“We have underestimated the importance of trees. They are not merely pleasant sources of shade but a potentially major answer to some of our most pressing environmental problems.” —author and science reporter Jim Robbins, New York Times, 2012.

MANY VOICES ARE WORKING HARD to convince Victorians to embrace Missing Middle rezoning. 

As proposed, the rezoning would allow multiplexes to be built on any residential city lot—without the need to consult with neighbours, go before council, or take time for a public hearing.

Developers and others argue that we should see the proposal as not just a good idea, but urgently necessary to address the housing crisis.

Leafy streets like this abound in Victoria's single-family neighbourhoods. Victoria’s Missing Middle Initiative, if implemented, would reduce such verdant yards.

However, getting it wrong could cause significant damage to the public good. Part of that damage would likely be a vast decrease in numbers of mature trees. Thousands of homes could be affected throughout the 70 percent of Victoria that is now devoted to single-family neighbourhoods. At least two-thirds of Victoria’s mature trees are on private property. 

Why would losing trees be a problem for Victoria citizens? Two big reasons: A large loss of canopy could decrease air quality, and decrease our ability to cool neighbourhoods during heat events. 

Both would cost lives. While housing is desperately needed, we must take care not to obliterate the urban forest that provides us with so much value for citizens’ health and wellbeing.

Examples of  Missing Middle-type housing from the City of Victoria's design guidelines. Most of the trees shown are on public boulevards.

Heat mitigation

Right now, cities all over the world are urgently planting trees to lessen effects of extreme heat events, which all too quickly have become normal. 

But the large, mature trees already growing in Victoria are far more efficient than tiny saplings at capturing air pollution, cooling neighbourhoods, and reducing the urban heat-island effect (not to mention storing carbon). 

The heat-island effect occurs when built surfaces like cement and asphalt bake in the sun, retain heat, then release it slowly. It causes urban temperatures—indoors and out, both day and night — to be much higher than those in rural areas. 

During last year’s heat dome, 98% of the 619 BC residents who died were heat-injured within a residence. 

Of those, 39% were in a condo or apartment. Another 33.9% were in single detached homes. 

Often, those who died lived in poorer neighbourhoods. Studies with satellite imagery verify that lower-income neighbourhoods generally have hotter surface temperatures because they have fewer trees. 

A Tyee article told a touching story of one older woman, who feared she would die in her very hot New Westminster apartment during last year’s heat dome. She tried to escape the heat by parking under the cool shade of mature trees, until a friendly stranger offered help. Those trees helped her survive, but many others died in their homes.

Some suffered heat injuries that caused kidney, brain, or other organ damage, and died days or weeks later. Others survived, but with permanently damaged health.

Finding ways to increase canopy in poorer neighbourhoods is considered a climate justice issue. 

A Fernwood Community Association working group is well aware of that. They wrote council recently: “The more green space removed from private dwellings, the hotter the neighbourhood gets.”

They cited a CBC report that revealed three large postal-code areas with much less vegetation than any other neighbourhoods in Greater Victoria—V8T, V8V and V8R respectively have 94%, 87%, and 50% less greenery than the coolest neighbourhoods.

Although a recent UBC study reportedly stated that Victoria’s urban forest is more equitably distributed compared to other (mostly larger) municipalities, CBC’s clearly shows a great deal of room for improvement in large areas of the city.

As the working group added, “The mature urban forest is desperately needed to mitigate the extreme heat events” predicted by the city’s own climate reports.

In a recent CBC article, Alex Boston, executive director of Simon Fraser University's Renewable Cities, made the same point. There is a “powerful business case for mitigating flood risk and for mitigating heat mortality events… it is those neighbourhoods that don't have the same strength of an urban tree canopy where you do have higher mortality rates, and that is something that we have to turn around,” he said.

In the same article, UBC professor emeritus Stephen Sheppard reported that the best and cheapest way to cool both individual homes and whole neighbourhoods is to create and preserve consistent urban tree canopy, 

Sheppard’s research found that well-treed neighbourhoods could be up to 8 C cooler than those where cement and asphalt predominate. And a 2018 Vancouver Park board report found even greater differences, of up to 20 C.

The US Forest Service says deciduous trees planted to the south and west of buildings can reduce the need for air conditioners by 30% or more.

Trees cool not just by casting shade, however, but also by releasing moisture through their leaves—a process called evapotranspiration. Research has also found that tall trees increase the movement of air, which provides a further cooling effect.

