A patch of underutilized green space between busy roads in Halifax is set to become the newest addition to the city's urban forest.

The area around the Windsor Street Exchange, near the MacKay Bridge, is mostly grass and is maintained by the Halifax Regional Municipality.

But researchers at Dalhousie have a plan to turn that area into a stretch of urban Acadian forest. They've planted more than 3,000 seedlings at the site, including white, red and black spruce, larch, red maple and yellow birch.

Benefiting the urban environment

James Steenberg, a postdoctoral fellow at Dalhousie, is leading the project, which is a collaboration with the municipality and the Sierra Club.

Steenberg told CBC's Information Morning the forest will help the municipality save money.

"They won't have to mow the grass anymore and [the forest] won't affect sightlines [for traffic] because of the nature of the roads out there."

While consideration of urban forests typically focuses on the mental and emotional benefits to city dwellers, Steenberg's interest in the Windsor Street Exchange project is in the benefits of that forest to the urban environment.

"We want to focus on the kinds of benefits that come from lots of trees in forest conditions in the city: storing carbon to mitigate climate change; slowing down stormwater in big rain events; and, especially important for this particular area, capturing air pollutants and removing air pollutants from the atmosphere."

Planting a diverse forest

Steenberg said at many green spaces in the city, the municipality focuses on planting hardy, shade-giving trees rather than conifers that would typically make up part of an Acadian forest.

Creating an urban forest involves planting an array of seedlings. Dalhousie University's James Steenberg said the forest will eventually regenerate itself. (James Steenberg/Dalhousie University)

But because it's surrounded by busy roads and is unsuitable as a recreational space, the site is ideal for an urban Acadian forest that includes a mix of trees, he said.

"We don't expect people to be having picnics around the Windsor Exchange, so we can plant high densities of conifers … and naturalize them so we can create the density of forest setting as opposed to more of a managed setting."

'A real nice patch of trees'

Steenberg said the density also reduces the cost of planting an urban forest.

Large trees can cost the municipality hundreds of dollars to plant.

"Our trees cost 40 cents a pop … and we can handle high mortality rates because we have a higher density of them," Steenberg said. "And because we're essentially converting these areas to forest, they'll start to replace themselves."

The area doesn't look like a forest quite yet. Most of the seedlings are only between 20 and 50 centimetres tall.

But Steenberg said he has high hopes.

"In 10 years, we hope to have [trees] taller than us or more … and then in decades to come a real nice patch of trees."