Boulevard of Dreams
By Lois Hole
Originally published on September 18, 1999, the impetus for this article came when a boulevard tree with a root ball girdled by a nylon cord was brought into our greenhouse in St. Albert, Alberta. The cord could only have been left there as the result of carelessness, and the indignation I felt forced me to examine what could be done to improve the health of city-maintained trees.
A city that has boulevards lined with vigorous, healthy trees tells me something about that place: it tells me that its citizens care about beauty and the environment. A stately procession of big, beautiful elms or maples lining the streets takes my breath away. But I’ve come to realize that these trees are not just the city’s responsibility.
Back in August, our son Bill saw that some well-established boulevard trees up the road still had braces on them—long after the trees could stand on their own. Fortunately, Bill noticed the braces just as they were beginning to cut into the bark. A quick phone call to inform the city’s parks department solved the problem. The endless profusion of cords and straps wrapped around the trunks and branches of young boulevard trees is a definite problem. These devices look harmless, but they’re killers. Christmas lights are lovely on outdoor trees, but the straps that hold the strings of lights in place must be removed annually. Leaving these straps on the trees makes it easier to hang the lights every year, but as the tree grows, the straps inevitably cut the circulation to the branches, ensuring premature death.
We must realize that planting trees is just the first step. Diligent maintenance is just as important as proper planting. While limited city budgets and honest misconceptions can make it difficult to provide long-term care to boulevard trees, regular upkeep and a little common sense can preserve a community’s investment. Several practices contribute to the downfall of boulevard trees, but a little care and planning on our part can ensure that they have a long and healthy life.
One practice that countless boulevard trees are subjected to is the relentless torture by weedeaters. Trees appear so tough and sturdy that many people don’t realize the extent to which these buzzing devils can damage trunks. Young trees are particularly vulnerable: the snapping cord of the weedeater slashes through and injures the thin cambium (the layer of bark responsible for growth) very easily. The damage is easy to spot: it manifests as a raised circle that girdles the trunk. Weedeater wounds can stunt growth, make trees more vulnerable to insects and disease, or kill them outright. It is simple to prevent such wounds. Just allowing the grass to grow a little taller around your boulevard trees can eliminate the problem, although many people think this looks unkempt. A plastic collar or a circular bed of annuals around the trunk can solve the problem, too. In the short term, it’s an expensive solution, but far less expensive than replacing the tree.
Like any trees, boulevard trees need regular pruning. If left to their own devices, many trees develop weak branches attached to the main body of the tree at dangerously narrow angles. Unless they are pruned at the appropriate time, these branches may snap off during a strong wind and expose the trunks to insect and disease pests. Most cities have excellent pruning programs, but occasionally a tree or two gets missed. If a tree looks particularly neglected it might be worthwhile calling the city’s parks department.
Construction is a necessary evil in cities but can cause severe damage to nearby trees. A magnificent 80-year-old silver maple that I drive past regularly is surely doomed: a couple of years ago I watched, horrified, as construction crews tore up the earth around it to put in parking spots. The idea was to create a few lovely shaded spots under the tree, but at least one of the tree’s largest roots was severed during construction. Ironically, the soil preparation for that pristine circle of asphalt will likely cause the tree to crash on top of the cars parked beneath its huge canopy.
Most Canadian cities are forced to use salt on the roads to increase traction in the winter. Unfortunately, salt usage has a number of disadvantages, including tree damage. Whenever a snowplow dumps a load of brown mush onto the boulevard, the ground beneath absorbs the salts, cutting off root absorption of water. While larger trees have a sufficiently extensive root system to evade salts, young trees don’t. In our area, a related problem is the all-too-common practice of homeowners dumping sump pump water, high in sodium salts, onto the soil around boulevard trees. Saline sump water should never be dumped around the base of trees.
Sometimes, a tree’s poor health can be traced back to the day it was planted. On one street close to home, there’s a long line of superb lindens—but every August, their leaves turn an ugly brown. Since this occurs during hot weather, there’s a tendency to blame the change on high temperatures. However, closer inspection reveals that the trees were planted in small holes cut into the sidewalk. Removing a chunk of concrete and planting into a little hole with compacted clay leaves little room for roots to expand and absorb water. The loss of moisture through the leaves far outstrips the capacity of the confined roots to draw in water. During periods of drought, the leaves invariably turn brown, severely weakening the tree.
Fortunately, awareness of the importance of maintaining city trees is growing. Just a few months ago, an venerable and rare horse chestnut smack in the middle of downtown Edmonton, Alberta made the news when a concerned horticulturist noted that the paving recently installed around the stately old tree would surely kill it. A group of concerned citizens raised enough cash to remove the pavement and re-landscape, saving the chestnut and beautifying the whole area. Many citizens contributed time and money to the project; my family donated lilies. I hope this story reflects a growing concern about the plants that are so very important to a city’s image. It’s everyone’s job to look out for their health.