Tree myths and misconceptions

Why planting trees is good for the Glebe

 By Jennifer Humphries

Funny thing about trees: Most people like them, but even when they do, some adamantly do not want any on their property.

What reasons do they give? Among others, they’re messy, they damage sewer pipes and foundations, and they’re dangerous.

Dig a little deeper and you find that people know the benefits of trees, but a few are still determined to forego them. But these views are rooted in myths and misconceptions.

Last autumn, on a door-to-door canvass of several streets, the Tree Team (members of the Glebe Community Association’s Environment Committee) set out to encourage neighbours to plant a tree or two. Where they already had good tree coverage on their property, we asked them to keep us posted on any tree gaps they detected in the neighbourhood. Where residents lacked trees but had space, we urged them to consider planting.

The Tree Team aims to encourage the planting and preservation of enough sturdy canopy trees to ensure a green Glebe for the next century. Our neighbourhood is known and even envied for its tree-lined streets. But trees planted in the early 1900s – think little-leaf lindens along the avenues – are declining. Big red Xs declaring imminent removal appear on a frequent basis.

Age isn’t the only factor in the disappearance of the iconic Glebe canopy. In addition to root disruption during services replacement in streets, development – both infill and demolish/rebuild projects – is accelerating, with trees considered by builders to be literally standing in the way of their work. This attitude prevails, despite a municipal Tree Protection bylaw which clearly states that tree preservation is preferred and despite the new Official Plan which recognizes trees as green infrastructure central to climate change mitigation.

Our Tree Team canvass will resume this spring. If you have a question or comment, please email us at environment@glebeca.ca (Trees in the subject line).

The Glebe top nine tree myths and misconceptions – debunked

1. Tree roots damage foundations.

This is a common refrain. But the truth is, roots can’t pierce foundations. They can get in to an opening caused by something else, but they can’t create the opening. “If there’s a crack and moisture associated with the crack, the roots can colonize the space to access water,” said Daniel Buckles, long-time advocate for Ottawa’s urban forest and Tree Co-Animator for Community Associations for Environmental Sustainability. “Keep your foundation in good repair. New foundations are built with an impermeable surface, which won’t leak, so roots can’t get in. Foundation damage isn’t due to trees, it’s due to cracks.”

When it comes to city trees, the foundation issue arises so frequently that the City has initiated a four-phase process to determine whether a tree is playing a role in damage reported and, if so, how it can be mitigated. Trees are valuable – if there is a solution that saves the tree, that’s the ideal. I asked the City for some specifics on foundations and trees – their responses are in a sidebar in the web version of this article at glebereport.ca.

2. Tree roots break sewer pipes.

The notion that tree roots are so strong that they can break sewer pipes is simply incorrect. What they can do is take advantage of a leak by penetrating the pipe in search of water and nutrients. While they are unlikely to block a pipe, they could reduce flow. A plumber can check the pipe from inside your house and clear out the pipe if necessary. By the way, most roots are found within the top 60 cm (24 inches) of soil, above sewer lines.

As for water pipes, the City of Ottawa now uses copper for water mains and pipes. They are designed not to break or leak. If you have the old lead water pipes prevalent in early Glebe construction, you may wish to change them before they develop leaks. It’s a good idea anyway, in order to reduce your lead consumption. The City may be able to help with costs. See the city website for its “Lead Pipe Replacement Program.” And if your street is being redone, make the switch at that time.

3. Trees hit and smash things.

When properly cared for, trees aren’t a nuisance, and falling branches rarely hit or smash parked cars, houses or poles. Maintenance is key – pruning and cabling, for example.

You can also choose a tree that is known for its wind resistance. I asked Owen Clarkin, first vice-president of the Ottawa Field-Naturalists’ Club, about what are known as “weak-wooded” and “strong-wooded” trees. “This differentiation comes from the logging industry, and is related to their value as timber,” he said. “When it comes to wind, the species doesn’t matter as much as wind dynamics.” Conifers have evolved to withstand wind – hence their use as windbreaks. And during the ice storm of January 1998, many strong-wooded trees such as oak, ash and maple broke, while weak-wooded trees such as birches and poplars, bent but held firm. Their flexibility was their strength.

When it comes to city trees, homeowners should notify the city of possible hazards such as a rotting limb or cracked trunk. Then it’s the city’s responsibility to inspect and take action. On liability, see the city’s website, “Trees and Property Damage.”

Keep in mind that there are ways to preserve an otherwise healthy tree that seems to pose a risk to your home or to passersby on the sidewalk. Last April, a city forester suggested that we consider “reduction” of our 90-year-old linden, which had developed a major split in its trunk. We agreed, and one of the three major sections was removed. The tree continues to thrive and provide us with the shade and beauty we prize.

4. A tree would ruin my lawn.

Variations on this concern include “nothing will grow under a tree” and “tree roots will surface and wreck my lawn and lawnmower.”

It’s true that trees will shade a lawn, and grass is sun-loving, so it may not grow as well. They also take water. But there are remedies. As is frequently seen in the Glebe, you can make a circle around the tree that is landscaped differently – ground cover, natural mulch or wood chips. It needs to be permeable – no hard surfacing and keep mulch away from the trunk so it doesn’t trap moisture and create fungi. You can choose a deeper rooting tree that won’t take as much surface water. To be avoided: Norway maple, which is invasive and predisposed to surface roots.

According to a blog from Arbor Day, titled 8 Tree Myths Dispelled: “Under good conditions tree roots grow through the soil, not on top of it…in community settings roots grow well beneath the surface. Root surfacing is often the result of a combination of construction and compacted soil, leading to erosion which can surface tree roots.”

5. 

