The Role of Local Ordinances in Protecting Oaks and Oak Woodlands    1998

Tedmund J. Swiecki and Elizabeth Bernhardt
Phytosphere Research, Vacaville, CA

Additional key words: tree protection ordinance, heritage tree ordinance, tree preservation, woodland conservation

The many benefits that oaks and oak woodlands provide to communities are well-known. They reduce air and noise pollution, provide shade and cooling, furnish habitat for wildlife, stabilize soils and protect against erosion, enhance aesthetics and property values, and are an important contributor to community image and quality of life. It is therefore in the best interest of the local government to protect and enhance these natural resources to promote the health, safety and general welfare of its citizens.

If a local government's objective is to protect and enhance its oak resources, well- planned, careful resource management is necessary. Tree ordinances can provide the legal framework for the management of oak resources by enabling and authorizing management activities. The management of oaks on both public and private properties can be influenced by a tree ordinance.


There are at least two major pitfalls to be avoided in the drafting of a tree ordinance. First, it is important that ordinances facilitate rather than prescribe management. Ordinances that dictate management specifics can unnecessarily limit management options, and may end up requiring the use of inappropriate, ineffective, or outdated techniques. Ordinances are not as likely to become outdated if they provide that specific management practices be established by trained professionals. Resource management practices need to be site-specific to be effective, so the "one size fits all" approach is doomed to failure.

To avoid the second potential pitfall, policy makers must recognize that their primary goal should be management, not regulation. In many cases, regulation has been the "tail that wags the dog", and management has only been considered as an afterthought. Experience has shown that local tree ordinances are often developed in response to public outcry over specific perceived problems. This "band-aid" approach often leads to ordinances that are not consistent with sound management practices, and which can actually thwart good management. For example, public pressure has led to the development of ordinances designed to protect old "heritage" oaks in many communities. However, most of these same ordinances permit the routine destruction of younger trees. The end result may be an unsustainable woodland, short on young trees and long on old, declining trees. By focusing too narrowly on individual trees, such ordinances can result in the degradation of the entire oak woodland resource.


Few, if any oak ordinances in use in California have been developed entirely from scratch. More commonly, persons interested in drafting an oak ordinance obtain one or more existing ordinances, and then pick and choose the provisions that seem most suited to their situation, modifying or adding to them as they see fit. However, there are several common problems with this approach. First, important elements may be inadvertently omitted in this process. Second, provisions are often selected without any information about effectiveness. Most importantly, this approach often results in the development of an ordinance that has no relationship to an integrated management strategy. The ordinance is often seen as an end in itself, rather than one means to promote oak conservation and stewardship.

A better alternative is to focus on the development of a comprehensive resource management plan that addresses the needs and desires of the county's residents to conserve their oak woodlands and other significant resources. The county should then pursue those actions which are necessary to implement its management strategy. The tree ordinance is simply one tool that may be used in the implementation of a comprehensive resource management program for oak woodlands. By following this approach, the local government can develop an ordinance that is uniquely suited to its own particular needs and constraints.

Most of the shortcomings attributed to oak ordinances can usually be traced to the lack of a clearly thought-out management strategy. Poor planning leads to poor ordinances, and even the best-written ordinance is unlikely to be successful in the absence of an overall management plan.


Effective tree ordinances do not exist as separate entities from the management process, but are integral parts of it. Therefore, in order to develop an appropriate and effective ordinance, it is necessary to first develop an overall management plan for oak resources. The management planning process can be expressed in terms of the steps necessary to answer four basic questions about oak resources in your jurisdiction: It is important to note that resource management planning is an ongoing process. Because oak resources and the external factors that affect them are continually changing, management strategies must change to cope with new circumstances. Asking the fourth question of the series helps to bring the process full circle. To determine whether you are getting what you want, it is necessary to again ask what you have, which restarts the planning process. The steps required to answer these four basic questions are discussed in the following sections.


1. Assess the tree resource.

To be successful, management must be based on knowledge of the resource being managed. An assessment of oak resources provides the basic information necessary for planning management strategy. It also provides a baseline against which change can be measured. Most oak resource assessments rely on various inventory methods. Data may be collected through ground surveys, aerial photography, or some combination of the two.

