To: Lexington Select Board

Cc: Tree Committee, Conservation Commission, Planning Board, Permanent Building Committee, Sustainable Lexington Committee, Town Meeting Members, and Town Manager

Re: Statement of Concern for Lexington’s Trees

Our streets and neighborhoods are losing too many large trees. The undersigned express our urgent concern that we are not doing enough as a community to protect and enlarge Lexington’s tree canopy, particularly at a time when a robust tree canopy is needed more than ever.

Trees are one of the best defenses Lexington can have against the growing impacts of climate change.

Middlesex County has historically had 8.7 days each year above 90°, but by century’s end we are expected to have 35 such days under a low-to-moderate emissions scenario and 67 days with business-as-usual emissions.  Heat like this creates health risks for our children, elderly and other vulnerable populations. Heat like this places an enormous energy burden on our cooling systems and will make many summer outdoor activities unpleasant if not dangerous.  

What can trees do?

• Trees shade our homes in the summer and buffer against wind in winter, reducing heating/cooling energy use by 25-40%.

• A tree canopy can have a 15-20°F impact on the hottest summer days, the difference between our children playing outside or sitting in an air-conditioned room.

• Trees combat climate change both by sequestering carbon directly and by reducing building energy demands (due to tree shading and windbreak).

• Trees mitigate stormwater and flooding impacts by promoting soil infiltration and intercepting rainfall that then evaporates.

• Trees improve air quality through uptake of gaseous pollution via leaf pores, intercepting particulates, and inhibiting the formation of smog.

• Trees are a foundational part of the ecological communities that surround and sustain us, especially in New England. Trees provide habitat to countless species of insects, fungi, moss, birds, mammals, and plants, serving as critical elements in most food chains.

• Trees enhance property values. A range of studies have found increases of about 3 to 10 percent in residential property values associated with the presence of trees and vegetation.

• Studies have shown that trees provide a wealth of mental health and quality-of-life benefits, from increased cognitive function to reductions in stress and anxiety, reduced crime, and even more rapid recovery from surgery.

Shade trees can take 100 years or more to mature and fill the canopy.  While we must continue to plant for the future, we must also recognize that what is cut down now cannot be regrown in our children's lifetimes.

We ask that you make the preservation and enlargement of Lexington’s tree canopy a greater priority through all the means at the town’s disposal, including education, resources, and regulation. We ask that you set actionable goals reflecting the magnitude of the challenge, and that you marshal every relevant committee and department to identify concrete steps they can take to help meet these goals.

We NEED a robust canopy to help minimize the localized impacts of global climate change. The best time to make these investments was thirty years ago; the next best time is NOW.  

Click here to add your name. 

See who has already signed the statement.

We are a group of residents, many of whom are engaged with environmental and sustainability organizations in town, who think now is the time to tell our elected representatives that we need to do more to protect our trees. 

Marcia Gens Rick Reibstein

Dan Miller Nancy Sofen

Ricki Pappo Barbara Tarrh

Gerry Paul Charlie Wyman

There are many things the town can do, through education, financial incentives, direct town action, and stronger regulation and enforcement. What we need is the political will to do so.

A first step is to demonstrate that there is widespread public support for protecting our existing trees and planting more, to build the robust canopy that will make Lexington a more livable place to call home in the years ahead.  

With a strong statement in hand, our intention is to hold a public workshop, meet with the Select Board and other town committees, and work with existing organizations in town to press for change. Together, we can create a healthier, more livable Lexington in which to raise our families in the years ahead. 

How big is the problem?  Has it been measured?

The adequacy of a tree canopy is difficult to measure. The Town will soon finalize and make public both an inventory of all street trees and a tree canopy survey that will shed some light on this question, but an across-town average may not reflect conditions in your neighborhood or on your street. We do know that Lexington averages about 75 teardowns and several new subdivisions each year, and that many builders clearcut these lots before building new homes; if you live near one of these lots, your experience will be particularly acute. Beyond that, many of our trees, both street trees and those on private land, would benefit from pruning care to extend their lives and minimize rot and disease. 

But beyond the losses, we also know that climate change is bringing higher summer temperatures to Lexington, and a robust tree canopy is one of the best things we can do locally to prepare. We need to strengthen our canopy, not just stop the attrition. Trees lower ambient temperatures and shade people and buildings. A drive through most neighborhoods will reveal many places where the town and individual property owners, if interested, could plant more.

