Fewer planted trees due to drought could have long-term consequences
Posted July 23, 2015 9:05 am.
This article is more than 5 years old.
METRO VANCOUVER (NEWS 1130) – Our drought has led to a lot of heated debate about our landscaping needs in the region.
And while some developers are shying away from traditional greenery, one expert says you can’t lump trees into that. Neglecting our urban forests could come with some long-term consequences.
The “heat island effect” is something we’d have to deal with, says Douglas Justice, associate director of the Horticulture and Collections at UBC Botanical Gardens.
That’s when fewer trees in cities cause paved surfaces and buildings to better retain heat. Justice says that is one of the reasons downtown can be warmer than some suburbs.
“When we have a good tree canopy, that really helps to reduce that heat island effect. So I think if people are not planting trees, [it’s] probably a bad thing. When you think about how much water a lawn uses and if you were to use at least some of that water to water a tree, we can establish trees with not very much water.
“And as long as we can get those roots deep, then they essentially take care of themselves and they really don’t need much water except when we have these hot, dry periods that — let’s be honest — don’t happen very often. And so, I think, if we were to stop planting trees because of this year’s drought, next year may be wetter than normal and it might, in fact, be a great year to plant trees.”
“I’m certainly in favour of continuing to plant trees, but I think we need to water intelligently — that is, early, infrequently, and deeply,” he adds.
He says there are some types, like oaks, which are more tolerant of dry spells than others.
Japanese maples for example, are not as drought-tolerant, particularly if it’s planted in the open, under the sun. Justice says the roots of that tree also tend to be fairly shallow.
“So, if we choose trees that root deeply and are somewhat drought-tolerant in the beginning, then we’ll be a lot better off. But I think we don’t have to only grow drought-tolerant trees. How about don’t wash your car for three weeks? All the water you’d save would easily keep a Japanese Maple alive in your front yard.”
You may have noticed water bags around city trees, but Justice says in some cases, the requirements for those bags were likely underestimated, which would mean a lot of the bags have come in too late for some of the newly-planted trees.
