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One sunny June day, Cynthia Dwyer and Marianne Maddeford rushed to finish their day’s work at Robert F. Legget Park in Ottawa as storm clouds began to roll in.

The vibrant flower-lined park sits just off Main Street in the centre of Old Ottawa East and Dwyer volunteered to care for the site through the city’s “adopt-a-park” policy.

It’s a significant commitment. Dwyer is responsible for cleaning and maintaining the park and ensuring its trees, flowers and plants keep growing.

“I planted most of the plants all around this outskirt … from nothing,” Dwyer said.

“I had to be in all the time making sure they survive long enough to live on their own. The city, I don't think, likes to do a lot of it because then the onus is on them.”

Despite the best efforts of volunteers like Dwyer, Canadian cities are losing greenspace, a Statistics Canada report shows. A study on urban greenness measured the amount of vegetation in Canada’s 31 most-populated areas.

Researchers used satellite images to find how much green vegetation exists in cities. Areas that appeared green in colour indicating vegetation concentration were classified “green.” The rest were classified “grey,” usually indicating urban development. Research shows an average of 6.6 per cent of the area of Canada’s 31 most-populated cities changed from green to grey from 2001 to 2021.

Weather also affected the study’s results. Drought summers could dry out a city’s vegetation, meaning the city was considered less green in any particular year. Although there were some fluctuations due to weather, the study’s author Jennie Wang said the overall trend was a decrease in green space. Researchers found a correlation between that decrease and development due to population growth.

Only nine of Canada's 31 most populated urban centres saw an overall increase in vegetation in this time frame, the study shows. Ontario cities led the way, accounting for five of those spots.

“If you actually want a space to be greener and thrive, the people who live in that space have to take care of it,” says park volunteer Cynthia Dwyer. #UrbanGreenspaces #Trees #Vegetation #Parks #Cities

Guelph saw the largest proportion of vegetation growth, with 11.6 per cent of its area going green.

Kanata ranked second with five percentage points of growth, and Kitchener took third with 4.4 per cent of its area turning green.

Winnipeg, Edmonton, Kelowna, Abbotsford and Vancouver lost the largest proportion of greenspace over the years covered by the study.

Losing greenspace can have serious public health consequences, according to Dr. Courtney Howard, an emergency physician and green policy researcher based in Yellowknife, N.W.T. She said urban vegetation can cool communities by up to 15 C during extreme heat events.

“It matters if we can really reduce the number of people who are really heat-stressed or die during a heat emergency,” Howard said.

Besides preventing “mass-casualty” heat events, Howard added urban vegetation helps cities reduce greenhouse gas emissions and improves mental health.

“We need to find ways of adapting that will save lives and make life more pleasant and increasing green space is really one of those,” Howard said.

Parks managers from Guelph and Kitchener spoke to Canada’s National Observer about how they have grown their city’s greenspaces.

Luke Jefferson attributed Guelph’s green growth to policies that protect existing vegetation and city plans that include canopy growth targets.

“The city has been interested in protecting the environment and improving our landscapes for a long time. I think that that is being reflected in the study,” Jefferson said.

Guelph and Kitchener protect a large amount of their existing parkland by classifying it as “ecologically sensitive.”

Dwyer said she’d like to see similar policies to protect mature trees in other cities, especially near residential and single-family neighbourhoods.

“Stop saying, ‘We love trees’ and then have every Tom, Dick and Harry come down, buy a little house, go to the borders of it and take down every tree that's on there,” Dwyer said.

“That’s environmental suicide.”

Dwyer also manages the park’s community garden and runs a local farmers' market in her neighbourhood along the Ottawa River. The nature in her community made it more nurturing, she said.

“I can walk down with my kayak and I'm on the river. It's beautiful,” Dwyer said.

She said promoting policies like “adopt-a-park” that encourage volunteers to keep their cities green can also help.

Niall Lobley, Kitchener’s director of parks and cemeteries, said vegetation growth in his city starts with protecting maturing trees. Kitchener’s tree canopy has grown by about two per cent since 2015. Now, 83.2 per cent of the urban centre is classed as “green.”

“We’re looking to grow and optimize the growth of the existing canopy and see all the benefits that come with having a rich urban forest canopy,” Lobley said.

Jefferson and Lobley said growth poses the biggest challenge to keeping cities green.

“As you start to see cities intensify, that really does start putting pressure on urban greenspace,” Lobley said.

Kelowna, which lost the third-largest proportion of greenspace, also saw the highest population growth rate in Canada at 14 per cent between 2016 and 2021, according to Statistics Canada.

But not all cities with a growing population lost greenspace. Kitchener ranked the fifth-fastest growing city from 2016 to 2021 with a population growth rate of 9.9 per cent. Guelph ranked ninth with a rate of nine per cent.

