The Multitasking Marvel: How Street Trees Can Solve Many Municipal Problems
It’s no secret that street trees are a favorite topic at Strong Towns, and over the last few years, I’ve been involved in plenty of projects and advocacy work in my city with the goal of getting more of them planted and better cared for. When I first started getting involved in this type of grassroots work, I did tons of research about street trees so I could write persuasive grant applications.
There was a lot to learn, and I took from it a tendency to see almost any urban challenge as something that could be helped by the presence of street trees. Too hot? Plant some trees. Too noisy? Plant some trees. Folks driving too fast? Plant some trees. You get the idea! I feel quite strongly that, whatever the problem, chances are good that trees are a key “next smallest step” to improving places.
While trees aren’t a panacea, they are different from other types of infrastructure because they can do so many helpful things at once. One of the coolest tree tidbits I’ve come across is that, unlike grey infrastructure (pipes, roads, bridges, buildings, etc.) that will never be worth more than it was on the day it was installed, trees actually increase in value and capacity over time. Urban trees have been dubbed “the miracle municipal asset.”
They can be a miracle individual asset too; plenty of research has shown that the presence of trees (particularly street trees) has a significant positive effect on property values. According to the Arbor Day Foundation, “yard trees in good condition may add 10% to 20% to the resale value of your home. In Portland, Oregon, street trees in front of or near a home added an average of $8,870 to sale prices –– and reduced time on the market.”
Money talks. While the critical environmental benefits that trees provide (like capturing carbon, cleaning the air and supporting biodiversity) have tremendous and calculable value, advocating for trees on an environmental basis isn’t always effective. These semi-invisible benefits can be difficult to assign value to when people can’t see them with their own eyes. So here are a few examples of easy-to-grasp, tangible tree benefits that, in my experience, are more persuasive:
Longer Lasting Roads
One of my favorite street tree facts — one that's hard to argue with because it's purely economic and practical — is that street trees prolong the life of road surfaces by keeping them cooler and reducing temperature fluctuations.
I took this photo in my neighborhood in June 2021, during a heat dome event that gripped North America.
The day before, dozens of regional heat records had been broken; here in Winnipeg, temps had reached 35 degrees Celsius (95 degrees Fahrenheit). This street has little shade and is in full sun most of the day, so it was no surprise when I came across this dangerous collapse. This year is shaping up to have similar challenges: There have already been numerous reports of roads buckling and heaving with the heat.
Winnipeg architect Brent Bellamy is a huge proponent of street trees. In taking temperature measurements of road surface on two adjacent blocks of the same street — one shaded by a tree canopy and the other whose trees had been removed in the 1960s as part of a road widening project — he found a staggering difference of 15 degrees Celsius (27 degrees Fahrenheit) between the two.
The Center for Urban Forest Research has a fantastic document that explains exactly how shade helps protect road material investments, noting that “more shade means more time between repaving. 20% shade on a street improves pavement condition by 11%, which is a 60% savings for resurfacing over 30 years.” This translates directly into money saved on road maintenance. See "Why Shade Streets? The Unexpected Benefits" for more info.
Fewer Flooded Basements (and Raw Sewage Events)
If you’ve ever walked down a lush, tree-lined street in the rain and barely felt a drop, then you know where I’m going with this.
A mature tree can intercept 30%-40% of rainfall before it even hits the ground.
Why is this important? In the face of growing numbers of extreme weather events, any precipitation that can be prevented from becoming runoff and making its way into the stormwater system is a good thing. There are costly consequences to too much runoff: sewer backups, water in basements and untreated sewage outflows.
Precipitation that goes into the stormwater sewer system — as well as precipitation that doesn’t go through any sewer system at all — isn’t usually treated before it goes back into nature. And as it runs through paved surfaces within a town or city, it’s picking up all manner of toxic pollutants that wind up back in our water systems, where they cause serious harm to wildlife.
