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It's raining acorns: Garry oak 'mast year' a boon for city nursery replanting the native species

A team of urban foresters is in the process of regenerating drought-tolerant Garry oaks around the city, where they provide much-needed shade and other cooling effects as temperatures ramp up

Colleen Partlow is used to acorns pounding down on her property in the Summit Park area of Victoria.

But this year, the rain of hard little nuts seems especially prolific.

“It’s like machine guns pelting the roof … pop, pop, pop … it wakes you up,” said Partlow, who has eight mature Garry oaks around the home she’s owned for 37 years.

“Careful of your footing,” Partlow added, noting the river of acorns in the driveway, ricocheting off parked cars and bouncing off Topaz Avenue, where ­passing vehicles have pounded the pooling nuts to dust and shell fragments.

It’s being called a “mast year” for Garry oaks in the region, as the gnarly limbs drop more than their usual amounts of acorns.

Mast years can happen every two to five years — it’s a trigger in a tree’s genetics that ensures the species’ survival. By dropping nearly 20 times the usual amount of acorns in one year, the trees ensure there will be enough to feed the squirrels, birds, deer and others that typically feast on acorns — and for future seedlings, too.

“I would say this is definitely a mast year for Garry oaks,” said Nancy Turner, ethnobotanist and emeritus professor of environmental studies at the University of Victoria, who lives on Protection Island off Nanaimo. “They were falling all night here.”

Retired forest ecologist and author Andy MacKinnon, who called it a mast year similar to the late summer of 2021, said it’s either a very productive year for acorns and cones, or trees could be in distress from prolonged drought.

“A lot of trees, if they are suffering, will produce a distress crop of fruits,” he said. “There is also the interpretation that [the oaks] may be concerned about their longevity and that they had better get their offspring out in the world on the off-chance they pack it in.”

In a mast year, when there are more acorns that any predator can consume, at least some will fall into a crevice or sprout from a bird’s forgotten stash to grow to seedlings and future oaks, says MacKinnon.

Ryan Senechal, president of the Garry Oak Preservation Society, said there is debate among experts as to whether this year is a typical crop of acorns or an exceptional one. He believes it’s a typical crop, from the many trees he’s observed in the past month.

He said 2021 was an exceptional crop, but last year saw an “acorn crop failure” across the Vancouver Island and Gulf Island Garry oak populations, said Senechal. “A low yield is much more common than no yield.”

Experts say high-seed production seasons are typically followed by a season with hardly any acorns, leaving the oaks to focus on making new leaves and wood on their trunks and limbs.

James Miskelly, who runs Satinflower Nurseries with Kristin Miskelly in Saanich and Metchosin and specializes in Garry oak and native plant restorations, said the acorns are highly reproductive, if the conditions are right.

They are packed with starch and sugar and quick to germinate after a little rain. By spring, the acorn’s roots can start producing leaves and its root can be up to 40 centimetres long, he said.

Garry oaks ecosystems are among the most endangered in Canada, with only 3% remaining in a natural state. In Canada, they are only found in British Columbia, on the southeastern tip of Vancouver Island, some of the Gulf Islands and a few spots on the mainland.

They are drought-tolerant trees because they are slow-growing and have deep root systems, and their waxy leaves prevent excessive water loss in dry seasons.

But they’ve suffered over the years due to increasing development pressures, habitat fragmentation and invasive species.

Most of the mature Garry oaks in Greater Victoria are 300 to 400 years old and live in long-established neighbourhoods and parks.

While Miskelly said younger seedlings are often pulled up by homeowners or browsed repeatedly by deer, they are very resilient to the wet-dry cycles of the south Island.

They grow large with majestic canopies in richer soils, but also survive in rocky places, said Miskelly, noting even the scrub-like and stunted Garry oaks that live on Mount Tolmie — though very small in comparison — have rings that show hundreds of years.

Steller's jays are one of the main dispersers of acorns, while squirrels work overtime chewing off nut clusters on oak branches. The acorns also attract deer, rats and mice, which in turn bring out owls and red-tailed hawks to feed on the rodents.

Ken Wong, who has lived on Topaz Avenue since 1996, has let his yard grow as a natural Garry oak meadow. His backyard is on the edge of Summit Park and has a range of oaks from seedlings and saplings to trees over the two-metre mark.

A mature oak that fell in a storm is now pushing up new trees around the stump, and a fallen limb in his front yard is growing edible mushrooms, oak seedlings and native plants like Oregon grape. A friend has even ground the acorns to flour and served Garry oak pancakes, “which weren’t bad,” said Wong.

He also points to two arbutus trees on the edge of his property, which grew from berries he picked at the University of Victoria and planted there 25 years ago. They now are several metres in height.

“I like to keep it all natural because the Garry oak ecosystem is becoming rare,” said Wong.

Ensuring genetic diversity

Mast years are a boon for the City of Victoria’s plant nursery in Beacon Hill Park, where parks supervisor Mike Creighton and a team of urban foresters are in the process of regenerating Garry oaks and dozens of native plants for parks and restoration areas around the city.

During mast years, crews are sent out to collect thousands of acorns from different areas that will eventually become seedlings.

The acorns are sorted. Green and cracked ones and those with weevil and insect holes are composted, and the large brown mature acorns are float-tested in tubs of water. The floaters are discarded, but the large heavy ones that sink are kept, since they are the most likely to germinate.

Acorns from different areas are mixed to ensure genetic diversity, said Creighton. Thousands of years ago, those Garry oak ecosystems were connected, but now roads, development and other barriers have fragmented them.

Mixing the acorns and seedlings helps ensure their vitality, said Creighton.