   Trees are more work than they are worth.

Yes, trees are work. But once established, not so much.

“The joy of raking, why has it disappeared?” Carol MacLeod asked. She is chair of the Glebe Community Association Membership Committee, former chair of the Environment Committee and a long-time community resident. “Beyond the sensory pleasure of the signature fragrance of autumn leaves, they are great for gardens and lawns,” she said. “I rake leaves onto my garden to provide overwintering shelter for insects. And I mulch leaves into my lawn.” She urges residents to give up their leaf blowers for environmental reasons – air pollution in the case of gas models and noise from both gas and electric blowers. There is also the fitness aspect. Why not get a workout doing day-to-day chores like raking, rather than a scheduled run or cycle? Cheaper than the gym!

Finally, speaking of worth, it’s hard to overstate the value of a lovely tree when it comes to real estate sales. That may compensate for the occasional watering and pruning your tree requires.

6. Trees are too expensive to buy (and maintain).

On our canvass, the Tree Team learned that many residents had no idea that the city has a program to plant street trees in the municipal road allowance. Others knew about the program but had been waiting for staff to contact them. In fact, the city’s “Trees in Trust” program works by application, which must come from the property owner. There is no charge for the trees, but the property owner must agree to care for it, including watering, with special attention during the first three years.

Even on private property, trees don’t need to be expensive, Owen Clarkin told me. “It’s a myth that it’s hard to grow trees from seed, which can cost nothing if you collect nuts or seeds from nearby trees,” he said. “Anyone who can grow snap peas, lettuce or beans can grow a tree.”

“It’s also a myth that trees grow extremely slowly,” he said, responding to the concern that a tree from seed or a seedling – such as those distributed by Ecology Ottawa each year – will take years to even look like a tree.

When compared to a two- to three-metre-tall sapling from a nursery that often comes with its roots in a burlap bag, a seedling planted at the same time will usually catch up within a few years; in a decade, it may exceed the nursery tree in height and trunk diameter. “The nursery trees have been transplanted, the root bag is kind of like life support,” said Clarkin. “Seed or seedling trees grow in their home environment from the start, which gives them an advantage.”

You might also obtain a tree from a neighbour who has a sapling growing in the wrong place or from a plant exchange on social media. On Facebook, try Buy Nothing The Glebe or Being Neighbourly The Glebe/Old Ottawa East and South.

As for maintenance costs, your tree will need watering, especially while establishing and during drought conditions. But experts note that some homeowners drown their trees. The amount of water required isn’t likely to be a major expense. Consider a rain barrel to minimize costs. Regarding fertilizer, less is more, and you may not need to fertilize at all.

7. Glebe streets are not designed for trees.

Actually, they are. Lynn Armstrong, a member of the GCA Heritage and Parks Committees, told me, “Building on the success of the tree-lined boulevards of Monkland and Clemow Avenue developed in the early 1900s, the concept was adopted on the undeveloped lots in the Glebe by requiring 25-foot front yard building setbacks, so providing space for large canopy trees. Hydro easements were placed in back yards on many avenues, from Percy Street to Bronson Avenue, to remove the visual clutter of the poles and lines and so that hydro wires would not conflict with the trees. It’s a myth that the Glebe is not made for trees. In fact, it was designed for large canopy street trees.”

If you have hydro wires in your front yard, you can consider a shorter tree – it could still be a canopy tree, but not an especially big one. Tree advocates are urging the City to change its rules to allow for trees to be set back into private property, with the owner’s permission, so that a tall canopy tree can be accommodated.

Keep in mind, Daniel Buckles advised, that not all overhead wires are the same. Hydro wires can pose a hazard, but communications lines do not; planting under them is not dangerous, although pruning may be required over time.

If you do have a small yard, take a look at the two-page brochure Planting Trees in Small Spaces (it’s on the Champlain Park Community Association webpage).

And don’t forget conifers. They have many advantages, including their taper which makes them less likely to run into overhead wires.

8. The City (or landscaper) won’t give me the tree I want.

While canvassing, we heard several times from residents who said the City encouraged them to choose small trees, even though there were no obstacles or there was a location to plant that would avoid obstacles.

If city staff offer you a serviceberry or crabapple or other small species but you want a maple or an oak and believe it can work in your yard, ask them to consider it. Large canopy trees enhance air quality, cool the air on hot days and provide the greatest benefit in mitigating climate change. Canopy trees are typically at least 12 metres (40 feet) at maturity, but smaller trees can also provide canopy.

The City may offer a number of trees that are not native. The exotic Japanese Tree Lilac is commonly planted, even though it is becoming invasive and taking over space in conservation areas.

If you are buying a tree from a landscaper, they may not advise a canopy tree or a native one. Instead, they may suggest a tree based on rapid availability or showiness that they can charge more for. If you can wait a while, they can likely acquire the tree you want.

Why should you plant or ask the City to plant a native tree species? They typically require less maintenance because they are adapted to the locale. As well, native insects and birds recognize native trees as food and habitat, whereas they may be confused by exotic species.

9. My old tree died and the City won’t replant in the same spot. That’s the only good place for a tree.

“Old roots won’t impede the growth of new roots,” Clarkin told me. “Plant a tree near the stump, maybe a foot or so away from it. Don’t remove the old roots or you’ll be doing the new tree a disservice. The decaying roots become nature’s fertilizer.” Some find the stump unsightly, but leaving it provides great habitat for insects as well as giving nutrients to the surrounding soil.

Jennifer Humphries is passionate about trees. She is the tree rep for the Glebe Community Association Environment Committee, tree co-animator for Community Association for Environmental Sustainability Ottawa and co-chair of the Glebe Report Association.