If the Missing Middle bylaw is implemented by the next city council, it could eliminate hundreds, perhaps thousands, of mature trees throughout the city, worsening the heat-island effect.

A Vic West house in the urban forest (2013 photo)

If this Victoria corner lot was redeveloped as Missing Middle housing, with up to 12 townhouse units, Victoria’s urban forest would likely lose 15 trees. 

Air pollution

Air pollution harms us at much lower levels than previously believed. In fact, the World Health Organization stated last year that no level of air pollution is safe. 

Even in nations that consider their air clean, the WHO says air pollution is already a public health emergency—in fact, the biggest environmental threat to human health. 

And, when wildfire smoke fills our city, our air quality quickly descends to among the worst in the world. This has happened frequently in recent years, with smoke carried from as far as Idaho and California. Wildfires are expected to increase, along with drought and extreme heat events.

When tiny particles of air pollution are inhaled, they can pass from the lungs into the bloodstream, where they can cause harm to any organ. Toxins in the air also cause inflammation. 

Studies show air pollution can reduce intelligence. It causes earlier mortality from heart attacks, strokes, lung disease, diabetes and dementia. 

It can cause serious problems for children, including retarding normal development of the brain and lungs. It also causes problems for fertility, and even for the developing foetus.

Trees help clean the air by capturing those particles on their leaves and trunks. They also absorb harmful gases such as ozone and nitrogen dioxide, as well as carbon dioxide. And they produce oxygen.

A UK study even concluded that the effectiveness of trees to reduce the health hazard of particulate matter might be “seriously underestimated.” 

Their study merely installed temporary trees along a roadside, but produced startling results– inside nearby homes, air pollution decreased by more than 50%.

So, as we reduce tree canopy, we reduce air quality—just as we need to safeguard it more than ever. If instead we could increase tree canopy, we could actually improve public health and reduce health costs.

Aren’t trees protected by the city?

Under the Missing Middle bylaw, a mere 6.5% of each lot (or 35 square metres, whichever is greater) would be required to be left unpaved, according to a City spokesperson.

That size is considered enough room for the roots of a single large-canopied tree, such as a Garry oak, Douglas fir or Big-leaf maple.

The City’s design guidelines do try to encourage developers to provide more green space. And, when any protected trees (30 cm diameter at breast height or larger) are removed, Victoria’s tree protection bylaw requires they be replaced. (More on “replacement” below.)

In addition, a minimum number of trees per hectare are now required on developed properties—usually three to four. However, if there is no longer enough room for tree roots and canopies to grow around the new, much-larger building, they can pay the City to plant trees elsewhere.

That may not benefit neighbourhoods that lost trees. And it still facilitates an enormous loss of mature canopy. 

Moreover, none of this really encourages developers to leave any large trees in place. Far from it—in the vast majority of developments, all trees and shrubs and even the soil are removed. 

“It has become standard practice for a developer to scrape the lot,” says Janet Simpson, a past president of Rockland Neighbourhood Association and a member of Community Trees Matter Network. 

At Abstract’s Bellewood development, 1201 Fort Street, 29 bylaw-protected trees were removed, including mature Garry oaks and the two giant sequoias in this photo. Abstract did save a number of mature trees on the site.

Tree removal plans can even exceed the boundaries of the lot, she adds.

“I’ve seen development plans that suggest adjacent pocket parks be deforested and paved over, to accommodate greater densification; that trees on neighbours’ properties be removed, to accommodate their own larger footprint; and that boulevard trees be sacrificed to accommodate perceived infrastructure needs.”

Susan Simmons, one of the new candidates running for city council, estimates that more than 11,000 properties could be affected by the proposed upzoning.

“There is no protection for the urban forest, our tree canopy, based on the current proposed policy,” she concluded in a post on her website. 

Simmons’ website shows one developer’s plan, identified as Missing Middle housing, which removed about 50 trees on a property. The developer only needed to apply for two tree-removal permits, she noted. 

Why? Because no trees are protected if they, or their critical root zones, are growing within the boundaries of a planned, allowable building. Otherwise, permits are only required for trees over 30 cm DBH (diameter at breast height). With a permit, even so-called “protected” trees can still be cut down.

As Simpson explained in the Times Colonist recently, “Two-thirds of the trees in Victoria are on private land, within the setbacks [minimum distance from property line] of buildings that do not maximize the allowable footprint. Up-zone most of those properties, and you provide the financial incentive to remove thousands of Victoria’s mature trees.” 

