Before reviewing your results, verify how your state governs local authority. States follow either Dillon’s Rule, which limits municipalities to powers explicitly granted by the state, or Home Rule, which allows broader local authority unless specifically prohibited by state law. If you’re in a Dillon’s Rule state, your tree ordinance must follow state-enabling legislation. Check your state statutes, municipal league, or community forestry program to confirm your state’s model.
When developing or revising a tree ordinance, we recommend you work with your community’s legal counsel. Legal counsel will help ensure your ordinance complies with state and local requirements, properly establishes enforcement authority, and can achieve your community's goals, while avoiding potential legal challenges.
Introduction
The section or sections that define tree preservation requirements are the backbone of a functional tree ordinance. As will be covered in “Basic” level below, preservation requirements may apply only to public trees. The “Intermediate" and “Advanced” levels add preservation requirements for new development and removal permits for trees on private property.
The sample language and examples below will demonstrate these recommended components for effectual tree preservation:
- Public tree preservation: Prohibition against unauthorized pruning or removal of trees within the public right-of-way or parks.
- Protected trees: Trees with certain characteristics (i.e. 6 inch diameter or larger) that earn protection under the ordinance and must be preserved and/or replaced.
- Heritage or Specimen Trees: Trees with certain exemplary characteristics (i.e. a certain species with an 18-inch diameter or larger ) that earn additional protections under the ordinance and must be preserved.
- Tree Removal Permit: Setting limits and defining the process for individuals to remove trees on public and/or private property.
- Incentives/Exemptions: The best tree preservation requirements build in flexibility to meet tree objectives, while not putting undue burdens on residents and developers. Incentives and exemptions are a great way to boost that flexibility.
Key Definitions
DBH or DSH
The measurement of a tree trunk’s width, measured 4.5 feet above the ground. Diameter at standard height (DSH) is used similarly to diameter at breast height (DBH). In practice, DSH and DBH can refer to the same measurement, but “standard height” may be specified in certain codes or ordinances to clarify where the measurement should be taken.
Protected Tree
Any tree meeting specified size (e.g., ≥6" diameter at breast height [DBH]) or species criteria, as defined in the ordinance.
Heritage Tree
A tree designated for preservation due to exceptional size, age, historical significance, or ecological value (e.g., ≥24" DBH for native species).
Critical Root Zone (CRZ)
The area beneath a tree’s canopy, extending 1.5 feet radially per inch of trunk DBH, where root protection is required.
Example Language
Basic Level
Basic tree preservation ordinances establish an essential foundation for urban tree care. They introduce communities to the importance of tree protection, often through straightforward requirements such as basic permits and general oversight. This tier is especially useful for cities beginning to formalize their approach to tree management, providing a starting point for future growth and improvement.
Basic
Preservation of Public Trees
- No person shall remove or significantly prune a public tree without prior written approval from the City Arborist or designated authority.
- Protected trees are defined as those with a DBH of 12 inches or greater on public property.
Examples
Meridian, Idaho
Meridian, ID Code of Ordinances. Article B - Landscaping Requirements, Sec. 11-3B-10. Accessed May 29th, 2025.
Dubuque, Iowa
Dubuque, IA Code of Ordinances. Chapter 13 - Site Design Standards, Sec. 16-13-4-5. Accessed May 29th, 2025.
Brookfield, Wisconsin
Brookfield, WI Code of Ordinances. Chapter 12-28 Urban Forestry, Sec. 12.28.060. Accessed May 29th, 2025.
Intermediate Level
Intermediate tree preservation sections incorporate more structured standards and clearer definitions, such as specifying protected tree sizes and introducing permit processes. These ordinances often help communities address both public and private trees and offer some enforcement tools, making them effective for communities seeking to balance flexibility with increased stewardship. By doing so, they encourage broader participation in tree preservation and set the stage for more comprehensive protection as community priorities evolve.
Intermediate
Preservation of Public and Private Trees
- Removal of any public tree greater than 12 inches DBH or private tree greater than 18 inches DBH requires a permit from the City Arborist.
- Tree removal permits for trees on private property may be issued only when:
- The tree is determined to be dead, diseased, or hazardous, as verified by city staff.
- The tree is interfering with underground public utility lines, the foundation of a building, or a private sewer lateral and no reasonable alternative exists.
- The tree prevents reasonable use of the land, as determined by the Zoning Official and City Attorney.
- Heritage trees are subject to additional review by the Tree Board. A tree is considered a Heritage Tree if it meets any of the following criteria:
- A native oak tree that has reached 30 inches DBH or larger.
- Any tree species found on the Protected Species List, which is administered by the City Arborist.
- Any tree identified on the Historic and Cultural Sites of Significance list, which is administered by the Board of Arts and Culture.
Examples
Bothell, Washington
Bothell, WA Code of Ordinances. Chapter 12.18 - Tree Retention and Landscaping, Sec. 12.18.030. Accessed May 29th, 2025
Wildwood, Missouri (Canopy-based example)
Wildwood, MO Code of Ordinances. Chapter 410 - Tree Preservation and Restoration Requirements, Sec. 410.030. Accessed May 29th, 2025.
Lakeway, Texas
Lakeway, TX Code of Ordinances. Chapter 28 - Subdivisions and Site Development, Sec. 28.09.020. Accessed May 29th, 2025.
Advanced Level
Advanced tree preservation sections represent a community’s strong commitment to sustaining and enhancing its community forest. They incorporate best practices such as certified arborist involvement, robust protection during construction, canopy-based requirements, and a full suite of incentives and enforcement measures. This tier is ideal for communities aiming to maximize environmental, social, and economic benefits from their trees, ensuring a high standard of care and long-term resilience.
Advanced
Preservation of Public and Private Trees
- All protected and heritage trees on public and private property require a preservation plan before removal.
- A protected tree is defined as:
- Any tree 24 inches DBH or larger that is not an invasive species.
- Any tree 6 inches DBH or larger that is on the protected species list.
- A heritage tree is defined as:
- Any tree 36 inches DBH or larger that is not an invasive species.
- Any tree identified on the Historic and Cultural Sites of Significance list, which is administered by the Board of Arts and Culture.
- A protected tree is defined as:
- A preservation plan shall contain the following information to be considered for approval:
- A tree survey completed by an ISA Certified Arborist that correctly identifies the species, DBH, and location of each tree on the property, noting which trees are proposed to be removed and which trees are to be preserved.
- Specifications for protective fencing and signage during construction as outlined in section [referenced section].
- Commercial development projects must retain at least 30% of existing tree canopy or provide equivalent mitigation.
- Removal of any heritage tree requires approval by the Tree Council.
Examples
Edmonds, Washington
Edmonds, WA Code of Ordinances. Chapter 23.10 - Tree Related Regulations, Sec. 21.10.060. Accessed May 29th, 2025.
Davis, California
Davis, CA Code of Ordinances. Chapter 37 - Tree Planting, Preservation, and Protection, Sec. 37.02.040. Accessed May 29th, 2025.
Rodgers, Arkansas
Rodger, AR Unified Development Code. Article 3 - Land Development Standards, Sec. 3.3.5. Accessed May 29th, 2025.