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Protecting Your Trees Against Pollution

Hazy sky and red sun from air pollution over Toronto Photo Designocologist Pexels

We know trees are beneficial against pollution. But how can you protect your trees against pollution?

Trees help capture carbon, reduce particles in the air, and reduce water pollution by preventing soil erosion. They also reduce noise pollution in busy areas, and have a secondary effect on reducing some other types of pollution: tree-lined streets help cars to slow down, creating less pollution at lower speeds, and they provide a cooling effect, reducing pollution from air conditioning and indoor electricity usage.

However, your trees can also be vulnerable to various sorts of pollution in urban environments. How can you ensure your trees stay healthy in a busy city area?

What Types of Pollution Affect Trees?

Air Pollution

Your trees can be affected by different types of pollution in the city. Air pollution is an obvious one. Trees are pretty resistant against air pollution — that’s why they’re one of our best tools for fighting it. Studies have shown that planting trees near highways and factories helps reduce air pollution from these sources. However, during intense conditions, like heat waves and extended air quality warnings, it’s advisable to make sure your trees get some extra TLC.

This includes times when smoke from forest fires affects air quality. Yes, even in Toronto — air quality can be affected by fires as far away as Northern Ontario. We’ll talk more later about how to keep your trees hydrated during times of high air pollution.

Salt Damage

At the opposite time of year, road salt can also cause damage to trees. Toronto’s love affair with rock salt is no secret, but salt can damage tree roots and soil quality. This especially happens during freeze-thaw cycles, in the spring or throughout the winter, where salty runoff can get into the tree’s roots.

This can be helped by picking the right tree species for hardiness, and having your soil tested in the spring. If too much salt has disrupted your tree’s pH balance, an arborist can help you with fertilizer or soil amendments to restore balance. And if you’re salting your own property, only use as much as you need!

Construction and Wastewater

Tree construction protection at University of Toronto campus

Your trees can also be affected by construction and other waste fluids. Some contractors will pour excess construction materials or wastewater into gardens and yards without concern. Some will simply be careless when cleaning up during a job. Some pool contractors will set up pools to drain into your, or a neighbour’s, garden.

Prevention is the best method for treating this. If you’re hiring contractors, make sure they have an effective plan for waste disposal. Make sure you’ve obtained the proper permits and have a tree protection zone established.

If you have a pool, ensure the water drains into the municipal sewage system. And if the issue stems from a neighbour’s property, speak with your neighbour, the contractors, or call 311 if there’s a concern about improper disposal of wastewater or construction waste.

If the damage has already been done, an arborist can help you with restoring soil quality.

City Street Trees and Pollution

Toronto Urban Forestry recommends tree species for planting that are adaptable to the local climate. They avoid planting coniferous trees on front lawn road allowance areas, in part due to these trees’ vulnerability to damage from road salt. However, some trees predate this policy. If you have an evergreen tree close to a sidewalk or roadway that gets salted, consider extra fertilizer in fall and spring and/or adding a physical barrier from the road.

Tree Varieties

If you’re planting a new tree, choose a hardy species that’s resistant to pollution and weather conditions. Ontario native species tend to be the most resistant to weather, drought and pests. An arborist can help you pick the best species for your space, depending where you’re located and where the tree will be planted.

Watering and Fertilizing

Haze from wildfire smoke over trees in Toronto July 2021

Making sure your tree gets enough water is one of the best ways to help protect it against environmental effects. During times of drought, extended hot weather, or poor air quality, it’s important to make sure your tree is watered. Young trees need the most water, but mature trees can use help too! Trees do best with a deep watering a couple of times per week, rather than a smaller amount daily.

Soil quality can also help determine if your tree is getting enough water. In poor quality soil, your tree may receive too much or too little water. An arborist can assess your soil and make sure it’s right for the tree.

Fertilizer can also help restore balance to your soils and plants in the spring and fall.

Soil Quality and Air Spades

If your property has been damaged by previous pollution, whether it was your neighbours’ reno last summer or long-gone industry, an arborist can help check out your soil. We can conduct an evaluation on the spot, or take a soil sample to send for testing for a more extensive profile.

After we’ve gotten a closer look at your soil, we can recommend next steps. Soil amendments are any substances added to soil to improve its quality. They can include plant material, compost, minerals, and other nutrients. Soil amendments are used to improve fertility, water retention and drainage in soil, providing a healthier growing environment for your trees and plants.

We can also use a tool called an air spade to turn over your soil. This helps to adjust the layers of soil, especially when the topmost soil has been damaged, and reduce soil compaction. Use of an air spade gives your tree’s roots more space to grow and breathe.

There are lots of ways you can help keep your trees healthy, even in a busy crowded city! Contact Vista Tree if you need some help getting your trees back to health.

Are you concerned about your garden and climate change? Read more in our blog about Climate Change-Resistant Tree Care

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