As the COVID-19 pandemic stretched into the summer months of 2020, people around the world began to flock to outdoor green spaces in and around cities. For some, safe and socially distanced relief from indoor lockdowns came from picnicking in nearby parks, walking through tree-shaded neighborhoods, hiking along trails through the mountains and forests, or simply getting fresh air in their own backyards. However, not all city residents have the same access, geographically and historically, to nearby green space.
This tumultuous time has “put everything in really high relief about the importance of having a safe green space in every neighborhood,” said Sharon J. Hall, who researches the intersection of ecosystem management, environmental quality, and human well-being at Arizona State University (ASU) in Tempe. “We know that nature brings mental health benefits, physical benefits, spiritual and community connectedness, and all sorts of recreation benefits and cultural benefits, but not all people feel the same way about nature. There are populations that have really long histories, problems, and challenges with nature and what nature means to them.”
Developing new urban green space—places covered with grass, trees, shrubs, or other vegetation—and infrastructure that works with it is a priority in many cities these days. But experts agree that the solution is more complicated than simply planting more trees in certain spots. Done right, adding new green space in and around our cities can improve human health, revitalize ecosystems, and boost a region’s economy. Done wrong, it can worsen existing socioeconomic and ecological problems or even create new ones.
Urban Forests Benefit City Residents
Green spaces in and around cities, collectively known as urban forests, can mitigate regional and local flooding from storms, reduce water scarcity, improve air and water quality, regulate temperature, and aid soil nutrient cycling, all while sequestering carbon.
Each tree in that forest is important. With all of their steel, asphalt, and concrete, cities are typically a few degrees hotter on average than the surrounding undeveloped land, a phenomenon known as the urban heat island effect. The same phenomenon occurs on a subcity scale to a degree that depends on a neighborhood’s green space. “Trees are a really important contributor to reducing heat in neighborhoods,” explained Fushcia-Ann Hoover, an urban hydrologist whose research is informed by environmental justice. She is a postdoctoral researcher at the National Socio-Environmental Synthesis Center in Annapolis, Md. “If a tree shades part of your home or much of your neighborhood, it’s going to be cooler than neighborhoods where you don’t have trees on the block at all.”
Moreover, “there are cultural benefits of having green space in and around your community,” said John-Rob Pool, “for leisure and for recreation, which has been proven to improve health and well-being of people, and for creating streets that are more livable and more accessible.” Pool is the implementation manager of Cities4Forests, an international program that helps cities conserve, manage, and restore their forests.
Combined, these ecosystem services “are the broader benefits of green spaces,” said Ayushi Trivedi, gender and social equity research analyst at the World Resources Institute, “but to have a socially equitable impact, they need to be distributed in a way that all communities derive benefits from them. This is especially important for vulnerable communities—marginalized communities, low-income populations, racial minority communities—that live in neighborhoods that are more exposed to heating, stormwater flooding, and pollution.”
Where the Green Spaces Are
Environmental justice affirms that all people have the right to land, water, and air that are clean and safe; it requires environmental policy that is free from discrimination and bias and is based on mutual respect and justice for all people. In assessing whether all residents of a city have equitable access to urban forests, the first question to answer is, Where does the city have green space? To tackle this on a citywide scale, most researchers either collect satellite or aerial imagery, which can measure down to only a certain scale, or conduct laborious on-the-ground surveys.
Because of the limitations of data collection methods, most studies that look at the distribution of urban green space focus on just one or two cities at a time, which can hinder analysis of nationwide trends. “The amount of work it takes to generate an urban forest cover map of a single city is so incredible that to do something on a larger scale can be quite difficult,” explained Shannon Lea Watkins, a public health researcher focused on health equity at the University of Iowa. “We know that the urban forest is different across the country because the ecosystem is different. So we would expect a different amount of tree canopy cover in Philadelphia than we would in Tulsa.”
Watkins and her colleagues aggregated many individual studies into meta-analyses in which they combined data from both verdant and sparsely forested U.S. cities. Trivedi said such methods can help researchers and city planners identify which groups benefit the most from an existing or planned green space. “What is their race? Where do they live? What [relationships] is their household composed of? If you disaggregate by demographic social characteristics, then you are able to see what the social implications can be. Whether it is mapping or doing a statistical study, the simple act of disaggregating your data and then seeing the patterns that come up…will be very helpful in telling you what the gaps are, who is benefiting the most, who is impacted by the costs the most, and who is taking the most risks.”
