Three times a week, rain or shine, committed volunteers with the Dedicated Invasives Removal Team (DIRT) troop into Stanley Park to remove English ivy, Himalayan blackberry, and other invasive species. This Sisyphean and somewhat thankless task is all part of the Stanley Park Ecology Society (SPES) mission to help the park thrive while providing social, educational, and conservation opportunities.
According to Andy Ferguson, stewardship coordinator at SPES, this work is especially important right now due to the major loss of tree canopy after the Park Board removed thousands of trees that posed risks to the public in 2024 following a hemlock looper moth infestation. Without the shade from those trees, and left to their own devices, Himalayan blackberries and other invasives could run rampant.
The trouble is, not everyone agrees that SPES should be removing these plants. “Working for the parks, you walk around, everyone’s going to yell at you,” Ferguson says. “With birders in particular, it gets tricky,” he adds, noting that most birders have “some understanding of ecology, but it’s usually pretty focused and pretty obsessed just with birds, and so they’re viewing it only from that one perspective, and usually on a shorter-term lens.”
Ferguson explains that some birders get upset that DIRT is removing what they see as vital nesting habitat and a food source. The reality is more complicated, though, he says, citing the example of the overgrowth of Himalayan blackberry DIRT removed from the edge of Lost Lagoon. “Birds would only nest there about a third of the rate that they would if it was a native shrub.”
Himalayan blackberries. Photo by Michael Schmidt.
Ferguson acknowledges this approach is hard for most people, including birders, to understand. “A lot of the time they don’t even believe us.” He says it can help to look at the problem from a different angle. “Himalayan blackberry only produces fruit at the very end of bird nesting season, late July into August.” … By then, most of the bird species have already migrated.
In contrast, the 10 to 12 native shrubs SPES plants in place of Himalayan blackberry—including huckleberries, trailing blackberry, salmonberry, snowberry, and thimbleberries—produce fruit earlier and for far longer. “Now there’s food for the birds throughout the year.”
This misunderstanding was clear in a on October 8, 2024. A member of the public called in to oppose tree removal in Stanley Park, suggesting the close the park to the public. She added, “By the way, the ecology society were busy pulling out all the blackberries. Birds like blackberries. So do I … Invasive or not, it was food she was throwing away.”
Ferguson bemoans “this obsession with blackberry and leaving it because people think somehow it helps the birds.” It just doesn’t reflect the work he and the volunteers are doing. “Honestly, we’re going as far as we can to help these birds. We’re making people cut blackberry stalks when it’s, like, freezing or pouring rain,” he says. All this effort is meant to avoid cutting blackberry during nesting season.
Letting Himalayan blackberry take over is also just bad ecologically, Ferguson says. “Anytime you have an ecosystem become just one species, it’s so susceptible to mass death” from insects or disease. This was exemplified by the diseased and dead hemlock in Stanley Park, which replaced old-growth trees cleared decades ago for legacy logging and development.
“Ecosystems change. Things die. That’s the whole thing about ecosystems. They change,” Ferguson says. Now, though, “all of this forest understory is now open to the sun, and that’s actually what kept the blackberry out, is how shaded the park was.”
According to Ferguson, Himalayan blackberry wasn’t a major concern in Stanley Park, except near Lost Lagoon, until recently. “As the tree canopy dies, that blackberry might be able to start spreading through the understory in a way it never has before.”
As of August 2020, Himalayan blackberry was second only to water hyacinth on Metro Vancouver’s Invasive Plant Prioritization Rankings. SPES is concerned about the potential spread of Himalayan blackberry in cut areas and is working with the Vancouver Parks Board and the city’s urban forestry team to ramp up removal efforts.
“It’s so big that we can’t handle it well,” Ferguson says, adding that the city will “probably have to bring in contractors and things to work on it, and then we might do some of the cleanup or replanting afterwards.”
English Ivy, another invasive plant species found in Stanley Park. Photo by Michael Schmidt.
Last season, SPES replanted some cut areas with noninvasive shrubs and other ground cover around the trees planted by the city. “Normally, we’d let it just naturally regenerate, but we really wanted to push it so the blackberry doesn’t just have all this free real estate to just take over.”
