PORTLAND – It’s getting easier to walk on the sunnier side of the street these days, and that has city officials concerned.

The Tree Endowment Committee, appointed by Mayor Cheryl Leeman, said the city’s trees are being killed by road salt, Dutch elm disease and development. The city had more than 40,000 trees in the 1960s, but nearly half have died since then, according to committee estimates.

The committee is proposing a plan to plant more than 2,000 trees, primarily in the neighborhoods of East Deering, Deering Highlands, Oakdale and areas off Brighton Avenue.

The planting program would cost $500,000, to be paid for with a combination of public and private funds. It must be approved by the City Council.

“Trees are a long-term investment,” said Jeff Tarling, the city’s arborist. “We’re growing infrastructure.”

Officials say trees make the city more livable by muffling noise, creating shade, absorbing pollutants and reducing erosion.

Sixteen different species would be planted, including ginkgo, ash and locust, Tarling said.

Portland once was known as the Forest City for its thousands of mature elms, maples and pines.