Tree Management Guidelines for Common Areas

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Part 1: The Urban Forest

1A: Tree Assets

Thank you for the opportunity to help manage the common area tree population. Because the value and importance of your trees may appreciate over time, they require a higher level of stewardship than other components in the landscape. In partnering with an independent, third- party, highly experienced, consulting arborist the community has recognized the long-term worth of its tree population.

Trees provide social, communal, environmental, and economic benefits. They create a sense of beauty, add order and unity, promote wildlife diversity, produce oxygen, reduce noise and air pollution, decrease soil erosion and storm-water runoff, and increase property values.

Trees are important assets to communities and should be cared for as such to protect and enhance the benefits they increasingly generate over time.

1B: Tree Biology

Trees are living things that can persist for decades, in some cases even centuries. Their health is affected by how people, plants, animals, or microorganisms interact with them. They shed bark, flowers, and foliage as they grow. Trees support insect and animal habitat, which also have an associated level of debris with their activity.

The area under any given tree naturally accumulates a layer of organic debris, or humus, which generally improves growing conditions for the tree. This layer of organic material protects and replenishes the soil over time, allowing for a healthy balance between the tree’s canopy and root system. Unfortunately, leaf-blowers tend to remove this important component of a rich soil.

Trees naturally shed branches (i.e. experience failure), which defined by the International Society of Arboriculture (ISA), is the breakage of stem, branch, roots or loss of mechanical support in the root system. Any part of a tree can fail, whether or not it has visible defects or weaknesses, if an applied force exceeds the strength of the roots, trunk, stems, or branches.



Trees can also fall down as a result of soil failure, which is usually associated with drastic changes in moisture conditions, particularly when coupled with high winds.

1C: Tree Risk

Tree risk, as defined by the ISA, is the likelihood of a conflict or failure occurring and affecting a target in relation to the severity of consequences such as personal injury, property damage, or disruption of activities.

Though all trees present some level of risk, the overall risk to human safety is very low. Failure occurs infrequently and serious damage, injury, or death resulting from it is rare. For example, many more people are injured in car accidents than by tree failure.



In landscaped environments, like the common areas of a homeowner association, some level of risk must be accepted to experience and realize the many benefits trees provide. It is possible to reduce tree risk to a level that is acceptable, or even as low as reasonably attainable. The only way to completely eliminate tree risk is to remove the tree.

1D: Duty of Care

Tree owners have a legal duty to provide balanced and proportional care for their trees. Because every situation and tree is unique, services should be applied appropriately depending on the circumstances. Tree management is essentially a function of risk; low tree risk requires little or no mitigation. As the level of risk increases, more management strategies are required to keep it as low as reasonable possible. The frequency of care, or pruning cycle, for any tree population should promote a safe environment, maintain tree health, and work within a reasonable budget. Trees growing in target-free locations present little risk and require less care than trees growing near areas occupied by people or objects of high importance.

Tree Life has written a "Tree Pruning Specifications" document that explains and refines much of what has been said above. Though provided separately, the specifications can be read in tandem with these guidelines when deciding what course of action should be taken for a given situation.

Trees may have more frequent pruning cycles based on function, species, irrigation, fertilization, weather conditions, aesthetic preferences, or other specific reasons. Pruning should only be performed to accomplish a clearly defined objective. The most common objective is risk mitigation - which involves reducing the likelihood of branch failure or crown conflict.

Debris that falls from trees (leaves, needles, flowers, etc.) sometimes requires cleaning based on safety, health, or aesthetic concerns; organic material otherwise improves the soil and should be maintained under a tree, preferably within the dripline.

In general, the critical zone of each tree is the circular area within three feet of the trunk. Vegetation should not be planted or allowed to grow under a tree, particularly in the critical zone; this includes turf grass and color installations (i.e. flowers).



An approximate three-inch layer of organic material (bark or wood chips preferably) should cover the soil of the critical zone. It can be refreshed as needed if naturally occurring leaf litter is routinely taken away. The mulch should not touch the trunk, and it can extend out to the dripline (the optimal width of mulch rings are as wide as the canopy).

1E: Levels of Acceptance

Communities must determine what levels of tree risk and tree debris that are willing to accept. Acceptance is based on intended function compared to actual performance, care requirements compared to value, and associated consequences compared to desired outcome.

