Benefits of Retaining Mature Trees

Benefits of Retaining Mature Trees

A healthy mature tree environment

Summer is approaching and in our ‘new normal’ that brings worries about drought and wildfire risk. The role of trees in climate change mitigation and fire risk can seem at odds. In 2018 the Fanny Bay Community Association, Baynes Sound Garden Club and Beaufort Watershed Stewards sponsored a town hall with a Certified Arborist, a Hydrogeologist and a Registered Professional Technologist. They reviewed the scientific evidence that underscores the value of mature trees in the landscape. Six years later this information is just as relevant.

This article reviews the arborist information with additional notes added by Verna Mumby, of Mumby’s Arboriculture Consulting. She highlights four key points regarding the retention of mature trees in the landscape: the overall benefits of trees, valuation of trees, how trees work together and retaining large trees.

A key benefit of mature trees is that they capture and store carbon. For example, in one year an average tree inhales 26 pounds of carbon dioxide – as much as a car emits in an 11,000-mile trip! Trees purify the air by removing pollutants such as carbon monoxide, sulfur dioxide and nitrogen dioxide. A mature tree can produce as much oxygen in one season as ten people inhale in one year. Mature trees also provide storm water benefits by intercepting rainwater, mitigate flooding and replenishing groundwater. Tree shade and cooler ambient temperature helps retain water in groundcover and surface soil. 

The monetary value of large trees may not be considered by homeowners. You may be surprised to know that large trees on your property can add from 3 to 15% to the value of your home. For homeowners with trees, summer energy costs can be up to 14% less, thanks to the shade that large trees provide.

The interdependence of trees is a more recent discovery. Trees work together in groups as they support and protect one another. These processes also enable trees to secure and protect the foreshore making them critical for maintaining waterfront embankments. This is why the Comox Valley Regional District bylaw restricts tree work withing 30 meters of high tide or a stream. Studies have shown that the roots of veteran trees can use from 40 to 60% of photosynthetic by-products to exude nutrients into the soil thus enriching the environment for undergrowth and future trees. This synergy is a hallmark of healthy ecosystems, including healthy home properties. 

“Limbing up” or the removal of the lowest branches on mature trees, especially cedars, will cause the roots to dry out faster as will removal of the natural debris (duff) from around the base of your trees. With climate change, mature trees are struggling during droughts and these actions are detrimental to their survival. 

Wildfire prevention programs offer advice concerning wildfires in the wildland urban interface, often the removal of trees and duff. BALANCE is needed when considering the benefits and risks in an ecosystem. How much will removal of debris from a yard negatively impact the large trees? How much shrubbery and ground cover can be removed without killing trees? Each property is unique, and optimal ecological solutions will vary.

How will your actions affect the local ecology and the mature trees that are one of the best ways to fight climate change?

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