More Trees More Life

PIELC speaker presents benefits of natural environments

Kathleen WolfPhoto by Mary Levin

Kathleen Wolf, a researcher at the University of Washington, says that when she was an urban forester in the ’80s, requesting from the city of Key West more resources for street trees, her proposal wasn’t taken seriously.

“I was told ‘Oh trees, they are so pretty. But we have the fire and police department, and all these other needs,’” Wolf says.

Wolf, however, says that recent research shows tree abundance as essential for a community’s wellbeing over a lifetime.

As a keynote speaker Saturday, March 5, at the Public Interest Environmental Law Conference, an annual gathering of environmental lawyers and activists, Wolf presented research on the effects of tree abundance on psychological and physical health.

She also addressed disparities in how much access underrepresented groups have to the benefits of trees. She was hosted at the University of Oregon’s student union by the Eugene- and Portland-based nonprofit, Friends of Trees.

According to Wolf, natural environments have an effect on our lives before we take our first steps. She presented research by Jeff Donovan, a Portland-based research scientist, which showed that houses with 10 percent more tree-canopy covering within 50 meters were more likely to have a lower number of low-weight births.

As children become students, Wolf says researchers show that access to trees has an impact in classrooms, too. She discussed how University of Illinois researchers carried out an investigation where students were instructed to perform public speaking and solve math problems — simultaneously and on the fly. The studies found that those who were in a classroom with a window view of nature had higher attention and lower stress scores.

Similar signs of nature’s therapeutic potential were shown in studies of adults. Wolf said University of Chicago’s Marc Berman recruited 20 adults with major depression to walk through either a park or human-made surroundings. Those who came out of the natural environment, Wolf said, showed a more positive mood and a better ability to process information.

During the presentation, Wolf said she helped uncover tree benefits on a communal scale. Her research team looked into canopy covering information in Sacramento County to find that people who had more tree cover had better health and social cohesion.

Wolf didn’t refrain from discussing issues related to who benefits most from tree affluence: those living in wealthier areas with overwhelmingly white populations. She demonstrated this with a diagram of Seattle showing that more Caucasian areas had more canopy coverage. But there’s a way to respond to that, Wolf said.

Wolf suggested becoming more strategic about tree-planting programs rather than setting a coverage goal of 35 percent, for example, across the entire city.

She advocated “outreach and engagement with particular neighborhoods in a way that makes sense. And a reflection and acknowledgment of cultural differences when these programs are put into place.”

You can read more about Dr. Kathleen Wolf’s research at

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