2. Review past and current management practices.

The current condition of oak resources is the result of existing and past management practices. Oak conservation has generally not been a major focus of land management practices in most locations. However, cultural practices that may have been followed, such as grazing, fire suppression, and tree and brush removal, have significant consequences for oak resources.

In addition to private land management practices, the impacts of land use planning and other local government regulations on oak resources should be considered. General Plans, development guidelines, fire codes, and other regulations may have profound and possibly unintentional impacts on oak resources. Before attempting to alter oak woodland management, local governments should thoroughly evaluate the consequences of their current and past actions.


3. Identify needs.

Based on the assessment of the resource, needs must be identified at several levels. The biological and ecological needs of the oak resource itself must be identified. Regeneration, habitat size and continuity, understory vegetation management, and other factors that affect the viability of oak woodland resources should be considered. The needs of those charged with resource management responsibilities should also be considered. Their needs may include better access to resource specialists or information, more personnel, increased training, or authority to implement, monitor, and enforce elements of the management plan. Finally, the needs of the community with respect to oak resources must be identified and considered. Education about the oak resource and its associated values and information about land management methods that conserve oak resources are among the more commonly identified community needs.

4. Establish goals.

Goals are set to address some or all of the needs and problems that have been identified and guide the formation of the management plan. If it is not feasible to immediately address all of the needs identified, it will be necessary to prioritize goals, distinguishing between those that can be achieved quickly and those that may require a long-term approach. To ensure that realistic goals are established, community support, economic realities, and environmental constraints should be taken into consideration.

It is absolutely critical that local citizens become involved in the process at this point. Like it or not, most tree ordinances rely heavily on voluntary compliance by the public. Such compliance is only likely to be achieved if county residents support the goals which have been set. Management goals reached with public input are more likely to reflect community values and will enjoy greater support. Public participation in the goal-setting process also serves an educational function, providing an opportunity for citizens see how oak management affects them.

Goals are the tangible ends that the management strategy seeks to achieve. It is therefore important to set goals which are quantifiable in some way, so that progress toward the goals can be monitored. If very general and diffuse goals are set, it may not be possible to measured progress toward these goals in any meaningful way. Some specific goals for oak woodland management might include:


5. Select management tools and formulate the management plan.

At this stage, you should have the information necessary to develop a management plan that addresses the goals that have been established. All of the options available to implement the management plan should now be researched and considered. The drafting of an ordinance should not be contemplated until this step has been reached.

Cities and counties have a variety of tools at their disposal to develop a strategy that promotes conservation and good management of their oak resources. Land use planning instruments, including the General Plan and Specific Area Plans, can be used to direct development away from the most sensitive areas, and establish a framework for resource protection during development. Within the planning process, local governments can require or encourage dedication of oak woodlands as public open space as a condition of approval or in exchange for higher density or other bonuses. Other planning tools such as the transfer of development rights (TDR) and cluster zoning can be used to minimize the intrusion of development into oak woodlands. The local government can trigger the review and mitigation requirements of the California Environmental Quality Act (CEQA) when a project will have a significant impact on sensitive and important natural resources including oak woodlands. Public education, assistance, and incentive programs can be implemented to encourage good stewardship of oak resources on private lands. Finally, ordinances may be used to authorize various management activities or prohibit especially destructive practices.

Feasibility, practicality, legality, and economics should be considered in selecting the appropriate management tools. For some goals, several management options may be available, whereas others may require the use of a specific tool or several tools in combination. The methods to be used to attain various goals are integrated into a functional action plan.

Citizen involvement and support continues to be important in this phase of the process. Management approaches and tools that are unacceptable to county residents are unlikely to succeed. If a local government intends to push for more progressive oak management than the citizens are prepared for, it should choose tools that will build citizen awareness and support, including educational and incentive programs.

6. Implement the management strategy.

Although a plan may appear ideal on paper, it clearly cannot achieve anything unless implemented. This requires the commitment of resources necessary to hire personnel, update or amend General Plans, establish new development guidelines, enforce ordinances, run educational programs, and carry out other components of the management plan.