Saplings cannot really ‘replace’ mature trees

A building can be erected within a year or so. In contrast, it took long decades for our mature trees to achieve their present size. 

“Replacing” large trees with saplings causes an immediate local loss of canopy, as well as habitat for birds and wildlife. A neighbour of 1475 Fort Street said over the years she has spotted 22 species of birds in the abundant canopy of the big-leaf maples soon to be removed. Although the trees are on the outer edge of the property, developers were granted variances on all sides, which necessitated their removal.

This majestic Big-leaf maple tree, along with others on the perimeter of 1475 Fort Street, will be cut down, as the approved building will impact critical root zones.

Though we treat trees like disposable backdrops, in general, the bigger trees grow, the more carbon they sequester, the better they prevent floods, and the better they cool and purify the air. 

Yet developers and municipalities continue to propagate the fiction that the great benefits bestowed by mature trees will transfer to the puny saplings used to replace them. 

Mature trees don’t simply cast a great deal more shade. They are also more cost-effective than planting more saplings. With well-developed root systems that have withstood extremes of weather over decades, they are far more resilient than newly planted saplings. 

Saplings are vulnerable. Their small, shallow root systems recently fit in a pot. They have been stressed by transplanting, especially when it is not done properly, and by the demands of a new environment. Young, transplanted trees require regular watering for one to several years in order to survive. Even then, they can be more likely to succumb to droughts and weather extremes than mature trees.

What about the 60 soccer fields of new growth?

Last year, the City of Victoria celebrated the fact that its LiDAR survey showed our urban tree canopy had actually grown by 111 acres, or the equivalent of 60 soccer fields. In the middle of a hard year, this seemed astonishingly good news.

An FOI revealed that the growth was not attained through tree-planting, however. New plantings were “not considered a significant contribution,” Terra Remote Sensing’s report stated. The increase was achieved instead through natural growth of the entire canopy, at an average rate of 2 to 3% a year.

The “60 soccer fields” are actually more like compounded interest—yet another dividend paid by a mature urban forest: when left to grow, it gives even more.

As the LiDAR report explained, “the horizontal growth of existing vegetation offsets the effect of vegetation loss from urban development” and other causes. Mature coniferous trees, for instance, can grow two to three feet per year.

Between 2013 and the 2019 scan, there was so much growth (22.14 %), that there was still an overall gain, despite the fact more vegetation was lost than in the previous interval, between the 2007 and 2013 scans (-12.81%).

An image from the City’s LiDAR report indicating areas of vegetation loss (in red) from 2013 to 2019. Missing Middle policies will likely extend these areas into the 70% of the landbase now devoted primarily to single family zoning.

All vegetation taller than 2 metres was measured. However, scans don’t differentiate between healthy trees and those that might, for instance, be shrouded with invasive ivy. For this reason, data should be “ground-truthed” around the same time as the scan is done. 

The report’s final sentence encouraged the City to continue gathering information on the age, distribution, and species growing in the urban forest. This, they noted, will help it forecast future trends of growth—“and potentially predict when vegetation growth will cease to offset losses.”

If the Missing Middle is passed, that day will likely come sooner rather than later. (Portland is considered a leader in sustainable development. But its 2020 LiDAR scan found it had lost canopy for the first time—about 324 hectares. Worse, it lost that canopy mostly in the areas that were already hottest. Vancouver has so far managed to maintain its canopy level, by planting 150,000 trees over 10 years.)

The report also did not evaluate the health of Victoria’s publicly owned trees. That detail is at least as important as validating it was actually trees, not ivy, that filled those hypothetical 60 green soccer fields. 

Information that used to be available on Victoria’s open data portal (but has since been removed) showed that more than one-third of publicly owned trees are in fair to poor condition. Trees that are only in fair health cannot be expected to respond well to the stresses of nearby development, not to mention climate change.

Additionally, a few years ago it was reported that many of Victoria’s street trees are nearing the ends of their lives. That fact was also was not mentioned. 

As we have seen, the health and resilience of the urban forest are key to our own health and resilience. We need to track, invest in and maintain this vital inheritance to continue benefiting from its gifts.

How many saplings does it take?

An app called i-Tree (developed by the US Forest Service) can show a user approximately how many saplings it would take to reproduce the same environmental benefits that a mature tree provides. In one example, for instance, it would take 269 saplings, each 2 inches in diameter, to reproduce the benefits provided by a single 36-inch tree. 

