An Inconvenient Tree

(Source: Unsplash/Jonathan J. Castellon.)

The heat of summer is firmly here in my little corner of the world. We’ve already had several days with heat warnings, and I’ve been reflecting on how much of a difference trees make for people in cities (this thought is especially top of mind as I wait at a bus stop in full sun with virtually nothing but concrete and asphalt nearby).

Trees are arguably the hardest working and highest returning municipal infrastructure there is. We all know that trees look beautiful and are good for the environment, but there is so much more that they contribute to a city’s bottom line. They significantly reduce stormwater runoff and reduce the burden on sewer systems, they prolong the life of asphalt by keeping it cooler, and they increase property values and therefore the tax base.

For residents, the presence of trees nearby has a major impact on home heating and cooling costs, it improves air quality, and calms traffic. There’s even research showing that neighborhoods with more street trees experience less crime! 

Given all that trees do, right up to and including making money, cities should be enthusiastically planting tons of them, everywhere they possibly can. 

And yet, most places aren’t. What gives? 

Of course, planting trees isn’t as simple as digging a hole, popping a seedling in, and filling it up with dirt. Care must be taken to put the right tree in the right place, and a tree without a plan to maintain it is a recipe for failure. 

In my years advocating for public trees, I’ve learned that there’s a lot stacked against trees in an urban environment. Soil conditions have greatly degraded in the decades since my neighborhood’s original trees were planted. In a cold climate, you’ve got harsh de-icing salt. Extremes in precipitation and heat are stressful for trees. And, of course, there’s also the vulnerability of monocultures to pests and diseases. 

When a city has limited resources for urban forestry, it’s understandable that they would not want to invest time and energy into planting trees that will never thrive. But I think there’s something a little more systemic going on here. We like planting trees where it’s easy and logical, and in my estimation those are basically in two types of places: spots where there have recently been trees, and blank slates like new developments and greenspace. 

When we’re trying to beef up canopy cover, often the space that remains has challenging planting conditions, but it’s the space that needs trees the most: for tree equity, for traffic calming, and pollution removal. 

Places where trees would have the biggest impact are often the places we systemically avoid planting in because of outdated rules or auto-oriented priorities. Here are some of the practices that hold back our potential to have ample and thriving urban canopies. 

Defaulting to Rules That Don’t Make Sense

I encountered this firsthand when the tree committee I’m part of was identifying re-planting sites for the many mature boulevard elms we’d lost to Dutch Elm Disease. We had to compare each planting site we were proposing to a list of the public works department’s site criteria.

Some of the parameters made sense, like not planting too close to fire hydrants or catch basins. 

Others were sort of debatable, like avoiding planting under overhead utility lines. If we say we’re not going to plant new trees anywhere there’s an overhead line, that restricts a heck of a lot of public space. In this situation, we successfully argued that we be allowed to plant smaller trees in these spaces. These more compact trees might not offer all the benefits of big shade trees, but they’re still an asset. 

Then there was the “no planting trees at intersections” rule. To be precise, no planting within 6 meters (almost 20 feet) of intersections. The rationale was that trees can impede sightlines for stop signs and other important signage. On its surface, this makes sense, but when we really thought about it, this seemed like overkill and even a little counterproductive. 

Refusing to plant trees at intersections creates large breaks in the canopy, which has a big negative impact on the pedestrian experience. But trees near intersections also play an important role in slowing traffic through the “edge effect.”

One resident, who lived at one corner of a four-way stop half a block away from an elementary school, shared her observations with us. She said since three of the four giant American elms on that corner had been cut down, drivers were regularly blowing the stop signs. There was much less visual clutter around the intersection, hence less need to slow down.

Before the loss of big intersection elms:

And after:

From another angle, before the loss of big intersection elms:

And after:

Which conditions do you think would make you drive a little more slowly?

