In midwinter it is not uncommon to have intermittent mild days that tantalize us with reminders of spring. Walking through a park on a warm February day, we might even look to the trees for some confirmation that spring is around the corner—a swelling bud or hint of green, perhaps? Alas, all we’ll note are markers not of the season to come but of the season past: some branches retain from the fall a few straggling, brown leaves. In Boston parks, the only trees that do this are beeches and oaks—both in the same family: the Fagaceae. The botanical word for leaves that remain on trees well into or through the winter is marcescent (from the Latin marcere, meaning enfeebled or withered). Such papery leaves hold fast until the wind rips them free, or until the emerging bud of the spring leaf pushes them off. Scientists speculate that the abscission layer, which forms in most deciduous trees to cut leaves off in the fall, is delayed for some of the leaves of beeches, resulting in a characteristically half-dressed look. In the wild, American Beeches (Fagus grandifolia) form mature forest in parts of central New England alongside Sugar Maples (Acer saccharum). These forests are strikingly beautiful as the Beech often reproduces vegetatively, through sprouts from roots or from rooted branches. This can result in a mother tree surrounded by her offspring in a circle, or, if she is dead, a perfect circle of beech trees of uniform age—a fairy circle in the forest.
All but one of the beeches in our Parks, however, are cultivars of European Beech (Fagus sylvatica). There are some striking horticultural forms represented in the collection, including the Pendula cultivar, with weeping, sweeping limbs; the Rotundifolia, with dark blackish-green leaves and a beautiful, round canopy, and the Asplenifolia, or fern-leafed variety, with lacy cut leaf margins: and the Spaethiana,which holds its deep purple color longer and emerges in the spring with a rich burgundy color. It is fitting that the sole American Beech in our parks is found on the Boston Common, just north of the Frog Pond, as one looks toward Beacon Street.
The Friends of the Public Garden cares for 14 Beech trees in the Garden, some of which date back to the original plantings during the 1870s. These older specimens are special both because of their age and size, but also their placement—three of the oldest are near the Bagheera and Triton’s Baby’s fountains near the mid-block Charles Street crossing. One venerable specimen reaches out over the pathway and over the Bagheera fountain, with a large branch that has rooted in the bed beyond and is cabled to its multi-stemmed main trunk. This tree, which may be over 150 years old, is in its decline, but the Friends work seeks to prolong its lifespan. To do so, we may need to reduce the weight of the wood in the crown, since it has significant interior rot and is vulnerable to wind damage because of its weakened wood. Click here to learn more about load reduction pruning in the Public Garden, Boston Common, and Commonwealth Avenue Mall.
One striking feature of ornamental Beech trees is their bark, which is characteristically smooth and light grey, like an elephant’s skin. Their beautiful bark is unfortunately threatened by two major concerns: vandalism by humans, and a suite of fungal diseases. The Friends of the Public Garden works tirelessly on both of these issues. Together with the Parks Department of the City of Boston, the Friends strives to maintain these parks at the highest level of excellence, to inspire the public to love and respect these important public resources (and refrain from vandalizing them!) And most significantly, the Friends hires hard-working professionals who use the latest scientific practices of Integrated Pest Management to treat the beeches for fungal bark diseases, such as the phythoptera canker and nectria.
Across from the Hampshire House and Cheers, one finds a grove of Beech trees, planted in the 1980’s by two significant early Friends of the Public Garden, Polly Wakefield and Westy Lovejoy. Both woman were long-term members of the Board and Horticulture Committee. This cluster of trees, a testament to these two volunteers’ many years of service, is thriving thanks to the careful pruning, disease management, and judicious fertilizing the Friends has provided over the decades. I like to imagine that in 150 years a new generation of park lovers will look up at the marcescent leaves and wonder when spring will ever arrive.
Claire Corcoran is an ecologist and member of the Friends of the Public Garden Board of Directors. She is a self proclaimed “tree hugger” and dedicated advocate for greenspace in Boston and beyond. Claire lives in the South End of Boston with her husband and three children.
Photos by Claire Corcoran
The Friends of the Public Garden is expanding its Public Garden tour program in 2016 and is actively recruiting new docents to lead the tours. We are looking for men and women who are passionate about the trees, plantings, sculpture, and history of the Public Garden and who would like to share that knowledge and enthusiasm with others. Training will be provided. An information session will be held at the Friends office at 69 Beacon Street on Wednesday, February 24th at 1:00 p.m. For more information or to sign up to attend the information session, email firstname.lastname@example.org.
The Friends of the Public Garden is preparing to embark on an exciting three-season study of the Boston Common to better understand how the park is used, the numbers and intensity of various types of use, where park users come from, and what their interests and needs are to help inform planning and management of this important greenspace. We are working with an experienced research firm to conduct this survey and are in need of volunteers to assist. Volunteers and some Friends staff will be carrying out the survey including observing and recording uses and conducting interviews.
Who: Volunteers who are available to work occasional shifts, usually ranging from 3 to 4 hours.
What: Interviewing and counting people on the Common
Where: Boston Common and Friends of the Public Garden offices across from the Common
When: Spring, summer and fall, various times of day (some early morning, some evenings but only during daylight); we will not observe or interview during winter.
► clear speaking voice in English, able to be heard outdoors;
► enthusiastic and comfortable approaching park users and asking questions about their patterns of park use and opinions about park issues;
► attention to detail and following instructions about interviewing and observing;
► nimble in making quick counts of large numbers of people while walking around the Common.
