While the Twin Cities’ verdant tree canopy of summer, and golden version of fall are distant memories in these short winter days, now is the time to assess your urban canopy and attend to your trees’ pruning needs.

That filtered light that many take for granted does not come easy in an urban environment. To help others understand the importance of the tree canopy, Twin Cities resident and fervent tree advocate Barb Spears suggests: “Look out the window. That’s urban forestry. Now picture all the trees gone.”

It’s this apocalypse that Spears works against, supporting trees — she calls the “ultimate perennial” — through her volunteer roles with the St. Paul Tree Advisory Panel, the “tree team” of the Hamline Midway Environmental Group, as a member of the Board of Directors of the MN Shade Tree Advisory Committee, and leader in the Minnesota Women’s Woodland Network.

Friends Through Forestry

Spears counts friend and colleague Teri Heyer, as her inspiration. They met in their early career years working for the USDA Forest Service, and both had urban roots — Heyer was a New York City native and Spears had grown up in St. Paul. Both cite Dutch elm disease, which ravaged urban forests in the 1970s, as early inspiration for their dedication to this work. And both continue their commitment to trees, now through the challenges of emerald ash borer, in advocacy roles that are personal and professional.

Urban tree canopies provide many benefits.
A verdant tree canopy provides many benefits.

Benefits of Urban Tree Canopy

It is easy for the two friends to tick off the advantages of the urban tree canopy not only to water quality, but also to the larger community.

1)  Cleaner lakes and rivers

A big tree can hold up to 100 gallons of water after a rain.
A big tree can hold up to 100 gallons of water after a rain.

Key among the benefits are the ways trees help with storm water management, from the top of the tree acting like an umbrella where leaves and bark break the impact of a rain events and absorb water, to the roots that both take up water and bind soil preventing erosion. As the Arbor Day Foundation notes, depending on the size and species, a tree may store 100 or more gallons of water after one to two inches of rainfall.

Even decomposing leaves on the ground have a role. As insects eat the leaves, a spongy layer spreads that — together with fungi — retains moisture and provides nutrients such as nitrogen and phosphorus used for plant growth.

2)  Cleaner air

Spears notes that Minnesota’s Department of Health recognizes the importance of healthy trees because trees help improve air quality by removing air pollutants without harming the tree. Trees also shade streets, cars, and parking lots from high temperatures in the summer that can produce more air pollution. Indirectly, trees help reduce air pollution by lowering energy use and costs in both the summer and winter.

3)  Safer, healthier communities

Spears also cites the benefits of what she calls “community forests” — any area where trees and people come together. According to Tree Trust, a nonprofit in St. Louis Park dedicated to preserving and growing the urban forest, among the societal benefits of trees are: reducing violence, healing, bringing diverse groups of people together, and encouraging civic pride.

Caring for the Urban Canopy

Spears and Heyer see roles for every resident in tree care and maintenance. “It has to start outside your back door,” says Heyer. “Every tree counts.”

1)  Provide regular maintenance

Care for your urban tree canopy by pruning before the sap flowsl.
Maintain your tree canopy by pruning sap trees in the winter.

At the individual home-owner level, the management of these natural resources often means maintaining one or two trees in a front and back yard — and, ideally, “adopting” a boulevard tree in a collective effort with neighbors. Homeowners can take these simple steps:

  • mulch around a tree’s base to retain soil moisture and reduce competition from grass and weeds;
  • water, as needed;
  • mow and weed-whip carefully, to avoid damaging tree bark.
  • For more information, see: The Tree Owner’s Manual.

2)  Call a professional.

Both Spears and Heyer are fans of maintaining existing trees, with the help of a certified arborist who can assess pruning needs and risks of such nemeses as emerald ash borer, as well as the consequences of weather events. Heyer recently began treating a large green ash tree in her backyard against emerald ash borers. As she says: “The cost of taking down a large tree was a big factor in the decision to treat the tree, but there is an emotional attachment as well.”

Contact http://www.isa-arbor.com/ to find a local arborist.

3)  Plant the right tree in the right place.

Understand the importance of the urban tree canopy, and plant accordingly. Some areas may favor fruit or smaller ornamental trees over taller shade trees. Make sure taller trees have space to grow without interfering the electrical infrastructure or buildings. Over a tree’s lifespan, pruning will be necessary.

“We want to encourage ownership and build concern for individual trees in yards, so that people can extrapolate how their trees contribute to the overall community tree canopy, to state forest resources, the national forests, and beyond,” says Spears.

Nothing less than the quality of water and air, and the health of communities themselves, depend upon this understanding and commitment.

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  1. Hi Nick –
    The City of St. Paul has information on their Parks and Rec page about how they are managing EAB. They are treating some of the trees with insecticide, as you mentioned, but are also removing trees in some parts of the city to strategically reduce the number of ash in places where the trees aren’t healthy enough to treat with insecticide. Here are some links to their info:
    St. Paul EAB: https://www.stpaul.gov/departments/parks-recreation/natural-resources/forestry/disease-pest-management#emerald
    Citywide EAB management: https://www.stpaul.gov/departments/parks-recreation/natural-resources/forestry/disease-pest-management/citywide-eab
    Structured removal: https://www.stpaul.gov/departments/parks-recreation/natural-resources/forestry/disease-pest-management/structured-removal

  2. Maybe you should talk to the city of St. Paul. They’ve been overcome by the Emerald Ash Borer hysteria and are in the process of deforesting my entire neighborhood. I was under the impression that EAB is treatable.

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