Because a number of steps are usually involved in implementing the management strategy, it is useful to map out an implementation schedule. This time/action schedule should show the sequence of steps that are involved and the time frame they should be completed within. Progress checks should be built into the schedule to ensure that delays or problems are detected and dealt with. These progress checks could be in the form of required progress reports to the County Board of Supervisors or City Council. It is important to keep a high profile for the management program during implementation to foster public interest and maintain the commitment of the local government. If interest and support dissipate before the plan is implemented, the efforts spent to get to this point may be for naught.


7. Evaluate and revise.

Even a successfully implemented management plan must be monitored and evaluated to ensure that progress is being made and standards are being met. If the implemented action plan is not evaluated, there is no way of determining whether management actions are having their desired effects. Furthermore, needs may change over time, requiring adjustment of goals and changes in management.

Evaluation requires that oak resources and management practices are reassessed. If evaluation shows a lack of progress toward goals or a deterioration the oak resource, a change in management plan may be required. In turn, these changes will need to be monitored and evaluated. The evaluation and revision step allows the management planning process to cycle repeatedly, so that the management plan can evolve to keep pace with changes in the oak resource.


In the process outlined above, an ordinance may be selected as an appropriate tool for accomplishing certain oak management goals. There are no magic formulas for writing effective ordinances, but good planning and common sense will help immensely. It is important to realize that ordinance effectiveness can be affected by a variety of factors that cannot simply be legislated away, including community support, environmental limitations, and economic constraints. For these reasons, very similar ordinances may have quite different outcomes in different locations.

Despite the variability in form, content, and complexity that exists between tree ordinances, effective ordinances generally share the following basic features. The first two features common to effective ordinances reflect the background in which the ordinance is developed, whereas the remaining five features are key elements of the ordinance itself. Although consideration of these features does not guarantee that an ordinance will be effective, ordinances lacking one or more of these features will definitely be handicapped.

1. High level of citizen support.

Citizen support cannot be legislated into an ordinance. Rather, an oak ordinance must be developed within the context of an informed and supportive citizenry. As a practical matter, most tree ordinances rely heavily on voluntary compliance and reporting of violations by members of the community. Few communities would support the concept of a "tree cop" that seeks out violations, but citizens in many areas are willing to report obvious violations to protect their local oak resources.

In jurisdictions where citizens strongly support the protection and enhancement of oak resources, highly restrictive ordinances can be effective. However, passing a highly restrictive ordinance in a nonsupportive county would not only be politically difficult, but may be counterproductive. In at least one location, local citizens attempted to thwart an oak protection ordinance by cutting down trees before they reached the size where ordinance restrictions came into play.

2. Part of an overall management strategy.

As discussed in detail above, an ordinance should only be considered in the context of a more comprehensive plan for managing oak resources. Unfortunately, many oak ordinances have been enacted in the absence of an adequate management strategy. As noted earlier, without the broader view of a comprehensive management strategy, an ordinance may permit the degradation local oak resources to continue, or even be accelerated.

3. Goals clearly stated and addressed.

A clear statement of goals within the ordinance is critical. These stated goals provide the basis for interpretation of the ordinance and evaluation of its effectiveness. The goals should be specific, so that a clear relationship between the goals and actual ordinance provisions can be established. Specific goals, such as the examples mentioned above, can also be objectively evaluated to determine whether the ordinance is having its desired effect. More general goals, such as "to prevent wanton destruction of oak trees", do not lend themselves to an objective evaluation.

4. Responsibility is designated, and commensurate authority is granted.

The management actions authorized in an ordinance do not happen by themselves. Permit applications need to be reviewed and acted on, standards must be enforced, educational and incentive programs need to be administered. It is generally more efficient if a single position is charged with the responsibility to oversee and coordinate all oak- related activities. Ordinance effectiveness tends to suffer when the responsibility for implementation is split between many different positions.

Whenever responsibility is assigned, authority must also be granted. It does little good to assign enforcement responsibility to a position that is not empowered to issue citations. Likewise, a person with responsibility to develop educational programs will not go very far without the authority to approve the expenditures for these programs. If the responsibility to conduct various activities exceeds the authority necessary to make them happen, those charged with implementation are likely to become frustrated, and the ordinance is unlikely to fulfill its goals.

5. Basic performance standards.

An ordinance should set standards that indicate what is acceptable and what is not. The type of activities that may be regulated, such as tree removal, are based on such standards. Beyond determining what should be regulated, an ordinance should set basic targets for performance. These standards should reflect good management practices and be sensitive toward public attitudes.

