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Urban Trees

Catherine Tapner

This is a great time to be talking about Urban Trees. Across North America, projects are underway to protect the trees in urban areas that collectively form a forest. Peterborough is one of these cities, and the support is growing. Our project is a partnership between the City of Peterborough, Peterborough Green-up, and the Ontario Trillium Foundation and comes at a time when there is much concern over the environment and natural heritage.

The benefits of urban trees are monumental. Trees beautify your outdoor living area and the community, and increase the value of your home. They also provide shade, and shelter from the wind which reduces your home's energy consumption. They reduce summer heat trapped in pavement and buildings by providing shade and transpiring moisture back into the air. They take in carbon dioxide, reduce pollutants, reduce flooding (roots, leaves, and branches help catch the rain, reducing runoff) and erosion . All of these factors are especially important when you consider concerns over climate change. An added bonus is the benefit to local wildlife, which not only aid in natural pest control, but which also give us great viewing pleasure.

If each of us, given the right amount of space and proper conditions, were to plant and care for a tree, we would collectively grow thousands of new trees. What a great forest this would be! What a beautiful community we would have, and wouldn’t the birds love it too! We would have a sustainable community, a natural Peterborough, a city that demonstrates its commitment to the environment and the legacy we pass on to our children.

We must not forget about the trees we already have. They are vitally important, as the benefits we gain from trees increase with their size and leaf area. Statistics from other cities show that older trees make up less than 20 percent of urban trees. So how does Peterborough compare?

The first stage of our Urban Forestry project is to inventory our existing trees, and assess their age, species and condition. Once we have determined our assets, we can establish what we need to add. What is most important? Do we increase diversity? Do we need more native species, heritage trees or unique trees? These are all factors to be considered. Knowing where to plant certain trees and how to care for them comes with education, which is not as formidable as it may seem. However, it is important to realize that not all trees are suitable for urban life.

Compacted soil, girdled and damaged roots, lack of growing space, salt spray, overhead wires, all take their toll on trees. So when you plant a tree, choose a variety that will suit the particular location, and give it lots of space, including space for the roots. Think about the tree when it matures. How big does it grow? Roots of most trees extend far beyond the drip line, 2 – 7 times the length of the branches. This is why trees planted too close to the street often don’t survive. Roots need water, oxygen, and nutrients in the soil to survive. Soil compaction resulting from vehicles and building projects damage roots.

Road salt also causes stress for the trees. Some trees can tolerate salt and others cannot. Check with your local garden centre for salt tolerant trees if you are going to plant a tree along roads and walkways.

Small trees are good choices for small lots, and for spaces under power lines. Many beautiful trees stay small when they mature, and are the perfect choice for restricted spaces.

Water your trees carefully, young or old, mulch and protect, and prune. Pruning when a tree is young is easier and causes less stress for the tree. Choose native trees whenever possible. They support native wildlife and are tolerant of our climate.

Numerous organizations are getting involved with this movement and have a great deal of knowledge about the care of urban trees and site selection: Peterborough Green-up, the City of Peterborough, the Kawartha Heritage Conservancy, MNR, the Otonabee Conservation Authority, local arborists, Peterborough Master Gardeners, the Peterborough Horticultural Society and more. Many interested citizens are also coming out to educate themselves and volunteer. Call Peterborough Green-up at 745-3238 for upcoming events and urban tree information.

The movement is on, and momentum is picking up. This is a great time to get involved, reduce our carbon footprint and live up to our logo: “Peterborough - it’s a natural!” We can turn our city into a sustainable, vibrant, ecologically viable urban forest by planting and caring for our Urban Trees.