Regardless of whether your town or city has separated or combined sewers, every place can benefit from more trees to capture rain before it hits impervious surfaces, thereby reducing the burden on sewer systems.
In Winnipeg, the urban canopy prevents an estimated 1 million cubic meters of water from winding up in the stormwater system every year. That’s the equivalent of 488 Olympic swimming pools!
Cooler Commutes and Lower Energy Bills
It’s evident that shade and windbreak are essential to good walking and biking conditions. But people often forget that those things are also essential to good public transportation. Every trip begins and ends with a walk or a bike ride, and there's usually at least some waiting involved. Bus stops are some of the worst places to be on a hot day because you’re stuck in one spot and can’t wander around to find a shadier place to wait.
This is a major bus stop in downtown Winnipeg, serving multiple routes. It is surrounded by concrete and other hard surfaces, which absolutely bake in the sun. Frankly, this is a miserable place to wait for the bus.
A small cluster of trees stands behind the bus stop, and in the summer, people congregate under it for some respite from the sun’s harsh rays. There is a covered bus shelter, but since it’s partially enclosed in glass, it’s not exactly a cool oasis on a sweltering day.
You’ve maybe heard it said that trees are nature’s air conditioners. This is no exaggeration. Even aside from the respite that shade provides, trees actually lower the nearby air temperature through the process of evapotranspiration. This makes them far more effective at cooling than the “artificial” shade created by buildings or other grey structures.
According to the U.S. Forest Service, the net cooling effects of a young, healthy tree are equivalent to 10 room-sized air conditioners operating 20 hours a day!
If shade (or rather, the lack thereof) has such an impact on folks walking or waiting for the bus, consider the cooling benefits to the city as a whole. It’s estimated that trees in American urban and community areas reduce residential energy use by an average of 7.2% — a national savings of $7.8 billion per year!
Back to the boiling hot bus stop for a moment. Behind it is the Centennial Concert Hall. From the vast and boring expanse of concrete, you’d be forgiven for not realizing that you’re steps away from the entrance of a great cultural gem.
This entire plaza could be filled with trees (with benches!). It would provide a grand and beautiful welcome to patrons of the concert hall, and it would serve the practical role of making the bus stop a heck of a lot more comfortable for riders by providing shade and cooling in the summer, windbreak in the winter, and noise absorption year-round.
A Worthwhile Investment
North American cities today are in big trouble financially. The money they spend has to stretch as far as possible, and the multipurpose nature of trees fits that bill. In addition to the benefits I’ve mentioned here, plentiful research has found that street trees have a positive effect on traffic calming, boost spending in retail areas, and encourage walking and biking.
If you'd like to see more street trees in your town or city, lead with economic arguments and examples of the practical, easy-to-grasp infrastructure benefits that urban trees deliver.
Planting and maintaining street trees is an investment, but it’s one that pays for itself over and over again. Cities around the world are starting to calculate the economic value of their urban forests, a task made feasible with tools like i-Tree.
And more research is finding that trees pay for themselves many times over. A U.S. Forest Service study “conducted in five U.S. cities found that every dollar invested in the management of urban trees [ …] yields annual benefits of $1.37 to $3.09.
Trees are also the perfect example of a small bet. They cost relatively little, but the many varied returns are so high.
Whatever the goal for your street or neighborhood, chances are good that trees can help you get there. Advocating for or collaborating with your town or city to plant street trees on public property is one way to increase the canopy. But if your municipal government isn’t yet on board with tree planting, that doesn’t mean your efforts are doomed. There is always a next small step you can take. Planting trees on private land adjacent to the street is powerful too, and so is encouraging your neighbors to do the same.
Emma Durand-Wood likes walkable cities, front porches, street trees, bumping into neighbors, riding her bike, downtowns, and any excuse to check out a new coffee shop, bakery, or shop. A Winnipegger by choice, she lives in Elmwood with her husband and three children. You can connect with her on Twitter @emmaewood.