Kitchener increased both its population and greenspace by expanding city boundaries instead of developing in the existing “urban envelope.” But it will be a challenge to maintain all the existing vegetation as Kitchener continues to grow.

“It's difficult to see how green works when we're intensifying our urban areas,” Lobley said.

Expanding city boundaries instead of intensifying where people already live can also mean paving over greenspace and increasing carbon emissions. The Ontario government has demanded municipalities in the Greater Golden Horseshoe Area submit growth plans by July 1.

Several, like Hamilton, have voted against sprawl and instead plan to densify their existing land base, primarily for financial reasons. But those decisions are also backed by the provincial Green Party and environmentalists concerned about farmland preservation.

Howard said it is important to maintain a healthy level of greenspace as development continues. Urban vegetation that provides amenities like tree-lined bicycle paths for commuting and community gardens that increase food security encourages people to help keep their cities green.

“The more strategic we can be about it to improve more than one thing at the same time, the more lovely it will be,” Howard said.

Lobley and Jefferson said the biggest reason their cities saw urban vegetation thrive was because people were willing to take care of nearby trees, gardens and urban parks.

Cynthia Dwyer, a volunteer garden manager, is responsible for maintaining the Children's Garden at Robert F. Legget Park in Ottawa, Ont. Photo by Isaac Phan Nay/Canada's National Observer

Besides helping people, Dwyer said vegetation nurtures birds, bees, butterflies and everything else that lives in cities.

It’s why Dwyer said she adopted the park in Ottawa.

“You can't (just) put a tree in the ground and have it live,” Dwyer said. “Somebody needs to water and take care of it.

“If you actually want a space to be greener and thrive, the people who live in that space have to take care of it,” Dwyer said.

Updates and corrections

| Corrections policy
June 22, 2022, 02:25 am

This story was updated to explain the impact of hot dry summers on the data.

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Unfortunately, the first two graphs shown on this page are not statistically valid. The data is nominally correct, but the presentation is highly misleading.
Greenness in any given summer is a function of weather. In a dry summer, the city will be less green. So there is huge variability in the data, depending on weather.

The greenness value for Edmonton, Alberta in 2021 (a dry summer) was 34.8%.
The values in the five preceding years (2016-20): 58.6%, 49%, 44.3%, 59.6%, 60.8%.

You can't define a trend by picking the start and end points of your time interval (2001-21).
Conclusions based on the first two graphs are meaningless.

StatsCan Table: 38-10-0149-01: "Urban greenness and normalized difference vegetation index by population centre"
https://www150.statcan.gc.ca/t1/tbl1/en/cv.action?pid=3810014901

StatsCan report: "Urban greenness, 2001, 2011 and 2019"
https://www150.statcan.gc.ca/n1/pub/16-002-x/2021001/article/00002-eng.htm
"In 2019, 76% of the area in 996 population centres in southern Canada could be classed as green. This percentage varied based on city size and regional differences.
"In large urban population centres, an average of 70% of the total land area was classed as green, with the share ranging from 38% in Winnipeg to 94% in Kanata. These values reflect peak summer greenness and can vary greatly depending on local climate conditions. A comparison of the top five large urban population centres shows that 65% of Toronto, 70% of Montreal, 68% of Vancouver, 42% of Calgary and 60% of Edmonton were classed as green in 2019."

Given such high interannual variability due to weather, single-year snapshots are unlikely to be representative of the situation/trend.
On the graph "Urban Centres showing the most decrease in proportion of greenery, 2001-2021", our author derives a figure of -30.6% for Edmonton, and ranks it accordingly.

He arrived at this figure by simply subtracting the value for 2021 (34.8%) (an atypical year) from the value for 2001 (65.4%). A decrease of 30.6%.

If these years are atypical (i.e., if they sit far off the trend line), this simple subtraction is invalid.
The 2001 value (65.4%) is ten percentage points higher than the average for the next five years.
The 2021 value (34.8%). is twenty percentage points lower than the average for the previous five years.

Date...Greenness (%)
2000...70.5
2001...65.4
2002...43.6
2003...59.3
2004...64.1
2005...54.4
2006...53
2007...55.8
2008...50
2009...38.6
2010...56.2
2011...60.5
2012...65.1
2013...64.3
2014...51
2015...39.9
2016...58.6
2017...49
2018...44.3
2019...59.6
2020...60.8
2021...34.8

Further, it is very likely that some of the decrease is due to loss of green space from land use change ("paving over paradise").
But the decrease may also be partly due to changes in precipitation (either climate change or natural variability). If Edmonton dried out over those two decades, that would also help to explain the loss.
The StatsCan report makes no attempt at attribution. To make that determination, you would have to know how much green space Edmonton actually paved over.