Street Trees: More than Meets the Eye

By Marguerite Huber

Tree-lined street

There is more to street trees than meets the eye.

Ever since I took an urban forestry course in graduate school, I can’t help but always look at trees. I look at their bark, their roots, and their leaves. But when I look at trees, I am not just seeing their physical attributes. I also see all the conceptual benefits they provide to our communities.

Trees are not just a pretty fixture in your backyard. They provide many ecosystem services to our cities and towns, including: improving air quality, absorbing and storing carbon, supplying privacy, reducing noise, increasing property value, and decreasing building energy use. Trees are an important aspect of the green infrastructure that helps reduce storm water flow.

Amazingly, you don’t have to be an arborist to calculate tree benefits; you can use i-Tree, a USDA Forest Service model that uses sampling data to estimate street tree benefits.

In the fall of 2013, EPA scientists began research on “street trees” (trees growing in the public right-of-way, usually in between the street and the sidewalk) in nine communities in the Cincinnati, Ohio metropolitan area. The randomly selected communities all differ in geographic setting, socioeconomic characteristics, and street tree management practices.

Their research aims to answer such questions as: Can street tree structure and benefits be explained by management practices, socioeconomic conditions, or historical or geographic factors? How might invasive pests affect street trees and their benefits? How will existing street tree structure and benefits change in the future under various scenarios of tree growth and mortality, management practices, and pest outbreaks?

Researchers sampled more than 53 miles of street right-of-way along more than 600 street segments and inventoried nearly 3,000 trees. The street tree benefits were estimated using i-Tree Streets.

At this time researchers are still analyzing street tree benefits and their relation to community characteristics such as management practices, socioeconomics, and geographic setting. So far they have found management practices to be particularly important, with Tree City USA participants gaining greater benefits than communities that do not participate. Since analyses are still continuing, the findings on the other community characteristics will be released in the coming months.

When the project is completed, the researchers will have deliverables such as street tree inventory data that can be shared with community officials and an understanding of which community characteristics influence street tree structure and ecosystem services.

I invite you to check out i-Tree for yourself; I suspect as you’ll realize there are more to street trees than meets the eye.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.