For instance, “in most studies there’s a demonstrated pattern between income and urban forest cover; that is, higher income is associated with more urban forest cover,” explained Watkins. What’s more, across the nation, race-based inequity in urban forest cover is higher on public land than on private land: Private residences with yards and tree-lined streets are more common in higher-income and predominantly white neighborhoods, and the same is true to an even greater degree for publicly owned parks and forested areas.
The Type of Green Space Matters
After you know where the urban forests are, it’s helpful to analyze what form they take, because not every type of green space provides nearby residents with the same benefits. Hoover, who coauthored a recent paper that examines race and privilege in green spaces, explained that “[historically] redlined neighborhoods have less green space, and the green space that they have is also not as high quality.”
Parks, for example, look very different in urban areas that are more heavily policed, which tend to be neighborhoods with more people of color, more housing-insecure people, or more people with lower incomes. “If a tree is blocking the line of sight for a police camera, for example, the tree gets cut down or drastically trimmed so that it’s no longer effectively providing shade” and cooling the area, Hoover said.
In these neighborhoods, “parks aren’t necessarily made to be places where people sit or relax,” Hoover explained. “They are places to be passed through. I think that is also reflective of the way that housing-insecure individuals are criminalized and the way that cities often respond to folks who are housing insecure by wanting to prevent them from setting up camp or being able to lie down on a bench.”
Vacant lots that have been renaturalized can contribute green space, said Theodore Lim, but the benefits of that space to the surrounding community are going to be far less strategic than the benefits of a planned park. “One is developed under conditions of growth and proactive planning, and one is developed in conditions of decline and reactive planning,” he explained. “You’re often being opportunistic about where you can get ecosystem services.” Lim researches connections between land, water, infrastructure, and people in sustainability planning at Virginia Polytechnic Institute and State University in Blacksburg.
“In cities, I think we need to be more expansive with how we think about green spaces,” Hall said. “Green spaces can occur anywhere…. It’s these in-between, accidental spaces that are sometimes the more creative ways to think about green space.”
Whether proactive or reactive, for them to benefit a community “urban green spaces should be designed on a case-by-case basis depending on the climate, the geography, the soil conditions, and the water supply needs of that area,” said Kimberly Duong, a water resources engineer and executive director at Climatepedia. “In an agricultural region, for example, a sustainable green space would likely rely on seasonal cycles of precipitation. In a drought-prone region, a green space might also consider water retention strategies.”
“I was designing a green street for [an area near the University of California, Los Angeles] that incorporates sustainability concepts, stormwater capture concepts, and green space concepts,” Duong said. “That region has a lot of clay soil,” which meant that installing pervious pavement wasn’t an option because water would soak through the sidewalk but not into the soil. “But for other regions with sandier soil, where water can absorb more readily, a pervious pavement might be a strategy for a parking lot [to capture stormwater on site].”
“There are strategies at many different geographic scales,” Duong said, from rain barrels to bioswales and from rain gardens to watersheds.
Community Ownership Is Key
Green spaces should be intentionally designed to meet needs that the community has identified so that residents will be comfortable using them. Such a design strategy requires engagement and dialogue between communities and project managers.
“People theoretically may have the same amount of access to acres of park space but still may not feel welcome or safe in that park space,” Lim said. “It’s about recognizing that there are systemic issues that shape people’s experiences and that those have really historical roots.”
For example, “a white man might go off by himself in the woods and get all sorts of spiritual benefits from being alone there,” Hall said. But for people who have been made to feel unwelcome or unsafe in the outdoors on the basis of their gender, race, or other aspect of their identity, she continued, that historic experience may be very different.
There are positive historical relationships to consider as well, she added. “You might think about Latinx populations who are living in the Southwest; the desert might have a different sort of meaning to them if they have history with the desert through their families and through generations.”
“When a city, for example, plans a new train station, they engage with residents about where they should put it, who needs it, are residents going to use it if they put it here versus if they put it there,” Pool said. “Nature-based solutions need to be treated like all other infrastructure and deserve the same participatory approach during planning stages. I think the reason that this is not as commonplace yet is that it’s an emerging field.”
