Seeing trees for the forest


If you were out freezing your nose off Wednesday in Heritage Lakes, you might have seen a woman in a yellow coat holding an iPad and a set of big orange calipers.

That was city tree department operator Wendy Bosma, who braved blowing snow and frigid winds this week as part of her ongoing quest to inventory every tree in St. Albert.

“My hands and feet are what get the coldest,” she said, as she scrutinized a green ash on Heritage Drive. She also gets a lot of residents asking her if she’s going to cut a tree down or give them a ticket. But it was interesting work, and she gets to see a lot of rabbits, magpies and gray jays.

“You know you’re gathering information that is valuable.”

Bosma is one of a few city workers working on the city’s new tree inventory.

About 13 per cent of St. Albert is currently covered by trees, and the city is looking to raise that to 20 per cent by 2037, said Louise Stewart, parks and open spaces manager with the City of St. Albert. The tree inventory will help crews determine where best to plant those additional trees.

While the city did an inventory in 2009, that one wasn’t kept up to date and didn’t record much beyond a tree’s species and location, Stewart said. This new one will also record the health and size of each tree and allow for real-time updates on each tree’s status.

“If a tree gets removed, it’ll be recorded instantly.”

The new inventory will help the city better plan tree maintenance, Stewart said. By knowing where old, mature trees were, crews could plan to plant more young trees around them to lessen canopy losses when the old ones die, for example. It will also help the city quantify the benefits it gets from its trees.

How to count

Bosma said that she and a few other city workers have counted roughly 56,000 trees since they started the inventory in mid-2016, and covered about 70 per cent of the city.

To do the inventory, Bosma walks up to a tree, eyeballs it to determine its species (“It’s a lot easier in the summer because the leaves are on,” she said), measures its width with the calipers, and notes the state of the tree and its surroundings. A tree might need pruning or show signs of disease, for example, or have scars from a car or lawnmower. She then logs this information on an iPad, which links it to a map showing the precise location of each tree, and moves on to the next one.

While counters will count individual trees in parks, they won’t try to count every tree in a forest or ravine, Stewart said. Those zones will be recorded in terms of overall area for the purpose of canopy calculations.

Stewart said she hoped to have the inventory complete by next spring. Using special software, she’ll use data from the inventory to calculate the carbon, stormwater, and energy benefits of St. Albert’s public trees.

She also planned to do a random survey of about 300 plots in the city next year to calculate the ratio of private to public trees. In most communities, 60 to 75 per cent of the tree canopy is in private hands.

Stewart said the three most common street trees in St. Albert were green ash (round, first ones to drop their leaves each fall), American elm (vase-shaped, common in Forest Lawn), and Autumn Blaze maple (the ones with red maple leaves). Some of the least common are the Ohio buckeye, olive, and pear, of which there are 15, 10, and three, respectively, on city property. City residents will be able to locate these and other trees using the tree inventory once it’s put online in a few years.

Questions on the tree inventory should go to Stewart at 780-418-6698.


About Author

Kevin Ma

Kevin Ma joined the St. Albert Gazette in 2006. He writes about Sturgeon County, education, the environment, agriculture, science and aboriginal affairs. He also contributes features, photographs and video.