With vast swathes of the American west baking under a record-setting heatwave, a new study has revealed how unevenly trees are spread throughout cities in the United States and how much it disadvantages communities of color and the poor.
In order to address the balance, America needs to plant more than 30 million trees in major urban environments across the country, according to a major new report.
The first-ever nationwide tally of trees, known as the Tree Equity Score, combines several metrics, including socioeconomics, population density and existing tree cover. Their goal is to show which locations have enough trees for optimal health and economic benefits.
The study examined 3,810 municipalities, including 150,000 neighborhoods and 486 cities with at least 50,000 residents across the country. It found that in order to establish tree equity, cities need to plant about 31.4 million trees – about a 10% increase from the tree cover of today.
Trees are especially lacking in neighborhoods where minorities live, and more prominent in white, affluent neighborhoods. Neighborhoods with a majority of people of color have 33% less tree canopy on average than majority white communities. And neighborhoods with 90% or more of their residents living in poverty have 65% less tree canopy than communities with only 10% or less of the population in poverty.
The cities that will benefit the most from achieving tree equity include Chicago, Columbus, Detroit, Fresno, Houston, Jacksonville, Los Angeles, Memphis, New York City, Oklahoma City, Phoenix, Portland, Sacramento, San Diego and San Jose.
“We need to make sure the trees go where the people are. Tree Equity Score steers us in the right direction, and now it’s up to all of us to go beyond business as usual and take bold action,” said Jad Daley, president and chief executive officer of American Forests, the non-profit which commissioned the study, in a statement.
“Tree Equity Score steers us in the right direction, and now it’s up to all of us to go beyond business as usual and take bold action.”
Numerous studies show a clear relationship between the urban forest and physical health: shade trees promote physical activity and mitigate the effects of heat on health – especially during heat waves.
Trees cool the area immediately around them through shade and transpiration, or the evaporation of moisture from leaves – usually leaving the surrounding 100ft about 3F cooler than other places. Trees also remove fine particulates from the air, letting residents breathe easier. American Forests research in Dallas showed heat-related deaths could drop by 22% with a combination of trees and reflective surfaces.
Urban forests are responsible for almost one-fifth of the country’s captured and stored carbon emissions, according to the report.
But the number of urban trees is shrinking due to storms, construction and insects: at the moment, the US is facing a projected loss of 8.3% in urban tree cover by 2060.
Planting trees can have economic benefits, as well: the study authors write that 228,000 jobs would be created – and there would be a savings of nearly $1.6bn a year from things like asthma-related emergency room visits avoided by less polluted air.
Some cities have already invested in shade equity – in Los Angeles the mayor, Eric Garcetti, appointed a city forest officer in 2019 to oversee the planting of 90,000 trees, focusing on neighborhoods that are lacking in shade. Phoenix has also pledged tree equity by 2030.