The Terrestrial Biomes
The terrestrial world can be divided into areas called biomes. A biome is a large area of land classified by its distinct plants and animals. The characteristics of each biome are dependent on its temperature and the amount of precipitation the area receives. The plants and animals found in each biome are adapted to the particular environment of the biome.
A biome is made up of many ecosystems. An ecosystem is the interaction of living and nonliving things in an environment. However, a biome is the specific geographic area in which ecosystems can be found.
For the purpose of this backgrounder we will identify major terrestrial biomes of the world based on the Whittaker biome classification scheme. It is interesting to note that not everyone agrees on the number and types of biomes.
Distribution of the Earth’s Major Biomes
The map below shows where each of the eight major terrestrial biomes are located in the world. Canada contains four biomes: temperate deciduous forest, grassland, boreal forest/taiga, and tundra. A biome has the same characteristics in any part of the world when it can be found. Therefore, the boreal forests of Canada look like the boreal forests of Russia. The characteristics of each biome are dependent on its climate, particularly temperature and the amount of precipitation the area receives.
The boreal forest, also known as the taiga, covers about 11% of the land mass of this planet. This makes it the world’s largest terrestrial biome! It is located in the northern hemisphere, approximately between the latitudes of 50° N – 65° N. The term “boreal forest” tends to mean the more southern part of the biome, while the term “taiga” tends to mean the more northerly part of the biome where it transitions to the tundra.
This biome is known for its coniferous (cone-bearing evergreen) forests and many freshwater bodies in the form of rivers, lakes, bogs, fens and marshes. Overall, the soil has relatively low fertility, which means that it is not good for growing plants. Most of the nutrients occur in the upper layer of the soil where organic matter is found. The soil also tends to be slightly acidic because of the breakdown of evergreen needles when they fall to the ground and decompose. The boreal forest has cold winters and relatively warm summers. Typical temperatures range from 21 °C in summer down to -54 °C in winter. Precipitation is moderate, averaging around 200–600 mm per year, and droughts are relatively rare.
Plants & Animals
Vegetation found in this biome is adapted to a cold climate and low nutrient availability. Many of the plants have shallow root systems which work together with mycorrhizal fungi to get the most nutrients they can out of the organic matter in the soil. Southern boreal forests have a thick tree canopy formed by fully grown trees. This is called the closed canopy forest. In open spaces called clearings there are some shrubs and wildflowers.
On the floor of this type of forest are mainly mosses. Northern boreal forests have trees which are more spread apart. This is called the lichen woodland. Here, lichens, which are fungi which live in partnership with algae, form most of the ground cover. Some of the common trees found in this biome include conifers such as spruce, fir, hemlock, larch and pine and deciduous trees such as aspen, birch and willow. The mix of trees varies depending on which part of the world the forest is found in. The boreal forest of North America is mostly made up of spruces. The boreal forest of Eastern Siberian taiga is basically one large larch forest. Larch trees don’t follow the common evergreen rule and keep their needle-like leaves year-round. These trees are actually deciduous. The needles of larch trees turn a brilliant yellow in autumn and then drop off.
Similar to the vegetation, the animal life in the boreal forest is adapted to the cold climate. Common animals found in the boreal forests of Canada include large herbivores such as caribou, moose, elk and wood bison. Caribou are called reindeer outside of North America and wood bison also called wood buffalo.
Large predators found here include the Canada lynx, gray wolf, black bear and brown bear. Smaller mammals, such as beavers, raccoons and voles also live here. Many species of birds use this biome for their nesting grounds. Many freshwater bodies provide a unique habitat for many migratory fish such as the North American Atlantic salmon. Finally, the forests, bogs and marshes of this biome are home to a large variety of insect life.
Human Impacts & Conservation
Humans have had a long history of interacting with boreal forests. One way we know this is through art. Cave paintings and rock drawings that are thousands of years old show people hunting boreal forest animals for food.
However, human impact on the boreal forest has been relatively minor since the unfavourable climate makes it difficult for people to live there.
