Guidelines for Developing and Evaluating Tree Ordinances

Effectiveness of existing ordinances

The effectiveness of a tree ordinance can be influenced by many factors. Do the residents support or oppose various ordinance provisions, or are they even aware of them? Is the ordinance enforced adequately? Does the ordinance account for environmental limitations that affect tree health, growth, and survival? Does the local government have the financial resources to fulfill ordinance requirements? Since the answers to these questions will vary from place to place, even very similar ordinances can have quite different outcomes in different communities.

In our 1992 survey of city and county tree programs in California (Bernhardt and Swiecki 1993), we asked tree program managers about the effectiveness of their existing ordinances. The majority of respondents from cities and counties with existing ordinances believed that their current tree ordinance was in need of revision. In some cases, respondents from different programs within the same city had widely divergent opinions on the effectiveness of their existing ordinance. Enforcement was not the only issue affecting effectiveness ratings - 52% of the city respondents felt that tree ordinance enforcement was adequate. (A note of caution here: many of these respondents were probably responsible for ordinance enforcement in their cities.)

As we discuss in Part 3, Evaluating the urban forest and ordinance performance, it is possible to objectively assess the performance of a tree ordinance. This assessment requires both an evaluation of the ordinance and related regulations and evaluation of the urban forest itself. In our analysis of California tree ordinances, we looked to see whether each ordinance had the structural elements necessary for effectiveness. Although ordinances may vary widely in form, content, and complexity, an effective tree ordinance should meet the following criteria:

The first five criteria are key features of the ordinance itself. The last two criteria reflect the background in which the ordinance is developed. Although an ordinance meeting these criteria is not guaranteed success, ordinances lacking one or more of these elements will definitely be handicapped. In our review of city and county tree ordinances, we looked for evidence that the first six of these basic criteria were met.


A clear statement of goals is essential, since goals provide the basis for interpreting the ordinance and evaluating its effectiveness. However, only 52% (88) of the ordinances we reviewed began with a stated purpose which can be interpreted as the goal of the ordinance. Goals were most commonly lacking in street tree ordinances. Among street tree ordinances that did list a goal, it was often of the form, "to establish rules and regulations governing tree planting, maintenance and removal on the public right of way". This type of goal suggests that the ordinance is seen as an end in itself, rather than as a tool to help achieve certain community forestry goals. Some street tree ordinances do show a clear link with a wider management strategy, as indicated by a goal such as "to create a master plan governing tree planting, maintenance, and removal".

Tree protection ordinances nearly always begin with a stated goal, such as "to prevent wanton destruction of trees", or "to preserve as many trees as possible during the development process". However, goals such as these may be too general to allow for meaningful evaluation. How many are "as many as possible"? The lack of clear, specific goals is a common shortcoming of many tree ordinances.

Responsibility and authority

Of the ordinances reviewed, 54% (91) designated a single position responsible for enforcing the ordinance and carrying out the urban forest program. In the remainder of the ordinances, responsibility was split between two or more positions, or worse yet, was not designated.

In most cases, the most efficient way to manage the urban forest is to have a single person responsible for overseeing all tree-related activities. This allows for better coordination of management activities and reduces conflicts between departments. However, in small communities, it may not be possible to have a single central tree authority. Responsibility may be split between a tree commission, which sets policy and has administrative duties, and city staff, which is responsible for operations and enforcement.

The tree program manager should be vested with the authority necessary to carry out his or her responsibilities. A reasonably clear link between responsibility and authority is found in many tree ordinances. However, in some ordinances, responsibility appears to exceed authority, whereas in others, authority is granted, but specific responsibilities are not stated. The management of the urban forest is likely to suffer when responsibilities are ill-defined or the authority to act is not granted.

Basic performance standards

Many tree ordinances focus on setting specific standards that pertain to trees. A tree ordinance should indicate which practices and conditions are acceptable and which are not. For example, damaging public trees is unacceptable in most communities and is addressed in many tree ordinances. Some communities find that damage to or removal of oaks and other native trees without cause is unacceptable, and address this in their ordinances.

Besides stating what is regulated, an ordinance should set basic standards for performance. Many older ordinances are deficient in this regard. For instance, many ordinances require tree planting in conjunction with new construction. However, relatively few ordinances set standards for the eventual amount of canopy cover or shading that is to be provided, or the level of species diversity to be achieved. Similarly, many ordinances require an extensive permit process before native trees can be removed, but few set a standard for the maximum amount of canopy that can be removed overall.  If basic standards for performance are not set, it is possible that all individual actions taken will conform with the ordinance, but that the overall goals of the ordinance are never achieved. Effective performance standards address the urban forest as a whole rather than focusing exclusively on individual trees.

Excessively vague standards (e.g., "as much as possible") may not only be unenforceable, but may not survive a legal challenge.  In 1999, a Fulton County Superior Court Judge ruled in favor of developer against the City of Atlanta because a section of the city's tree ordinance lacked sufficient objective standards.  The section in question included the following language (underlined sections are our emphasis):

...the city arborist shall require that  improvements be located so as to result in minimal disturbance to the natural topography of the site and the protection of the maximum number of mature trees on the site. It is the specific intent of this section to require that damage to mature trees located within setback and required yard areas and to trees located on abutting properties owned by others be minimized to the greatest degree possible under the particular circumstances, as determined by the city arborist in the city arborist's discretion. [Atlanta, GA: 1999 Code of Ordinances Part II, Ch. 158, Art. II, Div. 2, Sec. 158-104]
Although the concept advanced in this provision may be reasonable, additional language is needed to more clearly define what constitutes  "minimum disturbance" or the "maximum number".   For example, tree retention standards based on a percentage of the existing tree density or canopy cover (see Provision 32. Conservation of forest and woodland resources during development) could provide a sufficiently objective standard for assessing whether a project complies with the ordinance.