Many Detroit residents, for instance, expressed the belief that the city had neglected or mismanaged the green spaces and trees in their neighborhoods. Because of that historical precedent, people were distrustful when a local nonprofit offered them free trees to plant in front of their houses. Despite wanting greener neighborhoods, a quarter of residents rejected the planting of new trees, anticipating that the city would neglect that green space too.
“There’s not going to be a one-size-fits-all approach” to creating new urban green spaces or for ensuring equity in those spaces, Hall said. “What’s going to be good for pollinators or people in Washington, D.C., may be very different from what’s going to work in the Sonoran Desert in Phoenix. And even still, the history of Phoenix is very different than the history of Albuquerque or Los Angeles.… Approaches are going to need to be locally determined, about what types of plants you’re going to plant and what’s going to be really good for the history of a community.”
What Community-Driven Solutions Look Like
Let’s say you’re a geoscientist with an idea of how to improve an urban neighborhood by adding more green space, and you want the project to be a participatory process. How do you then get the community on board? “Nobody really trains you on how to be a community researcher. You learn by doing,” said Marta Berbés-Blázquez. “You scan the news, you scan Facebook, you start following activists in a region, you start figuring out who’s who. That takes a little bit of time, and a lot of it is very subtle.” Berbés-Blázquez researches the human dimensions of social-ecological transformations in rural and urban ecosystems as an assistant professor at ASU.
“I might go to a random community event,” she continued. “I might go to a webinar or go to community meetings. And I would just sit in the background and listen and not talk.” By doing so, a researcher learns what issues are at the forefront of a community’s agenda, who key leaders are, and what historical or systemic issues that community is facing.
After so many residents rejected free trees, for instance, that Detroit nonprofit shifted its approach to include communities in the decisionmaking process regarding the types of trees and where to plant them. It also expanded its youth employment program to maintain the trees and teach residents about them.
“I think the tendency is for geoscientists to focus on data analyses,” Duong said, “and then point to them and say, ‘This makes sense for scientific purposes. We have this much water deficit, therefore carrying out this strategy [would provide] 200% of the amount of water that we need.’” Such analyses are necessary ingredients in any green infrastructure project, but there are other considerations that go outside the scope of a geoscientist’s expertise. “That doesn’t take into account the political considerations, the budget required, the maintenance required, or the disruption to the community during construction. Those are nontrivial components of implementing green space projects.”
By taking a step back and learning about the community before initiating a project, a geoscientist will be able to evaluate neighborhood-specific risks, such as attractive new green space pushing rents up, and have steps in place to protect residents from harm. “Having those mechanisms in place has shown that you can reduce some of these green gentrification crises that are happening,” Trivedi said.
Consider, for example, Washington, D.C.’s 11th Street Bridge Park project, a recreational park bridge that will cross the Anacostia River at Ward 7 and Ward 8, areas that are majority Black and have incomes lower than the D.C. average. Green infrastructure projects in neighborhoods with similar demographics have, in the past, created gentrification crises that ultimately harmed residents. Residents of Wards 7 and 8 initially pushed back against development of a bridge park in their neighborhoods for exactly those reasons. In response, the project managers partnered with community leaders to create equity-focused development strategies: setting up community land trusts, safeguarding affordable housing investments, providing skills training and jobs for local residents, and investing in local small businesses.
The process of codeveloping solutions isn’t easy, Berbés-Blázquez said, and the structure of academic research, such as grant cycles or tenure clocks, can often get in the way. “The speed at which projects have to happen, be it academically or politically, doesn’t necessarily give enough time to foster true, genuine, trusting relationships between the different actors who are involved,” she said. “Don’t bring your own agenda, but if you do have one, then be very clear about it. And then be patient” and be willing to recognize and acknowledge when you make mistakes.
Community-led organizations focused on regreening cities are working across the country, Hoover said, and each one knows how scientists can best help them achieve their goals. “I would really encourage other scientists, planners, practitioners, and researchers to start listening and to start reaching out,” she said, “to just learn and to really push the boundaries of their own fields and their own assumptions within their science.”
“Environmental justice is not only equitable distribution of resources but also equitable access to decisionmaking,” Watkins said.
Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer
Cartier, K. M. S. (2021), Growing equity in city green space, Eos, 102, https://doi.org/10.1029/2021EO158443. Published on 21 May 2021.
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