WATERLOO — Struggling, scrawny trees in neighbourhoods a few decades old don't surprise local biologist Andrew Dean.

Several factors ranging from inadequate practices in new developments to poor care of newly planted saplings hamper trees from growing to maturity. That means those idyllic big canopies shading mature neighbourhoods in Waterloo Region are unlikely to ever appear in newer subdivisions.

"We won't have that with our current way of doing things," Dean said.

Concerns about the health of trees in the Westvale neighbourhood of Waterloo were recently expressed by a resident of 25 years. She noticed recently an inordinate number of trees of all sizes and species and on public and private property that seemed to be dead or dying.

A story in The Record earlier this month sparked emails from residents living in other Waterloo neighbourhoods who said they have noticed a similar trend, and also wondered about the cause.

The Region of Waterloo was confident any issues with tree health in Westvale were not related to the nearby landfill site it oversees, which is closely monitored to ensure nothing is migrating into the ground that would affect the environment.

The city's manager of forestry confirmed that trees are dead or ailing in the area, but almost all are ash trees affected by the emerald ash borer and slated to be removed and replaced. Climate change, linked to recent seasons of heat and drought, was also raised as a possible cause for the trees' lack of vigour.

There's little mystery to the struggling trees for Dean, who works for a local environmental consulting firm serving property developers and municipalities after he pursued environmental studies at the University of Waterloo.

He sees more fundamental problems and solutions. Most important, better management practices need to be adopted and enforced by municipalities for new developments to provide guidance on what's done before, during and after a subdivision is built.

That starts with the soil.

The standard depth of topsoil is about 10 centimetres, but 60 is best — especially on boulevards where trees are planted and there already are constraints on space for roots to grow.

Typically, top soil is stripped from a site, stockpiled into towering heaps and then spread back out once construction is done. But Dean, vice-chair of the Waterloo Regional Environmental and Ecological Advisory Committee, said that practice kills off beneficial organisms and reduces the soil's value.

To preserve the soil, it should be piled no more than two metres in height.

Subsoil also need attention. During construction, heavy machinery compacts the subsoil to the point where it becomes an impermeable surface. The topsoil is spread back out on top of that hardened layer, which stops tree roots from spreading.

"They can't go any further," Dean said.

Roughing the subsoil down about 30 centimetres and mixing in topsoil avoids having two stratified layers that limit a tree's growth.

These engineered measures that set up suburban trees for a long, healthy lifespan aren't being implemented, and then once planted trees face further challenges to thrive.

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Neighbourhoods are highly impermeable landscapes with many surfaces — streets, sidewalks, driveways — that stop water from getting into the soil and nourishing trees like in forested habitats.

Trees are not cared for properly by residents and municipalities, starting when they are planted. They're not watered enough during summer drought, and in the winter they're hit with salt from roads and sidewalks.

And often the species planted are not well suited, although Dean said cities are getting better at picking trees. Good options are hackberry, bur oak, honey locust, basswood, red oak, Kentucky coffee tree, tulip tree and sycamore.

"They're native species that can tolerate more urban conditions," he said.

But even those species will never reach their full growth potential in neighbourhoods where careful attention wasn't paid to the conditions where they are re planted. They may look fine in the first couple decades, but then growth slows.

"The trees aren't growing to maturity," Dean said. "They're struggling. They're small."

Ensuring trees prosper has never been more vital, he said.

"A healthy urban tree canopy is one of our best defences against climate change."

jweidner@therecord.com

Twitter: @WeidnerRecord

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