Doesn’t Lexington’s Tree Bylaw prevent clear-cutting?

The bylaw only applies to trees in the "setback” – the area within 30 feet of the property line on the front of the property and within 15 feet on the sides and back – and only during major construction.  Those trees may be removed, but their removal must be mitigated by replanting or by paying into a fund that the Town uses to plant trees.  Trees in the interior of the lot may be removed without any mitigation required. 

The bylaw applies retroactively to trees cut in the year preceding a demolition permit application.  Some developers try to get around the regulations, such as by cutting trees and then waiting a year to begin demolition and construction.

Is it just construction that’s the problem?

Construction may be the largest contributor to tree loss, as Lexington averages about 75 teardowns a year.  We also see healthy large trees being removed by homeowners who don’t have any construction underway.  And climate change, with its higher summer temperatures and more erratic rainfall and storm patterns, affects tree health.  This is especially true for young trees that are not yet established.

We can't save every tree, nor do we need to. But we need a discussion about the importance of trees in our community and what we can do collectively to improve their contribution to our quality of life in the years ahead. 

What is the condition of Lexington’s public shade trees?

Many of our more than 25,000 public shade trees (those lining our streets, in parks, and around schools and town buildings) need pruning, either to remove damaged limbs or to shape the tree for future healthy growth.  Our DPW does what it can but lacks the resources to do more. 

How many trees does the Town plant each year, and how are they faring?

The DPW aims to plant 140 trees each year – usually 70 in the spring and 70 in the fall – but falls short of that goal in some years.  The contractor who plants them guarantees their survival for one year.  In very dry years, watering hundreds of young trees each summer requires more resources than the DPW has.  This summer’s drought was particularly hard on the trees that were planted in the last few years and a number of them died.

How many public trees does the Town remove each year, and why?

The DPW removes on average about 50 public trees each year due to their condition. This number does not include trees removed for the purpose of town construction projects such as sidewalks or buildings, which is not reported. 

Is preserving mature trees a consideration in Town construction projects?

Consideration of the trees on a site is not currently part of any formal approval step for Town projects, except for compliance with Conservation Commission regulations and the state public shade tree law called Chapter 87.  Some departments are better than others at consulting the Tree Committee early in project planning to explore alternatives to removing mature trees.  We'd like to see this become a regular practice across all departments.

Doesn’t this campaign conflict with adding housing and solar energy systems?

Absolutely not. There is plenty of room in Lexington for all three, and we desperately need all three. We are not asking that no tree ever be cut down. We ARE asking that the public value of trees be properly considered in all decision-making, including their ability to ameliorate the growing impacts of climate change. Trees do an enormous amount of good for all of us, individually and as a community, and their contributions should be valued, and alternatives and compromises explored, before trees are removed.

What about removing trees to install solar panels on my roof?

Solar energy systems are an important tool in combating climate change.  Green infrastructure – i.e., trees – can also help us reduce our reliance on fossil fuels by keeping our yards and homes cooler in summer and blocking winter winds.  Trees also sequester carbon.  One approach is to work around your trees, perhaps with modest pruning, to install solar panels.  Installing solar at your own cost gives you more flexibility than leasing panels, as the company leasing those panels to you needs to maximize the electricity output and may require that you remove trees.

What can we do to address the concerns you raise?

There's a great deal. Other cities and towns around the country can help point the way. From public education to financial incentives for homeowners, to neighborhood tree planting campaigns, to stronger regulations and enforcement, there are many good ideas and programs from which we can learn. We're asking our existing committees and organizations -- both on the town side (Select Board, Tree Committee, DPW, Conservation, Planning, Town Meeting, and others) and the community side (nonprofits, PTAs, neighborhood associations, and others) -- to help and to take action.  

You too can help by maintaining the health of the trees on your property, planting more if you are able to, and watering nearby public street trees during times of drought.  Check out Lexington’s setback and street tree planting program if you would like the town to plant a tree at the front of your property.  

To Learn More...

Visit the websites of the Lexington Tree Committee, LexTrees.org, Lexington DPW Forestry Division, and Lexington Living Landscapes.

Cambridge recently issued a short, very readable urban forest master plan, Healthy Forest Healthy City, with lots of good ideas. Other nearby communities that have recently written urban forest master plans include Boston, Brookline, and Somerville.