While avoiding the pitfall of vagueness, an ordinance should also avoid slipping into the abyss of excessive technical detail.  Many ordinances have focused on very detailed implementation standards instead of setting basic performance standards.  For example, many ordinances include lists of species that are allowed or prohibited for use as street trees. Others specify the size of planting stock to be used in plantings. Implementation standards such as these change as new methods and materials are developed and old ones fall out of favor, and as a result, ordinances with these details can quickly become outdated.  If detailed specifications are needed, they are more appropriately placed in the urban forest management plan, which can and should be updated frequently.


While ordinances should set basic performance standards, it is important that they allow for flexibility. If the tree ordinance sets objective performance standards, it can also direct the community arborist or forester to implement the standards by making decisions on a case-by-case basis. This can reduce the need for overly detailed implementation standards and allows for the flexibility to make decisions based on site-specific physical and biological factors.  Even if a community does not have personnel with the necessary expertise on staff, the ordinance can allow for the input of qualified professionals on specific issues. For example, many tree protection ordinances require a report by a qualified consultant as a part of the permit process.  Outside technical consultants should work for and be responsible for representing the interests of the community, not clients that may have a financial interest tied to tree removal or damage (e.g., a property owner or developer).

About three-quarters of the ordinances have a process for appealing decisions. The appeal process provides a degree of flexibility, in that it serves as a check against the authority of the tree program manager. Ideally, this helps to ensure that decisions are based on all pertinent information, and that they stand on technical merit. Unfortunately, appeals may also serve to undermine good urban forest management if they routinely allow political pressure to override the decisions of competent tree specialists.


Enforcement is an important aspect of every ordinance. Only slightly more than half of the ordinances we received contain an enforcement element. Although 48% (81) of the ordinances specified penalties for violations, only 24% (41) designated a position or positions responsible for enforcement. Thus, many tree ordinance provisions may not be enforced because nobody is specifically charged with this duty.

In ordinances with enforcement provisions, many kinds of penalties are employed. Fines, jail terms, and forfeiture of performance bonds are among the penalties invoked in both street tree and tree protection ordinances. Many jurisdictions also require specific replacement plantings as penalties. In some street tree ordinances, occupancy permits are withheld until required trees and landscaping are satisfactorily installed. Many of the penalties available appear to be sufficient to help deter offenders, but only if consistent enforcement makes it likely that violators will be cited and penalized.

Comprehensive management strategy

Few existing ordinances have been developed as part of an integrated tree management strategy. Only 6% (10) of the Californian ordinances we reviewed showed clear evidence that they were an element of a comprehensive management strategy. Without this underlying strategy to guide the process, inappropriate provisions may be included, or necessary provisions may be omitted. Furthermore, local governments may unsuccessfully use a tree ordinance to pursue goals that are more readily achieved through other means. The tree ordinance is often seen as an end in itself, rather than as one of a number of tools which must be used to attain a healthy, vigorous, and well-managed community forest. The lack of integration between urban forest management and tree ordinances is probably the most prevalent and serious problem with tree ordinances overall.

An ordinance is not a panacea for poor or inadequate management of community tree resources. Properly applied, an ordinance can help facilitate good management. Improperly applied, ordinances can legitimize counterproductive practices, provide disincentives for tree conservation, and undermine the long-term sustainability of the urban forest. By focusing on community forest management, rather than simply regulation, communities can determine whether an ordinance is necessary, and what its role should be. By following the process we present, Developing a Community Forest Management Strategy, communities can develop effective ordinances that are uniquely suited to meet their specific needs.

It seems that relatively few communities have followed this approach in developing their tree ordinances. Far more commonly, tree ordinances are drafted after reviewing a few existing ordinances or "model" ordinances. As a result, we found that many California tree ordinances were very similar to one another. In several instances, two or more communities had identical ordinances. Certain frequently-copied provisions are found unchanged in many ordinances, often complete with dated terms or concepts. Although it is possible to construct an ordinance using a "cookie cutter" approach, such an ordinance is unlikely to be well integrated with a comprehensive urban forest management strategy.

Community support and ordinance success

Community support is critical to ordinance effectiveness, but community support cannot be legislated into an ordinance. Rather, the ordinance must be developed within the context of community values and priorities if it is to enjoy public support. Even a technically correct tree ordinance is apt to be ineffective without public support.

Passing a highly restrictive ordinance in a nonsupportive community is not only politically difficult, but may be counterproductive. Rossi (1990) described such a situation that occurred after the passage of a tree protection ordinance. Local citizens attempted to circumvent the ordinance by cutting down trees before they attained the diameter specified for protection in the ordinance.

As a practical matter, most tree ordinances rely heavily on voluntary compliance. Few communities would support the concept of a patrolling "tree cop" that seeks out violations. However, citizens in many communities are willing to voluntarily comply with restrictions they perceive as reasonable, and report obvious violations to protect their local tree resources. To be successful, tree ordinances should not impose regulations that most local citizens are unwilling to support.