Tree Risk: All trees present a level of risk, assuming there is a target. A target is defined as anything of importance that can be impacted by the tree. Without a target associated with a given tree, there is no risk related to that tree. An acceptable level of risk can be attained with routine visual assessments that identify and address specific concerns. The community or consultant may request or recommend higher levels of assessment if more data is needed to inform a decision.

Tree Debris: Naturally occurring debris or other organic material improves the soil and should be allowed to continually accumulate under a tree. Situations involving acceptable levels of tree debris should consider the intended function of the tree compared to its actual performance, maintenance requirements and repair costs to determine appropriate actions. That is, do the benefits of a given tree outweigh the needed resources and costs associated with it?

Thank you for the opportunity to help manage the common area tree population. Because the value and importance of your trees may appreciate over time, they require a higher level of stewardship than other components in the landscape. In partnering with an independent, third- party, highly experienced, consulting arborist the community has recognized the long-term worth of its tree population.

Trees provide social, communal, environmental, and economic benefits. They create a sense of beauty, add order and unity, promote wildlife diversity, produce oxygen, reduce noise and air pollution, decrease soil erosion and storm-water runoff, and increase property values.



Trees are important assets to communities and should be cared for as such to protect and enhance the benefits they increasingly generate over time.

Part 2: Tree Reporting

2A: Purpose and Use

The role of the tree consultant is to maintain or improve tree health by providing unbiased, accurate knowledge based on accepted standards, practices, science, and technology. The goal of the consultant is to allow trees to mature by promoting a growing environment favorable to them.

This document discusses strategies to promote an aesthetically pleasing, sustainable urban forest containing dozens of species of varying age. Though aesthetically pleasing is defined by the client, it generally relates to good health and subsequent appearance. We define a sustainable urban forest as a tree population that requires minimal care to maximize the safe, useful life expectancy of each member.

A safe, useful life (SULE) is defined as the length of time a tree provides appreciable benefits which outweigh the consequences of its existence. The consequences include pruning requirements and other services required to preserve and enhance tree function. The average SULE of a tree in the urban environment depends on species, growing conditions, and care practices. The SULE of many trees in the urban forest is short, or less than 15 years. Our goal is to allow trees to mature for periods longer than 40 years, which would be considered high.

This document is meant to be used in conjunction with a Tree Action Plan (which is described in more detail in section 2C, found on next page). A Tree Action Plan is a two-component tree report written specifically for HOA common areas. Suggestions in a Tree Action Plan are valid for one year, the standard time interval between planning inspections. Longer intervals between inspections are considered less efficient and accurate as many things can change even within one year (i.e. one annual growing season).

2B: Procedures and Methodologies

To report on the tree population, Tree Life employs terminology and methods found in Best Management Practices: Tree Risk Assessment, published by the International Society of Arboriculture in 2018. These standards define the three levels of tree assessment: limited visual, basic, and advanced.

A first level assessment, or Limited Visual Assessment (LVA), is performed to develop a Tree Action Plan. The LVA identifies obvious tree concerns, conflicts, or other issues that can be improved. Observations are generally made from ground-level while walking past one or more sides of the tree. Though it has in inherent limitations, the LVA is the standard method to assess and manage large populations of trees.

An LVA is not a formal, qualitative risk assessment because individual trees are not evaluated.

Basic or advanced level inspections are required to conduct qualitative risk assessments; they employ a more systematic inspection, documentation, and analysis process. Qualitative tree risk assessments are usually performed on a limited number of important or high-value trees growing in close proximity to important or high-value targets. They can be applied on an individual basis, as requested or recommended, and are not performed as part of the annual inspection.

2C: Tree Actions Plans

Our action plans contain a list of suggested tree care services with a specified time period, which is usually one year. While performing the assessment for an action plan, Tree Life may also look at one or two requests made by homeowners during the interval between regular inspections. However, if more than a few requests are expressed on a regular basis, then we typically deal with them as a separate assignment, prepared between the annual assessments.

2C.1 Tree Requests

Arborist recommendations dealing with tree requests from homeowners, managers, or other agencies will conform to the protocol established in this document.

Tree requests requiring a site visit during the interval between annual assessments will be handled on a case-by-case basis.

