by Nancy Furness
Trees have 350 million years of experience in looking after our planet and over time humans and trees have developed a beautiful relationship. Trees provide us with food, oxygen and many other useful products, while we produce carbon dioxide and water which trees use in the process of photosynthesis. We could not survive without trees. Trees contribute to mental and physical health, and community building as well. Additionally, the ecological services that mature trees provide is staggering.
While urban trees provide a source of beauty and interest in a potentially bleak urban landscape, humans are drawn to trees by more than aesthetics. Trees reduce our blood cortisol levels, which means less stress. Our brains view cities as hostile, violent environments eliciting a “fight-or-flight” response. Connecting with nature in contrast, lights up the part of our brain responsible for empathy and altruism.
Trees build community and provide favourite gathering places. In neighbourhoods with more trees studies show that people get out more, know their neighbours better, and experience less anxiety and depression, mental fatigue and violence. Urban trees may provide the only opportunity to enjoy nature for less mobile folk including children, the elderly and less affluent.
Trees are good for business too. Mature trees buffer street noise and increase property values. People prefer to shop and browse in areas with ample trees. Business areas with tree-lined streets are even perceived to offer product of higher quality and value.
Increased canopy coverage increases the livability of cities in many other ways too. One large tree can absorb 150kg of carbon dioxide a year, as well as filter out airborne pollutants, including fine particulates. One medium sized tree produces enough oxygen for a person for an entire year. Even a single tree can provide much needed habitat for birds, insects and small mammals including bats.
Extensive paved surfaces contribute to warming referred to as the urban heat island effect. Shade provided by trees can drop summer temperatures by up to 8ºC providing much needed relief. This can reduce air conditioner use by 12-30%, thus reducing costs and carbon emissions. Unlike impermeable concrete and paved surfaces, mature trees hold and absorb water reducing localized flooding during intense rainfall events.
However, canopy coverage in many urban areas is declining. As a result of densification and space constraints, large mature trees are often replaced with smaller species and conical varieties – if at all. These replanted trees then struggle to establish and reach maturity due to the demands of an inhospitable environment.
Despite research findings city councils, planners and developers, in whose hands the fate of urban trees ultimately lies, often fail to heed the value of retaining our leafy giants. Mature trees are generally viewed as costly impediments to development – nice, but not necessary.
Putting a price on the value of retaining even a single mature tree is challenging. The subjective value we place on trees and nature is informed by childhood experience. Childhood dislocation from nature can result in an “extinction of experience”. Each generation passes on less experience of the natural environment – and as policymakers and future environmentalists, they have a poorer understanding of nature and so value it less.
Use of tree valuation procedures and the open source software i-Tree now allow us to appeal to city officials by monetizing some of the quantifiable benefits of trees. This helps cities, planners and developers understand the value of retaining mature trees.
The value of retaining one particular tree in Port Coquitlam has recently become a point of contention between the City of Port Coquitlam and a local tree advocacy group (PoCo Heritage Trees) as it stands in the path of a proposed major downtown revitalization project. Impending loss of the tree has also raised the ire of many folks in the community. It should be fairly noted that despite the complete disregard for retention of mature trees on site, the development is much needed, otherwise thoughtfully planned and contains many positive aspects.
The amenity value of the tree, a healthy, structurally sound Deodar Cedar (Cedrus deodara) tree adjacent to 2263 McAllister Ave in Port Coquitlam has been calculated to be $158,154.50 using above methods. Additionally, using i-Trees’ “MyTree” application, the ecological services value of the Deodar Cedar can be calculated to quantify storm water run-off avoided, rainfall intercepted, details of pollution intercepted, energy emissions avoided and carbon sequestered (e.g., the lifetime CO2 equivalent of carbon absorbed by the Deodar Cedar is 27,852.99 lbs).
Instead of incorporating the tree as a welcoming focal point of a community plaza, a natural meeting place out of the baking sun or pouring rain, and a place for musicians to perform and children to play, the tree will be removed to make way for eleven parking stalls. During a time of climate change and densification, it is concerning that urban renewal and development in public spaces fail to consider the merits of retaining mature trees.
The fight to protect the Deodar Cedar appears to have been lost, highlighting once again the need for consideration for retention of mature trees during the development phase of projects and the importance of meaningful public consultation prior to finalizing major public development plans.
Now more than ever, trees are a vital component of healthy, livable, and sustainable communities. Going forward, we need to educate the decision-makers and maintain political and public knowledge over the long term with respect to why mature trees must be retained and replaced as required. We must be keepers of the knowledge that even a single tree within the urban forest contributes to making our community a greener, healthier and happier place to live, work, learn and raise our children.
The PoCo Heritage Tree (PHT) group and TriCities Community Television will be on site at 2263 McAllister Ave. on Monday August 10th from 7 – 8 pm. PHT welcomes you to join us for a family-friendly celebration of trees as we bid farewell to our beautiful Deodar Cedar. There will be live entertainment (one of our favourite local musicians will be performing Big Yellow Taxi under the tree) and we will be receiving a visit from the Lorax and other colourful characters. Information about the importance of trees and how we can move forward together to protect and enhance our local urban forest will be available.
Note: In order to meet COVID 19 requirements, masks are required. We have a plan to ensure social distancing should our group size exceed 50. Please RSVP with number in your party to email@example.com