The past month has seen our communities burst into a state of green. Buds have turned to leaves and the canopy overhead has filled with foliage. Here in Ottawa, we’re fortunate to have many neighbourhood streets lined with majestic trees, and I’m always humbled to witness this seasonal transition. There’s certainly no better time to reflect on the value that trees bring to your community than when you’re sitting beneath one having a picnic!
Trees are an objectively beautiful part of our communities, and urban forests were historically valued based on their esthetic contributions alone. But as our scientific practices and understanding of ecosystems have evolved over time, so too have the ways in which we appreciate the many benefits that trees bring to our communities.
Bringing communities together
The presence of urban trees fosters a sense of community. Whether it’s seeing children crouch together to carefully plant the seedling that will shade them as adults, or spending time as a family watching the acrobatics of squirrels as they leap from one branch to the next, urban forests bring many a social benefit to the communities we call home.
Tree-filled parks provide a place for recreation and exploration, impacting not only our physical health but also our mental health and well-being. While COVID-19 has presented countless challenges, it has also offered greater time to appreciate the restorative power of chatting at a distance with a neighbour beneath a giant silver maple or pausing during a walk with a friend to spot the red blaze of a cardinal perched on a branch.
The presence of trees also makes people feel safer, and evidence shows that large trees can reduce crime in neighbourhoods. As our municipal leaders grapple with alternative ways to ensure community safety, healthy urban trees could be one piece of the puzzle.
The economic benefits of trees
Trees are one of the best long-term investments we can make in our communities.
For one, trees are a valuable green infrastructure. Green or natural infrastructure is the term used to describe when plants, soil, and other living parts of ecosystems are managed to help mitigate the effects of climate change or natural hazards.
The services provided by trees are just as important as those offered by human-built infrastructures such as storm sewers and flood prevention technology. Anyone who has ever sought shelter beneath a tree during a rainstorm knows that the dense canopy of a mighty deciduous tree can buffer the impacts of heavy rain. This allows rain to fall to the ground at a rate in which it can be absorbed by the soil, preventing sediment run-off into storm sewers and nearby water bodies. Adversely affecting lake health, clogging drains and ditches, and blocking important water navigation routes, sedimentation costs Canadians in excess of $100 million each year. Investing in urban forests can reduce this bill.
Invisible to our eyes is the role root systems play — long arms outstretched beneath the soil that prevent erosion and secure landscapes and other vegetation. The ability for trees to reduce erosion is of added importance for coastal and agricultural communities, the latter of which face an estimated $3.1 billion loss in productivity each year due to soil erosion.
Unlike human-built infrastructure that can deteriorate over time, trees only get better with age, storing more carbon, providing greater shade, and offering further habitat for urban wildlife.
Trees keep our urban temperatures in check
Perhaps you’ve experienced the sensation of being outside on a sweltering day, only to find respite under the shade of a tree. On the warmest of days, the relief can be akin to jumping into a swimming pool!
These anecdotal experiences are backed by scientific research. Urban trees reduce the intensity of heat islands — areas created when built environments such as asphalt and concrete are scorched by direct sunlight. Overhead urban tree canopy can reduce daytime air temperatures by up to 2.5 degrees Celsius, and is especially important to increase in lower-income neighbourhoods that have less access to green space and typically more concrete cover.
Sitting beneath certain varieties of trees can even make us feel physically cooler than resting in the shade provided by a man-made structure — interesting research that supports the psychological connection we have with trees.
The cooling capacity of urban trees has added public health importance this year. Some of the places where people may typically go to cool down and avoid heatstroke — public libraries, community centres, and shopping malls — are operating under reduced hours or remain closed due to COVID-19. Not everyone can benefit from air conditioning or natural ventilation in their homes, and tree shade can offer essential affordable relief.
Trees are an essential part of our communities and will take on even greater importance as the climate continues to change and Canada becomes more urbanized. We are laying the groundwork today for the type of communities we want our children and grandchildren to live in — with all the benefits trees contribute, we need to ensure they are included in the big picture plan for our future.