Why Do We Burn Slash Piles? Exploring Options for Forest Residuals
If you've noticed slash piles in our recently harvested areas of the Community Forest, you may have wondered why we are burning wood waste. It's a good question, and one we have heard from community members, and think about ourselves - we're interested in all opportunities to reduce the environmental impacts of forestry, and burning seems like low hanging fruit right?
The short answer is that pile burning remains one of the most practical ways to manage the branches, treetops, and other woody debris left behind after harvesting. But that doesn't necessarily make it the best solution, and while we haven't found the right alternative yet, we continue to explore solutions.
Why is slash burned?
After timber harvesting, the branches, tops, and other material that cannot be economically utilized are commonly referred to as slash. Some of this material is beneficial to leave on the forest floor, where it provides habitat, protects soils, and gradually returns nutrients to the ecosystem.
However, excessive accumulations of woody debris can create a significant wildfire hazard, particularly as our climate changes and we experience longer periods of hot, dry weather.
Forest licensees in British Columbia are legally required to assess and address fire hazards associated with their operations. Piling and burning excess slash is one of the most common ways to meet these obligations.
Burning is regulated to reduce impacts on air quality, with restrictions on when and where it can occur. Weather conditions, including atmospheric ventilation, are important considerations intended to minimize smoke impacts on neighbouring communities.
What about the carbon emissions?
Burning releases carbon dioxide and other emissions into the atmosphere, along with smoke and fine particulate matter that can affect air quality and human health. These are legitimate environmental concerns.
However, evaluating alternatives requires looking beyond the emissions from the burn itself.
For example, transporting woody debris to another facility, grinding it, or processing it into chips requires heavy machinery, consumable steel parts for grinding and chipping, and a lot of fuel. The carbon stored in that wood will still eventually be released through decomposition or combustion within a few years.
Chipping and leaving material on site can be useful in some circumstances to reduce the environmental impacts of transporation, but concentrating large amounts of fine woody material on the forest floor can also present ecological and wildfire management challenges.
The question isn't simply whether burning produces emissions, but which alternative method produces a better overall environmental outcome. That means considering greenhouse gas emissions, smoke, wildfire risk, soil health, and biodiversity. The solution also has to be possible, including economically feasible.
What are we doing differently?
SCCF already diverts a significant amount of wood from slash piles by having contractors pile usable wood at roadside to make it accessible for people gathering their own firewood using our free permits. We also haul some of this away to supply our community firewood program, an investment in diverting waste and supporting community need at the same time . We have also been investigating other ways to reduce the amount of material that needs to be burned over several years.
These include:
Chipping and grinding: Evaluating where mechanical processing is practical and environmentally beneficial, including the fuel consumption, transportation requirements, and potential uses for the resulting material.
Air curtain burning: Investigating portable systems that use directed airflow to promote more efficient combustion and reduce visible smoke and particulate emissions, including opportunities to produce biochar, a carbon-rich material that may have beneficial uses.
Prescribed broadcast burning: Exploring whether carefully planned, controlled fire across a treatment area could offer ecological and wildfire risk reduction benefits compared with conventional pile burning.
Could fire itself be part of the solution?
One opportunity we are beginning to explore is prescribed broadcast burning.
Unlike pile burning, which concentrates burning in individual locations, broadcast burning uses carefully planned fire across a larger treatment area. Under suitable conditions, it may be possible to reduce surface fuels while avoiding some of the concentrated soil heating associated with large slash piles.
Fire is a natural ecological process in many forest ecosystems. Depending on the ecosystem and the conditions under which it occurs, fire can influence nutrient cycling, vegetation, habitat, and the development of future forest stands.
We have recently begun discussions with the BC Wildfire Service about the potential for a collaborative prescribed burning project within the Community Forest. Their staff have identified opportunities worth exploring and offered to assist with planning and evaluating possible projects.
This is still at an early stage. Any proposed project would require careful consideration of ecological objectives, public safety, smoke impacts, appropriate locations, and the necessary planning and approvals.
We are also interested in learning more about the historical and contemporary use of cultural fire by Indigenous Peoples. Cultural burning is grounded in Indigenous knowledge, objectives, and stewardship practices, and is distinct from an operational forestry burn. Exploration of this connection includes respectful dialogue with the shíshálh Nation whose territory we work within.
There is unlikely to be one solution that works in every circumstance, and pile burning is likely to remain in practice to some extent, for some time.
Our goal is to reduce unnecessary burning, make better use of forest residue, and explore approaches that deliver the best outcomes for forest health, climate resilience, wildfire safety, and our community.
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