“I often visit a friend who lives on the 11th floor of the Mather and stand on her balcony overlooking the city. When viewed from above, it’s obvious how central trees are to Evanston’s identity and beauty. It’s our job to make sure we maintain that same clarity and sense of priorities when on the ground.” – Mayor Daniel Biss
“My favorite tree is the oak tree. Its leaves are bigger and it grows tall … Trees help the Earth’s environment. They also help Earth’s animals and birds.” – Bella V., age 8
Friday, April 26, is Arbor Day, a reminder that trees are almost magical in benefits they provide us. To celebrate, the City of Evanston last week planted a redbud, a red buckeye, a cornelian cherry and a tulip poplar in Ingraham Park, just west of the Morton Civic Center at Asbury Avenue and Leonard Place.
Arbor Day, started in 1872 in Nebraska, now is part of the Tree City USA program that includes Evanston.
Benefits of trees
Wendy Pollock, an Evanston TreeKeeper, found trees cooled an Evanston street 42 degrees. Last July, she compared the surface temperature in Valli parking lot (118o) and under mature trees on a residential street (76o) just a few minutes and one mile apart. This cooling is life-saving. Heat is the No. 1 weather-related killer, according to the National Weather Service, a threat that will grow worse with climate disruption.
Trees make such a difference because they provide moist oxygen, not just shade. They absorb moisture through their roots and, as part of the photosynthesis process, release moistened oxygen through their leaves. In addition, the water and nutrient uptake filters stormwater, reduces flooding, releases oxygen and absorbs carbon. A single mature oak tree with adequate water can release 150 gallons of water on a hot, dry day, according to the Illinois Master Naturalist curriculum guide.
There’s more: Their leaves capture smog and particulates, dropping pollutants to the ground with their leaves. Clearing the air helps people cope with respiratory or circulatory disorders (something that the Evanston EPlan reported most impacts lower-income residents). Plus trees lower stress, encourage drivers to slow down, draw communities outside, make our neighborhoods safer and encourage shoppers to dawdle and spend more.
Trees need our help. “Urban stresses make trees more susceptible to insect infestations and diseases,” says Michael Callahan, assistant director, Evanston Parks and Recreation. “We are going to have the cicadas this year and we will have to wait and see how that impacts the trees. We do see some vandalism at times as well as some damage from hot charcoal being poured at the base of park trees. Can you visualize your favorite park without the trees? Imagine how catastrophic it would be to lose them? They provide so much to so many!”
How you can celebrate Arbor Day
- Plant. Choose a native tree that benefits pollinators or birds. If you live in the Fifth Ward, ask Natural Habitat Evanston for a free native tree. Why native? Songbirds and insects are in dramatic decline even in our region. Native trees are best adapted to our soils and growing conditions, and they co-evolved with nature. Native insects need to eat native plants to develop. For instance, as the monarch caterpillar must eat milkweed, 90% of plant-eating insects also need particular families of plants, according to Prof. Doug Tallamy of the University of Delaware. Tallamy has prioritized plants by the number of caterpillar species they support, which he calls “wildlife value” because insects are the foundation of the food web. Native oaks, cherries/plums, willows, birch and poplars top the list. Tallamy will speak later this year in the Nurturing Nature Speaker Series.
- Care for your trees – and street or park trees, too. Water (1 inch of water per week from rain or watering during the growing season). Mulch 2 to 4 inches deep in a circle around the trunk about 2 to 3 inches wide, leaving a space around the tree trunk to allow air to circulate (and not rot the trunk). Mulch protects trees from mowers and provides nutrients. Cage trees with 2-foot-high chicken wire where rabbit protection is advisable.
- All trees need help. Young trees need care to get going, and old trees need help too. “We have numerous large and old trees in our parks and these are more susceptible to the extreme weather events we are experiencing,” Callahan says. “Changes in the climate are making it more challenging to manage our urban forest.”
- If you don’t have your own tree, adopt a street or park tree. Callahan reminds us, “The best time to plant a tree is 30 years ago, so plant a tree today for tomorrow and the years to come!”
Climate Watch is a series of occasional articles and essays about what climate change means for Evanston and what we’re doing locally to make a difference.