The hemlock looper moth infestation in Stanley Park that has resulted in the need to remove 160,000 trees is becoming increasingly costly and Vancouver city council is being asked to approve another $4.9 million to continue work in the park.
A staff report that goes to council Jan. 24 says the money is needed to fund “immediate work required to mitigate immediate safety risk of trees” damaged by the moth, an endemic insect that defoliates trees, particularly Western hemlock and Douglas fir.
“There is no feasible treatment for the insect, and the use of pesticides would impact all other moths, butterflies and other non-target insect species,” said the report in explaining the need to cut down so many trees.
Last year, the park board was able to manage $1.9 million for the initial work from within the department’s budget. The requested $4.9 million would be a one-time temporary addition, while a multi-year funding strategy is developed.
'Significant tree mortality'
The looper moth outbreak started on the North Shore in 2019 and spread to Stanley Park, where the insect was identified in 2020. The moth’s attack on the forest has led to “significant tree mortality,” the report said.
“Residual risks remain throughout the park and time is of the essence as risk will increase as dead trees begin to decay and lose structural integrity,” the report said. “Failing trees pose a public safety risk and will result in increased fuel loads, leading to increased wildfire risk.”
A briefing memo from park board general manager Steve Jackson in July 2023 noted there had been 94 fires in Stanley Park in the first half of the year, with June alone seeing 23 fires.
'Not something we take lightly'
The report said “mitigation and restoration” with extensive tree planting and vegetation management will need to take place from 2024 until 2026 and beyond. Tree removal crews are currently focused on areas around the Stanley Park causeway, Prospect Point, Pipeline Road, Chickadee Trail, the Aquarium and Brockton Point.
Those areas alone total 86 hectares.
When the park board announced the work in November 2023 — and the anticipated traffic delays and road restrictions to allow crews access to the trees — the board’s director of parks said removing trees was “not something we take lightly.”
“But this work is essential to restarting the forest afresh and giving it the strongest chance at withstanding future threats to its health,” said Amit Gandha in a news release at the time.
“With the park being so popular, this work will require time and an extra level of care to minimize impacts, and we thank the public in advance for their cooperation as we work to protect this very beloved space.”
The park board said some dead trees will be left in place as “nurse logs” to support regeneration of the surrounding ecosystem. Impacted areas will be replanted with tens of thousands of native species, including Douglas fir, western red cedar, grand fir, big leaf maple and red alder.
Typically, looper moth outbreaks occur on a 15-year cycle and last for up to two years before collapsing from cold winters and natural predators. The outbreak in Stanley Park is in its fourth year, with a park board document attributing its longevity to warmer winter and spring conditions.
Motorists, cyclists and pedestrians should take note of Jan. 28 as a morning to avoid the Lions Gate Bridge. According to the park board’s work schedule related to the work in the park, there will be a full closure between 8 a.m. and 11 a.m. of the causeway and bridge.