The Road to a Thoughtful Street Tree Masterplan

Street Trees

By Ken Simons and Gary R. Johnson

Download the entire document: The Road to a Thoughtful Street Tree Master Plan (PDF, 6.9MB) and see the accompanying slideshow series, added in December 2011.

Down through the ages, the roadside planting of trees has mirrored the order, prosperity and achievements of civilized societies. Man-made row plantings of uniformly spaced trees are evidence of man’s presence, power and ability to organize his surroundings, and to influence the environment for his comfort, safety and visual pleasure. Row plantings of trees are one of the earliest and simplest expressions of an intentional and functional design.

The “greening” of towns and cities, also known at times as “reforestation” and “beautification”, has long been pursued in this country. Interest in urban greening has three notable historic peaks. The first occurred in the mid to late 1800s, when Andrew Jackson Downing and Frederick Law Olmsted, pioneers in the field of landscape architecture, influenced public thinking with their creation and promotion of urban green space and beautification projects. The second peak took place in the 1960’s and 1970’s when many thousands of trees were lost to Dutch elm disease. The last peak happened as part of the current rise of urban forestry as a profession.

The importance of urban greening is supported by recent research and study that verifies the social, economic and environmental benefits of urban trees. Unquestionably, the urban forest contributes to a community’s quality of life. Together with public parks and open space, street trees are a primary component of urban greening.

Primarily, streets serve as transportation and utility corridors. Street trees are an ancillary use and should be regarded as guests within these corridors. As such, decision makers must strive to ensure that street trees will not become unwelcome intruders.

Unfortunately, many street tree planting efforts have not been guided by a thoughtful master plan. All too often, in a rush to qualify for government grants, reforest denuded streets or maintain momentum of volunteer interest, street tree planting initiatives become a haphazard, ill-considered process with no concern for after-care needs. Without a thoughtful master plan, trees that should be long term assets can become costly liabilities.

Street trees are an integral part of a community’s infrastructure, and as such, warrant thoughtful planning and budgeted management. Some decision makers have not learned from past mistakes, and they are the reason that negative history repeats itself. For example, in many cities where Dutch elm disease devastated miles and miles of streets that were graced by Gothic-arching elms, decision makers have replanted those barren streets with miles and miles of green ash or Norway maple.  One monoculture tree population was replaced by another. Familiarity, popularity, adaptability and availability of certain species can cloud judgments. Today, the threat of emerald ash borer, Asian long horned-beetle and ash yellows causes city foresters to view the future of these replacement ash populations with great anxiety.

Regardless of concerted education endeavors by utility companies, decision makers continue to place tall-growing trees under overhead utility wires, creating potential service disruptions and making such trees candidates for disfigurement by line clearance pruning. Like-minded short sighted decisions also result in the placement of trees in dedicated border areas and limited ground-space locations that, over time, bring the trees into conflict with road improvement projects (e.g. widening), adjacent hardscape infrastructure (e.g. curbing, sidewalks, paths) and underground utilities. Another common error often made by decision makers is the planting of intolerant trees in unsuitable growing environments that, over time, contribute to abnormal growth, decline or mortality.

In order to prevent such negative history from repeating itself, decision makers need to recognize and understand the relevant lessons of the past. Street trees can be a unifying thread that weaves through the urban fabric. If street tree initiatives are to fulfill the good intentions of decision makers, the right tree needs to be planted in the right place for the right reason and given the right after-care. This is the on-going challenge that confronts decision makers. A thoughtful street tree master plan that incorporates intelligent designs, derived through the recommended comprehensive planning process, is the road decision makers need to follow to accomplish their worthy objective.

Gary Johnson
Gary is a Professor Professor of Urban and Community Forestry within the Department of Forest Resources/Extension at the University of Minnesota. His work addresses a variety of urban natural resource issues.

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