It is in this area that many current ordinance provisions are deficient. Very few oak ordinances set basic performance standards that define limits for the depletion or destruction of oak woodlands. For instance, many oak ordinances require an extensive permitting process before oaks can be removed, but few ordinances set a standard for the maximum amount of canopy that can be removed overall. If basic performance standards 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.

6. Flexibility.

While ordinances should set basic performance standards, it is important that they allow for the input of qualified professionals in the implementation of the ordinance. This flexibility is critical, because "cookbook" methods are often inadequate for dealing with complex biological systems such as oak woodlands.

Unfortunately, many ordinances tend to take a "cookbook" approach toward oak resource management. Instead of setting basic performance standards, ordinances have often focused on detailed implementation standards. For example, some ordinances specify the size of planting stock to be used in replacement plantings. This decision should be based on plant and site characteristics, and would best be left up to a qualified professional who has reviewed the relevant information. Rather than locking in a specific type of planting material, the ordinance could require that a replacement value be established. The city or county oak specialist would then have the flexibility to decide how to best apply these funds to restock the targeted location.

Implementation standards are subject to change. As new information becomes available, old methods and materials fall out of favor. An ordinance with sufficient flexibility will not become outdated as knowledge and technology change. By leaving the formulation of detailed standards up to qualified specialists, the ordinance can ensure that its oak management practices are kept up to date and are appropriate to each particular site.

7. Enforcement methods are specified.

No matter how well-conceived and written an ordinance is, it is unlikely to accomplish much if it is not enforced. To be effective, oak ordinances need to assign enforcement responsibility and authority, as well as specify penalties for violations. A variety of penalties may be used, including fines, jail terms, forfeiture of performance bonds, replacement planting requirements, and withholding of permit approval. Penalties may help to deter potential offenders, but only if consistent enforcement makes it likely that violators will be cited and penalized.

Before specifying enforcement methods, ordinance writers would do well to ensure that ordinance provisions are indeed enforceable. Based on common sense alone, one could probably conclude that a provision requiring a permit to cut oaks more than two inches in diameter cannot be enforced on large privately-held properties. However, it might be possible to enforce an even more stringent provision if it applied to oaks in patrolled public lands.


Most oak ordinances currently in use in California can be classified as tree protection ordinances. Such ordinances are often referred to as heritage or landmark tree ordinances. This type of ordinance is best suited to protecting conspicuous individual oaks that are of unique historical, ecological, or aesthetic value, and therefore constitute an important community resource. Tree protection ordinances seek to limit indiscriminate removal of significant trees on private property by requiring a permit to remove protected trees. In some municipalities, permits or notification are required to perform any operation that could injure a protected tree, including pruning.

Unfortunately, the tree protection type of ordinance is rather poorly suited to the conservation of oak woodlands for several reasons:

Recognizing some of these shortcomings, some jurisdictions have attempted to modify the tree protection ordinance in various ways to provide better protection for oak woodlands. In some cases, protection is extended to small-diameter oaks. However, even in these cases, small shrubby oak saplings less than four feet tall are not normally covered, even though such saplings can be many decades old. In some jurisdictions, restrictions apply to all parcels, whether they are being developed or not. However, the issue of monitoring and enforcing the ordinance on private properties that are not being developed is not addressed. The problem with all such modifications of the tree protection ordinance is that the ordinance is still basically tree-oriented, and not woodland-oriented.

In most cases, protection of oak woodlands would be better served by a woodland protection ordinance. Such an ordinance is concerned with functional oak woodlands, rather than individual oaks. Very few good examples of this type of ordinance are currently in use in California. At minimum, conservation of oak woodlands requires that:

A permitting process analogous to that used in the tree protection ordinance could be used to administer a woodland protection ordinance. Activities regulated through the permit process should include all those that directly affect oak trees, including removal, cutting, and disturbance of oak roots. In addition, activities that affect other significant woodland resources, including understory vegetation, soils, and watercourses, should also be controlled. These activities might include grading, tilling, burning, application of chemicals, or any other activity that significantly alters the existing woodland habitat.

