As new studies show the fundamental connection between trees and human health, cities are recognizing the essential elements in cultivating thriving urban canopies. And they're enacting policies to ensure their protection and growth.
As Lindsay Abrams noted recently in The Atlantic, our ability to quantify the ways in which trees improve our physical and mental health - by providing oxygen, cleaning our air of pollutants, and in more nuanced ways - is steadily increasing. Despite this recognition, writes Leda Marritz, "The USDA Forest Service recently determined that U.S. cities are losing around 4 million trees annually — this at a time when average urban canopy cover in North America is still lower in most places than what is recommended by American Forests."
Why is it that cities continue to struggle to protect and grow their tree canopies? According to Marritz, creative director of DeepRoot Green Infrastructure and an ISA-certified arborist, at least part of the problem lies in the challenge of providing the right type and volume of soil to support tree growth. She points to examples from Toronto, Denver, Emeryville, and West Virginia, of ambitious policies that require street trees to receive a certain minimum amount of soil in order to support healthy urban forests.
"None of these policies is perfect," says Marritz. "There are tweaks, of varying sizes, that I would make to all of them. Still, they represent a critically important step to creating lasting, healthy, thriving urban canopy cover in cities."
"It takes more than a soil volume minimum to cultivate a thriving, mature urban canopy. Good tree stock, soil quality, adequate water and regular maintenance cannot be undervalued. But we’ll continue to lose canopy cover at an alarming rate if we don’t change the way we plant trees in cities," she concludes. "We know what this means, and we simply need to do it. It starts with soil."
FULL STORY: Saving the Urban Canopy

Legendary Parking Guru Donald Shoup Dies at 86
Urbanists are mourning the loss of a dynamic voice for parking reform and walkable cities.

Analysis: Cybertruck Fatality Rate Far Exceeds That of Ford Pinto
The Tesla Cybertruck was recalled seven times last year.

DOT Memo Directs Transportation Funding to Communities With Higher Marriage and Birth Rates, Compliance with Immigration Officials and No Mask Mandates
The memo ties immigration enforcement to federal funding and prohibits mask or vaccine mandates.

Housing Measure Wins in Seattle Special Election
Voters approved a new tax that could bring in $50 million per year for social housing.

Resilient Communities, Healthy Ecosystems: A Balanced Approach to Wildfires
Effective wildfire mitigation in California requires a holistic approach that goes beyond large-scale vegetation removal, emphasizing home hardening, defensible space, strategic planning, and reducing human-caused ignitions.

St. Petersburg’s Bike Infrastructure Efforts Pay Off
New bike infrastructure is encouraging more people to take to the streets on two wheels, but advocates say safety challenges remain.
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.
Planning for Universal Design
Learn the tools for implementing Universal Design in planning regulations.
City of Bakersfield
Standridge Inc.
City of Brookings
Harvard GSD Executive Education
Chaddick Institute at DePaul University
Great Falls Development Authority, Inc.
HUDs Office of Policy Development and Research
NYU Wagner Graduate School of Public Service