Scotch broom increases wildfire risk. What can we do about it?

Bev Agur has been cutting the invasive Scotch broom since 2010 with Broombusters. She is now the contact for Comox Valley’s arm of the organization. Photo courtesy of Bev Agur

In 1850, Scottish Army Capt. Walter Colquhoun Grant planted a European perennial shrub on his farm on T’Sou-ke Nation’s traditional territory (Sooke). He thought the shrub — Cytisus scorparius in Latin — would bring back nostalgia of his Scottish homeland, covered with hills of yellow flowers.

One-hundred and seventy-five years later, this shrub is now one of the most notorious invasive species on Vancouver Island known colloquially as Scotch broom. Vast areas of the Island are covered in this plant, exhibiting what a changed landscape can look like if invasive plants are allowed to spread and take over. It competes with native plants, disrupts streams and has no known natural predators. It can also live up to 25 years and produces seeds that can survive in the soil for 30 years.

Scotch broom is also extremely flammable, leading to growing concern as the climate changes and Earth warms.

Luckily, one Vancouver Island-wide organization has been working for nearly two decades to decrease the abundance of Scotch broom in local areas, and an invasive species expert says groups such as these, along with other forms of traditional land management that draw on Indigenous knowledge, give him hope that disastrous wildfires sparked by broom can be mitigated or avoided.

Invasive plants and wildfire: a ‘sleeping giant’

Hunter Jarratt is an ecological restoration consultant based in the Nanaimo area, and is more famously known as the Invasive Species Guy. He told The Discourse that Scotch broom has a high oil content, so it’s flammable even while it’s still green and alive.

“I’m about six feet tall, so if you have a pile that’s as tall as me the flames would easily grow to three or four times that in a matter of minutes — seconds, even,” he said, adding that he hopes Vancouver Island doesn’t see a fire similar to the one in 2023 that devastated Lahaina, Hawaii, and was amplified due to invasive grasses.

The grasses were left over from sugar cane plantations and, similarly to broom, would crowd out native species. According to reporting from the Washington post, powerlines fell on the fields of grass in 2023 leading to a disastrous wildfire that killed 102 people.

“It’s pretty concerning, especially the ecosystems that have grasslands that are a mix of these dry grasses, Scotch brooms and maybe some other shrubs in there too. There’s just so much fuel in those places that it’s a sleeping giant,” Jarratt said.

Jarratt also explained how invasive species can fuel fires by changing the natural fire cycle of an ecosystem. This is referred to as the invasive plant/fire cycle.

These new invaders, he explained, will add fuel to the ecosystem so more intense and severe fires will occur. After the fire, because those species were already present in that ecosystem, they will be the first to colonize and repopulate those sites.

Jarratt said the invasive plants push out native species that can’t adapt quickly, taking advantage of sunlight and nutrients. The increase in invasive species makes the ecosystem less resilient, creating a monoculture and setting the stage for another fire.

This is all amplified by climate change and increasingly common drought conditions, he added.

“It’s leading to a pretty rapid instability of an ecosystem. It’s invade, burn, repeat over and over again. So it’s quite concerning.”

Jarratt said the undermining of Indigenous knowledge and land stewardship is another big contributor to the spread of invasive species.

The colonial government has historically put forth policies of fire suppression, such as the 1874 Bush Fire Act that banned Indigenous cultural burning. Research shows these policies have led to a build-up of forest fire fuels, increased fire risk, decreased forest resilience and, in turn, more out-of-control wildfires.

“As much as fire is scary, not all fire is bad,” Jarratt said, adding that ecosystems such as the Garry oak ecosystem traditionally relied on regular, low-intensity ground fires to limit the spread of competing tree species.

“That’s one thing I always like to talk about with this kind of conversation with burning and with Scotch broom is the Garry oak ecosystem, which there is way less of in the Comox Valley now,” Jarratt said.

Busting broom

Jarratt said he still sees opportunities for people to learn how to manage invasive species in their areas.

“There’s been a lot of effort to control it,” he said.

“People who have farmland and natural areas on their land, as long as you’re doing your part to keep invasive species in check, I think we’d be in a much better position.”

One of the organizations that inspired Jarratt to learn more about invasive species involves a group of committed people who are determined to get rid of as much invasive Scotch broom as possible: The Broombusters.

Bev Agur has been committed to cutting down broom since 2010, when she became involved with Broombusters. It’s an organization that was founded in 2006 by Joanne Sales, who noticed a lot of Scotch broom growing near her blueberry farm in Coombs. Since then, this volunteer-run organization has expanded all across Vancouver Island, including in the Comox Valley, Cowichan Valley and Nanaimo.

Hunter Jarratt told The Discourse that Scotch broom poses a fire risk due to its high oil content. Photo Courtesy of Hunter Jarratt/Invasive Species Guy

“My husband and I moved out to the Comox Valley in 2009 from Alberta, and we didn’t really know anything about broom,” Agur said.

She has been cutting broom with the organization since 2010, and is now the area organizer for the Comox Valley’s division of Broombusters. For six days a week, for six weeks of the year when broom is in season, the group of Broombusters goes out to cut it down.

Like Jarratt, she’s learned how much of a fire risk it is.

“If there’s broom that’s growing under a powerline … if a wildfire gets there, it’ll just take off,” she said.

Agur said the summer is not the best time to cut broom, because if it is cut and sits and dries out, it is a fire risk.

“And the problem is it’s full of seed pods, so you run the risk of spreading those around,” she said.

Those who are curious to learn about Comox Valley broom cutting can keep their eyes out for when to join in the spring. She added that there is a video on the organization’s website that explains how to cut broom properly.

“We have lots of tools so people could show up and cut broom with us,” she said. “I suggest they bring some work gloves or gardening gloves, and wear dirty shoes and old clothes, because often broom is growing around blackberries and roses.”

Controlling the fire

Jarratt said getting involved with invasive species control and learning more about controlled burning(also known as prescribed burning) are some of the best ways to manage invasive species and fire risk.

Controlled burning helps reduce the amount of fuel load — what is available to burn in an area. After years go by, the fuel builds up on the ground as vegetation grows and falls to the forest floor and then is available to burn again, Jarratt explained. He also said some plant species such as Lodgepole pine are dependent on fire, so they won’t germinate unless there is a fire.

Comox Valley Broombusters after a successful cut. Photo courtesy of David Stapley/Comox Valley Land Trust

Prescribed burns are often lighter and less hot as well, he said. They’re small enough to support germination but not big enough that it burns the whole ecosystem down.

On the south Island, Jarratt pointed to biologist James Miskelly who does prescribed burns at Rocky Point, home to a Garry oak ecosystem which has historically relied on controlled burning to keep it healthy.

In B.C.’s southern interior, known for its dry landscape and frequent wildfires, groups such as the Salish Fire Keepers Society and Ntityix Resources have taken up Indigenous-led controlled burning, something that was suppressed from colonialism after being practiced for millennia.

“I feel like this is going to be an increasingly important factor as more areas evidently burn on Vancouver Island in the future,” he said.

“Especially all these hilly ecosystems that have huge fuel loads that have built up over many, many, many years, but are now also invaded by these highly flammable species like Scotch broom.”