The City of Charlottetown is experimenting with a new way of growing forests, using native species and denser plantings to encourage faster growth.
It’s called the Miyawaki method, after the Japanese ecologist and botanist who developed the idea of mini forests and how to grow them in the 1970s.
The technique is now used in urban areas in Canada and around the world.
“When we think of a forest, we think of trees over four meters tall, so hopefully within a decade we will reach that point in most of this area,” said Simon Wilmot, program coordinator for Charlottetown environment and sustainability team.
“We’re talking about creating forests in an urban or suburban area that can grow faster.”
Wilmot said the first step is to amend the soil to simulate the type of organic matter that would be found in a mature forest. That means adding a lot of compost and mulch.
“In this case, we added 12 cubic yards of wood chips to the site and really tried to make sure the site was as healthy as possible in terms of soil before we started planting,” he said.
High density planting
It’s not just about richer soil. Trees in the mini forest are also planted closer together, about a meter apart, compared to the three meters that would be seen in a more traditional planting, Wilmot said.
“That high density does a number of different things. Number one, there’s competition. Competition between trees will force them to grow faster, faster,” he said.
“Secondly, they will squeeze out space for invasive species. In most urban watersheds we have problems with invasive species, so they don’t really leave room for them.”
Competition between trees will force them to grow faster and faster.— Simon Wilmot, City of Charlottetown
Wilmot said the method “allows nature to take its course with the trees,” making the strongest ones thrive.
“Those trees that don’t survive or die will simply feed the soil and provide organic material for the next generation.”
Wilmot said his team planted two mini forests in June, a larger one in Wright’s Creek with 200 native trees and shrubs and a smaller one in the Ellen’s Creek watershed.
“The downside to this method is that it’s expensive. It costs a lot to take the time to amend the soil,” he said.
“So you’re working in a smaller area which costs more in the initial stages, but the long-term benefits will hopefully outweigh any short-term inefficiencies arising from the cost.”
Wilmot said the mini forest method would not work in downtown Charlottetown’s Victoria Park, which post-tropical storm Fiona left in need of reforestation, but is more suitable for areas that are currently grass.
He said he hopes to add more microforests soon.
“My aspirations always exceed my budget, so I always look forward to planting these things,” Wilmot said.
“When we look at Europe, where this has been common practice for a while, thousands have been planted. So hopefully, in PEI and our urban and suburban areas, this is the methodology that can really get going. Certainly, “It has been adopted in Ontario and Quebec much recently.”
The watershed coordinator for Ellen’s Creek Watershed Group said she was initially wary of the new planting technique.
“In some ways, it sounded too good to be true. You know, ‘We’re going to put a bunch of trees in an area and hopefully they’ll grow into a more mature forest faster,'” Emma said. Doucette.
“That’s the part that made me skeptical. But working on the site, I realized it’s a great approach and I learned a lot too.”
Doucette said the additional expense of soil preparation could be a challenge for associations like his.
“Watershed groups sometimes work on a pretty limited budget. So I think it comes down to planning and doing what we can within our resources,” he said.
“It was a lot of initial work, but I think if we’re going to go out here and plant all these trees, we have to do it right.”
Doucette would also like to see more mini-forests planted.
“Any space that is perhaps being underutilized in the city, I would love to see this technique used there,” he said.
“My advice would absolutely be to do it, and if you’re skeptical, maybe start small and see where it takes you.”