“Oh happy days,” I mutter as I read the Guardian headline: “Tropical forests face massive leaf death.” When I read the associated article, I think back to my last journey through the city, wondering if I wasn’t witnessing something similar - oaks with leafless crowns, elms whose canopies are sparse with leaves that are a strange translucent lime green.
On a hot day in early August, I stood with the man inoculating my boulevard elm against DED and watched as he looked up at my tree then pointed down the street. “Look at the thick dark green canopy on your tree. Now look down the street. Two years, I give most of those elms. Yours at least has a running chance.”
But it’s not just the boulevard elms on my street that are struggling. All across the city you can see Birch dieback, Sudden Oak Death, and other trees, from aspen to ash, succumbing to everything from cankers and fungi to tree borers, cottony psyllid, and most significantly, repeated years of drought.
And as our summer world gets hotter and dryer, thanks to climate change, our trees will experience even more stress. In their study of tropical trees researchers found that if climate change drives temperatures up by 4 degrees C., tropical leaves will no longer be able to photosynthesize.
Who knows how rising temperatures will impact trees adapted to a cooler climate like ours.
So what can be done to protect and nurture our suffering trees? Well, I think it’s pretty fair to say that it all begins with you.
Many of us are bereft when we lose our boulevard trees, yet we fail to do even the most basic maintenance to keep them alive.
Take watering – it’s one of the main things you can do to relieve the stress that makes trees more vulnerable to pests and disease.
In drought conditions like the ones that have dominated this and so many of our recent summers, even big mature trees need to be watered at their drip line – the area on the ground which corresponds to the canopy’s width. In dry spells, that watering needs to happen weekly or at very least biweekly for a duration of 30 minutes to keep the tree healthy.
Watering is even more essential for newly planted saplings. Any boulevard sapling planted this spring that wasn’t watered regularly between June and August is likely dead or half dead at this point. So, if you have a new boulevard tree, and city contractors don’t do their job and return to water it, do it yourself or share the burden with neighbours.
Because watering trees is essential. 80-90% of a tree’s tissue and 50% of its woody parts are made up of water. That water fuels photosynthesis, makes soluble soil nutrients more available and reduces the stress that weakens a tree, making it more susceptible to pests and disease.
Pruning also protects your boulevard and yard trees, by ensuring their structural integrity and making them more resistant to pests.
So why should you spend the time and money to do this? Well, just imagine your street without any trees. Not only would it be 5 to 8 degrees hotter in summer, it would also be more susceptible to storm water floods and more adversely affected by air pollution.
Yup, that’s correct – trees reduce air pollution by trapping particulates in their leaves and are key players in keeping city air clean and breathable.
But maintenance is just part of the job, There a couple of other things you can do and the main one is this – stop cutting down your healthy mature trees! And I’m not just directing this at private homeowners. First and foremost, it’s a message to builders and developers.
Developers who blithely clear-cut their properties need to stop and remember that they are also environmental stewards of the land. In fact I would argue that the best developers know that and work with arborists to retain as many mature trees as possible.
By doing that, they may also be among the most financially savvy developers, given that more than 2000 respondents recently surveyed by Builder Magazine indicated that mature landscaping and trees were among the top five features desired by new homebuyers.
Finally, if you really want to ensure your grandkids live in a lush treed city like the one you enjoyed, start making some noise. Tell our government representatives to act now to protect our trees and reduce the fossil emissions that drive-up temperatures and the extreme weather which doesn’t just kill or damage trees but also threatens humans. And water-in every tree on or near your property this fall, before winter sets in. Because, in the end, saving our trees is also about saving us.
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