About the Urban Forestry Division

Tree City USA Growth Award

The Urban Forestry Division manages, plans and cares for Somerville’s more than twelve thousand public trees. Somerville’s urban forest offers countless ecological, economic, and health benefits to the community. Trees remove carbon dioxide and harmful pollutants from the air, cool city temperatures, reduce storm-water runoff, all while increasing property values and beautifying urban landscapes.


  • Tree Planting Map

  • Videos

  • Emerald Ash Borer

The City of Somerville planted over 100 trees during the 2017 Fall planting season. The map below shows details about where the trees were placed and what species were planted.


Emerald Ash Borer

Officials with the Massachusetts Department of Conservation and Recreation (DCR) and the Department of Agricultural Resources (DAR) have confirmed that the Emerald Ash Borer (EAB) has been detected in a number of locations in Massachusetts, the 18th state in the country to detect EAB. The destructive beetle was first detected in the Commonwealth in the western town of Dalton on August 31, 2012. The Boston Globe reported that on July 16, 2014, an ash borer was found in an ash borer trap in Boston at the Arnold Arboretum in Jamaica Plain. Also in 2014, ash borer-infested trees were discovered in North Andover, in November 2015 ash borers were found in Worcester, and in 2016 they were detected in Wilbraham in central, MA. To prevent its spread, the entire state of Massachusetts is now under ash borer quarantine, meaning that untreated firewood and other related materials (see below) may not be taken from the Commonwealth into any neighboring state. Officials have also urged all residents in Massachusetts to be alert for any sign of this invasive species.

About Ash Borers

The EAB is a small, flying beetle, native to Asia. It was first discovered in North America in 2002, in the Detroit, Michigan area. Unlike other invasive beetles, the EAB can kill a tree fast, within just a few years, because it bores directly under the bark, where the tree's conductive system is. Since its discovery in North America, it has killed millions of ash trees and has caused billions of dollars in economic loss across the nation.

Ash Trees: Popular in New England & Somerville

Ash is a main component of the Northern Hardwood forest in Massachusetts and is a common species in the Berkshires. Ash is also a common street tree in eastern Massachusetts. The City of Somerville has approximately 900 public ash trees, which represents roughly 7 percent of the ~13,070 public trees currently in the city.

Photo of a D-shaped Emerald Ash Borer exit hole in a treeSigns of Ash Borers

Residents are urged to take the time to learn the signs of EAB tree damage and be sure to report any sightings.

  • Look for tiny, D-shaped exit holes in the bark of ash trees, die-back in the upper third of the tree canopy, and sprouting of branches just below this dead area.
  • The Emerald ash borer is a tiny, emerald-green metallic beetle, so small that seven of them could fit on the head of a penny.

To report suspicious tree damage or insect sightings, or to learn more about this pest, visit www.massnrc.org/pests. You can also call the toll free EAB hotline at 1-866-322-4512.

More information about the Emerald Ash Borer can be found at http://emeraldashborer.info

Stopping the Spread of Ash Borers at the State Level

DCR and DAR officials are working together, in collaboration with the United States Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) and the USDA's United States Forest Service to take a number of swift proactive steps aimed at preventing the spread of the invasive beetle, including:

Regulated items that would fall under quarantine include the following:

  • The Emerald ash borer, in any living stage of development;
  • Firewood of all hardwood species;
  • Nursery stock of the genus (Ash);
  • Green lumber of the genus (Ash);
  • Other material living, dead, cut, or fallen, including logs, stumps, roots, branches, and composted and uncomposted chips of the genus (Ash);
  • Any other article, product, or means of conveyance that an inspector determines presents a risk of spreading EAB.

Ash Borer Prevention in Somerville

Along with other cities and towns in our region, the City of Somerville is taking preventive measures to stop the spread of ash borer in our area to avoid tree loss:

  • Trapping: Ash borer traps have been installed on ash trees across the city for early detection of this pest.
  • Preventive Treatment: As a preventive measure, healthy and fair condition trees are being injected with the organic insecticide TreeAzin, which can ward off ash borers. This treatment must be applied every two years.
  • Tree Removal ONLY When Necessary: Unfortunately, sometimes trees are too sick to respond to treatment. In these cases, where absolutely necessary, dying and sick ash trees, which are more susceptible to infestation and can thus endanger nearby healthy ash trees, will be removed and replaced with other varieties of tree that thrive well in an urban environment.

Prevention by the Numbers:

  • 783 Trees to Be Treated and/or Monitored
  • 117 Require Removal and Replacement

Of Somerville's ~900 ash trees, ~783 have been deemed to be in good or fair enough condition to benefit from preventive treatment with TreeAzin or to be in borderline poor condition warranting continued monitoring rather than removal. First-round injections for good-to-fair trees began in summer 2016 and will continue through summer 2017, with regular boosters.

Unfortunately, as of June 2016, 117 of our ash trees have been confirmed to be in such poor or dying condition (independent of the ash borer) that removal is recommended. As noted, trees in poor condition are more susceptible to ash borer infestation and they do not respond well to preventive injections (due to poor circulation). If these more vulnerable trees become infested, they will provide an ideal breeding ground where the ash borer will thrive and build up populations that will attack and likely overwhelm our healthy ash trees.

To protect our ~783 healthy trees, the City arborist has recommended that the ~117 poor condition or dying ash trees be removed and replaced with other species of trees that thrive well in street and sidewalk environments. An additional 7 dead ash trees must also be removed and replaced regardless of the ash borer risk. The removal of these trees will be staggered over the 2016 and future seasons to reduce visual impact on our neighborhoods.

The schedule is still being determined and will be shared with residents once available, but again, they will not all be removed at once and our City arborist will continue to monitor their condition and the ash borer risk and adjust accordingly if needed. The schedule will also be adjusted should ash borer arrive in the area.

Please note: In October 2015, ~155 trees were identified as in poor or dying condition and their removal was announced for Spring/Summer 2016, but reexamination in spring 2016, during more favorable spring conditions when ash trees are under less stress, moved 34 previously designated trees to fair condition or monitoring status, so they will be treated and/or monitored and not removed.

Public Hearing on Ash Borer Prevention Tree Removal/Replacement

A public hearing on the proposed removals/replacements was held on:

Wednesday, May 25, 2016 at 5:30 p.m.
Somerville Water Department
17 Franey Road, Somerville (next to the DPW building)

Click here to view the presentation from the May 25th meeting.

Tree Notices: Updated June 28, 2016

View a listing of vulnerable ash trees scheduled for PHASED removal over the coming seasons citywide. Removal of the City's seven dead ash trees will commence in summer 2016 immediately. Removal of the City's 117 sick and dying ash trees will be phased over the 2016 and future seasons.

Why Do City Trees Get Sick?

There are many reasons that tree health can deteriorate in high-stress urban environments. These factors apply to all tree species as well as the ash tree and are among the factors that have contributed to the poor condition of the ~117 ash trees proposed for preventive removal/replacement:

  • Inadequate oxygen or water intake due to compacted soils and impervious surfaces
  • Soil chemistry changes, including impacts of road salt, dog waste or competing plant growth
  • Poor air quality associated with vehicle emissions
  • Heat stress on root systems due to asphalt and sidewalks heating up in the summer sun
  • Physical injury due to vehicle collisions, storm damage, vandalism, etc.