Banishing broom from the Denman butterfly reserve to help wetlands
By Chris Junck, Taylor’s Checkerspot Butterfly Recovery Project Team
BC Parks is continuing to implement the wetland restoration plan that was developed in 2021 for the Denman Island Park and Protected Area butterfly reserve. The primary purpose of the 10-hectare reserve is to sustain suitable habitat for a subpopulation of endangered Taylor’s checkerspot and other butterflies. Ongoing vegetation management within the reserve is required to maintain open meadow and wetland habitat that the butterflies require.
Conifers and Scotch broom quickly regrow in the butterfly reserve. Ongoing vegetation management is needed to maintain open butterfly habitat. Photo by Chris Junck.
In 2023, the focus was on clearing invasive Scotch broom from the wetlands that were constructed in the southwest corner of the reserve in the fall of 2021. Last spring, four BC Parks student rangers swept through the wetlands to remove dense patches of small broom plants. They then moved to adjacent areas to take out mature Scotch broom. Two Denman Island residents were contracted in the fall to remove any remaining broom from the southwest lobe of the butterfly reserve, and clear large broom that blocked the trail on the west side and near the information kiosk.
Nineteen large piles of Scotch broom were removed from the butterfly reserve in 2023. Photo by Bonnie Zand.
“The crews removed an astounding amount of Scotch broom,” said Erica McClaren, BC Parks protected area ecologist and one of the project leads. She added, “when they finished there were nineteen huge piles of broom, and the total area cleared was almost 22,000 m2.” That’s approximately the same area as three soccer fields!
It’s a challenge to keep up with Scotch broom invasions. A mature broom shrub may produce more than 18,000 seeds annually. The seeds can be viable in the soil for decades. Left unchecked, broom will rapidly recolonize cleared areas. The butterfly reserve wetland restoration plan indicates that ongoing work to remove invasive plants, seeding and planting native species, and monitoring the results will be required to ensure the success of the project.
Cleared area and site where Scotch broom was burned. Photo by Bonnie Zand.
BC Parks and the project team thank the Cowichan Tribes, Halalt, Homalco, K’ómoks, Lake Cowichan, Lyackson, Penelakut, Qualicum, Snaw’Naw’As, Stz’uminus, Tla’amin, We Wai Kai, and We Wai Kum First Nations for allowing us to restore ecosystems in their traditional territories. Several local volunteers also contributed to the success of this wetland project.
The recovery project has benefited from funding and in-kind contributions from the BC Parks Licence Plate Program, the Habitat Conservation Trust Foundation, the Environment Canada Habitat Stewardship Fund, and the B.C. Ministry of Environment and Climate Change Strategy (Ecosystems Branch), and others.
The Taylor’s Checkerspot Butterfly Recovery Project Team includes biological consultants and representatives from the B.C. Ministry of Water, Land and Resource Stewardship, B.C. Ministry of Environment and Climate Change Strategy, BC Parks, Denman Conservancy Association, Garry Oak Ecosystems Recovery Team, Greater Vancouver Zoo, Mosaic Forest Management, Wildlife Preservation Canada, and others.
Learn more about the Taylor’s checkerspot butterfly: goert.ca/activities/ and gov.bc.ca/taylors-checkerspot