In more recent times, as the number of humans living in this biome has increased, and so has our impact. In general, humans have looked towards the boreal forest as a source of natural resources. At the beginning, this meant cutting down trees for wood and mining the land for various metals. More recently, this has expanded into oil and gas exploration and extraction. Human-induced climate change is predicted to have a large impact on the population and ranges of both plants and animals living in boreal forests. For example, warmer, drier conditions associated with climate change will likely cause more trees to die during the summer and insect populations to increase. However, conservation groups, such as the Boreal Conservation are working hard to help others create sustainable solutions for Canada’s boreal forests.
Spotlight on Innovation
Fire can be a very destructive force both in populated areas and wilderness areas. One such fire caused billions of dollars in damage in Fort McMurray, Alberta in 2016.
Despite the devastation that fire can cause, fires are very important parts of Canada’s ecosystems. Fires recycle decomposing forest materials, such as dead leaves, into nutrient-rich soil. Fires can also open the tree canopy which can allow more sunlight to get through. This helps seedlings and small plants and the forest floor as well as create new habitat for insects, etc. Some trees, such as lodgepole pine and jack pine can only reproduce after a fire. This is because only fires can open their cones and release their seeds. Fires also help to maintain ecosystems such as open grasslands by keeping trees and shrubs from growing there. Finally, fires can maintain biodiversity by creating many different types of habitats for wildlife to live in.
Wildfires are suppressed in Canadian parks. However, because they are important for some ecosystems, parks may use prescribed burns.
These are closely controlled forest fires. To begin a prescribed burn, fire specialists create detailed plans in order for the burn to be effective and safe. For example, they will define specific boundaries for the fire to make sure that the fire does not go beyond where it is supposed to go. Once the proper weather conditions are met, the prescribed burn can take place.
In Canada, many of the ecosystems found in national parks are fire-adapted. This means that controlled burns are necessary to maintain and/or restore the environmental health of the park and the organisms that inhabit it. Fires can have a regenerating effect on ecosystems and can help ecosystems stay around in the future. The history of a particular ecosystem can actually be determined by examining the effects and occurrence of fires there. Each ecosystem’s unique fire history can mean that it can be home to some unique plants and species not be seen in other locations!
Fire Management Technician.
I grew up near Quebec City and I have a bachelor's degree in forestry from the University of Moncton, New Brunswick. I also have a Master's degree in Geography from Laval University. At the moment, I am working at Cape Breton Highlands National Park, in Nova Scotia.
My role involves planning controlled burns. This practice helps certain species of trees to grow. In fact, some trees need fires in order to grow. It's true! I start fires to help the forest!
Before burning, you have to prepare a very detailed burning plan. I first have to spend some time in the forest assessing the site. I use aerial photographs, and maps of the forest, watercourses and roads. I make sure that I am very familiar with the area. What type of vegetation is present? Are there any cliffs, streams or lakes? I collect all of this information to include in my plan.
When I prepare the burning plan, I use specialized software to analyze all of the information collected in the field. This software can predict fire behaviour. A fire doesn't burn the same way on flat ground as it does on a slope. And a hardwood forest does not burn the same way as a coniferous forest. I then try to identify the best weather conditions in which to conduct the burn safely. I consider factors such as wind, moisture and temperature to determine the ideal conditions for the burn. If it is too hot, too dry, or too windy, it could be dangerous. Safety is our top priority. On the other hand, if it is too wet, we would not be able to get the fire started. So weather forecasting tools play a very important role.
On the day of the burn, we start the fire in the locations that were identified in my burning plan. We use helicopters, which drop small balls that catch fire, and manual burners. This work keeps us in shape, because you have to walk quickly if you are carrying a lit torch through the forest! At the end of the day, we usually let the fire burn freely, but continue to monitor it until it is completely extinguished.
As you can imagine, I love my job with Parks Canada. I am lucky to have a job that gives me so much pleasure and excitement. You have to like variety to be a fire management technician, because every day is different. You also have to enjoy teamwork and working outdoors.