Shade Crusade: Why City Trees Are Good Medicine Print
Written by Sandra Hines   
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Shade Crusade: Why City Trees Are Good Medicine
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“If we don’t have contact with nature on a daily basis, we become more stressed, less able to focus on tasks at work and at school. We need green around our homes, schools, places of business.”

Wolf’s research in central business districts, for example, found people were willing to pay more—up to 12 percent more—for the same products if the business district had large trees. Not only were customers willing to pay more, they judged the merchants to be more helpful and the products to be of higher quality.

Kathleen Wolf
UW Research Scientist Kathleen Wolf is looking for a way to assign a dollar value to the health and psychological benefits of urban greenery. Photo by Mary Levin.
Currently Wolf is looking for a way to assign a dollar value to these health and psychological benefits. Environmental psychologists need help from economists to do that, says Wolf, who has submitted a grant proposal to tackle the question.

There’s a pressing need to understand the economics because saving trees is not going to be easy as cities become denser. Infill development is a way to concentrate housing in existing urban areas to avoid sprawl and ever-longer commutes. But setting aside land for trees could make housing even pricier.

“We’re all for trees, and we think they make communities more livable; the problem is with regulations that take away inventory for buildable lands,” Tim Harris, an attorney with the Building Industry Association of Washington, said in a Seattle Post-Intelligencer article.
In a blog about efforts to save urban trees, one citizen wrote, “Can the tree huggers just hug the trees on their own property where they pay the taxes and just leave the rest of us alone?” Another wrote, “Pack houses into small areas and oh, by the way, save room for trees and make the houses affordable? When is the next election?”

Having the economic benefits in dollars and cents would make the case for urban trees and green more compelling, Wolf says. We already know there’s an economic value when someone increases their physical activity: A study in 2000 said that annual mean medical costs are reduced by $865 per person when inactive adults engage in regular moderate activity.

What needs to be determined is just how much green spaces contribute to people’s motivation to head out for a walk, ride a bike or go for a run. Knowing just what increment of that motivation can be attributed to the landscape would give researchers a way to assign a dollar value to that contribution.

Even while awaiting the economic studies, the importance of health and social benefits from green spaces is beginning to be incorporated into building and community planning.

For example, the organizers behind LEED—the Leadership in Energy and Environmental Design certification process for green buildings—are partnering with those participating in a Sustainable Sites Initiative to better develop the sites around such buildings. There are some standards now but they’re considered weak by those in the field. More thought needs to be given to the environment around the buildings, not just the environment within them, Wolf says.

Wolf and colleagues across the nation have been considering the amount of vegetation and how to manage water and other materials on the grounds of buildings. Because of her involvement, the goals for sites were recently expanded to recognize environmental psychology. A new human well-being subcommittee will be formed, the first group of its kind in the nation, and Wolf will be a leading member.

While Wolf’s research is about “why” green is important, others are busy with the “how.”

Over in the UW’s Green Futures Research and Design Lab the talk is about how to preserve and enhance “green infrastructure.” If roads, sewer systems and bridges are examples of gray infrastructure, then open spaces, parks, wetlands—even ditches and gardens in parking strips—are examples of green infrastructure, according to Nancy Rottle, associate professor of landscape architecture and director of the UW Green Futures lab.

It’s all about helping communities understand how to plan for and establish green spaces. In a recent project, for example, the lab helped the community of Lake Forest Park, north of Seattle, with a 100-year legacy plan. Citizens and city officials determined the elements they would like to see in the future—habitat corridors, trails, parks and access to Lake Washington and streams in the area. Priorities were then set for the next six years with funding approved by the Lake Forest Park City Council.

“If you don’t plan for green infrastructure first, it’s much more costly to go back and do it once development has occurred,” Rottle says. “Seattle’s existing green-space framework, for example, was the result of visionary planning and acquisition 100 years ago that anticipated Seattle's growth into a world-class city.” She hopes her lab’s faculty and students can help with the next 100 years.