A walk down any quiet residential street in central Winnipeg in summer would traditionally be shaded by a sprawling expanse of branches over the road, with a leafy canopy providing relief from the city’s famously muggy summers.
However, unless the pace of destruction of their tree canopy can be reversed, such shade-dappled walks may soon be a thing of the past.
Over the past few decades, Winnipeg’s urban canopy has been under attack from all sides.
Dutch elm disease was first identified in 1975, when the city had over a quarter million elm trees, many of which would qualify as monument trees. Since then, the disease, aptly acyonymed DED, has wiped out over 33,000 trees, as it spread progressively faster through the urban canopy.
Elms have long been a vital part of Winnipeg’s urban forest. Home to the largest elm urban forest in Canada, the city’s elm population delivers an estimated $594 million a year in environmental services to the city, not including the boost to the property value of home with a large shade tree.
Winnipeg’s urban canopy, like many cities of any size, is mostly a monoculture, with elm and ash trees dominating. In fact those two trees together make up more than half of all trees in the city.
This wouldn’t be so bad if ash trees were not also under threat.
The emerald ash borer arrived in Manitoba in 2017 and is has been wreaking havoc on the urban forest. Hopes that a cold winter, even by Manitoba standards, would kill off enough of the beetles to slow their advance were dashed recently by a study that showed the invasive pest can survive temperatures as low as -50C, and are highly adaptive to environments that would kill most other pests.
To make matters worse, the cottony ash aphid, another invasive pest that preys on Ash trees, and is now killing 1000 ash trees a year – more than the emerald ash borer.
Cities across Canada continue to wrestle with the devastation caused by invasive species. In Hamilton, the local conservation authority recently moved to stop spraying for LDD moths, admitting that the invasive caterpillar’s previous 10-12 year cycle of appearing and devastating local tree canopies was now an annual event. The voracious consumers of healthy tree leaves would have to be controlled using much more labour intensive means such as egg mass removal and tree banding.
Cities like Winnipeg and Hamilton are responding to these attacks with Urban Forestry strategies to attempt to solve the problems of urban forests that are both insufficient and shrinking.
In Hamilton, which is still working towards approval of its strategy, the canopy – defined as the percent of the surface area of the city that is covered by leaves in the summer – is just over 21%, well shy of its own target of 30%.
While this number is considered low by Ontario standards – the only nearby municipality worse is Mississauga at 19%, the story on the prairies in Winnipeg is quite different.
According to Winnipeg’s strategy, their canopy sat at 17% in 2018, down from 18% in 2005 – but still dramatically higher than other cities in similar ecosystems like Calgary (8%) and Edmonton (10%). As prairie cities go, Winnipeg’s reputation as a forest city is well earned. However, the onslaught of pests and fungus has been steadily reducing that forest for decades.
As with most problems of this kind, you can’t manage what you can’t measure. Both cities’ urban forestry strategy discussions have begun with gathering important data on the state of their urban forests. Data that will be crucial to the success of any proposed solutions.
This coupled with strategies to not only plant more trees, but – perhaps more importantly – keep existing trees from being removed.
Hamilton and Winnipeg are in fact considering a number of measures to counteract the steady decrease in their canopies. For instance, in both cities, it is perfectly legal to remove a mature tree in the downtown on private property without a permit or any consequence (in Hamilton it is not prohibited anywhere in the city). In Hamilton, Councillors may soon be asked to consider a by-law restricting property owner’s ability to just remove any tree they find inconvenient. Winnipeg is also contemplating a similar move.
Both city’s proposed strategies also point to the importance of public education when it comes to the value of trees and the difficulty in replacing the benefits of mature trees once they are lost. Too often homeowners are quick to remove trees from their properties for things like root incursion into sewer pipes – which can be solved with plastic sewer liners that remove the need to cut down a mature tree that provides considerable other benefits.
Hamilton’s Urban Forest Strategy will be going before Council soon for deliberation, while Winnipeg’s is currently in the public consultation phase. It will be fascinating to watch how each city progresses in the quest to reverse the shrinking of their precious urban forests.
IPCC Report Out with a Glimmer of Good News
Yesterday saw the release of part two of IPCC’s most recent report on the state of the climate. Titled Impacts, Adaptation and Vulnerability, it describes the very difficult situation that humanity has created for our planet.
The good news? It’s not too late to act. The report stated that “Near-term actions that limit global warming to close to 1.5°C would substantially reduce projected losses and damages related to climate change in human systems and ecosystems, compared to higher warming levels, but cannot eliminate them all…”
So while it’s well understood that it’s too late to prevent every impact of climate change, decisive action can prevent the worst of it.
One of the key lessons of the recent war in Ukraine, has been that when presented with an immediate enough crisis, the world can take dramatic, coordinated action to address that crisis. Hopefully this report provides a similar wake up call.
Coyotes are not Trying to Lure your Dog
If you are on social media in a city that has a healthy coyote population nearby, no doubt you have been exposed to the meme that alleges that coyote ‘packs’ will use a female to lure your dog away from you and then attack and kill it. Anyone who knows the first thing about coyote behaviour knows how ridiculous this is, but countering the meme in February and March when coyotes are highly visible and in their mating season, can be like playing science education whack-a-mole
Fortunately the good people at Coyote Watch Canada are here with their fact filled, evidence based rebuttal of the widespread meme.
Simply put, coyotes are not more aggressive this time of year, they are more curious. Especially the young ones who are looking for mates, as this species mates for life. Coyotes will act to protect their mates, lair, food and pups, so if your dog chases a coyote, as some dogs will do, and the chase leads back to the coyote’s den, mate, or food cache, then things will turn ugly for your dog.
Your best defense is to ensure your dog is well trained for recall, and you can recall it quickly and safely under a variety of conditions. If not, for your dog’s safety and the safety of other wildlife, a long (not retractable) leash is for the best.
End Fossil Fuel Subsidies
By now it should be clear that heavily subsidizing fossil fuel extraction is incompatible with the goal of keeping the heating of our planet to 1.5C above pre-industrial levels. And yet in Canada, we subsidize oil companies every year to the tune of billions of dollars. Money that could be applied to things such as investment in green jobs and infrastructure, to say nothing of the needs of public transit for sustainable funding, or the affordable housing crisis.
The David Suzuki foundation is taking action just as the federal government is entering into deliberations for its next budget. You can learn more and sign their petition here.
Jason Allen
The Environmental Urbanist
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