Maintaining a Healthy Tree Canopy
The trees of Mount Holyoke College have long been admired as part of our beautiful campus landscape. Maintaining the health of these trees is an ongoing collaboration between the Botanic Garden and the Grounds Department, with input from certified arborists as needed. A large percentage of the trees on campus were planted at the same time in the 1940’s, replacing trees lost during the hurricane of 1938. The many changes to the campus over the last 60 years have stressed many of the trees, resulting in a tree canopy that is in decline.
Knowing many in the MHC community are concerned about campus trees, we thought it would be helpful to give you more information about the process of tree management. Every tree on campus is in the Botanic Garden’s database. Included in the database is a description of the health of the tree with an assessment of overall health as excellent, good, fair, or poor. Trees in the poor category are inspected annually to determine if any have become hazardous, and need to be removed.
The primary reason trees are removed is safety. The generally accepted definition of a hazardous tree is: “a tree with structural defects likely to cause failure of all or part of the tree, which could strike a ‘target.’ A target can be a vehicle, building, or a place where people gather such as a park bench, picnic table, street, or backyard.”1
Besides hazardous trees, some trees need to be removed as part of construction projects, and, in spite of appearances to the contrary, we work very hard to save as many trees as possible. Any tree small enough to move has always been relocated to another site on campus. In some cases, utilities have been rerouted to avoid damaging tree roots. Tree removal is only done as the last choice.
Planting for the Future
Because there had not been a tree planting program for many years, during the 1990’s the Botanic Garden and Facilities Management planted nearly two trees for each tree removed. Now we plant one tree for every tree removed. Sometimes the replacement tree will be planted in the same location; at other times we might determine that the original site is unsuitable for a tree. In this case, a tree will be planted at another location on campus.
Everyone on campus can help us preserve the health of our trees by keeping vehicles off the lawn areas, especially around trees. Most trees have roots that reach far beyond the spread of their canopy, and most roots are in the top 18” of soil. This means most of our campus is criss-crossed with tree roots. Even pedestrians can have an impact. Continual use of non-paved paths will compact soil and negatively impact tree health.
While tree removals are unavoidable, we can all help prolong the lives of our trees, and leave the legacy of a healthy landscape for future members of the Mount Holyoke College community.
If you have any questions or concerns about campus trees, please contact Russ Billings, Director of the Botanic Garden at x2265.
1 Minnesota Department of Natural Resources, and USDA Forest Service. 1996. How to Recognize Hazardous Defects in Trees. USDA Forest Service NA-FR-01-96. 20 pp.