The ordinance should set performance standards to limit the amount of woodland removal or disturbance that will be allowed. Standards for oak retention and reforestation will vary with the types of woodlands involved, but standards could be expressed in terms of percent canopy cover and/or stocking rates (trees per unit area). It is obvious that development of any kind will generally result in more canopy loss in areas with high levels of canopy cover than in areas with low levels of canopy cover. Therefore, it may be desirable to establish different standards for canopy retention based on the baseline level of canopy. An example of a provisions that uses such a system follows:

Canopy retention standards. The following table shall be used to determine the minimum amounts of woodland canopy that must be retained during development on wooded lands:

Canopy retention standard shall be the greater of Column A or Column B:

Baseline canopy cover Column A Column B
80-100% .75 x baseline canopy cover 65% canopy cover
60-79% .80 x baseline canopy cover 51% canopy cover 
40-59%  .85 x baseline canopy cover  36% canopy cover
20-39% .90 x baseline canopy cover  19% canopy cover
19% or less  1.0 x baseline canopy cover -- 

Example: For 50% baseline canopy, the minimum allowable canopy after development would be the greater of Column A, (.85 x 50% = 42.5% canopy) or Column B, (36% canopy). In this case the minimum allowable canopy after development would be 42.5%.

Retention standards shall be applied to retain stands of trees and undisturbed woodlands in priority over individual specimen trees which will be incorporated into the development. No more than 10% of the canopy retention standard may be met by individual trees not included within designated woodlands.

In this example, two standards are used to provide a smooth transition between the required retention levels. For example, the top canopy class (80-100% canopy) allows for 75% retention of existing canopy, the second canopy class (60-79% canopy) has a slightly higher retention standard of 80%. With these ranges, a potential problem arises when the low end of one canopy class is compared to the high end of the adjacent class. The retention standard according to Column A for 80% canopy is 60% residual canopy (.75 x 80%), but the standard for 79% canopy (the next lower class) would be 63% residual canopy (.8 x 79%). When Column B is used, this reversal doesn't occur and the percent residual canopy steps down as you drop in canopy between classes (80% baseline = 65% residual, 79% baseline = 63% residual). Oak specialists and other resource professionals should be consulted to help establish meaningful and appropriate standards for a given area.

Establishing the resource baseline is a potential source of problems for virtually all resource conservation ordinances. As noted earlier, unscrupulous individuals may destroy or alter much of the resource prior to development in an attempt to avoid the ordinance requirements that are invoked when development occurs. To prevent this practice, the provision should provide a strong disincentive for such resource destruction.

To encourage good resource stewardship prior to development, historical aerial photos could be used to establish the resource baseline. This baseline would be used to set both retention and reforestation standards. Parcels showing an increase in tree cover beyond the baseline could be allowed greater flexibility when developed. Parcels showing a loss in tree cover could be required to reforest up to acceptable levels before development could occur. Property owners would protect their future options best by maintaining or increasing tree cover on their lands prior to development. The following provisions provide examples for setting the resource baseline and reforestation standards:

This ordinance shall apply to all unincorporated lands within the jurisdiction for which approval for a discretionary project is requested and for which either of the following conditions apply:
    A. Parcels having canopy cover by native trees or other woody vegetation of at least 10% as of (month/year), as determined from baseline aerial photography dated (date) on file with the county Planning Division.

    B. Parcels that currently support or historically supported native trees or other woody vegetation but were farmed to agricultural crops at the time of the aforementioned baseline aerial photography.

The approving authority shall be authorized to determine whether the provisions of this ordinance apply to any specific parcel. The burden of proof that the ordinance should not be applied to a specific parcel shall be on the property owner.

Reforestation standards. In situations where tree removal, clearing, fire, or any other intentional or accidental canopy reduction has resulted in canopy levels below the baseline level, the standard for reforestation shall be set at 100% of baseline levels, except that no reforestation standard shall exceed 85% nor be less than 15% canopy cover.

All reforestation required as a condition of approval must be initiated at least one year before any permit for clearing, grading, or construction is issued. The approving authority, at its sole discretion, may withhold the issuance of any or all permits for longer periods to ensure that an adequate level of reforestation is attained prior to the start of project construction.

