MS Science-Biomes and Ecosystems: Taiga (Boreal Forest)

Taiga is the largest land (terrestrial) biome in the world.  It is made up of mainly conical-shaped evergreen trees with needle-like leaves. These trees are called conifers because their seeds are clumped into cones. The taiga has long, cold winters when most mammals hibernate and birds migrate, or leave the area because the winters are too cold for them to stay. Animals like weasels, grouse and rabbits that do not migrate or hibernate grow dense feathers or fur and turn white to match the snow.

If you walk through the Canadian taiga in early April, you may encounter a bizarre phenomenon on the forest floor. At first, you may think that someone just left a pile of shiny, twisted dark ropes on the ground. Upon closer look, you realize that not only is this pile wriggling, but it composed of many slender heads and tails.

Congratulations! You have stumbled upon a knot of red-sided garter snakes. This phenomenon occurs when warming temperatures wake garter snakes from hibernation. Males first emerge from their dens and wait. Once a female slithers out, the males jump on her all while wrestling each other to try to mate with the female.

Huge numbers of garter snakes emerge from their overwintering dens in spring. Image by Christopher Friesen

If you come back to the same spot in the middle of the winter, you will only find a blanket of snow on the ground. In fact, it may be difficult to find any wildlife in the taiga at all in the winter. A snowshoe hare may dart past you as it sprints from a pack of hungry wolves. At night, the hoot of a Great-gray owl may echo through the dark forest. In general, however, the winter of the taiga is quiet and lonely.

https://askabiologist.asu.edu/animals-taiga

This white-throated sparrow migrates to the taiga for the summer insect blooms in bogs. Image by Cephas.

Some animals, especially birds, can't handle the year-round taiga experience. On one hand, these birds love the warm and moist taiga summer, especially with the blooming insect populations. On the other hand, they just don't want to deal with the winter. To solve this problem, birds such as the Siberian Thrush and White-Throated Sparrow spend their winters in the south. They migrate north so that they arrive in the taiga bogs just in time for the warm weather and the swelling clouds of mosquitoes, dragonflies, and moths.

The swampy grounds erupt with the mating calls of these migratory birds when they pause from eating to seek partners. Before long, eggs begin hatching and baby birds start to demand for food. Bird parents stuff regurgitated insects and seeds into the mouths of their offspring so that their young can quickly grow before the short taiga summer ends. If something happens to the nest and baby birds, there is not time to start over again. Once temperatures begin to cool down, these migratory birds pack up and move back south.

https://askabiologist.asu.edu/animals-taiga

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Since 2000, The Pew Charitable Trusts has been working with partners in Canada to protect the boreal, the world’s largest remaining intact forest ecosystem. Here’s why its conservation is vital for the planet.

Canada’s boreal forest:

• Is the world’s largest intact forest ecosystem. It stretches across 1.2 billion acres (485 million hectares) of northern Canada, from the Yukon to Newfoundland and Labrador.
• Represents 25 percent of the world’s remaining intact forest, even more than the Amazon rain forest.
• Contains 25 percent of the world’s wetlands.
• Includes more surface freshwater—about 200 million acres (81 million hectares)—than anywhere else on Earth.
• Is North America’s bird nursery. Each year, 1 billion to 3 billion birds migrate north from the United States—and from as far away as South America—to nest in Canada’s boreal forest. Between 3 billion and 5 billion return south each fall after a successful breeding season.
• Stores twice as much carbon per acre as tropical rain forests. In all, Canada’s boreal forests and peatlands lock in a minimum of 229 billion tons of carbon. Peatlands, also known as bogs and fens, are wetlands that include vegetation such as sphagnum mosses, shrubs, and spruce. This natural carbon storage helps cool the planet and provides a critical bulwark against climate change.
• Is home to some of the cleanest and deepest freshwater lakes on the planet. Great Bear Lake, in the Northwest Territories, is considered the world’s largest unpolluted lake. Great Slave Lake, also in the Northwest Territories, is North America’s deepest.

https://www.pewtrusts.org/en/research-and-analysis/articles/2015/03/19/fast-facts-canadas-boreal-forest

When overwintering, wood frogs not only drop their body temperatures, they also partially freeze. Image by Janet Storey.

Most year-round residents of the taiga sleep through the harshest winter months. Once the temperatures start dropping, these animals first eat as much as they can to store thick layers of body fat. Then, they look for dark, quiet places. Terrestrial (land) animals such as chipmunks and garter snakes will find burrows underground, and semi-aquatic animals like snapping turtles will burrow into the muddy bottom of ponds. Once they are safely tucked away from winter, the body temperature of these animals drop drastically and they enter hibernation. Bears in the taiga also bulk up and sleep through the winter, but the body temperature of bears does not drop enough for their sleep to be considered true hibernation.

When these year-round taiga residents are sleeping, they do not eat. Luckily, they have a lot of body fat to keep them from going hungry. The arrival of spring and warming temperatures stir these hibernating animals from their slumbers. It takes a lot of energy to wake up, though, and these animals burn through the last of their stored body fat to wake up and greet the sun.

https://askabiologist.asu.edu/animals-taiga

Not all animals leave before the taiga winter. Some animals, like the Siberian tiger and the snowshoe hare, not only live in the taiga for the entire year, but also remain awake through the winter.

Though many animals avoid the freezing taiga winter, that is the only season barren-ground caribou can live in the taiga. It is too warm in the summer months, so they migrate to the colder tundra for the summer. Image by Per Harald Olsen.

To survive, these animals have special adaptations like large paws to maneuver through the snow and thick coats to protect against the bitter cold. Snowshoe hares lose their summer brown coat and grow one in winter white to help them blend into the winter landscape.

Fish that live in the lakes and ponds of the taiga have little choice over whether or not to spend the winter in the boreal forest. When temperatures drop below freezing, the surface of the lake freezes over. Luckily, because ice is lighter than water, ice remains on the surface. Fish like northern pike and Alaska blackfish wait under the ice at near-freezing temperatures until spring arrives. 

https://askabiologist.asu.edu/animals-taiga