The Case for a Thriving Tree Canopy
This article is a synopsis of research from the Sun-Times, Chicago Tribune, Morton Arboretum, and Climate Central.
This information has been responsibly recycled by Julia Utset and Claudia Jackson.
What Is a Tree Canopy?
Tree canopy refers to the upper layer of forests formed by mature tree crowns, including the leaves, branches, and stems that shelter the ground below.
A high-quality canopy from large, healthy trees with abundant leaf area provides more benefits than small trees such as buckthorn and honeysuckle. Benefits include pollution filtration, carbon sequestration, oxygen production, stormwater management, urban shading and cooling as well as better illness avoidance and recovery and improvement to overall mental health and well being.
The Facts
Chicago's tree canopy cover shrank from 19% in 2010 to just 16% in 2020, trailing behind New York and Los Angeles, largely due to the loss of mature ash trees.
The tree population in the greater Chicago area grew from 157 million in 2010 to 172 million in 2020 due to the proliferation of the invasive European buckthorn. However, buckthorn reduces the diversity of the forest by outcompeting native plant species and does not grow large enough to provide the benefits of canopy trees.
On average, each year Chicago has lost about 10,000 more trees than it has planted since 2010 due to pests, disease, resident request and development.
Why It Matters
Trees can alleviate impacts from urbanization and help communities adapt to climate change.
By cooling air and surface temperatures, trees reduce the health hazards of extreme heat.
Trees also slow and soak up rainfall, filter the air, and absorb harmful carbon pollution.
Trees in the region remove 18,600 tons of pollutants from the air per year, valued at $192 million annually in public health savings, including the health care costs avoided due to lower rates of diseases and respiratory issues.
In addition to trees lessening the negative effects of air pollution, studies have shown that exposure to trees can boost mood, speed recovery times from illness, and improve overall mental health and well-being.
So What Can You Do?
See something, say something. Submit a tree service request through CHI311 to report a dead tree or damaged tree.
Consider helping water trees in city parkways.
Join a group like Openlands TreeKeepers.
Property owners can help by planting the right tree, in the right place, with the right care, ensuring that trees mature to provide the greatest possible benefits.
Residents should replace buckthorn on their property with native species such as dogwood and witch hazel.
Demand more green space.
Continue to support the conservation work of the park districts and forest preserves.
Chicago’s official motto is “urbs in horto” — City in a Garden. For the health of the city and its residents, let’s do all we can to live up to that motto!
Leave a comment below, or contact the Environmental Action Committee at environment@lwvchicago.org with questions or suggestions.