For an example of the kind of leadership a nonprofit can provide, check out what Canopy is doing in the Palo Alto area.

For a national perspective on these issues, take a look at the websites of the Vibrant Cities Lab (a joint project of the US Forest Service, American Forests, and the National Association of Regional Councils) and the Arbor Day Foundation.

A national overview of the benefits of urban forests and the challenges they face is the 2010 U.S. Forest Service report Sustaining America's urban trees and forests: a Forests on the Edge report.

You may find four recent webinars of interest: Stand for Trees, featuring William Moomaw and Robert O’Connor, Cary Library, October 6, 2020; What Every Homeowner Should Know About Their Trees, featuring arborists Steve Vernon and Greg Mosman, Cary Library, November 14, 2022; Nature’s Best Hope, featuring Doug Tallamy, Lincoln Land Conservation Trust, December 9, 2022; and Beyond Beauty: Establishing the Value of Urban and Suburban Trees, featuring David Bloniarz, January 11, 2023.

Attend one of the workshops we are planning later this winter to discuss the problem and to enlist your help in identifying steps the town can take.  Watch for details.  (UPDATE: We had our first workshop on 3/2/2023.  You can watch Nancy Sofen's introductory presentation here.)

Specific references for the Statement of Concern:

For days above 90o:

Climate Change Impacts and Projections for the Greater Boston Area, Ellen Douglas and Paul Kirshen, UMass Boston, 2022. (An earlier version of the Statement mistakenly listed the days above 90o in the two scenarios as 27 and 58, instead of 35 and 67, due to an error in interpreting the chart.)

For the effective temperature:

The influence of increasing tree cover on mean radiant temperature across a mixed development suburb in Adelaide, Australia, Urban Forestry and Urban Greening, 2016.

Modelling the impact of increased street tree cover on mean radiant temperature across Vancouver’s local climate zones, Urban Forestry and Urban Greening, 2019.

The Comparison of the Solar Radiation and the Mean Radiant Temperature (MRT) under the Shade of Landscaping Trees in Summertime, Journal of the Korean Institute of Landscape Architecture, 2014.

For energy savings:

Stand For Trees. Robert O'Connor, Forest and Land Policy Director for the Massachusetts Executive Office of Energy and Environmental Affairs (EEA), talk at Cary Memorial Library in 2020.

Morzuch, Emma L. (2013). The Energy Benefits of Trees: Investigating Shading, Microclimate and Wind Shielding Effects in Worcester and Springfield, Massachusetts.

Potyondy, Philip John. (2013). Influence of Urban Tree Canopy on Single-Family Residential Structure Energy Consumption at the Community Scale in Hutchinson, Minnesota. Retrieved from the University of Minnesota Digital Conservancy,

When a single tree makes a difference: Individual trees in urban areas provide cooling during evening, research shows. Science News July 12, 2021.

Energy-Efficient Landscaping. U.S. Department of Energy.

For stormwater:

See EPA’s compilation of sources at Soak Up the Rain: Trees Help Reduce Runoff

For pollution reduction:

Nowak, David J. (2020). Urban trees, air quality and human health. In: Gallis, Christos; Shin, Won Sop, eds. Forests for public health. Newcastle Upon Tyne: Cambridge Scholars Publishing: 31-55

For ecological value:

Tallamy, Doug. Nature’s Best Hope, Timber Press, 2020, and The Nature of Oaks, Timber Press, 2021.

Trees and Their Essential Role in Biodiverse Ecosystems, Kyle Dart, 2022. Arbor Day Foundation blog.

For property values:

“Trees and Vegetation,” Chapter Two in Reducing urban heat islands: Compendium of strategies, U.S. Environmental Protection Agency, 2008. Draft. p. 9.

For mental health and quality of life benefits:

Urban Nature for Human Health and Well-Being: A Research Summary for Communicating the Health Benefits of Urban Trees and Green Space, USDA, 2018

“View through a window may influence recovery from surgery,” Ulrich, R.S. (1984), Science. 224: 420-421.

“The relationship between tree canopy and crime rates across an urban–rural gradient in the greater Baltimore region,” Austin Troy et al., 2012, Landscape and Urban Planning 106(3):262-270

Impacts of Trees on Mental Health, Canopy blog entry, 2020

The health benefits of trees, radio interview with Peter James, 2021, T.H.Chan School of Public Health, Harvard.