Invading plants take root

On a spring day in 2003, Karin Albert and a gang of plucky volunteers slipped on gardening gloves, grabbed shears and shovels, and headed into the thick brush ringing Burnaby Lake, prepared to do battle. Or at least they thought they were prepared. The foe was English ivy (Hedera helix), a member of the ginseng family often used ornamentally for landscaping purposes. Native to Europe and Asia, the plant was introduced to North America in the late 1800s and quickly proved itself an adept colonizer, helped along by well-intentioned green thumbs who plant English ivy in their gardens, oblivious to the plant's aggressive tendencies, its ability to strangle a tree trunk and kill it in 20 years or less.

“We worked one day and people saw that we were hardly making a dent. That's when we realized we needed an invasive-plant control strategy at Burnaby Lake,”  says Albert, a community-development coordinator with the Greater Vancouver Regional District.

The group dubbed themselves Weedbusters and organized work parties to tackle both the English ivy choking native trees in the park and the ubiquitous Scotch broom, part of the legume family known as Fabaceae. In a single year, Weedbusters removed six one-tonne truckloads of broom from the park. Three years ago, the GVRD started introducing a handy beetle called Galerucella calmariensis, which eats the leaves of purple loosestrife, thus killing it””a biological control program that has eradicated most of this invasive plant in Burnaby Lake Park.

In the mid-1990s, a discussion about invasive plants might have seemed like something from a science-fiction flick, barely a blip on the radar screen of environmental issues. For the most part it was the quiet concern of ranchers and range managers, who were worried about the spread of exotic plants like knapweed that were unpalatable to cattle, or a thorn in the side of an attentive gardener trying to rid a hedge of morning glory. However, in the past five years the ranching community, park managers, regional district boards, both the provincial and federal governments, ecologists, private landowners, and ordinary gardeners have started to realize that invasive species represent a much greater and insidious problem than previously thought. They threaten the wetlands that filter our water, the range lands on which ranchers depend, and the natural biodiversity that sustains the multifarious species of flora and fauna that comprise a healthy ecosystem.

A 2004 study paper, prepared for the B.C. Ministry of Water, Land and Air Protection, framed the issue in a stark light: “Conservation biologists have globally ranked invasive alien species as the second most serious threat to species at risk after habitat destruction.” 

When you consider how some of the roughly 140 problematic invasive plants identified by the B.C. government propagate and spread, it becomes vividly apparent why they are such a problem. For example, a single three-year-old bush of Scotch broom, allegedly first introduced to the West Coast by a Capt. Walter Grant in 1851, annually produces as many as 18,000 seeds that can remain viable in the soil for 60 years. Scotch broom has so thoroughly overtaken swaths of cleared land on the southwest coast that some people believe trying to get rid of it is already a lost cause. Just one plant of policeman's helmut, which grows vigorously along waterways, produces 800,000 seeds annually. The dreaded Japanese knotweed, native to Asia, spreads quickly with a network of rhizomes, a rootlike stem that emits both roots and shoots, that can extend a whopping 20 meters from the parent plant. A single cane of thorny Himalayan blackberry, prized by many for its succulent berries that make great wine, will quickly grow into an impenetrable thicket five metres in diameter and prevent the natural succession of plants and trees. As long as the wind has blown, exotic plants have been laying down roots in new territory. Many, if not most, are benign. However, botanical bullies, like the few already mentioned, all have characteristics in common: they can march across ecosystems like Alexander's army, are as prolific as rabbits, and are more resilient than a piece of sun-dried cowhide.

What's worse is that invasive plants don't respect boundaries. Whether it's Japanese knotweed obliviously planted by a homeowner as a hardy, fast-growing natural hedge along a property line or a blackberry seed transported across the land in the gut of a bird, invasive species present a complex management problem. An estimated 75 percent of invasive plants are introduced by humans intentionally, like purple loosestrife, which seduces the eye with pretty flowers while it colonizes and then chokes out aquatic ecosystems.

It was another realization””that groups of volunteers and government employees soldiering away against the invasion in isolation didn't stand a chance””that prompted the Fraser Basin Council to host a forum in Williams Lake back in 2002 entitled Weeds Know No Boundaries.

