At a time when the entire Chicago area needs to do more to protect trees and plant new ones, we were pleased to see an Evanston alderperson raise concerns about the effect the rebuilding of Northwestern University’s football stadium might have on her city’s tree canopy.
It’s not clear how much the university’s plan to divert groundwater to the North Shore Channel would affect Evanston’s trees, a worry Ald. Eleanor Revelle (7th) cited. But it’s high time a concern for trees is at the forefront in every discussion about development throughout the Chicago area.
Climate warnings are everywhere. In recent days, New England has been deluged with flash floods, and areas of the southwest have been sweltering under temperatures of 110 degrees or more day after day. Smoke blown in from Canadian wildfires rendered Chicago-area air unhealthy for many days recently. Mature trees can’t fix climate change, but they can mitigate the effects.
A healthy urban tree canopy lowers ambient air temperature and cools paved areas that otherwise would be heat islands. Trees filter the air, removing pollutants and helping people who have problems breathing, and by absorbing carbon dioxide they keep it from heating the planet as a greenhouse gas. They soak up storm water that otherwise would exacerbate flooding, and are of particular benefit to people who don’t have air conditioning. Migrating birds and other wildlife welcome the habitat trees provide. Plus, trees make walking about the city more pleasant.
According to the U.S Department of Agriculture, Chicago area trees are storing about 16 million tons of carbon.
Evanston’s tree canopy of close to 40% coverage has won the city numerous Tree City awards. The city has an active network of volunteers and organizations that works to protect trees. By contrast, Chicago’s tree canopy covered only 16% of city land, according to a survey in 2021. According to the Chicago Region Trees Initiative, the entire Chicago area’s canopy cover of 23% is far below the national average.
Call 311 to get trees planted
Last year, former Mayor Lori Lightfoot set a goal of planting 75,000 trees over five years in 22 community areas — many on the South and West sides — that suffer from pollution and heat islands and that have vulnerable populations. Chicago also has established an Urban Forestry Advisory Board that has started meeting, and tree ambassadors — neighbors and community organizations — now are getting paid to go door-to-door to encourage people to call 311 and ask that a tree be planted.
Among the barriers to expanding the tree canopy have been people who don’t want trees, worrying roots will get into their water or sewer pipes or that trees will drop large branches on their houses or cars. Tree ambassadors can explain how calling 311 to have trees trimmed or dead ones removed can prevent many of those problems. If a dead tree has been left standing for too long, it will discourage residents from wanting a new one.
Besides planting new trees, Chicago-area communities need to protect mature ones by doing such things as inoculating ash trees. Planting trees is important, but it is the full-grown trees that do the heavy work of improving the environment. And those trees need care. People don’t always realize, for example, that driving heavy equipment across roots can doom even a healthy tree within a few years.
Chicago was a leader a century ago in nurturing an urban forest. But other cities passed Chicago as it suffered a net loss of trees. From 2010 to 2020, the city’s number of trees declined by 10,000, partly because the city cut down healthy trees for development or to replace pipelines in streets. In recent years, the city also lost ash trees to the emerald ash borer.
Evanston’s concern for trees should be a model for the metropolis. We hope to hear more local officials talk about protecting trees when new projects are discussed.
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