The Don River Valley Park in Toronto in May, 2021. The City of Toronto plants 120,000 urban trees annually, though sustaining their growth is difficult.Christopher Katsarov/The Globe and Mail
A new alliance of industry, scientific, non-profit and government partners is collaborating to increase the success of urban tree planting, as high mortality rates remain a challenge for the perennial plant that is key to tackling climate change.
The goal of Greening the Landscape Research Consortium is to help seedlings survive to become giants, and its advantage is information-sharing along the “urban tree value chain” – from nursery staff tending seeds, to planting contractors, to municipal foresters nurturing the trees. The consortium was launched in Ontario’s Niagara region in 2021 by Vineland Research and Innovation Centre, or VRIC, a not-for-profit institution focused on improving the sustainability and competitiveness of Canadian horticulture.
While millions of urban trees are planted every year, sustaining them is difficult. The City of Toronto alone plants 120,000, and Montreal hopes to reach half a million annually by 2030. Yet from Belgium to Sacramento, Calif., studies show mortality rates of nearly 20 per cent in just the first year. Researchers say up to a third of a typical urban planting can die in the first five years.
A cyclist passes through the shade of trees at Bronte Beach Park in Oakville, Ont., in August. The newly formed Greening the Landscape Research Consortium is working to increase the success of urban tree planting.Cole Burston/The Globe and Mail
Trees are crucial to reversing the global warming that triggers extreme weather: They absorb greenhouse gas, generate oxygen, provide shade, reduce the intensity of urban heat islands and absorb stormwater. Increasingly frequent weather disasters – in one recent span of 14 months, regions at both ends of Canada were devastated by floods, winds, heat or wildfires – underscore the urgency to help seedlings flourish.
Rhoda deJonge, VRIC’s director of plant responses and the environment, says everyone in the tree value chain plays a key role in building urban forests. However, decisions about tree plantings often get made without evidence, simply because there’s been no multidisciplinary collaborative initiative where people can ask questions and get expert answers that can be immediately applied.
VRIC conducts research based on questions that consortium members raise that relate specifically to their most pressing problems, according to Ms. deJonge.
“Now, when a tree nursery asks, ‘How can I know what species to plant today if I don’t know what a city will want six years from now when the trees are ready for planting?’ we work together to find ways to actually answer this question,” she said.
To support the initiative, VRIC built a critical asset: the TreeCulture Research Park. The size of a football field, this living lab was exhaustively excavated, fitted with sensitive irrigation and drainage, then divided into separate growing compartments, each filled with varying ratios of soil types and compost, then planted with different species.
After just its second year, the consortium is up to 20 partners, including the municipalities of Hamilton, Waterloo, London and York Region. Commercial members include A.M.A. Horticulture, Moser Landscape Group, Walker Industries, and NVK Nurseries. Also involved are professional organizations such as Landscape Ontario Horticultural Trades Association and the Ontario Chapter of the International Society of Arboriculture (ISA), as well as government-regulated agencies such as the Niagara Parks Commission (NPC) and Niagara Peninsula Conservation Authority.
Among the first to join the consortium was the town of Lincoln. A growing rural-urban community whose subdivisions attract Greater Toronto Area commuters, the town strives for careful planning practices. One current improvement project in Jordan Village will see nearly 170 trees planted in limited spaces along new curbs, sidewalks and parking lots.
Trees dot the street amid the apartments and condominiums near Don Mills Road and Sheppard Ave. East, in Toronto, May, 2018. After just its second year, the Greening the Landscape Research Consortium is up to 20 municipal partners in the GTA.Fred Lum
“Residents want trees to grow into a big shady canopy for the neighbourhood,” said Shannon McKay, Lincoln’s director of community services. “But how do you ensure the plantings will survive and prosper? The consortium was an opportunity to do something science-based, for example examining soil amendments to see how they can handle water.”
Robyn Pollard, forestry and horticulture manager for the City of Hamilton, was attracted by communal problem solving and says the consortium’s membership “consists of peers who I consider to be at the top of their game and are well respected within the industry.”
“Hamilton has a significant number of trees and plants that are and will be impacted by climate change. Being pro-active will ensure we’re improving our resiliency.”
Waterloo-based Moser Landscape Group saw the collaboration as a chance to work with accomplished industry partners from different parts of the chain who are all invested in the same goals of success.
“From the grower, contractor, architect, developer and municipality, being able to discuss the different concerns from each member allows for a better understanding in addressing the problems of every group,” Moser general manager Jason Kropf said.
In St. Catharines, Ont., the municipality gives out 1,000 trees each year to residents to put on their property. Making sure they survive, with the consortium’s support, is crucial.
“Planting a tree is not as easy as digging a hole, adding a tree and walking away,” said Olivia Groff, the city’s climate-change adaptation co-ordinator. “The urban environment places a variety of stressors on trees. Establishing best management practices from the consortium’s diverse membership will help ensure trees are looked after beyond the initial planting.”
A hiker passes through a grove of poplar trees at Toronto's Rouge Urban National Park, in June, 2021. Trees are crucial to reversing the global warming that triggers extreme weather: They absorb greenhouse gas, generate oxygen, and provide shade, among other benefitsGiordano Ciampini/The Canadian Press
ISA Ontario represents more than 1,100 members involved in the care and preservation of trees. Spokesperson Bridget Dilauro said it was clear that consortium project outcomes would benefit members, who include arborists and nurseries.
“Hearing feedback from so many different stakeholders with a wide range of expertise is invaluable, as is getting the information into the right hands, whether that be homeowners, or decision makers at municipalities, or managers at tree-care companies,” Ms. Dilauro said.
An iconic name in the lineup is the NPC, the provincial agency mandated with sustaining the Niagara River corridor, a natural habitat and a jewel in Ontario’s billion-dollar tourism industry. Corey Burant, project manager for forest health planning, says the consortium is revealing better practices for conserving and expanding the NPC canopy.
“Historically, many areas of the Parks have been manicured or manipulated for aesthetic purposes, including Niagara River shorelines which had been hardened with rock or concrete and mowed to the edge. As a result, these areas are now failing due to erosion,” Mr. Burant said.
“Before we do any replanting, we want a better understanding of soil conditions and improving soil quality to increase the survival of new trees. We saw this as a great opportunity for collaboration.”
At Lincoln, Shannon McKay concurs: “It was a no-brainer to partner with a knowledge group that was examining the data on what helps trees flourish. Sometimes trees that have been planted in public spaces don’t survive, and we have to figure out why. Did we over-water? Under-water? We’re not scientists, we don’t know what we don’t know.”