Welcome to the Wildfire and Burned Forest Communities section of the Virtual Walk in the Forest Tour! Here we will explore different boreal forest communities affected by wildfire or a prescribed burn to find out what these communities can look like. Search each example community to find information on wildfire and the boreal forest. This is a Pine Forest, pictured here 2 years after a wildfire. Photo Credit: Government of Alberta; 360 Image provided by Fuse Consulting Ltd.

What does the field journal tell you about this burned forest? The heat of the fire has burned all of the mature pine trees, so this must have been a very hot (or high intensity) wildfire. However, that heat allowed thousands of seeds to be released to the forest floor. We can see that with the old growth removed, there is lots of sunlight, decomposing nutrients, and room for root growth to help the young pine trees to grow.

Some species, like pine, require the extreme heat of fire to release seeds from their protective cones (called serotinous cones). The new seedlings thrive in the rich soil and abundant sunlight that results from the burn of the old growth. 1) Regenerating pine trees (~5 years after a wildfire) 2) Regenerating spruce trees (6 years after a wildfire) 3) Closed serotinous cone on pine tree 4) Opened cones after a controlled burn Photos credits: 1 - Fuse Consulting Ltd.; 2 - EMEND Project; 3 - Nikki Yancey; 4 - Ajax9 (Shutterstock)

Mountain pine beetle (*Dendroctonus ponderosae*) and other tree parasites have historically been controlled by the presence of wildfire, which they cannot survive. Although they do have natural predators, it is not enough to keep these populations from killing entire forests. Without regular fire events, their populations continue to grow and spread. Photo credits: Beetle - Henrik Larsson; Tree Section - AlesiaMax589 (Shutterstock)

Fire as a Natural Regulator – with Mike Williamson This is a pyroscene landscape. So that means that fire is a natural event and a natural occurrence in the boreal forest. And when we remove fire from its role as a regulator of the forest, then we interrupt the natural processes that happen as a forest sustains itself over time. And that impacts us. The most obvious thing is that fuels accumulate over years, and what that leads to is more common ignitions, fire starts, and quicker spreads, and greater intensity of fire. And fire intensity can be a dangerous thing. So it can impede the biodiversity or the variety of biota of animals and plants. It can interrupt growth of the forest and diminish the health of all the species that live in the forest. When fire is absent, fire exclusion, does not lead to very many good outcomes. One of the most obvious, I suppose, that people would recognize, is mountain pine beetle. And everybody's heard about mountain pine beetle's a forest pest and forest disease that is directly contributable to the absence of fire because fire acted as a regulator for the mountain pine beetle. So when we remove fire, we are taking away a natural process that contributes to the health and sustainability of not just the forest, but also all the animals and the plants that live in the forest.

The Boreal Quilt – with Dr. Jen Beverly Fire plays a different role in different ecosystems, so it depends on the kind of forest ecosystem that you're looking at. But if we're looking at boreal forests, this is a natural, what we call, a crown fire ecosystem. So that means that the natural type of fire that you have in boreal forests can be very, very intense fires, and the tree species have evolved with those intense fires. So those intense fires, we call them stand replacing because they kill most of the trees, and it's basically like a reset button, and it's going to restart the forest. It takes away the mature trees and they're no longer living in the stand, and it also consumes the built-up vegetation on the forest floor, and that creates just the perfect place for new trees, new seedlings to establish and grow. So if you put out fires and you don't let them burn in a forest like that, then you're not going to get those resets. And that means that you don't have patches of younger forest coming in. And that means that you end up with a lot of mature trees. So you don't have variety in the patchwork of the forest because you haven't had those resets to the younger stands. So researchers think that that creates the opportunity for bigger fires when you eventually do get one. Because if there was patches of younger forest, those aren't as flammable, they don't have as much fuel in them. And so if you don't have that patchwork of younger trees and younger forest stands, you've got large areas where a fire could spread.

Fire Regimes – with Dave Schroeder Forests are always dynamic and in the absence of fire or any other disturbance will continue to change. Some vegetation will die out and other species may gain prominence. However, disturbance of some kind is bound to happen in a forest, whether it's from insects, a wind event, forest harvesting, or from fire. Forests in Western Canada are adapted to varying fire regimes, which are known to have regular patterns such as wildfire return interval. So, this means how frequently a fire returns to the same spot and that might be decades or centuries. When the return interval changes dramatically, there are some cascading effects on the vegetation and wildlife dynamics of a forest. If the fire return interval is extended due to suppression or wildfire absence, then there may be a decline in abundance for some plants and an increase in abundance for others. Forest communities are adapted to regional fire regimes. The fire regime is influenced by climatic patterns, landforms, or topography, the vegetation itself, and human activity. These influences dictate how often and how severe fires tend to be. Forest communities are adapted to thrive in any fire regime, whether it is a frequent fire return or a long term. Fire regimes exist for long periods and change slowly, which allows forest communities to adapt. When wildfire patterns match the adaptations of local forests, then we get healthy forest ecosystems.

The role of Wildfire in the Boreal – with Kelsy Gibos Wildfire is a significant natural disturbance in the Canadian forests, and it helps to determine which plants and animals can live there. A natural pattern of fire in a plant community is called a fire regime. The fire regime describes how often fires return to the forest, how hot they burn and how large they get. Different sizes and types of wildfires break the forest into a big mosaic-like quilt with patches of different-aged types of plants. When we stray away from the natural fire regime, forests continue to grow and grow, and patches can become denser, more uniform and more widespread than in historical forests. Native plants and animals may not survive in this changing environment. These extra full forests often burn more severely, and fires that start in them can be very difficult to control because there are no natural breaks in the landscape. Many people have homes and live in this forest type, which means extra measures are required to keep the people and property safe. The majority of fire that we have occurs far away from populated areas. Fire fills an important role in the ecosystem. Think of fire like giving the forest a bath. Fire clears out all of the plants that are piling up on the forest floor, gets rid of all the fallen dead branches and logs from trees that have died and fallen over, and removes pests and other things that might be damaging the ecosystem. Fire also stimulates new productive plant growth by clearing tree tops and allowing more sunlight to make it to the ground. Some of our forests in Canada even need fire to burn their cones in order for them to open up and grow new baby trees. By allowing natural fires, we restore the landscape mosaic, or quilt, where forests are made up of patches of different ages and types of trees, which provide a range of habitat for animals, and also prevent more severe fires from spreading extra long distances towards communities.