Jeremy Gye, a consulting arborist and urban forester who contributed to Victoria’s Urban Forest Master Plan, says that if mature trees are removed and replaced at a sustainable and closely monitored rate, a municipality can predict the expected overall change in tree canopy over the next 20 to 30 years. 

But, “If too many mature trees are being removed to sustain a healthy age-class mix and canopy cover, then ideally two things need to happen: Slow down the pace of mature tree removals, and increase the ratio of replacement trees.” 

Gye says his greater concern is the loss of space in which large-canopy trees can grow: “Urban densification seems to be chewing up green space at an alarming and increasing rate,” he said.

“While trees can be replaced, good growing soils and the three-dimensional space to grow trees are a finite resource, and are expensive and difficult to replace. Where are our replacement trees supposed to be planted, and have room—and soil volumes—to mature in?”

A member of Community Trees Matter Network went to City Hall to give the mayor and counsellors a graphic example of the difference between a mature tree and a sapling. The circle she is holding is the diameter of the biggest tree at 1475 Fort Street, a Big-leaf Maple. The much smaller circle inside it is the diameter of the sapling that will “replace” it.

Gye is pleased that more municipalities—such as Victoria and Oak Bay—are encouraging all properties to grow trees to help sustain the urban forest. Owners of any property who request a development permit of any kind must now have or plant a minimum number of trees. 

“This is a huge advance in policy, in my opinion,” Gye said. “As the urban forest is now recognized as a vital piece of green infrastructure, surely all residents should be contributing to it?”  

Trees seem to hold a special place in people’s hearts and minds, whether or not they know all their benefits. A recent report from the David Suzuki Foundation found that a majority of people in Toronto would be willing to pay more taxes for more tree cover in their city. Perhaps Victorians too would be willing to pay more, and plant and maintain more, in order to have more healthy trees.

“It’s not about tree planting, as much as it's about keeping the trees alive,” explained Cecil Konijnendijk, a professor of urban forestry at the University of British Columbia in Vancouver, in a recent CBC article.

He added that doubling the life of urban trees would greatly increase the benefits they offer.

“That’s where it starts: The good stewardship of the existing tree population and protecting the trees as best as we can.”

What are the solutions?

The city of Tampa, Florida’s tree-protection bylaw is considered a star. Interestingly, it was hashed out through a year-long discussion between builders, city staff and tree advocates.

The bylaw has some unique features. It protects trees from a much smaller size than Victoria’s: all trees 5 inches (12.7 cm) DBH or larger. 

But  where Tampa’s policy really shines is that it is one of the few that considers actual canopy size being lost. 

The removal of a  “grand tree”– defined as 32 inches (81.28 cm) DBH or larger—requires enough replacement trees be planted that their canopies will match the canopy of the removed grand tree within five years.

With smaller protected trees, replacement rate is based on the size of the removed tree’s trunk, and the tree’s health. Replacements don’t have to be planted on the same property, but must stay within the same planning district. 

“This was considered an appropriate way to reduce the chance for socially inequitable shifts in canopy, and loss of subsequent ecological services, by forcing trees into sites where they would not thrive and grow to an older age,” explained Robert Northrop, extension forester of the University of Florida, in an email.

Clearly citizens and council should thoroughly consider all sides before implementing the Missing Middle bylaw. Everyone agrees that affordable housing is desperately needed, and development will certainly continue. But the City must make intelligent choices, with full awareness of what each alternative will cost residents and neighbourhoods.

Sometimes this might mean retaining mature trees for the good of all. It could mean introducing tax breaks for properties that sustain large, healthy trees, or creating a tree-replacement policy that could truly replace lost canopy. It could mean the City or a group of philanthropists start occasionally buying well-treed properties that come up for sale, to turn them into mini-parks and carbon sequestration stations.

It also means being creative, and finding places to grow trees for the good of all. In San Francisco, Friends of the Urban Forest have an agreement with the city to “de-pave” and tear out sections of concrete or asphalt to plant trees. In Tokyo, 10,000 trees were planted at 31 schools, in “tiny forests” that grow 10 times faster than normal.

At this stage of climate emergency, mature trees are not really replaceable because they take decades to grow—decades we cannot afford to wait. The mature trees we have are a great boon, one that should be cherished and protected, not squandered. We also need to keep planting trees, and take even better care of them, so they can survive the increasing stress of climate change…So we can too.

Grace Golightly (her name since birth) is a freelance writer interested in the protection of nature and human rights. She is also a founding member of Community Trees Matter Network.