Page 16 - 07_Sept-2025

City
Opinion
What Grows Next?
Rethinking Edmonton's canopy before it falls
by Dustin Bajer
Dutch elm disease arrived in North
America nearly a century ago. We knew
what it could do. We watched it dismantle
the great canopies of Montreal, Toronto
and Winnipeg. And still, we planted our
streets and parks with a monoculture of
more than 91,000 American Elm. Toler-
ant of pollution, salt and clay, we found
the species too perfect, too well-suited
and too beautiful not to plant — believ-
ing, perhaps, that distance or vigilance
might spare us. They cannot. And now,
with confirmed cases of Dutch elm dis-
ease inside city limits, we're confronting
a long-deferred truth: what takes decades
to grow can be undone in seasons.
Dutch elm disease is a fungus. Spread
through beetles, contaminated tools, and
intertwined roots, the fungus blocks
water flow, killing leaves, then branches,
then limbs, and finally the base, potentially
wiping out trees as old as the city itself
in just two years. Imagine neighbourhoods
like Strathcona, Wîhkwêntôwin, West-
mount and Highlands without their
elm-lined boulevards. That’s why, in
August 2024, when Dutch elm disease
was discovered in Killarney and along the
Yellowhead Corridor, Edmontonians were
understandably alarmed.
But even as we respond to Dutch elm
disease, an arguably more severe threat,
the emerald ash borer — an invasive and
destructive beetle — continues to advance,
threatening just as many ash trees, but
at a much faster rate. The former is get-
ting more attention because of its threat
to civic symbolism, but the latter could
completely overwhelm our budget,
resources and capacity to replant.
Combined, the two diseases could wipe
out close to 40 per cent of the City of
Edmonton’s public tree inventory, in
addition to countless trees growing on
private property.
Edmonton’s urban forest is vulnerable
by design. That vulnerability has a shape:
broad boulevards lined with genetically
identical trees, canopies that feel quint-
essentially Edmontonian. So, it's under-
standable why the instinct is to fight
these diseases — and we are. However,
even if we’re successful in stopping our
most recent outbreaks, we’re still left
with a vulnerable urban forest. Mono-
cultures, even beautiful ones, are fragile,
offering little buffer against time.
Trees are living infrastructure, storing
carbon in their trunks and roots, moder-
ating temperatures, slowing stormwater.
The list goes on. As the climate becomes
more volatile, more extreme, we risk
losing mature trees just when they’re
most needed — and hardest to replace. In
other words, if we focus on maintaining
a monoculture, we risk overlooking the
deeper imperative: to cultivate a resilient
urban forest. That means encouraging
tree diversity — not single-species rows
planted all at once, but a polyculture of
trees planted over decades. It means a
shared responsibility for citizens and
the municipality to preserve trees while
growing denser, more climate-adaptive
communities. And it means recognizing
that this won’t be the last crisis.
But this isn't just about what we might
lose. It's about what we still have time
to grow: an urban forest for the next 100
years — messier, more complex, more
alive and more valuable to future
generations. The monoculture will fail;
that much is certain. The questions we
need to ask ourselves are: how quickly, and
what will replace it? Do we have the
dedication, resources and budget to
transform the makeup of our urban forest
for the next century? Or will we trap
ourselves in the perpetual maintenance
of monoculture? ED.
Dustin Bajer is an educator, master gardener
and nature-inspired designer.
16 EDify. SEPTEMBER.25
illlustration MATT FONTAINE