Mowing money on Yukon’s highways

According to David Polster, disposing of dead bodies is always a problem. During Wednesday’s Yukon Science Institute lecture, the visiting…

According to David Polster, disposing of dead bodies is always a problem.

During Wednesday’s Yukon Science Institute lecture, the visiting plant ecologist pulled up a slide of slash piles lining the North Klondike Highway.

Slashing and burning is not the best way to manage pesky vegetation, said Polster.

It isn’t cost effective, he said.

Polster, who studies roadside vegetation management, spent a fair bit of time driving back and forth to Dawson for another project.

“It’s a long drive and I had nothing better to do than think, ‘How might I manage this roadside?’” he said.

The troubles began with the initial clearing of its shoulders.

“Weeds respond to disturbance,” said Polster.

“They don’t become a problem in natural, undisturbed ecosystems.”

Once cleared, highway shoulders become havens for alien species like sweet clover, he said.

Natural species like foxtail and fireweed also do well in the cleared areas.

Next come woody species like poplar and willow, said Polster.

The young saplings are ideal moose fodder.

“So we’ve created moose pasture right next to the highways,” he said.

“Then they send in the brush cutters and next spring the cycle starts again.”

It’s a waste of taxpayers’ money, said Polster.

Depending on the road, the type of vegetation and the traffic volume, the Highways department pursues different approaches to vegetation management, said Highways transportation maintenance director Don Hobbis on Monday.

Sweet clover just needs mowing, while adult vegetation usually has to be cleared and grubbed, he said.

“The mature poplar growth on the road to Dawson was blocking sight lines and attracting animals,” said Hobbis.

It was also shading the highways, creating ice patches in the spring and fall. And in the winter, loaded with snow, the trees bend over the highway, he said.

By clearing the adult vegetation and reshaping the ditches, Highways hopes to “expend funds now to recoup savings in the future.”

It costs roughly $15,000 to clear, grub, shape and burn each kilometre of highway, said Hobbis.

So far, Highways has cleared and grubbed 230 kilometres of the North Klondike Highway.

That’s $3.45 million.

The reshaping will allow Highways to mow the shoulders on a cyclical basis.

“We hope to only have to mow every three years,” said Hobbis.

Mowing will cost the territory roughly $2,000 per kilometre, he said.

So, mowing the Klondike highway from Whitehorse to Dawson will cost taxpayers approximately $1 million every three years.

But the territory may have to mow more often if plant growth continues to accelerate.

“We’ve been noticing that re-vegetation is happening much more quickly than it did decades ago,” said Hobbis, who thought it might have something to do with climate change.

It’s not climate change, said Polster.

Plants take several decades to reach their biological potential, he said, citing sweet clover as an example.

Sweet clover has probably been in the territory since the construction of the Alaska Highway, he said.

“But it’s only taken off in the last 10 years.

“And when it eventually reaches its biological potential it will have colonized all spots it possibly can.

“When this happens, the cost to taxpayers goes up and successful management goes down.”

To get out of this “treadmill of succession,” Polster wants Highways to let the vegetation grow.

The foxtail, sweet clover and fireweed will eventually be replaced by the poplar and willow, which in turn will be overgrown by pine and spruce.

Once highways are framed by pine and spruce, the understorey is open and sight lines are no longer a problem, he said.

Trouble is, it will take decades.

So, it’s hard to convince politicians to head down this road, said Polster.

In the interim, with poplar saplings and willow luring moose to roadsides and blocking sight lines, there would need to be “heavy-handed pruning.”

But in the long term, “you are setting yourself up for vegetation that will contain itself,” said Polster.

The ecologist worked on vegetation management for rail lines in BC and found that by moving from a slash-and-mow method to a more ecological, self-contained approach, it was possible to save the province $23 million over 20 years.

In the Yukon, the crews that mow and slash vegetation could be trained to prune it instead, said Polster.

“If you understand vegetation and the way it operates, then you can develop effective management systems, instead of shooting yourself in the foot.”