Somerville, MA Tree Protection: Parkway Planting (2026)

Under the City of Somerville Native Planting Ordinance (Sec. 12-171 through 12-177), the city's Department of Public Works and its senior urban forestry and landscape planner must meet minimum native-species thresholds whenever new trees or plants go into the ground on city property. Sec. " A native plant is defined in Sec. 12-174 as one with origins east of the Mississippi River per the USDA plant database, with preference given to species from the EPA's Northeastern Coastal Zone ecoregion. The ordinance applies only to new trees and plants installed by the city or by a third party acting on the city's behalf; existing street trees already in the ground are unaffected (Sec.

12-175). Sec. 12-176 separately bars the city from including any invasive plant, defined by reference to the USDA Introduced, Invasive, and Noxious Plants list and the Massachusetts Prohibited Plant List, in any city planting, which includes street tree replacement stock. For other city planting areas such as riparian buffers, the Community Path, the Green Line Extension rail corridor, bioswales, plazas, and other city-owned property, Sec. 12-177(a) sets a stricter native-only standard, with up to 50 percent non-native, non-invasive plants allowed only where the city determines flexibility is needed for memorialization, aesthetic, geographic, or survivability reasons.

City parks carry their own separate 75 percent native threshold under Sec. 12-177(b). The ordinance took effect March 25, 2021 under Ord. No. 2021-05, and its stated purpose in Sec. 12-172 and Sec. 12-173 is to combat habitat and pollinator loss by maximizing native vegetation in public plantings, including along Somerville's streets.