“The economic and environmental impacts are potentially huge. It's been called the 'silent forest fire', but there was no coordination or comprehensive strategy,”  says Gail Wallin, a member of the council who helped organize the forum. “When it comes to invasive plants, we could have advocated for making a bunch of regulations so people can't do X,Y, and Z, but we didn't take that approach. We didn't believe a punitive approach would work.” 

Instead, there was broad consensus that the focus should be on education, coordination, and the development of a rapid detection and response strategy. The cost of waiting around with hands in pockets is significant. The provincial government says knapweed currently costs ranchers $400,000 per year in lost cattle forage and could balloon to $13 million if left unchecked. Ernie Selletin, a Comox Valley biologist, contracts out to the Ministry of Forests to remove knotweed and gorse from Crown forestland. Every summer he hires students to toil in the backbreaking battle against knotweed. Sometimes no amount of manpower will do the job, and when you have to enlist machinery the costs soon spiral out of control.

“It's virtually impossible to dig some of this stuff out manually. Removing it mechanically is futile. You're looking at a huge cost. I did a five-metre area of Japanese knotweed with an excavator and it cost $1,000,”  Selletin says. “I've seen it growing through rip-rap and under highways, and it's just not feasible to dig up highways.” 

Back in Vancouver, the GVRD is looking at a bill of about $2,500 per hectare if it chooses to plough under fields of reed canary grass, which has invaded large sections of Colony Farm Park in Coquitlam.

What's important now, Wallin says, is that people are talking about invasive plants. To ensure the forum wasn't a one-off effort, the Invasive Plant Council of B.C. was formed, of which Wallin is now the acting executive director, and it held its first annual conference in January 2005.

There's more than just talk going on. Recently the IPCBC, which receives both federal and provincial funding, was summoned to lead an effort to address yet another recently arrived invasive, carpet burweed, first identified in 1997 in Ruckle Provincial Park on Salt Spring Island and since discovered in Beacon Hill Park in Victoria and around Thetis Lake in the Capital Regional District.

“The Invasive Plant Council arranged a joint government meeting and they all agreed in principle to commit resources to eradicating the plant,”  says Wallin, who has been asked to put together a plan for a common approach that will ensure different levels of government won't be going in three different directions.

Two members of the plant council also sit on the Inter-Ministry Invasive Plant Committee, a provincial government body formed in 2004 that helps various government ministries coordinate and allocate a $4 million annual budget earmarked for invasive-plant control on Crown land. In the spring of 2005, the committee sought additional government dollars to fund a $1.2 million, locally driven, three-year pilot project in southeastern B.C. Quarterbacked by the Regional District of the East Kootenays, the project has organized 30 events and brought together more than 400 volunteers under the banner of Weed Warriors in the past year to pull weeds on Crown lands. It has also hired contractors to tackle noxious weeds in five different management zones, in a regional district that covers eight million hectares.

While dedicated volunteers pull weeds, the fight against invasive plants faces another big hurdle: the fact that much of the public doesn't know an invasive plant from a stalk of peaches-and-cream corn, or simply doesn't care. Furthermore, a lot of nurseries still sell noxious weeds as ornamental plants because people want them.

Annemarie De Andrade, manager of public programs for the Stanley Park Ecological Society, heads up a committee looking into how best to control a 50-hectare infestation of English ivy””20 percent of the park's land base.

“I was in Deep Cove the other day and there was a store selling pots of ivy,”  De Andrade says.

Wallin and the Invasive Plant Council of B.C. realize that interrupting the supply lines, stopping the problem at its source, is the key to success. The IPCBC is working closely with the B.C. Landscape and Nursery Association to get things like English ivy and English holly out of the greenhouses. However, she believes there's a dual responsibility shared by consumer gardeners, who need to learn about the consequences of planting certain species, and the nurseries, which can do their part by limiting availability.

There's no doubt that there's a buzz around invasive plants. Every day, plant cuttings travel around the province in boat propellers, in the back of dump trucks and pickups. Seeds arrive on our shores in the cargo holds of ships, are transported by the wind and in the droppings of starlings and other birds, are scattered like raindrops across fields between city and countryside. It's going to take a lot of Weedbusters, a much more educated public, and whole lot of cooperation between governments and the private sector to stop the onslaught. The biodiversity that most of us take for granted depends on it, the GVRD's Karin Albert says.

“The longer you wait, the bigger the problem becomes,”  Albert notes.

And the more expensive.