Somerville, MA Invasive Plant Rules: Tree-of-Heaven Removal (2026)

Section 12-102 defines "significant tree" as any living tree that is either (1) not an invasive plant and is eight inches or more in DBH, or (2) is an invasive plant other than Tree of Heaven (Ailanthus altissima) and is twenty-four inches or more in DBH. That second clause deliberately carves Tree of Heaven out of protection: every other regulated invasive species becomes a "significant tree" once it reaches 24 inches DBH and triggers the permit and replacement requirements of Sec. 12-112, but Tree of Heaven never meets either prong of the definition regardless of trunk diameter.

"Invasive plant" itself is defined broadly in the same section as a non-native plant able to establish on many sites, grow quickly, and spread to disrupt plant communities or ecosystems, including species on the Massachusetts Prohibited Plant List, of which Ailanthus altissima is a well-known member. Because Sec. 12-112's removal-permit requirement applies only to removal of "a significant tree from private property," a Tree of Heaven of any size falls outside that permit system entirely. The exclusion was added as part of the citywide tree preservation rewrite, Ord. No. 2025-05, effective May 8, 2025.