It was first detected near Detroit, Michigan, and Windsor, Ontario, in 2002. Its pathway is thought to have been facilitated accidentally through transported goods in infested wood packaging materials from Asia.
These introduced species have flourished in urban and forested areas, killing hundreds of millions of Ash trees. A combination of difficult circumstances has allowed their populations to thrive: the lack of notable natural enemies, difficulty in detection, and an ample supply of Ash tree species with low genetic resistance. Compounding these challenges has been the ease through which it has moved between municipalities; transported firewood. Since its detection, EAB has spread into 36 states and all Canadian provinces except Alberta and Saskatchewan. The Emerald Ash Borer is designated as an Alien Invasive Specie by Canada’s Invasive Species Center (ISC)
As an example, in 2011, the City of Montreal had approximately 30,000 ash trees in its urban and forested areas. As a result of the infestations, 90% of this inventory was lost, leaving most forested areas entirely devastated. The municipality spent more than $18 million dollars on immediate control and management efforts. It is important to note those monies do not reflect the regular and ongoing costs associated for the maintenance of remaining urban forest needs.
Implications for the City of Edmonton
In Edmonton, there are more than 100,000 public Ash trees. This number is estimated to be the same for private Ash trees. When walking, biking, and driving along our boulevards and green spaces, they make up 60% of the species planted. They represent 20% of our entire city tree canopy. As municipal assets, these Ash trees represent several hundreds of thousands of dollars in value. Boulevard trees grow in difficult areas: small planting spaces inhibit root growth and limit access to moisture, surrounding asphalt and/or concrete create intense heat islands, and road traffic sustains poor air and soil quality. Stressed trees are at greater risk.
In the absence of these assets, our urban communities are likely to experience challenges related to stormwater management, soil moisture and erosion, climate regulation and air quality, disruptions to ecosystem habitats and food sources, and further impacts related to wellbeing, recreation, and tourism.
The City of Edmonton has been monitoring for signs of the Emerald Ash Borer and remains alert for symptoms of Ash tree decline. Although there are treatments available after EAB detection, identifying the pest early is vital for implementing effective control and management strategies.