Members of the Metchosin Invasive Species Cooperative – Brenda West, left, Bonnie Farris, Neil West and Mark Atherton – hunt down English holly in Matheson Lake Provincial Park. (Kevin Laird – Sooke News Mirror)

Invasive English holly poses threat to Island’s eco-system

Not so jolly holly, say conservationists, as invasive species attacks indigenous plants

Neil West bends down and buries his fingers into the forest floor and picks up a handful of English Holly. He can’t resist the opportunity to kill it.

English Holly is a non-native plant, and leaving it to propagate will only lead to more problems for indigenous species.

On this rainy day in mid-December, English holly foliage with red berries flanks a trail at Matheson Lake Regional Park in Metchosin. To a passerby, the sylvan landscape may appear verdant and healthy. Not so to West and partner Mark Atherton.

Together, they work at destroying the holly, often one shoot at a time, but always with the plan to rid the forest of the green menace.

ALSO READ: Spread of invasive species in Canada costs billions, changes environment

Atherton, chairman of the Metchosin parks and trails advisory committee and a retired forester, admitted he has nothing against English holly just a great desire to control it.

“The holly is controllable,” he said. “It’s better to deal with it now versus 30 years down the road.”

The two men met two years ago when West brought scientific studies and anecdotal evidence of the proliferation of the holly.

West told the story of hiking in the park 10 years ago and coming up to a thicket of English holly, and the only way to transverse it was through a tunnel of prickly holly leaves.

At first Atherton was not convinced there was a holly problem, but once he took a walk through the woods with West, he also saw the problem of the plant’s spread.

English holly (Ilex aquifolium) is grown for its bright red berries and spiny, dark green evergreen foliage. A large shrub or small tree, English holly has become a serious invasive because of its adaptability to grow in shade or sun, and the ease with which its seeds are spread by birds.

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Seedlings are commonly found in mixed deciduous and coniferous forests on the Island, along the edges of wetlands and especially near residential areas.

English holly grows rapidly seven to 10 metres tall, casting deep shade that deprives native plants of light. Its roots effectively out-compete many native species for nutrients and water; it is a notorious water hog, preventing native plants from obtaining sufficient water. It can grow from seed (in berries) and vegetatively.

Don Hare, executive director of the Coastal Invasive Species Committee, believes English holly has the potential to begin rapidly spreading on Vancouver Island, with conditions almost identical to the Pacific Northwest forest region of the U.S.

There are an estimated 400 English holly sites on Vancouver Island covering an area of more than 300 hectares. Coastal Invasive Species Committee this year has concentrated on destroying large groves of English Holly on Newcastle Island near Nanaimo and in the Comox Valley

The English holly tree is dioecious, with only the females producing berries. Birds and small animals eat the berries and disperse the seeds throughout the range.

The life expectancy of trees are approximately 250 years.

“It doesn’t look like anything eats this or attempts to scavenge it, and that is very worrisome when you don’t have any natural controls on it,” Hare said.

For West, the most troubling aspect of the holly is its ability to double its biomass every six years.

“The six years we’ve been doing this it has gotten way ahead us,” West said. “Last year alone, we noticed hundreds and hundreds of shoots at Matheson Lake.”

Fighting the battle are volunteers like West and Atherton and the Metchosin Invasive Species Cooperative.

They take on the removal of English holly regularly combining elbow grease and physics, and their tools include saws, loppers, pruners, shears and tree pullers. In the three Metchosin parks the volunteers have worked on, the group has come close to eradicating it in two and is well on its way in a third.

The tallest holly tree they’ve brought down stood more than 40 feet, but trees start producing berries when they’re about a three feet tall.

If Metchosin and East Sooke are the target of the Metchosin Invasive Species Cooperative, then the Sooke Hills might be ground zero.

While pretty much every municipal and regional park in the Capital Regional District are dealing with some sort of invasive infestation, from Scotch broom to Himalayan blackberry, many ignore English holly. Case in point: in the Sooke Hills the holly is taking hold in places like the Sooke Potholes and Mount Wells Regional Park. Sooke, Highlands and the CRD are slow in protecting many of those areas from the invasive holly, West said.

“If significant action isn’t taken to control the spread of holly, I think it has the potential to become a significantly larger problem than Scottish broom,” West said.



editor@sookenewsmirror.com

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SIDEBAR

Want to help rid Vancouver Island forests of English holly?

The Metchosin Invasive Species Cooperative is always looking for volunteers, or hikers who have come across large thickets of holly in the Sooke Region.

You can contact the cooperative by email at metchosininvasives@gmail.com.

The cooperative is also sending out a special thank you to Habitat Conservation Trust Foundation, which provided a $1,000 grant to buy several Pullerbear tools for use in the battle against invasive plants.

The Pullerbears are available to borrow free of charge to any volunteer group or private property owners if they wish to use them to remove invasives.

– Kevin Laird

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Neil West stands next to an English holly tree. The spread of the plant has conservationists worried. (Brenda West photo)

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