New London — Norway maples are by far the most common tree in the city.

Most of the city's trees are in fair or good condition, few are dead or dying and most range in height from 11 to 22 feet.

These are a few of the things Isabelle Smith, who graduated from Connecticut College with a botany degree in December, learned from her recent New London urban forestry analysis.

Last summer, working with the New London Department of Public Works, she set out with two fellow paid interns to do an inventory of trees on city-owned streets and school grounds, excluding Riverside Park and other forested areas.

The team counted 1,887 trees, but the project involved a lot more than counting: It involved noting the location, species, condition, height, diameter at breast height — or the width of the tree 4.5 feet off the ground — and canopy.

After spending the fall semester analyzing the findings, Smith presented them to a group of more than 30 people at the Public Library of New London last Wednesday evening.

The project came about after the City of New London received a $12,000 America the Beautiful grant from the state Department of Energy and Environmental Protection, having identified a desire to improve the city's urban canopy.

Smith said the city then got in touch with the Connecticut College Arboretum, noting the city had the grant but not the knowledge about how to study the urban canopy.

Smith worked on the arboretum grounds one summer, in the curation department another summer and coordinated the Arbo Project during the school year, making her a logical choice to spearhead the project.

The college paid its interns to do the research through its own program, meaning the $12,000 was available to invest in expensive software and tools.

For example, the tool iTree determined that, based on New London's canopy and climate, trees save the city $171,350 per year, due to factors like the sequestering of carbon dioxide and the removal of particulate matter.

Smith noted that other benefits of trees include lower air-conditioning bills, fewer pollutants in the air and improved mental health.

Some of the most common trees in New London are pin oak, Kwanzan cherry, red maple, crabapple and sugar maple, but by far the most common is the Norway maple. And that's a problem.

The Norway maple lacks the ecological benefits of native species, and because it's invasive, it limits the habitat of native species, Smith explained. But the "excellent news" is that far fewer Norway maples are being planted: She found that the most common age range for the species in the city is 75 to 100 years old.

Smith also found that northern red oaks have not been planted in the past 25 years, which baffled her "because they do phenomenally as street trees."

The New London trees that reach the highest percentage of their expected height, are the healthiest and are the oldest are most likely to be found in parks.

Smith recommends that if the city wants to plant more trees, it should do so in parks, where they grow better. Another recommendation is that to sustain a healthy tree population in, say, 200 years, the city should be planting oaks now.

She also suggests planting trees in clusters, as this has a greater impact on a microclimate. Shade can make the air feel up to 15 degrees cooler, for example.

Smith, who now lives in Avon and is about to start a job at Bartlett Tree Experts, met with the Department of Public Works on Wednesday and she said the department struggles to make everyone happy. Some people want more trees, and some people want clear, even sidewalks.

Smith said a 2003 inventory of New London trees included species but not locations. Maggie Redfern, interim director of the arboretum, said a Connecticut College student's 1993 inventory documented about 2,900 trees that represented 55 species.

Smith is working on posting her findings online for the public to see. In the meantime, she said people can reach out to Redfern for more information.

e.moser@theday.com