Left to its own devices, Ferguson says that blackberry “eventually will probably impact tree succession too, because those brambles that you can see get, like, 10 or 15 feet tall. It’s full shade under there, so they can’t kill adult trees, but they’re going to harm the ability for trees or forest ecosystems to regenerate if we just let them go wild.”
This is something Park Board commissioner Tom Digby noted in response to Lamaitre’s comments in the October 8 meeting. “There is a lot of invasive species in the park, currently, right now,” he said. “And if we were just to close the park for five years, they would probably overrun the park in a big hurry. So it’s not likely to bounce back into any sort of primordial state if we just let it go.”
This is why SPES works with the city to create replanting strategies that promote biodiversity, encompassing plants, birds, and other species. “The city has already planted 25,000 new trees in the park to try to jump start the forest coming back,” Ferguson says. This is partly because the city doesn’t want the opportunistic hemlocks to take over again.
Most of the new trees are Douglas fir, cedar, and western yew, all of which are native to the park. The city consulted with Musqueam, Squamish, and Tsleil-Waututh Nations on what to plant to increase tree diversity. The importance of this consultation is laid out in the Invasive Species Management Strategy for Metro Vancouver, which took years to put together. It hasn’t been updated since its publication in 2014, despite the intention that it be a living document.
Ferguson suggests that plans are afoot to update this strategy, though with so many stakeholders involved, the process is necessarily lengthy and complex.
Recognizing the need to act now to control invasives, he has already begun incorporating more traditional ecological knowledge into SPES practices. This has changed how SPES approaches replanting, and it’s paying dividends with what Ferguson describes as a “massive increase in biodiversity” in recent years.
Where SPES once relied on “these really scientific prescriptions of what you’re supposed to plant in restoration sites,” it now plants a much wider variety of species, he notes. In 2022, “when I started, SPES would only plant about 600, maybe 900 plants a year, which is still a lot, but it was only about 12 to 20 species on average.” In 2023 and 2024, Ferguson estimates that SPES planted 1,940 plants and about 40 species.
SPES still uses the prescriptions but plants fewer numbers of each species and augments these with “culturally or medicinally significant species that grow in those same ecosystem types, or grow in relation to those plants.”
Salmonberry is a native shrub that helps prevent re-invasion. The Stanley Park Ecology Society suggests replacing invasive species with salmonberry plants, among others. Photo by Don Enright.
In addition to reworking its planting lists, Ferguson’s goal is to find “an ethnobotanist or a knowledge holder who will work with us and help direct that a bit more.” He acknowledges that SPES has a lot of work to do for meaningful reconciliation, and there’s momentum within the nonprofit to “recognize some of the mistakes we did in the past and talk to the people that were wronged and do public apologies and try to work together to rectify some things.”
Ferguson’s aim now is to support the newly planted trees and try to keep the invasive Himalayan blackberry at bay. “But we won’t know if it was successful for years and years and years, and it only will be if we continue to go back and work there.” It’s never just “one and done in ecology,” he says. “When people have invasives on their property, they think you can just dig it out once and it will go away, but you need to dig it out for like five to 10 years.”
Which brings us to the thorny issue of funding. As a nonprofit, SPES relies on grants and donations to pay its small staff, hire consultants, host educational events, and purchase plants to help bolster biodiversity. Fundraising for the removal of invasives is often a harder sell than other campaigns, Ferguson says. “If you can post a cute bird or something, everyone loves it, or especially the beaver baby photos and things like that. But talking about, like, the harder work of actually getting a baseline vegetation system to support those systems—that’s when people’s eyes start glazing over.”
Over his three years with SPES, Ferguson is happy to have helped expand the DIRT volunteer program. “Right now, it meets three times a week,” he says. “It’s the most frequent it’s ever been,” aside from during the pandemic when some volunteers went out in pairs almost daily.
This expansion of DIRT demonstrates both SPES’s commitment and the need for ongoing, aggressive management of invasive species in the park. “We have almost 600 volunteers on our list right now, [and] 5,000 volunteer hours in my programs alone per year.” Still, that’s nowhere near close to enough people power to stay on top of the invasives and replanting needs of a thousand-acre public park.
Ferguson clearly loves the work but admits, “Working in conservation is always kind of like an uphill battle no matter how good it is.”
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