Plants & Gardens Blog

Dr. Vivek Shandas on Trees and Equity in Cities

Dr. Vivek Shandas, a professor of climate adaptation at Portland State University, began thinking about the relationship between people and the nonhuman world at an early age.

“I grew up in Bangalore, a city in South India, where buildings, trees, monkeys, beetles, insects, cows, and chickens—they were all part of the city landscape,” says Shandas, who delivers the keynote address at this year’s Making Brooklyn Bloom. “It's where I first observed the relationship between people and nature, and internalized the fact that we have coexisted with nature in cities for as long as cities have been around.”

A man with grey hair and a navy button-down shirt smiles in front of a building.
Dr. Vivek Shandas. Image courtesy of Vivek Shandas.

Many cities, however—particularly in the U.S., where Shandas moved at age ten—have “systematically obliterated the bits of nature that still existed in them,” he says. This is disproportionately true in low-income communities and communities of color. Shandas and his colleagues have led a growing body of research demonstrating that formerly redlined neighborhoods in the U.S. are hotter, and have fewer trees, than non-redlined neighborhoods.

Here Shandas speaks about street trees, environmental justice, and how we can move toward a more equitable urban ecology.

Can you describe the relationship between street trees and environmental justice?

My colleagues and I are putting together a paper right now that addresses that question.

We looked at New York City, Washington, DC, Austin, Denver, and Portland, Oregon, and we found that the neighborhoods that have the lowest per-capita income have not only the fewest number of trees, they also have the smallest trees, and they have the highest number of potential spaces for trees where trees are not present. And we found that the higher-quality trees tend to favor the higher-income neighborhoods in each of these cities.

The quality of trees—as opposed to the quantity of trees—is an area that hasn’t been touched on as much in research. If a lower-income neighborhood tends to have smaller trees, then those trees are taking in less stormwater, providing less shade, filtering less air.

As a species, we evolved from the forests, and plants have been a direct form of medicine for us throughout our evolutionary history. And so when we start removing our ability to access green spaces, to access trees, we start removing our ability to breathe clean air, to find cool shelter, to stave off floods. We depend on plants, and many communities have been systematically restricted from accessing plants and all the medicines that they provide.

As we think about places that have fewer trees, we see through scientific literature that there is a connection to health outcomes like birth weight. We see that a family in a neighborhood with fewer trees would tend to have a higher likelihood of respiratory illness, simply because they were born in a neighborhood that a city has not prioritized for tree planting or green space development.

What is the “urban heat island effect,” and how does that relate to street trees and environmental justice?

More people live in cities than in any other part of the globe. Cities are largely built with cement, asphalt—these very hard, dense materials that absorb the sun’s radiation. Some neighborhoods have more of these materials than others, and so the sun’s radiation tends to amplify temperatures in those neighborhoods—more so than in areas that have less concrete, asphalt, and cement.

This means that there can be a 15-, 20-degree Fahrenheit difference between one neighborhood and another at the exact same time. So a household living in a neighborhood that’s 20 degrees hotter will likely be paying for it through health impacts, because we know that heat kills more people than any other natural hazard.

And we are warming up the planet as a whole—we see these enormous heat waves that are increasing in frequency, intensity, and duration. As they come through cities, their effects can vary by neighborhood. In 2021, when a heat wave called the “heat dome” came through Portland, Oregon, I went out with our sensors. I measured one neighborhood at 125 degrees Fahrenheit, and another neighborhood at 99 degrees Fahrenheit, all within a 15-minute period and within a five mile distance.

That is no coincidence. This has been happening for over 100 years. The communities living in these 125-degree neighborhoods were historically not a priority for city planning. Large infrastructure projects have landed there that have a lot more asphalt, concrete, and cement that absorb that sun’s radiation and re-radiate it out to adjacent households. These hardest-hit communities tend to be older, economically disadvantaged, and racial and ethnic minorities.

We published a study in 2020 that shows that, in the present day, the heat experienced in a historically redlined neighborhood—across 108 cities in the US—is on average about five degrees hotter than their non-redlined counterparts. But we’ve seen differences of upwards of 20, 25 degrees between redlined and non-redlined areas across the country.

What needs to happen, moving forward, to achieve more equitable tree cover in cities?

I live in a city where if the city goes in and plants a bunch of street trees, then it’s the responsibility of the adjacent property owner to take care of those trees. And it’s kind of like putting salt on a wound, in many ways. We have these under-canopied neighborhoods, and we say we want to center those neighborhoods. We go in and put in a bunch of street trees and say, guess what—it costs about 500 bucks a year to take care of these.

I chair the Urban Forestry Commission for the city of Portland, where after equity-centered research and community engagement, we were eventually able to get the City to move about $40 million into street tree maintenance and care in lower-income, historically marginalized, mostly Black and brown communities who are in tree-deficient neighborhoods.

Largely what I’ve been advocating for is engaging communities through a needs approach—bringing residents together to talk about the needs of the neighborhood. What are the current needs of the community, whether they want trees or have other needs? In what ways could green spaces or street trees help to alleviate or address some of their pressing needs?

I think we need to be more thoughtful, more intentional, about addressing the injustice that’s happened in our neighborhoods. We need to discuss how the lived experience of a neighborhood differs during extreme events, and how we work from a trauma-informed perspective to think about what the future might hold, in terms of climate change and the role that green spaces and trees may play.

You can’t just do this from the top down—it has to be a grassroots effort, deeply rooted in community, in terms of how we think about trees and communities coming back together.

Dr. Vivek Shandas will deliver the keynote address, “Deeply Rooted: Traditional Knowledge, Equity, and a New Era in Urban Forest,” at Making Brooklyn Bloom on Saturday March 11.

Image, top of page: Michael Stewart