- Minimum commitment: 20 hours (training time + 5 shifts on different days, 3 hours /day)
maximum commitment: 40 hours (training time + 10 shifts on different days, 3-4 hours /day)
- Desired work times: flexible, weekdays and weekends, normal park-use times from early morning through early evening; we hope that people will often work together in pairs
Please email us at email@example.com if you are interested in volunteering for this project.
From the 1970s, our advocacy for the Common, the Garden and the Mall has included protecting them from excessive shadow and wind resulting from development near the parks that would have a damaging impact on these centrally important greenspaces and the people who come to enjoy them.
We believe that development is essential to the vitality of Boston. We also appreciate that it brings new life and positive activity to our parks, and have seen this benefit in the recent growth of the Downtown Crossing residential and college communities. Recently, a project has been proposed across the street from the Common (171-172 Tremont Street) that exceeds the height limit of the Boston Common and Public Garden Protection Zone of the Midtown Cultural District. We are advocating for compliance with both the 1990 Shadow Law and Boston’s zoning code’s provisions protecting the Common as well as the Public Garden.
We wanted to provide an update to let our Members and supporters know that we continue to monitor projects and seek out information to understand their potential impact, including shadows, on the three parks that we advocate for. As always, we look forward to continuing discussions with our elected officials, residents groups, business community, and developers to speak on behalf of our parks. If you have feedback to share with us on this topic, please email us at firstname.lastname@example.org. As updates become available we will be sure to share them.
The Friends has been funding the expert care of trees since 1970 as part of our mission to preserve and enhance the Boston Common, Public Garden, and Commonwealth Avenue Mall. This work would not be possible without the financial support of our Members. We are always delighted when Members express a genuine interest in learning more about the details of the work we do. We noticed an increase in questions about tree care coming in over the past few months, and in particular inquiries about our work related to the elm bark beetle and Dutch elm disease, which seem to have been sparked by our Members Reception presentation (Digging In: Beyond the Roots of Urban Tree Care). We asked our contractor Christine Helie to explain some of the work she does for us. She is an entomologist and field scientist who works with her husband Normand at The Growing Tree. Chris is directly involved in developing an Integrated Pest Management program to preserve the mature and young elm trees in our parks. Here is what she had to say:
Among the trees in the Public Garden, on the Boston Common and on Commonwealth Avenue, is a unique collection of elm trees. This valuable assortment of European, American and Asian elms are susceptible to Dutch elm disease (DED). This disease is caused by a fungus that compromises the conductive tissue of the tree and eventually kills it. The primary vector of the fungus is the European elm bark beetle. Through its breeding and feeding behavior, this bark beetle transfers DED from diseased trees to healthy trees.
In 2012, with the support of Greg Mosman, Tree Warden of the Boston Parks & Recreation Department and on behalf of the Friends and its tree care program, a monitoring and management system for this insect was designed as part of a new elm tree preservation program for the mature and young elm trees in the three parks. The manner in which insects are monitored and managed can vary depending on the habitat in which they exist. For our purposes, a three sided box of plywood, painted green was built to house an 18”x25” sticky trap with a pheromone lure attached in the center.
Pheromones are chemicals produced by an organism that elicit a response from another organism. They are used by insects or animals to communicate with individuals of the same species. Depending on the type of activity, different pheromones will be used to relay a message.
For example, ants use a trail pheromone to mark a path leading to food that other ants in the colony can find and follow. However, when encountering a dangerous situation they use an alarm pheromone to warn their nest mates. The pheromones used in our beetle traps signal to both male and female elm bark beetles that this is a great spot for breeding and laying eggs.
There are over 24 traps in use throughout the parks. From the beginning, our goal was to
make them easy to access but discreet. Rather than placing unsightly posts throughout the parks, we decided to install our traps on trees at least 150 feet away from any elm trees.
Because the bark beetle is attracted to elm trees weakened by stress, one of the components in the pheromone mimics volatiles released by a stressed elm tree. As a result, the trees that we chose to place our traps on became substitute elms, luring the elm bark beetles away from the elm trees.
Pheromones are effective at very low concentrations and insect specific. This fact becomes evident when you compare some of the trees with traps to an actual elm tree. The vase shaped elm tree with upright branching is quite different from the pyramidal shaped Norway spruce with drooping branchlets.
The elm has a broad leaf with a serrated edge, whereas the spruce has needle-like foliage. The bark of an American elm tree has deep crevices that form diamond-shaped furrows, while the bark of a Norway spruce tree has thick round scales.
Regardless of these features though, the Norway spruce in the Public Garden has consistently captured high numbers of the European elm bark beetle on its trap.
Below are images showing the physical differences between Elm trees (top photos) and Norway Spruce trees(bottom).
Bark beetles appear to use different methods when locating a proper host tree. By crawling on the bark, they can sense the texture and determine whether the tree is susceptible to attack. Dispersing beetles are also guided by odors from weakened trees. From what we have observed in our program, it seems apparent that when the beetles land on a potential host, one of our stand-in elms, the odors detected override the physical clues they pick up from the tree. As a result the beetles continue to search for the source of the pheromones until they are caught on the trap or die trying to find the “elm.”
These traps have also allowed us to monitor the location, concentration, and pattern of movements of this disease host, helping to indicate the optimal times to treat, prune and, in some cases, remove a diseased tree.
Since their implementation, the elm bark beetle traps have become important tools in our fight against Dutch elm disease. The twenty four traps in use throughout the parks and surrounding areas are installed on thirteen different tree species. While these trees may be Oaks, Locusts, Maples, Lindens, or even a Norway spruce, they actually serve as substitute elms and are important allies in the preservation of our real elm tree population.
Landolt, Peter J. “Sex Attractant and Aggregation Pheromones of Male Phytophagous Insects.” American Entomologist Spring 1997 12-22. Print.