Tree Protection and Replacement Ordinance Standards

Municipalities can do a great deal to protect trees and woodlands in their communities through ordinance protection standards. These standards, implemented through the zoning and subdivision and land development ordinances, can both protect existing trees and add new trees as part of the land development process. Some amount of tree removal is often necessary during the development process; however, municipal codes can reduce the ecological impact of woodland and tree removal by limiting disturbance to mature trees and/or healthy woodlands with high ecological value. Municipal codes should prioritize the preservation of existing trees, particularly mature native trees, specimen trees and heritage trees, as replacing these trees' ecological, aesthetic and functional value takes decades.

Woodlands Protection Standards

Municipal tree protection standards should limit the removal and disturbance of existing trees during the land development process. Woodland protection ordinances are typically found in the zoning ordinance as part of a package of natural resource protection standards. Municipal ordinances can impose limits on woodland removal in a number of ways. Some examples include:

  1. Limiting the disturbance of existing woodlands to a given percentage: A maximum disturbance limit of no more than 50 percent should be considered, and potentially even lower disturbance of 35 percent permitted for residential development.
  2. Requiring a tree survey be performed as part of an existing conditions plan, and limiting disturbance based on the caliper size of existing trees. This approach may be most appropriate for smaller development projects where conducting a tree survey would not be cost prohibitive.
  3. Requiring a woodland delineation be performed, and attaching a maximum percentage of each class of woodland that can be disturbed. This approach is appropriate for large development projects, and for municipalities with important and high-value woodland resources on developable land.

Tree Protection Standards During Construction

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Tree Protection Zone

Equally important to protecting existing woodlands is to ensure that trees that are to remain on site are protected during construction through establishing tree protection zones. Tree protection ordinance standards are typically found in the subdivision and land development ordinance, although if a municipality wishes to protect trees outside of the land development process, these standards can be placed in the zoning ordinance or cited by a cross-reference from the zoning ordinance. The analysis of existing trees should occur early in the design process, and existing trees to remain should be shown on development plans. To demonstrate adequate protection of existing trees, plans showing existing trees to remain should also show tree and root protection zones, tree protection zone barriers, soil erosion and compaction controls, staging and storage areas, and existing and proposed utilities.

Municipalities may wish to refer to industry standards for tree protection within their ordinance:

Further information and ordinance examples for protecting woodlands, trees, and other natural resources are covered in a series of eTools on the Planning Commission website. The eTools that most specifically address topics related to tree woodland protection include:

These eTools include links to sample ordinance language for woodland and tree protection and replacement.

Tree Replacement Standards

In addition to protecting existing trees, municipalities can work towards a net-zero loss of trees by requiring the replacement of trees that have been unavoidably removed during the development process. The following examples of tree replacement ordinance standards have been adopted by municipalities in Chester County. As noted under Planting and Maintaining New Trees, the use of native tree species is highly recommended and can be included as a requirement in ordinances.

These examples are located in the subdivision and land development ordinance which provides some flexibility in how the standards are applied. While this flexibility can be useful where the replacement standards are difficult to fully implement due to site conditions, municipalities are highly encouraged not to waive the standards as a general practice. Please note that this list is not all inclusive and municipalities handle tree replacement in several different ways. Based on our inventory, at least 15 municipalities have enacted some form of tree replacement requirements in their ordinances.

New Trees

When enacting or updating tree replacement standards keep in mind that bigger is not always better in the case of new trees. Large replacement trees of (5"-6" caliper) can take years to get established and need to be carefully cared for longer periods of time. Larger replacement trees also have a higher mortality rate than younger trees and landscaping guarantees for new trees usually only last for one year. In fact, experience has shown that smaller trees can sometimes catch up and outpace the larger caliper trees while having a higher survival rate. This National Park Service site addresses a variety of considerations when selecting and specifying nursery stock.

Tree Planting Standards

Tree ordinances play a crucial role in promoting urban forestry and ensuring the integration of trees into new developments. These ordinances often mandate the planting of new trees as part of the land development process, typically included in zoning, land development, and subdivision regulations. For example, ordinances can require developers to plant shade and landscaping trees in parking lots, along rights-of-way, within stormwater management areas, and in riparian buffer zones to enhance environmental benefits and aesthetic value.

Many municipalities require developers to submit a detailed landscaping plan to ensure compliance. This plan typically outlines the quantity, species, and placement of trees and planting specifications designed to improve tree survival and long-term performance. Additionally, some ordinances require developers to provide a financial guarantee or performance bond to ensure that the proposed planting is completed and that newly planted trees are maintained and thrive.

In cases where on-site planting is not feasible, ordinances often include a fee-in-lieu option. Under this provision, developers contribute funds to a municipal tree-planting program instead of directly planting trees on the development site. The municipality can then use these funds to achieve broader tree-planting and preservation goals, such as creating community green spaces, restoring degraded areas, or expanding urban tree canopies.

For more information on the types and purposes of tree ordinances, tips on developing a successful ordinances, and other examples in Pennsylvania, see WeConservePA's Tree Ordinance guidance webpage.

Urban Tree Ordinances

The following tree ordinances work well in urban areas. These ordinances include protections for both public trees and larger trees on private property: