Montrealers on mountain bikes have been taking advantage of an unofficial network of trails on Mount Royal for years — but experts say doing so is destructive to the mountain's ecosystem, not to mention illegal.

Through a hole cut in the fence, cyclists gather on the mountain, donning helmets, gloves and equipped with super-bikes with which to charge down makeshift paths.

But repeatedly crossing the mountain's soil loosens tree roots, and affects its renowned Laurentian flora, according to Éric Richard, director of the non-profit organization Les amis de la montagne.

"We put up fences, and presto, they disappear," Richard said.

He said he's nervous to see the mountain's soil deteriorate and its paths widen — simply put, he's worried about the future of the mountain.

Reducing the capacity to regenerate

Alain Cogliastro, botanist at the Botanical Garden, explained that this creates difficult conditions for plants to regenerate.

"They are living beings. We don't realize that when we pile it on, we reduce its capacity to regenerate," Cogliastro said.

He said the practice simplifies the mountain's flora, when diversity is what makes these environments more solid.

Mountain bikes destroy the fauna and flora found in Mount Royal Park. (Émilie Dubreuil/Radio-Canada)

The practice of mountain biking on Mount Royal is becoming more and more popular.

It's also not permitted by law — but police did not give out any tickets last year, according to Marie-Claude Dandenault of the Montreal police..

"It's difficult to take them in full offence," Dandenault said. "But we're sensitive to the problem, and this summer we will have two more police officers on bikes."

Searching for solutions

Mountain biking on Mount Royal is not a new problem — Vélo Québec has been taking steps with the City of Montreal for years to find a solution, and, above all, to create a real site on which to practise the sport.

"The problem is that bikes use trails that aren't meant for biking," said Francis Tétrault, who's in charge of mountain biking at Vélo Québec.

"We want to find a solution — build a small part of the mountain or find a site elsewhere. Because, at the moment, there is none in town."

Luc Ferrandez, who's responsible for large parks on the city's executive committee, said he is aware of the problem, which he described as serious. He said he is seeking a solution.