Non-urgent tree requests should be collected throughout the year and dealt with between annual assessments. Generally, our annual assessments preclude most tree requests.

Tree requests related to leaves, pine needles, or view improvements are non-urgent.

2C.2 Tree Risk Identification

Obvious tree risks identified during the LVA process are:

2C.2a Risk of Conflict - Likelihood of a tree or its parts causing injury, property damage, or disruption of activities due to growth over time. Conflicts include trees growing into plants; trees growing next to or under electric utilities; low branches over streets, walkways, or houses; trees obstructing traffic control signs, signals, or roadways; tree roots lifting pavement; and root damage to infrastructure.

2C.26 Risk of Failure - Likelihood of a tree or its parts causing injury, property damage, or disruption of activities due to failure. Visible defects include dead or dying parts, broken or hanging branches, cracks, seams, longitudinal bulges, weakly attached branches, co-dominant stems, overextended limbs, poor taper, included-bark, missing or decayed wood, one-sided or unbalanced crown, uncorrected leans, low live-crown ratio, inadequate response growth, and fruiting bodies associated with wood decay.

Depending on the situation, mitigation options for trees with obvious conflict or failure concerns may include pruning, concrete repair, or any other accepted practice that reduces the risk potential. Tree removal is considered to be the last option.

2C.3 Area of Improvement

Opportunities to improve the function, health, diversity, or management of the trees may be identified during the LVA process. Common problems associated with a particular species, setting, or situation may also be identified.

Improvements may require cultural changes (such as eliminating leaf blowers), site modification (such as eliminating turf around tree trunks), use restrictions (such as moving picnic tables from under certain branches), and even tree removal.

Tree Action Plans are valid for one year, the suggested time-interval between tree care planning inspections.

2D: Recommendations

Recommendations are provided in the Tree Action Plans; they are meant to preserve and improve the tree population in general.

2D.1 Tree Pruning

Pruning is the preferred method to mitigate crown concerns. It is cost effective and creates minimal visual impact or controversy. The amount of pruning performed on a tree should be limited because it is essentially a form of wounding, and excess pruning can actually cause more harm than help. Trees can recover from several small pruning wounds faster than from one large wound. A common mistake is the cutting of small branches. It is important to maintain an even distribution of foliage along all branches, just as it's important to not remove large branches from the trunk. Excessive small branch removal creates end-heavy crowns that are more prone to failure. Excessive removal of small branches is known as "crown thinning" — and "thinning" or "lacing" should be avoided at all costs. With regards to proper pruning cuts, branch reduction cuts are most effective for most objectives.

Most pruning can be accomplished at any time of the year with little effect on the whole tree. Pruning cannot always be employed to solve a problem or address a concern. Different species should not be pruned to "match" each other. Some trees naturally have different growth habits than other species and require different pruning objectives.

Please refer to the separately included "Tree Pruning Specifications," written by Tree Life exclusively for our clients.

2D.2 Tree Removal

Removing between 1-3% of a tree population helps improve and maintain tree and age diversity in most urban forests. Removing trees is the most controversial method to mitigate risk or make an improvement because of the cost and visual impact to the community. Therefore, tree removal is generally considered the last option. Tree removal recommendations are meant to improve the overall population.



Specific criteria can be developed to assist in determining items for tree removal programs, but are considered outside the scope of annual planning unless otherwise specified and agreed upon. There generally are two reasons to remove a tree — to eliminate risk or to make an improvement:

Eliminate Risk

2D.2a Tree Defect — If the consequences or cost associated with a defect exceeds an acceptable level, as determined by the community, the tree can be removed to eliminate the risk.

2D.2b Tree Conflict — If the consequences or cost of a potential conflict exceeds an acceptable level, as determined by the community, the tree can be removed to eliminate the risk.

Make an Improvement

2D.2c Tree Function — Some trees may have a limited safe and useful life in the landscape if they are not functioning as intended even though best management practices are being followed. When trees are planted in an environment that does not favor their health, they tend to become predisposed to problems, no matter what care is provided. The function of many trees is to simply look healthy. If unchangeable site conditions do not favor the health of a particular tree, then it should be removed and replaced with a species that is more likely to acclimate.

