We can all help protect our ash trees

Opinion

Hey there, time traveller!
This article was published 29/12/2017 (2846 days ago), so information in it may no longer be current.

Buy local. Burn local. Don’t move firewood.

Non-native invasive species, including insects, diseases and plants, are one of the greatest threats to Canada’s biodiversity, and the emerald ash borer (EAB) is becoming an epidemic.

The non-native and invasive beetle has destroyed tens of millions of ash trees and continues to spread rapidly, threatening forested areas. It is having a significant ecological, social and economic impact, including considerable tree-removal costs and public safety hazards.

It is devastating news that Winnipeg is at risk of losing 350,000 of its ash trees over the next 10 years due to this invasive beetle, which has been ravaging communities in Eastern Canada. This is not just an urban issue, however. EAB will have an incredible impact on Manitoba’s natural areas and species.

This fall, the International Union for Conservation of Nature (IUCN) updated its “Red List of Threatened Species”. The Red List now includes five of Canada’s ash species as critically endangered because of EAB, including both of Manitoba’s native ash trees: green ash and black ash.

If this beetle continues to spread through our forests, we could be witnessing the functional extinction of ash, as well as the unique webs of life they support. Ash are a major part of several key ecosystems in Manitoba:

● Black ash are a major component of riverside forests and lakeshore swamps in the Whiteshell and Nopiming Parks and in the Whitemouth River Watershed.

● Green ash are common in the forests that line rivers and streams across southern Manitoba, including in the Brandon area.

● Green ash form a large part of the forests along the Manitoba escarpment, including Riding Mountain.

EAB won’t just impact the trees, but also the hundreds of species that live in these ecosystems. Ash-dominated forests along streams, rivers and lakes help filter runoff, capture sediment, slow erosion, provide shade and other benefits. In addition, the rapid loss of ash trees creates open areas in woodlands that can be impacted by the arrival of invasive plants.

Emerald ash borer insects lay eggs in clusters on the bark of ash trees. About 10 days after eggs are laid, larvae emerge and burrow their way beneath the bark, leaving distinctive “S-shaped” tunnels on the surface of the wood. These tunnels are visible when the tree’s bark cracks and splits as the infestation grows worse. Larvae become adult beetles that chew their way through the bark and leave “D-shaped” exit holes. The larvae feed on the inner bark, which interrupts the flow of water and nutrients. As a result, an infected ash tree is lost within one to three years.

Signs and symptoms of infection include general tree decline and loss of green colour in leaves, “D-shaped” exit holes and dieback in the tree crown.

Although woodpeckers, other birds and some insects will feed on EAB, unfortunately, there don’t appear to be enough natural predators or diseases to help keep this invasive species at bay. Researchers in the U.S. have introduced parasitic wasps that feed on EAB larvae. This biological control may not stop the loss of mature trees, but could allow more ash trees from the next generation to survive.

Although the borer does not fly far on its own, it will hide in firewood, logs, branches, nursery stock, chips or other ash wood and can come along for a ride if it’s transported.

To help prevent its movement, please do not transport firewood. While bringing firewood — even if just a short distance from a campground or cottage — may seem harmless, it can spread pests and diseases. EAB can limit your ability to enjoy the environment around you and decrease property values. Early estimates indicate the cost to remove and replace ash trees in Canada could reach $2 billion over 30 years. The broader cost to our forested areas and the species they support may be immeasurable. Trees also clean our air and mitigate the impacts of climate change.

For the past 40 years, the Nature Conservancy of Canada has worked with willing private land owners across Manitoba to protect sensitive areas. This important work is supported by the government of Canada’s Natural Areas Conservation Program. As a charitable land trust, our conservation efforts help ensure that nature’s species survive. Monitoring and maintaining the health of existing ash forests is critical for their recovery, along with preventing the spread of invasive plants and restoring the banks of streams when mature ash die.

If your ash trees look unhealthy or broken, contact your local Canadian Food Inspection Agency office (Winnipeg: 204-259-1400), Manitoba Forestry (204-945-7989 or toll-free 1-800-214-6497), or your local municipality.

Julie Pelc is manager of stewardship programs with the Nature Conservancy of Canada in Manitoba. Cary Hamel is NCC’s conservation science manager.