emissions scenario, but this would be offset by a 41% decline in tropical forests.

A 2022 experiment in North America found that young trees in the southern edges of boreal forests struggle with even small temperature increases and less rain. Temperate tree species that might benefit from these conditions are rare and grow slowly.

A 2022 study identified two related tipping points linked to climate change: the loss of taiga in the south turning into grassland (like the Amazon rainforest) and the conversion of tundra in the north into taiga. These changes are already happening but may not become unstoppable until global warming reaches about 4 °C. However, some scientists think 1.5 °C could trigger these changes, while others believe southern taiga loss may not happen until 5 °C, and tundra-to-forest changes might require 7.2 °C.

Once these tipping points are reached, changes would take at least 40–50 years to complete and could take over a century. The loss of southern taiga would release about 52 billion tons of carbon but cool the planet by about 0.18 °C globally and 0.5–2 °C regionally. Expansion of boreal forests into tundra would warm the planet by about 0.14 °C globally and 0.5–1 °C regionally, even though new forests would absorb 6 billion tons of carbon. These effects are due to snow-covered ground reflecting more sunlight than forests. Later studies suggest that boreal forest loss may increase warming despite albedo effects, and earlier conclusions about cooling from deforestation may have ignored the role of evaporation and plant water use.

Primary boreal forests store 1,042 billion tons of carbon, more than all human-caused greenhouse gas emissions since 1870. In a warmer climate, their ability to store carbon will decrease.

Other threats

Some of the larger cities located in this region are Murmansk, Arkhangelsk, Yakutsk, Anchorage, Yellowknife, Tromsø, Luleå, and Oulu.

Large areas of Siberia’s taiga have been cut down for wood since the end of the Soviet Union. Before this, the forest was protected by rules from the Soviet Ministry of Forestry. However, after the Soviet Union ended, rules that limited trade with Western countries were no longer in place. Trees are easy to cut and sell, so loggers have started harvesting evergreen trees from the Russian taiga to sell to countries that were once blocked by Soviet laws.

In recent years, outbreaks of insect pests have caused major damage to forests. These pests include the spruce-bark beetle (Dendroctonus rufipennis) in Yukon and Alaska; the mountain pine beetle in British Columbia; the aspen-leaf miner; the larch sawfly; the spruce budworm (Choristoneura fumiferana); and the spruce coneworm.

A study by Addison et al. (1984) examined how sulfur dioxide affects woody boreal forest species. Plants growing on natural soils and tailings were exposed to 15.2 μmol/m (0.34 ppm) of SO₂. The Canadian maximum acceptable limit for atmospheric SO₂ is 0.34 ppm. Exposure to SO₂ significantly reduced the rate at which plants take in carbon dioxide (NAR) in all species and caused visible signs of damage within 2–20 days. The decrease in NAR for deciduous species (trembling aspen [Populus tremuloides], willow [Salix], green alder [Alnus viridis], and white birch [Betula papyrifera]) happened much faster than for conifers (white spruce, black spruce [Picea mariana], and jack pine [Pinus banksiana]) or an evergreen angiosperm (Labrador tea) growing on a fertilized Brunisol.

These changes in plant metabolism and visible damage seemed to be linked to differences in sulfur absorption, partly because deciduous species have higher gas exchange rates than conifers. Conifers growing in oil sands tailings showed a more rapid decrease in NAR compared to those on Brunisol, possibly because of harmful materials in the tailings. However, sulfur absorption and visible damage did not differ between conifers on the two substrates.

Human-caused emissions that make rain acidic have been linked to harm to plants and lower forest productivity. However, 2-year-old white spruce exposed to simulated acid rain (pH 4.6, 3.6, and 2.6) applied weekly for 7 weeks showed no statistically significant (P 0.05) reduction in growth compared to a control group (pH 5.6) (Abouguendia and Baschak 1987). Symptoms of injury were seen in all treatments, with more plants and needles affected as rain acidity increased over time. Scherbatskoy and Klein (1983) found no significant change in chlorophyll levels in white spruce at pH 4.3 and 2.8, but Abouguendia and Baschak (1987) found a significant decrease in white spruce at pH 2.6, while foliar sulfur content was significantly higher at pH 2.6 than in other treatments.

Protection

The taiga holds very large amounts of carbon, more than all temperate and tropical forests combined. Much of this carbon is stored in wetlands and peatlands. Studies show that boreal forests store about twice as much carbon per unit area as tropical forests. Wildfires can release a large amount of carbon into the atmosphere, so managing fires costs about $12 per tonne of carbon not released, which is much cheaper than the cost to society from carbon emissions.

Some countries are considering protecting parts of the taiga by stopping activities like logging, mining, and oil and gas production. In response to a letter signed by 1,500 scientists urging leaders to protect at least half of the boreal forest, two Canadian provinces, Ontario and Quebec, promised in 2008 to discuss measures that could eventually protect at least half of their northern boreal forest. Both provinces acknowledged that planning would take many years and would involve working with Aboriginal and local communities to map protected areas. These efforts were expected to create some of the world's largest protected area networks once completed. However, little progress has been made since then.

For example, in February 2010, the Canadian government created limited protection for 13,000 square kilometers of boreal forest. This included a new 10,700-square-kilometer park reserve in the Mealy Mountains area of eastern Canada and a 3,000-square-kilometer waterway provincial park along the Eagle River from its source to the sea.

Natural disturbance

Fire plays a major role in lichen woodlands, but scientists still have many questions about how it affects these ecosystems. Wildfires caused by lightning are the main reason that plants grow under the trees, and these fires greatly influence the types of plants and animals that live in the area. Fire is important because the plants under the trees help tree seeds grow quickly, and over time, they affect how nutrients are used in the soil.

Large wildfires happen about every 70 to 100 years. Scientists study how plants grow back after fires by looking at the paths they take to recover. Trees, shrubs, and lichens grow again after fires by using parts of themselves to reproduce or by new plants growing from seeds that were already in the ground. Seeds that are buried do not help plants return quickly. Lichens come back because different areas have different amounts of light and nutrients. Studies show that after a fire, plants can recover in four ways: self-replacement, species-dominance relay, species replacement, or gap-phase self-replacement.

Self-replacement means the same plants that lived before the fire return. Species-dominance relay happens when different tree species take turns becoming the most common in the forest canopy. Species replacement occurs when fires happen often enough to stop one type of tree from becoming dominant. Gap-phase self-replacement is rare and has only been seen in Western Canada. It happens when surviving plants grow into open spaces left by fires that destroyed other plants. Which recovery path happens depends on how well the land supports trees and how often fires occur. Fire frequency also helps shape the edge of the lichen woodland forest.

Scientists like Serge Payette think that lichen woodlands formed when two major events happened: large fires and attacks by spruce budworms. Spruce budworms harm spruce trees in the southern parts of the taiga. J.P. Jasinski later supported this idea, saying that lichen woodlands are a stable type of forest that can exist instead of spruce-moss forests.