Intent is to remove loose, rolling logs that can smother the foreshore to allow the tidal marsh's natural vegetation to flourish as a buffer to waves and rising tides.
King tides and rising sea levels have helped wash logs ashore in sensitive salt marshes in the shadow of the Boundary Bay Airport. There, the loose logs can crush vegetation “like rolling pins” to smother the delicate foreshore.
Starting this week, Ducks Unlimited is hauling them out along the dike in Delta to help restore a larger area of salt marsh.
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“We’re kind of forcing the (Fraser River) delta into a certain state” with development, said Erc Balke, a Ducks Unlimited’s senior restoration biologist. “So you can imagine that, given how extensively we’ve modified the system, the ecosystems themselves may need some maintenance.”
Work on the project began this week, with excavators contracted to conduct the removal over the next several weeks.
Boundary Bay is internationally significant as Canada’s largest habitat for overwintering waterfowl and birds on the Pacific flyway, but is increasingly important for its “ecosystem services” to humans, Balke said.
Climate change is expected to raise sea levels around Metro Vancouver up to one metre by 2100, according to the regional district’s recent Climate 2050 Strategic Framework report, requiring adaptations such as the raising of dikes and expensive upgrades to sewers and storm drainage systems under threat of inundation.
Tidal marshes, however, help protect dikes from flooding and coastal erosion because their dense vegetation helps reduce the height and speed of waves being driven on king tides and build up sediments that add to coastal flood defence, Balke said.
“At the location we are removing logs, the tidal marsh is anywhere from 220 metres wide to 315 metres wide,” Balke said. “So you can imagine, if you didn’t have that tidal marsh in front of the dike, it would make our communities all that much more vulnerable.”
On top of that, Balke said tidal marshes have been shown to be “the most effective ecosystems on the planet at sequestering carbon,” with rich plant life trapping carbon dioxide from the atmosphere to hold in the sediment and substrates beneath their roots.
The carbon-sequestration aspect is helping pay for the project, with the majority of funding coming from the federal government’s Smart Climate Solutions Fund, with additional support from the U.S. North American Wetlands Conservation Act.
Some conservation groups, however, remain wary of wholesale log removal as restoration on Boundary Bay because previous projects have hurt habitat, according to Susan Jones, an advocate for the Boundary Bay Conservation Committee.
Log removal in wetlands at the end of 64th Street resulted in the removal of perches that migrating snowy owls used, Jones said, so “I would raise some question marks about this.”
The committee’s biggest concerns centre around the potential impacts of the Port of Vancouver’s Roberts Bank Terminal 2 project, but Jones said its members also want to see the province put a wildlife management plan for the entire bay in place to guide such projects.
“The Boundary Bay Conservation Committee is usually on record as saying don’t disturb it unless there’s real scientific evidence that that’s needed,” Jones said.
However, Balke said this project won’t involve wholesale removal of logs. Any naturally occurring logs, those with roots attached, deposited into waterways from windfall and erosion, will be left in place.
The root systems of those trees provide tidal habitat for aquatic species, including the fry of migrating salmon, and natural perches for raptors and other birds.
Logs that have become embedded in sediment will also be left in place over fears that “removing those will cause more damage than it is worth,” Balke said.
It is only one of several projects that Ducks Unlimited is working on. Balke said the conservation group is about to launch a sediment enhancement effort at Sturgeon Bank in Richmond.
“This is really just one drop in the bucket of addressing this much broader challenge in the estuary,” Balke said.
depenner@postmedia.com
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