I will concede that when planting trees close to important traffic signage, things can get complicated if there isn’t a commitment to regular pruning. Best practice for pruning is every 7–8 years, but in my city, public trees are only being pruned every 26 years. This is problematic for many reasons, beyond just keeping sightlines clear! Knowing this, I can appreciate public works’ lack of confidence that trees near stop signs will be adequately monitored and trimmed to ensure their branches don’t hide the signage.

But the practice of not planting in intersections is widespread and not limited to places with poor pruning standards. And it’s time to push back on it. In fact, research has shown that large parked vehicles pose a greater impediment to drivers’ ability to see approaching vehicles than trees do. 

Pitting Trees Against Other Desirable Infrastructure

Trees also become victims in a tug-of-war over public space. Let me give you an example. In my city, there’s a major street called Provencher Boulevard, in a neighborhood that’s immediately adjacent to downtown. In typical stroad fashion, Provencher teeters on the edge of trying to be at once a place with lots of great shops, restaurants, and cultural amenities AND a major thoroughfare route to move vehicles in and out of downtown and out to surrounding neighborhoods. This route has a relatively wide center median that includes trees, public art, flower planters, etc.  

For nearly the past decade, there’s been a grassroots call to install a protected bike lane on Provencher. The naysaying refrain goes something like this: “We can’t install a bike lane, because there isn’t enough space on the road. We can’t take away parking, so the only place it could possibly go is where the median is. And we can’t possibly change the median because that would mean removing the trees.”

This sort of false binary (we can have trees or bike lanes but not both) crops up all the time. When really, the treed median is the last thing you’d want to start chipping away at. It’s providing immense value in every regard. The lowest value part of all the available space is the space dedicated only to private motor vehicle traffic. That’s what should be reconfigured to allow for adding the bike lane, which can move a much greater number of people in much less space. 

Not Incorporating Trees as a Matter of Course

I recently worked on a community tree planting grant application for a part of town that has, by the city’s own measure, both below-average canopy cover and income levels. You’d be hard-pressed to find a better place to focus tree resources! 

But my enthusiasm was dampened in realizing that most streets in this area had no public right-of-way past the sidewalk, or else a very thin strip of boulevard that didn’t meet the city’s minimum width standards for tree planting. There was nothing that could really be done about the lack of public street trees under the current street configuration. It was so discouraging. This is a common situation where streets originally had trees, but lost them when the street was widened.

My thoughts have turned to starting a campaign to encourage residents to plant shade trees on their own property, but I think it’s also worth advocating for better city policies. Every time a street or road comes up for renewal, it should be standard procedure to plan to incorporate trees, especially in places that don’t currently have them.

We need to put the trees where they’re going to make the biggest impact: right along the street. Here, they provide traffic calming, absorb more pollution by being closer to the source, create shade and windbreak for homes and folks walking and biking, and help road material investments last longer.

Yes, it costs money to create spaces for street trees in new bumpouts or soil cells, but remember: investments in trees pay for themselves many times over. In the new edition of Walkable City, Jeff Speck suggests that “it could be considered financially irresponsible for a community to not invest heavily in trees.”

A Task Worth Working At

I’m not an arborist or urban planner, I’m just a tree aficionado, out there in my neighbourhood with a clipboard taking notes and talking to others about what’s happening in their own places. I know my understanding of the challenges of filling cities with trees is pretty rudimentary. But after spending a lot of time humbly observing what’s happening with our city’s trees and pushing for investment in them, I keep coming back to the same conclusion. 

It’s easy to put trees where it’s convenient. It’s easy to require new developments to install trees and to mandate their inclusion in parking lots and park spaces. It’s harder to incorporate plans for trees into a complex, existing urban environment, but that doesn’t mean we shouldn’t try. When we choose to remain beholden to existing street configurations and counterproductive planting policies, we deprive ourselves of putting trees where they could do some of the greatest good. 

Planting and caring for an urban forest isn’t a simple or straightforward task, but it is eminently worthwhile to keep it growing. And frankly, we’d be foolish not to.

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