About Evanston’s Trees

How many City (public) elms does Evanston have? As of 2020 the City had 2,371 that are 10” or larger in diameter, of which about 1,300 are larger than 30” in diameter. In 2004, Evanston had about 3,600 mid-to-large public elms. City elms are mainly on parkways and in parks and Ladd Arboretum. In 2020, the City was able to treat all these public trees for Dutch Elm Disease.  However, many elms are in overall decline with poor root systems, which makes it difficult for them to absorb the treatment.  The City is concerned that many elms may die in 2021-22.

How many Elms are in residents’ yards? The number of private elms is unknown.

What does it cost to treat an elm tree? $382 for an average sized elm. Healthy elms are treated every three years to prevent infection.

What is the cost if the elms are not treated? Elms tend to contract the disease and to die quickly if not treated. The disease generally is not reversible once contracted. It costs @$2,000 to take down an average big elm and $370 to plant a new tree. An elm that is diseased or dead must be removed to avoid injuring people or property.

What is Dutch Elm Disease (DED)? DED is a fungal disease that is spread by the elm bark beetle and kills elm trees. When the tree is infected, it tries to block the fungus and also blocks water and nutrients, starving itself.

Should residents pay to treat their parkway elms? Wealthier residents would be able to pay for elm treatment, and not poorer residents. This would result in the loss of some of Evanston’s largest trees in poorer neighborhoods. The damage that will be done will persist, since small replacement trees (if they survive) could take many decades to restore the economic, health and climate benefits that these old elms provide. Further, the City EPlan Assessment of Needs (2016-2021) reported that:

  • Poorer Evanston residents have higher rates of asthma: 21% of residents with incomes under $49,999 reported asthma compared to 18% of residents with incomes over $100,000.
  • 22% of Black or African American Evanston residents reported asthma compared to 18% of white residents.

Why should we care about trees, including elms?

Trees are important for people. They produce oxygen and release moisture, relieve heat and the result is they are calming. Trees are correlated with lower domestic violence, lower adolescent aggression, less driver rage, slower driving, quicker patient recoveries, and lower child asthma rates. And not just a little: 52% fewer crimes (property and violent) in apartment complexes with more greenery. New York City credits trees with saving 8 lives per year because of particulate capture.

Big trees are much more effective than the same number of smaller trees. A big tree removes 60 to 70 times more pollution than a small tree. A big shade tree can lower surrounding temperature by 10 – 15oF (“heat island effect”) and reduce noise by 6 – 10 decibels. They shade houses in summer and block winter winds reducing energy heat bills by 3%. Consider what it would cost in social services and infrastructure to calm tempers, cool us and save energy without trees. People might not miss them till they are gone.

The Evanston Climate Action Plan encourages preserving Evanston trees, expanding the city urban canopy and increasing green infrastructure to mitigate carbon emissions and enhance the city’s resilience to stormwater flooding.

Trees capture air pollution particulates. In a City Health Assessment, 19% of Evanston residents reported that they had been diagnosed with asthma, compared to 12% in the state and 14% in the nation. Trees help protect our residents, especially children who are particularly susceptible to pollutants and chemicals. A US Forest Service study found that owing to this particulate capture, trees saved on average one life per year in 10 cities studied, with 8 lives annually saved in New York City.

Trees reduce block winds and spread shade. A big shade tree can lower the surrounding temperature by 10 – 15oF, reducing the “heat island effect”, and saving an average of 3% on energy costs. Trees serve this function not only for homeowners, but also for their neighbors. Australia, a country that has felt the early impact of heightened warming, is considering rezoning areas to allow for more trees on lots to protect against devastating heat waves.

Trees filter and help absorb stormwater and release moisture into our air. This stormwater management is particularly critical as climate disruptions threaten increasingly heavy rainfall events. The US Forest Service reports a mature tree intercepts 2,500 gallons rainfall per year. Trees also of course capture carbon and release oxygen.

Trees are calming. They reduce stress, promote healing, encourage community and improve safety. Studies have demonstrated neighborhoods with trees have lower domestic violence, less ‘road rage’, slower traffic, higher home values, enhanced shopping sales, healthier residents with lower blood pressure, enhanced worker productivity, and greater reported sense of safety; adolescents exhibit less aggressive behavior.

Sources on trees

  • Value of trees
  • Big trees and pollution
  • https://www.theguardian.com/environment/2014/jan/15/trees-grow-more-older-carbon
  • https://environment-review.yale.edu/carbon-capture-tree-size-matters-0
  • https://www.wbur.org/earthwhile/2020/01/23/boston-urban-forest-street-trees