For urban forester Mark Mullins, 2014 is the Summer of the Tree.

There are 169 new trees being planted along Bloor Street West, between Lansdowne and Bathurst. Another 200 trees will go in on the Danforth, from Woodbine to Victoria Park, starting in September.

More than the sheer number of trees, the two projects mark an overhaul of the city’s approach to planting boulevard trees.

For Mullin, it’s also a banner year personally — the culmination of years of planning to make it possible for boulevard trees to flourish in hard surfaces. A new design for planting pits means trees will live much longer than the trees that struggle to survive in the concrete tree boxes that still obstruct many of the city’s main streets.

Mullins began his career in the City’s Urban Forestry Department 30 years ago as a tree climber. Today, as supervisor of Special Services for the City of Toronto’s Urban Forestry department, his "final frontier" was to close what he calls the biggest gap in the city’s tree canopy — proper growing conditions for boulevard trees.

Trees planted on main streets face unique obstacles. They share sidewalk space with a host of utilities — from sewage and water mains to phone, internet and gas utilities.

The concrete tree boxes were part of an earlier strategy to separate tree roots from those services.

As well, trees on the city’s main avenues face suffer other hazards, from corrosive salt damage to exhaust from idling vehicles to the heat island effect on hot humid days. Boulevard trees have a much shorter life span than trees planted in residential neighbourhoods.

“Trees need water, soil and air,” says Mullins. The new tree pit design gives trees more of all three — more soil volume, inlets built into the sidewalk to channel rainwater to the roots and keep air circulating — all of which dictate the tree’s eventual size and age.

The sidewalks are constructed to prevent soil compaction on top of a continuous soil bed below, allowing tree roots to connect, creating a more hospitable habitat underneath the sidewalk surface.

Of all the improvements urban foresters have made over the years, Mullins figures that creating proper conditions for a tree to grow in a hard surface is the most significant.

The tree bins used to take up room on Bloor West sidewalks. (Jason Diceman/City Of Toronto)

The first extended project involving continuous soil trenches for boulevard trees was two years ago on Roncesvalles, which saw about 100 trees planted from Queen Street all the way up to Bloor. It was a collaborative triumph, involving a number of city departments — technical, transportation, public realm, and public water -- as well as numerous utilities.

The projects along Bloor West and the Danforth are even bigger, with a total of about 370 Silver Maples, disease-resistant Elms and Purple Robe Black Locusts — “the proven contenders”, says Mullins. Mullins points out that about 30 trees will be planted from Dawes Road to Victoria Park alone, a particularly barren stretch.

To speed up construction, the contractor will have two crews working six days a week. The crews will focus on two blocks at a time in a loop. Each block will take six days on average. (City Of Toronto)

On Bloor Street West, the tree planting is well underway and expected to be completed by the next month. Along Danforth, construction has just begun, with tree planting expected to be completed by the end of the summer.

For Mullins, the summer of 2014 also brought another breakthrough for urban forests — an economic tally of the value of trees by a couple of bank economists.

Beyond more nebulous social and environmental impacts, Toronto's lush canopy of trees are worth about $7 billion to the local economy, TD Bank suggests in a report released Monday.

"Urban forests do more than beautify the scenery," the bank's chief economist Craig Alexander said. "They represent an important investment in environmental condition, human health and the overall quality of life."

Mullins says he found the bankers’ economic analysis staggering, in spite of a career spent caring for the city’s trees.

“We were all talking about it at the office when it came out,” he says. “We were very excited - just the fact of an economist making a comment about trees.”

“Seven hundred dollars per tree! Even I didn’t know it was that much.”