2D.2d Tree Health — Some plant species are predisposed to problems of a specific nature due to genetics and environmental conditions. Though these problems are often not lethal, they are untreatable, unsightly, and a common source of complaint in many communities. Trees, bushes, and shrubs with severe, persistent, or untreatable pest or disease problems should be cycled out of the landscape.

2D.2e Tree Diversity — Common area landscape design typically requires trees to be of the same size, species, and appearance. The trees are from the same nursery, planted at the same time, and are likely of the same genetic background.

Because of these conditions, most homeowner association common areas can benefit from having some trees removed and replaced to promote age and species diversity. In fact, a property can remove (1% - 3%) of its tree population every year, matched with an equal amount of new plantings, to create an urban forest that is better equipped to adapt to unexpected challenges. Ongoing removal and replenishment programs develop age and species diversity, an important attribute for long-term management, without making massive or sudden changes to the appearance of the landscape. Age diversity helps prevent groups of trees from maturing and senescing at once. Species diversity helps prevent pest or disease problems from affecting large portions of the population at one time.

2D.2f Tree Management — Trees or invasive plants (naturally reproducing) with high maintenance requirements should be considered for removal if the cost to maintain them exceeds the benefits they provide. Other management problems include, but are not limited to, too many trees planted in a particular area; trees planted too closely to other trees, structures, or roadways; trees with high maintenance requirements planted in remote, difficult to access slope areas; and trees with low water requirements planted in locations that receive frequent irrigation. Depending on the situation, mitigation options for management issues often involve tree removal and replacement. Tree replacements usually are of a different species when planted in the same location as the removal. Replacement trees are not always necessary, particularly if an area had been over-planted during the construction phase. Tree installation is discussed later in this document.

2D.3 Tree Health Care

Most pest and disease problems are secondary conditions arising from one or more initial stress factors. Organic treatments or other chemical applications should only be employed while the initial stress is identified and corrected. Improvement in tree health after corrections are made can take more than one-year to show. Tree health care treatments and applications will not correct an underlying stress factor. If underlying stress factors cannot be corrected, then tree removal should be considered.

Tree health care options may be employed during this period, but they should not continue indefinitely. If a tree does not show improvement after cultural corrections and treatment applications have been implemented, then tree removal should be considered.

Note: Recently installed trees should not require tree health care options. If a tree is not performing well after a recent planting, then it likely will never perform well. Poor performance in newly planted trees is usually due to root defects, irrigation problems, installation mistakes, or some combination of the three.

2D.4 Other Recommendations

Other recommendations include but are not limited to cultural changes, site modification, support system installation, and site-use restrictions.

2E: Higher Levels of Assessment

Suggestions in each Tree Action Plan are made based on multiple factors — such as knowledge of typical growth habits, known risk profiles, maintenance requirements, current arboricultural standards, and long-term care strategies. Not all defects may be visible from one or more perspectives during the time of the limited visual assessment (LVA).

The two higher levels of tree assessment, basic and advanced, can be performed on individual trees should the community want to understand or explore options, identify conditions, or analyze information that may not have been apparent during the LVA process.



Basic and advanced assessments can also be conducted to diagnose health or appraise value. Higher levels of assessment are not included in annual planning reports unless otherwise specified and agreed upon.

Part 3: Implementing Care

3A: Who Performs the Work

Tree care is a combined effort between tree service, landscape maintenance, and tree health care professionals.

3A.1 Tree Service Provider

Tree service providers are the primary care-giver. They should perform most of the services recommended in the tree action plans. This includes but is not limited to tree pruning, tree removal, root collar excavation, tree health care applications, or installing support systems.

Tree Care Industry Association (TCIA) accredited companies are the preferred tree care providers because they have voluntarily met or exceeded accreditation criteria regarding professionalism, training, business practices, ethics, and customer satisfaction. Decisions regarding proposals for tree services should not necessarily be based on price. Prospective tree care providers should be interviewed to identify which company can provide services in a safe, professional, and timely manner with minimal impact to the community.

The role of the arborist in a tree service company is to guide the work practices of their crews based on current standards, practices, science, and technology. Though an arborist in a tree service company can assist in identifying and addressing defects or improvements, their primary role is to provide a skilled service according to specifications and expectations.

With a few exceptions, tree care planning does not include native shrubs such as acacia, lemonade berry, or Manzanita. Sometimes specific shrubs may require clearance pruning from the tree service company, based on size or situation, but they can be addressed on an individual basis.