Whenever development occurs around sensitive natural resources such as oak woodlands, the primary goal should be to avoid adverse impacts through a sensitive development plan. To promote woodland conservation, the plan should strive to maintain groups of trees in contiguous areas that function as a cohesive habitat. Development patterns that cluster development on a portion of the overall project area and leave wooded areas as dedicated open space provide one means for maintaining functional woodlands.

Compensatory mitigation should only be considered after all reasonable efforts have been made to minimize loss. Reforestation on- or off-site is one form of compensation, but a newly-planted woodland does not provide the habitat value of a mature stand. While reforestation should be promoted for long-term resource conservation, suitable mitigation of short-term impacts can best be obtained by requiring that equivalent quantities of developable land be reserved from development. Such woodland reserves should remain undeveloped at least until reforested areas attain the habitat value of woodlands which were lost. It may be desirable to target certain areas for acquisition as permanent forest/woodland reserves through this system.

The woodland protection ordinance could encourage the use of such techniques by requiring that a woodland conservation plan be approved as a condition for development. An example of such a provision is shown below:

Woodland Conservation Plan. The purpose of the Woodland Conservation Plan (WCP) is to establish specific methods to conserve existing and potential woodland resources during development. The WCP shall be prepared by a qualified natural resources consultant retained by the county, and the charges of preparing the WCP shall be borne by the applicant.

The WCP shall provide that a project meets the Retention and Reforestation Standards of this provision through any or a combination of the following or other methods.

    1. Minimizing the extent of the development and siting it to avoid impacts on existing woodlands.

    2. Clustering of development on a portion of the project area to retain continuous stands of trees in the nondeveloped portion. Transfers of development density from nondeveloped portions of the project area may be allowed only if nondeveloped portions meet other criteria for developable land.

    3. Providing for reforestation of equivalent sites within or outside of the project area that will not be subject to future development. Where reforestation is used to replace existing woodlands removed for development, estimated canopy cover 20 years after planting shall be used to calculate the equivalent of canopy cover provided.

    4. Providing for the acquisition of developable lands with equivalent woodland resources outside of the project area for public open space. Total area, canopy cover, woodland type, and habitat value shall be considered in determining whether off-site resources are equivalent to those of the project site.

Methods that protect and enhance existing woodlands shall be given precedence over those that restore non-wooded lands. Protection of woodlands within the project area shall be given precedence over off-site acquisition.


It is worth reiterating that ordinances which regulate natural resources on private lands are unlikely to be effective without community support. Unless residents understand the importance of oak woodlands and support conservation efforts, the local government will have a difficult time obtaining compliance. Whenever possible, it is advisable to link oak protection requirements with some sort of benefit or incentive to balance the additional burden imposed. A variety of options are available, such as providing tree care assistance or consulting, reducing certain assessments, or instituting a recognition program to provide a tangible benefit to owners of protected private trees or woodlands. Education and incentive programs are needed to ensure that oaks and oak woodlands are seen as an asset rather than a liability. These programs can be established through language included in the ordinance itself. This helps establish the balance between regulation and incentive, it may make it easier to obtain consensus on the ordinance within the community.

An ordinance is not a panacea for poor or inadequate management of oak resources. Properly applied, an ordinance can facilitate good management. Improperly applied, ordinances can legitimize counterproductive practices, provide disincentives for oak conservation, and undermine the long-term sustainability local oak woodlands. By focusing on overall management of local oak resources, local governments can determine whether an ordinance is necessary, and what its role should be. By following the process outlined here, jurisdictions can develop ordinances that are uniquely suited to meet their specific needs. Finally, by providing for regular evaluation and revision, the local government can ensure that management plans and processes are modified and updated as needed to meet changing needs.

Authors note: This copyrighted article is available exclusively online, and as such may be revised from time to time. If you have comments on this issue or examples of effective woodland conservation programs and ordinances, please let us know. You can e-mail us at

Much of the material in this paper is based on Guidelines for Developing and Evaluating Tree Ordinances (1991), which was prepared for the Urban Forestry Program of the California Department of Forestry and Fire Protection. A complete treatment of tree ordiances is available at the Guidelines for Developing and Evaluating Tree Ordinances web site. Material from this article was also incorporated into A Planner's Guide for Oak Woodlands (1993), which is available from the University of California Integrated Hardwood Range Management Program.