Susan Thompson
Express Staff
A professional arbourist gave a presentation at Athabasca Hall on May 1 outlining why she thinks most of the trees marked for removal on 99 St. in Peace River can be saved.
Verna Mumby is an ISA certified arbourist, certified Tree Risk Assessor, and a Wildlife Danger Tree Assessor. She holds several degrees and regularly works with towns and engineers to retain mature trees through her business Mumby’s Arboriculture Consulting.
Throughout her presentation she gave different examples of mature trees that had been successfully saved in other communities such as Osoyoos and Vancouver.
Mumby was brought to Peace River by concerned residents seeking a way to save as many of the 13 trees marked for removal on their street as possible.
The Town of Peace River is replacing old valves and more on the local sewer lines as part of the neighbourhood renewal program.
Residents have made a presentation to council asking for more information, and were offered the solution of paying a local improvement levy for $185,000 to do additional work that will allow the trees to remain. Residents have since submitted a required petition to the town asking for the trees to be saved.
About 40 people attended the presentation, including both concerned residents and Peace River Mayor Tom Tarpey, CAO Chris Parker. and Councillor Byron Schamehorn.
“You guys have some really beautiful trees,” Mumby told the assembled crowd.
The arbourist reviewed some common issues with trees, such as the outdated use of “topping” or cutting off the top of the tree’s crown which can negatively impact its health, planting tall species under power lines, and decayed structural roots due to the placement of irrigation systems.
She reviewed the duty of care of trees and how that impacts liability, and how the structural stability of a tree and the risk it may pose can be assessed by an arbourist.
She noted that crown condition indicates health, not structural stability, and that a tree’s structural stability and therefore safety can’t be assessed on sight.
As a slide she showed outlined, not all wounded trees become infected, all infected trees do not decay, and all decayed trees do not fail.
She explained one method she uses to assess a tree is a Resistograph machine, which allows her to measure the resistance of the wood throughout the tree and determine how much is sound and how much is decayed.
She also noted that mature trees have less tolerance for change, and went over how tree growth changes over time as trees mature.
Mumby shared some data showing that homes with mature trees have better property values, and that trees have numerous other measurable benefits such as carbon storage, oxygen production, runoff prevention, and more, all of which can be quantified.
Trees are also assets to a town or municipality and can be assessed for value like any other asset.
She noted that the Society to Prevent Dutch Elm Disease had found that there were 600 elms in Peace River as of 2017, and that those elms alone were worth $2,019,625.00.
Mumby prepared a report on the 99 St. trees to share with the Town and residents.
Using the ISA trunk forumla method, she assessed the 15 m tall bur oak on 99 St. at a value of $66,900.00, and the large American elm at $30,000.
“Of the 13 trees I assessed, most are very healthy and structurally sound and can take the type of construction that is set forth,” she said.
“I don’t see a reason why the trees could not be retained on the construction site,” she said.
“Remember they probably got severed or damaged the first time they put the road in.”
Mumby said in order to save the trees, aside from three that had lines running right under them, most would just need a few mitigating measures such as pruning, keeping the root zones wet during excavation, and most importantly having an arbourist supervising and working with the construction crew and equipment operator during excavation to make sure the cuts to tree roots are clean and to assess whether the damage to the tree will mean the tree will need to be removed or not.
Having a certified arbourist present during those parts of construction would only cost in the hundreds of dollars, not thousands according to Mumby.
“I’ve looked at some nightmare situations. This isn’t a nightmare situation,” she said.
Now that a petition has been submitted by residents to save the trees, the Town will need to prepare a local improvement plan. It’s uncertain yet whether the Town will incorporate the arbourist’s advice into that plan.