The Future of Urban Forests

Why we need to rethink urban forest management

In a landscape of changing public perceptions, environmental challenges and new goverment legislation, it’s never been more important to understand how to best care for our urban forests.

Changing attitudes & changing ecosystems

If anything is constant, it is change. I have seen a lot of changes in attitudes over the years. There was a time when a well-kept property meant a highly manicured lawn, some well kept pruned hedges and shrubs, a small annual garden and maybe a tree planted in the middle of the front or rear lawn. People watered their lawns and gardens constantly, applied (sometimes heavily) herbicides and pesticides regularly, and created a very sterile environment. Any kind of bug or insect was to be eradicated as soon as possible.

Legisltation has helped protect our local ecosystems

A big change came in 2009 when provincial legislation came into affect superseding all the existing municipal by-laws creating a ban across Ontario on all cosmetic pesticides. Attitudes had shifted, the environment became more of a focus, we were doing more harm then good. Other things started to change, it seemed that summers were becoming drier, lawns became harder to manage and water shortages led to watering bans during periods throughout the summer. I remember a time when people used the garden hose to wash down their driveways. Gardens began to evolve as well. Some became “naturalized”, more wild and free. To some it was an eye sore, to others it was an eco-friendlier alternative to an outdated ideal of the perfect home lawn. Insects and nature were good things, pollinators were dropping in numbers and there were major concerns about the future of our planet. People had always had the odd bird house on their property but now there were bat houses, bee houses, toad houses. Things were starting to look up.

Invasive species bring new challenges

Another big change arrived in Ontario in 2002. A small green insect, detected near Windsor Ontario that would have a dramatic impact to our forests and urban canopy, the emerald ash borer. There had been other pests before, spongy moth, another non-native pest had arrived over 30 years earlier, it causes major deforestation but due to its cyclical nature many of the host trees have time to recover. There are also natural predators and pathogens to help keep it in check. Emerald ash borer was a different story, with no known natural predators it has had a devastating impact on the ash tree population, killing up to 99% of ash trees in its path. Ash tree was a very common forest tree and widely planted urban tree. With such high mortality the cost to remove and replace ash trees in the urban environment is in the tens of millions of dollars throughout Ontario and is ongoing. The costs to our forests are even higher. Economically, ash was commonly used for lumber, pulp, tool handles, furniture, and crating. Due to the complexity of our ecosystem, the loss of ash trees to our natural forests is relatively unknown and immeasurable in my opinion.

The damage to our urban forest has been high, naturalized areas and parks have been greatly impacted, residential neighbourhoods have seen dramatic changes in canopy cover, recreation and property values have been negatively impacted, the list continues. Trees are a long-lived organism, to most people they are an overlooked, under-appreciated back drop to our environments. They are just there. They seem to grow without much care or thought, they have always been there and will always be there.

Finding the right balance to support our urban forests

I think a big shift needs to happen now in regard to how we view trees. Trees evolved in a forest ecosystem, one that we still don’t fully understand. They evolved growing together in a complex web between the soil, the organisms in the soil, the air and sun and the weather. Roots grow freely, unrestricted by sidewalks, roads, driveways, and buildings, nourished by the decomposition or their own leaves and aided by the multitude of interactions between fungi, bacteria, and microorganisms. In our urban forests, we have removed them from their natural environment and placed them in an alien landscape. We remove most leaves and debris from around their roots, constrict them in compacted soils, devoid of any life, usually plant turf grass right up to their trunks, walk around and over their root zones (usually when cutting the lawn) further compacting the soil. Sometimes done with good intentions we bury them in mulch that is too high and causes further harm. Most people never think to water them or do anything else to help them survive. Urban trees are stressed, and things are not getting better. Climate and weather are changing, summers are getting drier and hotter, winters are getting warmer which means more pests and pathogens survive until spring, more non-native invasive organisms are on our doorstep.

The challenges aren’t stopping soon

In the fall of 2023, Oak wilt was found in Southern Ontario for the first time. It is a fungal pathogen killing thousands of oak trees in North American forests and woodlands each year and has the potential to due the same in Ontario. Trees have many documented benefits, they sequester carbon, produce oxygen, clean the air, assist with erosion control, increase property damage, reduce stress, and have a positive impact on mental health, the list goes on. Planting new trees helps but a recent study suggested that it would take approx. 200 small trees (1-4” diameter trees) to store as much carbon as one 26” diameter mature tree. With the survival rate of newly planted trees being very low, it would take years of planting to recover all the trees we lose annually.

Investing in your trees pays off financially and environmentally

It is time for another major change, people need to stop taking trees for granted, we need to think of trees as an asset and an investment in our futures. Urban trees are stressed and growing in less than idea conditions, they need our help. Are trees in our urban forest in trouble, I think so, but that can change.