Battling invasive species in Garry oak ecosystems
One of Canada's most rare and most diverse ecosystems is at risk, but with the help of Parks Canada and volunteers, a unique habitat is being restored
A mosaic of woodlands, meadows, grasslands and scattered stands of transitional forests, Garry oak ecosystems are important not only for their great beauty, but also for their biological diversity. Thousands of plant, animal and insect species inhabit these ecosystems, among them the Garry oak, which is the only oak native to British Columbia.
However, Garry oak ecosystems are at risk, along with many plants and animals that depend on this unique habitat. The Garry oak ecosystem is home to over 100 species at risk. Of these species, 23 are threatened or endangered through their global range, and 21 are listed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as being at risk nationally.
In Canada, Garry oak ecosystems are found only on southern Vancouver Island, the nearby Gulf Islands, and in two small stands on the mainland. Within this area, most of the original Garry oak ecosystems have been cleared and converted to agricultural, residential and industrial uses. Over 95% of the original plant cover has already been lost. Encroaching suburbs and invasive species continue to threaten what remains of this diverse habitat. At Fort Rodd Hill National Historic Site of Canada, a 54-hectare site with a significant Garry oak ecosystem, non-native plants once introduced into gardens now comprise more than 40% of the vegetation, presenting a serious challenge to maintaining ecological integrity. Daphne, Scotch broom and other invasive species choke out native plants as they compete for space, light, water and nutrients.
© Parks Canada / M. Fairbarns / 2002
Parks Canada staff and volunteers have worked together to stem this tide. Since 2002, funding from the Agency's Species at Risk Program has supported an invasive species control program at Fort Rodd Hill. Local community members, university students and Scouts worked alongside staff to hack, pull and remove invasive species from the site. Staff and volunteers removed 9.5 tonnes of invasive plants in 2003 alone. In 2004, staff broke through tangled masses of invasive shrubs to reconnect beautiful tracts of Garry oak habitat. A newly cleared, 1.3-hectare site was fenced to protect new seedlings from rabbits and deer. Seeds collected from native plants at Fort Rodd Hill are being grown in greenhouses and will be transplanted to the fenced site to restore native plant cover.
Parks Canada is educating as it restores, raising awareness about these rare ecosystems. In 2004, a large, full-colour interpretive sign providing information about Garry oak ecosystems was erected at Fort Rodd Hill. This was the first time that a sign of this nature had been erected at a site primarily dedicated to military history. However, Garry oak ecosystems need not be relegated to history. With the help of Parks Canada and dedicated volunteers, these ecosystems will remain a part of our present as well as of our past.
© Parks Canada / C. Webb / 2004
- Site staff and Garry Oaks Ecosystem Recovery Team botanists conducted a plant inventory at Fort Rodd Hill in 2002, finding 336 plant species. Seven of these species were rare, two of them at risk nationally.
- Last seen in the 1960s, the rare Deltoid Balsamroot was rediscovered at Fort Rodd Hill in 2002. Seeds have been collected and are being grown in a greenhouse. They will be transplanted later to help this endangered species survive.
- At Fort Rodd Hill, staff and volunteers continue to work to remove invasive species. In 2003, over 80 volunteers contributed 543 hours of labour. By the summer of 2004, about 12.5 tonnes of invasive species had been removed from the site.
- The Gulf Islands National Park Reserve of Canada was established in 2003, further aiding in the protection of Garry oak ecosystems.