Harvesting in the boreal forest
Doug Pitt: My name is Doug Pitt I’m a research scientist with the Canadian Forest Service, Canadian Wood Fibre Centre. My primary focus of research is silviculture.
Harvesting practices in the boreal forest have changed over the years. Back in the early days the primary focus of management was timber production. More and more over the last several decades we’ve become concerned with other objectives for forest management, social objectives such as recreation, aesthetics and in some cases spiritual values, as well as environmental objectives, maintaining wildlife habitat and food sources, water conservation and so on.
The most common type of harvesting in the boreal forest is clear cutting. It’s important to understand though why we use clear cutting in the boreal forest. One of the primary goals of our silviculture is to emulate natural disturbances and in the boreal forest factors like wind, fire, insects and disease play a very important role in forest renewal.
These all function to create openings in the forest that allow sunlight to reach the forest floor. Species such as Jack Pine, Black Spruce, Aspen have all evolved requiring more or less full sunlight to regenerate and grow properly. So any practice that aims to open the forest up to emulate some of these natural disturbances can be classified under the clear cut system.
So what we’ve seen is a move from fairly large clear cuts with relatively geometric shapes to clear cuts that include a lot more residual structure in them to provide wildlife habitat and contribute to diversity. We see this residual structure being left dispersed evenly throughout cut-overs as well as grouped into islands of intact pieces of forest that are left to maintain diversity and provide wildlife habitat.
You have to understand that our boreal forest consists of stands that are relatively even aged. That means that the trees in the stand are all the same age. They are like this because they’re what we call shade intolerant. So the ecological benefit of a clear cut is to create the environment required to regenerate and grow an even aged stand. And pre-settlement, our boreal forest existed as a patchwork mosaic of these even aged relatively pure stands of spruce, Jack Pine or Aspen.
While we strive to emulate natural disturbances with our silviculture, that emulation isn’t always perfect. The road systems for example that we use to access our harvest areas have no natural analog. Fires for example are much less discriminating than we are. So there are some differences that we strive to mitigate through some of our silvicultural techniques and management.
When a forest is managed sustainably, only the growth of the forest is harvested essentially. It’s like a bank account where we have capital and interest. And as long as we only remove the interest portion in that account, we can maintain the principle. A forest is exactly the same way. We have growing stock. The growth on that forest is what we should be harvesting. If we harvest more than that, then we’re not sustaining that forest, we’re not sustaining that bank account if you will.
Science has had a huge influence on our understanding of ecological function. And this is really reflected as an underpinning to our operational practice today. We’ve seen a lot of science contributing to our understanding of partial harvesting practices, mixed wood management, vegetation management, pest and fire management. And all of these contribute to our ability to manage our boreal forest sustainably and to maintain our social license to practice on public lands, which represent more than 90% of the lands that we operate on in the boreal forest in Canada.