“Our goal is to have a robust inventory to repair and restore suitable sites where reforestation can be completed. ”

Several areas have already been designated for planting, including Cecelia Ravine and Stadacona Park, as well as seven areas within Beacon Hill Park.

There will be other plantings in other places to “get canopy cover in disjointed areas,” he said.

But oaks take time — about eight to 12 years — before they are ready to survive on their own in parks, boulevards and other areas of the city, said Creighton.

Younger seedlings have to be protected from browsing deer and voles that can feed on their bark, as well as people who go off trails and trample them.

MacKinnon said municipalities, speciality nurseries and resident groups are taking the lead in the Garry oak’s regeneration efforts. “And that a great thing,” he said, “because we have a lot of old trees, but almost no younger ones, and that’s a real demographic problem for a species.”

The nursery is also producing several species of plants and flowers that were once common in Garry oak meadows, said Creighton, including yellow montain violets, species of lilies and camas.

Garry oak ecosystems also contain shrubs like snowberry, oceanspray, Nootka and baldhip rose, and wildflowers like camas, shooting star, chocolate and white fawn lilies, nodding onion, western buttercup, red columbine and sea blush.

First Nations have many traditions and cultural connections with Garry oaks and camas. The Lekwungen-speaking First Nations of the area regularly cultivated and burned the meadows, to prevent shrubs and conifers from spreading into them.

Camas was harvested in late summer for its bulb, which was cooked or dried and ground into flour.

A new beginning in Nanaimo

On a small plot on the Vancouver Island University campus in south Nanaimo, biology professor and botanist Caroline Josefsson, students, staff and community volunteers are building a Garry oak meadow in a 500-square-metre area once overrun with invasive species.

It’s taken the group two years to remove the Himalayan blackberries, Scotch broom, weeds and non-native grasses, and now Garry oak seedlings and other native plants are taking root.

Josefsson said it isn’t known whether Garry oaks were present on the Nanaimo campus in the past, but it is likely, since it’s near Harewood Plains, a remnant of the Garry oak ecosystem in the city and at its northernmost range, which extends to Courtenay.

The tree is also found in Washington and Oregon and as far south as the San Joaquin Valley in California.

Josefsson said Garry oak ecosystems are home to several species at risk in British Columbia, many of which aren’t found anywhere else in Canada. The most bio-diverse of all ecosystems in the country, they’re home to about 100 rare species of plants and animals, she said.

“Any one of these species is important in its own right, as it represents millions of years of co-evolution with all the other members of the ecological community in which it resides,” she said, adding preserving intact ecosystems is the best way to protect individual rare and threatened species.

With 33 hectares of meadow, forest and wetlands, the Nature Conservancy of Canada’s Garry oak preserve in Maple Bay, northeast of Duncan, is considered one of the best remaining examples of the ecosystem left in the world.

The land was acquired by the Nature Conservancy in 1999, when it was being considered for subdivision and development. A neighbouring parcel was purchased in 2001, according to the group.

When the conservancy acquired the land, it says, the meadows were largely choked with Scotch broom and other invasive species. For the last several years, it’s been restoring the meadows so native vegetation can re-establish, with the help of volunteers and a native plant nursery.

Josefsson, in Nanaimo, said building a Garry oak meadow is a passion project for many of the VIU students and volunteers, as everyone grapples with the effects of climate change.

“There are a few things we could do as individuals, but most people can’t afford to buy an electric vehicle or have solar panels on their house, so it can feel hopeless,” said Josefsson.

“By planting native plants in our community, which is affordable and within reach, you see from one day to another that you are making a difference in reversing the biodiversity crisis we’re in. It’s good for the soul.”

Appreciation for a robust species

Senechal, president of Garry Oak Meadow Preservation Society and a sessional lecturer and program co-ordinator at the University of British Columbia’s faculty of forestry, said we should be thankful for the Garry oaks that remain in our midst.

He said the slow-growing and long-lived trees support the life cycles of more than 1,000 species of plants, trees, insects, birds, mammals and lizards and snakes, some of which are at risk.

They are highly adaptable to a range of growing conditions, including some of the harshest locations on elevated rocky outcrops and along exposed sections of coastline.

They have another benefit, too, especially as temperatures rise due to climate change.

“It may be cooling off now in the Victoria region, but in the heat waves recently behind us, it is important to remember that Garry oaks are big contributors to mitigating the urban heat-island effect in areas largely characterized by pavement and concrete,” said Senechal. “That is especially the case where large oak trees currently exist and air conditioners in residences do not.”

The heat-island effect occurs when densely packed buildings and paved surfaces in urban areas trap heat, raising the temperature higher than in the surrounding non-urban area, particularly at night.

Garry oaks can mitigate the effect with large crowns and abundant leaf area, Senechal said, and because of their “incredible ability” to endure harsh urban conditions in times of drought and high temperatures.

Besides shading heat-absorbing surfaces like pavement, oaks provide cooling through “transpiration” — the release of water by evaporation through the leaves.

Senechal said acorns and leaf litter are “trade-offs” for a tree species that provides many benefits to the community and at a relatively low cost compared to engineered trees.

He said local tree-care professionals can make life easier through a few calculated interventions — for example, reducing branches overhanging homes, which can eliminate the noise of falling acorns and cut down on gutter clutter.

The society recommends a certified arborist familiar with best management practices for the care of oaks.

Get involved

The Garry Oak Preservation Society will have representatives at the District of Central Saanich Tree Appreciation Day, Sept. 24, 11 a.m., Adam Kerr Park

The society, operating since 2017, collects acorns and plants seedlings for distribution to groups, municipalities and individuals.

The society said people can collect acorns and drop them off at specified locations to be used for plantings. For more information, go to:

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