A tree ordinance regulates various aspects of tree maintenance, removal, and planting in a municipality, resulting in aesthetic and environmental benefits.
A tree ordinance is a tool to help protect and manage a community’s trees. It can be designed to regulate various aspects of tree planting, removal, and maintenance on public and private property within a municipality. By protecting trees, a well-planned, written, and implemented ordinance can enhance a community’s beauty, reduce air pollution, lower air conditioning costs, and increase biodiversity. (See the “Benefits of Urban Trees” factsheet for more information.)
William Penn drafted America’s first tree ordinance to establish standards for tree planting in some of the early settlements near Philadelphia. During the late eighteenth century, colonists planted trees in village greens and along streets to emulate European cities. Detailed tree ordinances began to appear around the turn of the 20th century. Municipal tree commissions, which oversee the administration of street tree ordinances, were first authorized in Pennsylvania in 1907.The paper “Tree Ordinances as Public Policy and Participation Tools” traces the rising popularity of tree ordinances in recent decades. In 1984, researchers could only identify 100 communities nationwide with tree protection laws. As of 2017, there are well over 3,400.
The International Society of Arboriculture categorizes arboriculture-focused tree ordinances, which relate to maintaining trees for aesthetic and environmental benefits, into three main categories:
Street and park tree ordinances regulate the planting, removal, and maintenance of trees in parks or along public rights-of-way, including private trees that could endanger the traveling public. These ordinances can include tree planting specifications (e.g., requiring tree planting in parking lots) and tree care standards (e.g., standards for pruning and removal).
Tree and woodlot protection ordinances protect specific tree species, trees of a certain circumference or height, or trees with historical significance on private property. These ordinances usually stipulate that permits are required to remove, encroach upon, or prune such trees. They also provide for the replacement of removed trees.
View ordinances help resolve conflicts between property owners that occur when trees block views or sunlight.
Municipalities may use timber harvest ordinances to regulate the commercial harvesting of trees for wood products; these ordinances do not apply to the removal of trees for non-commercial purposes like improved views or concern for public safety. Often, they outline a permit approval process and prohibit bad logging practices such as high-grading.
Timber harvest ordinances are beyond the scope of this guide, which focuses on the arboriculture-related ordinances listed above. For more information about timber harvest ordinances, see the Timber Harvest Ordinances topic at ConservationTools.org.
Other municipal ordinances, like those pertaining to subdivision and land development (SALDO) or riparian buffers, can address trees. For example, a SALDO could dictate the number of replacement trees required to offset tree loss during construction and development projects.
Historically, tree ordinances have used the total number of trees in a community as a metric to guide planting and protection requirements. Some newer ordinances use canopy coverage as a metric instead of or in addition to total number of trees.
To evaluate the necessity and feasibility of an ordinance, a community should create a working group to assess the municipality’s needs and wants, resources, and existing ordinances. In the beginning, the group should develop rules governing information sharing, decision-making, and conflict resolution.
An ideal group is composed of people who mirror the demographics of the community. It should include experts in relevant topics like forestry and public works, as well as people from other fields. A sample group could include a realtor, developer, garden club member, arborist, planner, environmental group representative, landscape architect, forest landowner, public works official, business owner, lawyer, and interested citizen.
See the recorded Penn State Extension webinar “Managing Municipal Trees” to learn more about how tree ordinances can play an important role in public landscape administration.
For an overview of the steps required to develop a tree ordinance, see “Developing Successful Tree Ordinances” published by the North Carolina Cooperative Extension.
For in-depth information on the process, see Guidelines for Developing and Evaluating Tree Ordinances. Published by the International Society of Arboriculture in 2001, it remains the most comprehensive guide on the subject, addressing everything from planning and implementation to evaluation and enforcement.
More than 100 municipalities across Pennsylvania have adopted tree ordinances. Below are links to ordinances for several of these municipalities. The ordinances are also included as “Featured Library Items” in the online edition of this guide.
The Arbor Day Foundation began the Tree City USA program in 1976 to promote sustainable urban forestry practices in communities across the country. In order to achieve Tree City USA status, municipalities must:
As of 2017, there more than 3,400 official Tree Cities nationwide, including 108 in Pennsylvania. Philadelphia and Upper Merion Township are longest-running Tree City communities in the state, having achieved that status in the program’s inaugural year. See the Pennsylvania Tree City fact sheet for more information.
 There are more than 3,400 official Tree City USA communities; one requirement for this designation is adoption of a tree ordinance. Numerous communities have enacted tree ordinances without applying for Tree City USA status.