The community should avoid selecting a new tree service company every year. The reason is that companies who have shown their value by performing the work according to specifications and expectations should be rehired when possible. Loyalty to one or two providers is beneficial to the trees and community.

Using the same crews from year to year creates consistency in tree appearance. Also, a crew is more likely to complete a job safely and as scheduled when they are familiar with a particular job and know what to expect.

For example, certain pruning can be performed more efficiently with specific equipment. A company that is familiar with a job can ensure specific equipment is available beforehand, preventing reduced efficiency.

3A.2 Landscape Maintenance Provider

The landscape maintenance company is an integral part of tree care. They can assist on an ongoing basis by managing large shrubs and bushes, delivering on contractual clearance pruning, maintaining a layer of leaf litter or mulch, and installing new trees:

3A.2a Large Shrubs and Bushes — Landscape maintenance crews can remove or perform clearance pruning on large shrubs and bushes. They sometimes can safely perform this work from the ground which will be more cost-effective than contracting a tree care provider. Pruning cuts should be made according to standards developed by the ISA.

3A.2b Contractual Clearance Pruning — Landscape crews can safely perform clearance pruning on trees that are growing within limits described in their service contracts. For example, the twig-like growth at the end of branches can extend out or droop down and conflict with pedestrians or vehicles — stop signs may be slightly obscured or pedestrian walkways may be slightly impacted. Using the same handheld equipment that is used to hedge bushes, they can safely eliminate these crown conflicts.

Heading or shearing cuts may be used to cut back foliage that is hanging too low; and this type of clearance pruning is expected in most landscape maintenance contracts.

3A.2c Leaf Litter or Mulch — When naturally occurring leaf-litter is routinely removed through normal maintenance procedures, chunky mulch (i.e. wood chips) should be applied on top of the soil within the drip-line of new and existing trees to improve the health of the soil and tree over time. In frequently used areas, mulch protects the soil from compaction, particularly if it contains larger size pieces (such as tree bark or chipped wood). Soil compaction from foot or vehicle traffic not only ruins soil structure and future root development, but it can physically damage or kill existing tree roots.

3A.2d Tree Installation — Tree installation should be a continual, ongoing process that can take place without the input of the consultant. Some trees will likely be removed every year, for purposes explained in Part II, and there will always be a need for new trees. Since our goals are to create a healthy, diverse, sustainable urban forest, certain tree species should be used in favor of others based on the situation. Considerations when selecting new trees should include size at maturity, function, management requirements, and resistance:

• Use tree species that are already performing well at the site since they have proven themselves to be well-acclimated to the existing conditions.
• Use species that are less represented. Many common area tree populations are monocultures. Though dozens of species are growing throughout a property, only one or two may make-up the majority of the population.
• Trees should be planted equidistant from objects (i.e., houses and walkways) and according to the ISA standards

3A.3 Tree Health Care Provider

Tree health care treatments and applications to correct pest or disease problems should be performed within appropriate time-periods.

Most insect and disease problems are secondary and can be controlled by correcting the underlying problem.

Initial stress factors that allow secondary problems to proliferate are usually associated with physical injuries resulting from human activity or related disturbance.

When recommending a course of action to alleviate a secondary problem, the tree health care provider should identify the initial stress factor, provide options for correction, and define the time limits of a treatment cycle. They should also be able to explain how the applications can be expected to help minimize a secondary problem within specified time limits.

3B: When to Prune

Though tree pruning between September-March is generally considered optimal for many species, the temperate climate of San Diego County allows for most types of pruning almost any time of the year. Trees that are fast growing, have heavy sap flow, or are susceptible to pests and diseases should be pruned during the dormant season. Trees with bird nests shall not be pruned during nesting season.

Some palm trees will effloresce, or flower, multiple times within a year. To reduce the chances of multiple flowering events in certain species, have the palm pruned late in the growing season. Depending on species, location, history of care, site conditions, etc., the exact timing will vary. It is not uncommon to prune palms twice a year: one pruning event targeting dead leaves (fronds) and flower stalks (seed pods), a second pruning event only targeting additional seed pods resulting from secondary efflorescence. If the palms are pruned twice a year, the first event should take place in the spring (April through June) and the second event should take place in the summer (July through September).