Researchers Finding Evidence of the Negative Impacts of Trees in Urban Settings

More and more evidence has emerged in recent years about the many benefits of trees in urban environments. Every now and then, however, a study finds evidence that tress might not always be as benevolent as they seem.

November 11, 2015, 10:00 AM PST

By James Brasuell @CasualBrasuell


Trees and People

WDG Photo / Shutterstock

Rob MacKenzie shares insight into new research that might complicate assumptions about the role of trees in urban environments. The problem, writes MacKenzie: "some recent studies have suggested that trees may in fact worsen urban air quality by trapping pollutants at street level."

It's not that simple, of course, and Mackenzie insists that a closer look at the evidence "can help us come to a more nuanced understanding of the impacts of trees on our urban environment."

It all has to do with effect of the cocktail of buildings, structures, and landscapes that make up the city, of which trees have a unique role to play. "Trees affect the urban environment in several subtle ways. From altering air flows, to collecting pollution deposits, to affecting the chemical make up of the atmosphere, their impacts are both pervasive and difficult to pinpoint," writes MacKenzie.

So while MacKenzie goes into more detail about the several different pollution processes tress take part in, no studies have so far managed to put all the pieces of a city together. In lieu of a comprehensive model, MacKenzie uses the article as an opportunity to suggest strategies for piecing together different studies to create a more complete picture.

For more on the complex questions posed by the role of trees in the urban environment, an earlier article by John Gallagher first raised some of the same discussion points.

Tuesday, November 3, 2015 in The Conversation

Chicago Commute

Planning for Congestion Relief

The third and final installment of Planetizen's examination of the role of the planning profession in both perpetuating and solving traffic congestion.

May 12, 2022 - James Brasuell

Twin Cities

Minneapolis Housing Plan a Success—Not for the Reason You Think

Housing advocates praise the city’s move to eliminate single-family zoning by legalizing triplexes on single-family lots, but that isn’t why housing construction is growing.

May 13, 2022 - Reason

LAX Cars

Car Noise Is Killing Us

It’s not just traffic collisions that kill—a new study from researcher at Rutgers finds that the loud noises emanating from cars has direct impact on heart health in Americans.

May 6, 2022 - Streetsblog USA

Rittenhouse Square, a park in Philadelphia, framed by large buildings.

Parks as a Weapon Against Climate Change

The 2022 ParkScore finds that cities are increasingly employing green space as a tool for mitigating heat and extreme weather effects, but the distribution of parks remains inequitable.

May 16 - Trust for Public Land

View of Louisiana state capitol building and downton Baton Rouge, LA

Louisiana Capital Shifting to Electric Transit

The Baton Rouge area is now served by a fleet of nine all-electric buses.

May 16 - American Journal of Transportation

Mount Rainier

New Community Engagement Practices for Seattle’s Comprehensive Plan Update

A major update of Seattle’s comprehensive plan is just getting under way, with new opportunities for local groups to get involved with outreach and engagement.

May 16 - Capitol Hill Seattle Blog

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Hand Drawing Master Plans

This course aims to provide an introduction into Urban Design Sketching focused on how to hand draw master plans using a mix of colored markers.