In the battle against invasive plant species, what’s left behind is often overlooked.

Scotch broom and daphne are common Garry oak ecosystem foes, but less familiar are plants that should be there, such as the deltoid balsamroot. The showy sunflower-like plant is nearing extinction in Canada and only two remain at Fort Rodd Hill national historic site in Colwood, making ongoing restoration work all the more critical.

“It’s our biological wealth that we have to lose,” said Brian Reader, a Parks Canada species at risk ecologist. “You may lose more marvelous genetic material.”

The rare species may not have a huge impact on the overall function of an ecosystem, but really “who knows?” he said. There may be species of animals or other plants that depend on the extinct species.

Balsamroot is listed as endangered under Canada’s Species at Risk Act. There are small populations throughout the Island and Lower Mainland, accounting for maybe 3,000 plants in Western Canada, Reader said. There is another plant, Macoun’s meadowfoam, found in two places at Fort Rodd that is listed as threatened.

“It takes a beautiful photo when you have a macro lens,” Reader said.

Protecting these plants is part of a larger strategy to remove invasive species from the 54-hectare site and replace them with native species.

A 2002 inventory of all plants on site revealed 44 per cent were invasive. Scotch broom, daphne, English holly and more were crowding out the native grasses, plants and trees.

Since then co-op students and volunteers have taken to the forested areas, focusing first on broom and now on grasses and daphne. Garry oak ecosystems are one of Canada’s rarest ecosystems. Many plants within that system are specifically adapted to that environment and may never have been overly abundant, Reader said.

“For the most part a lot of these (plants) are inherently rare,” he said.

All plants under the Species at Risk Act have recovery strategies and population targets. For the balsamroot the hope is to have upward of 40 plants at Fort Rodd, Reader said. The current plants are decades old and produce few viable seeds. It may be that they are so inbred that plants from other locations need to be brought in, he said.

Helping a species rebound isn’t always as easy as putting plants in the ground, however.

“We don’t understand their biology,” he said. “We are trying to let the plants tell us what’s good.”

Sensitive areas at Fort Rodd are fenced to ward off deer and areas along the nature trail cleared. Later in the summer native plants will be transplanted into the area, Reader said. The hardest part of the work is deciding which area to concentrate on, said Rob Underhill, a Garry oak ecosystem restoration technologist. It’s more about a balance, allowing native species to thrive while keeping the populations of invasive species under control.

“There’s always going to be non-native species in there,” Reader said. “We don’t need to remove all of them.”

Volunteers are needed to remove invasive species at Fort Rodd Hill July 25, 9:30 a.m. to 3:30 p.m. Call Rob Underhill at 250-812-8133 or e-mail robert.underhill@pc.gc.ca for more information or to register.

reporter@goldstreamgazette.com