108 Kenney et al.: Criteria and Indicators for Strategic Urban Forest Planning and Management
Arboriculture & Urban Forestry 2011. 37(3): 108–117
Criteria and Indicators for Strategic Urban Forest Planning and Management
W. Andy Kenney, Philip J.E. van Wassenaer, and Alexander L. Satel
Abstract. The success of urban forest management is frequently predicated upon achieving absolute canopy cover targets. This two-di- mensional view of the urban forest does not provide a comprehensive assessment of urban forest stewardship in a community and does not account for an area’s potential to support a forest canopy. A comprehensive set of performance-based criteria and indicators con- cerning the community’s vegetation resource, community framework and resource management approach is described. This set of broadly based measures provides a more useful tool for the evaluation of urban forest management success and strategic management planning. Key Words. Canopy Cover; Municipal Planning; Relative Canopy Cover; Sustainability; Urban Forest Planning; Urban Forestry.
The diverse benefits provided by urban forests are well under- where and help guide managers to improve the health of their tree stood (Dwyer et al. 1991). Recent efforts to quantify the value resource and the effectiveness of their management approach.
of ecological services such as heat-island mitigation, CO2 re- Implementing a criteria and indicators-based approach to as- duction, and stormwater attenuation (McPherson et al. 2005) sessing the urban forest and its management need not be a time or conclusively demonstrate that trees account for an important resource-consuming undertaking. The majority of criteria can be part of any community’s infrastructure, providing positive re- assessed as a simple collaborative desktop exercise, while others turns on investment and tangible benefits to urban residents. require some data, such as tree inventories or GIS-based mapping. Urban forests composed of diverse species and age classes Any criterion which cannot be readily assessed—be it due to a provide a wider range of benefits over the long term, particu- lack of available information, inadequate resources, or other rea- larly if urban trees are large-growing, long-lived specimens. sons—can still serve to highlight opportunities for improvement. Currently in North America, a common way to describe the As such, it is important that communities utilizing this approach extent of urban forests is to measure the amount of canopy cov- do not simply pick-and-choose certain criteria for assessment, er provided by trees. Canopy cover is essentially a two-dimen- but rather work through the entire set of twenty-five criteria and sional measurement of the horizontal surface area of the forest, indicators presented in this paper. The prioritization of each crite- as seen from a bird’s-eye view. As part of the emerging public rion can be addressed through the management planning process. policy and scientific dialogue on urban forest management, Finally, it must be noted that use of the C&I approach is canopy cover goals have received a great deal of attention as a not limited to municipal or other government staff, who are management target. While canopy cover provides a very sim- traditionally considered the chief managers of urban for- ple and intuitive measure of the extent of a community’s urban est resources. Rather, a collaborative approach among mu- forest, a much more effective measure of the success of urban nicipal staff, community and stewardship groups, and forest stewardship rests with moving steadily and aggressively other stakeholders will invariably result in more accurate toward a more comprehensive set of performance indicators. and, oftentimes, higher rankings on the assessment scale. This paper discusses some limitations to focusing primarily A need to modify and update the original criteria and indica- on canopy cover, and builds on the work of Clark et al. (1997) to tors developed by Clark et al. (1997) was identified by the authors describe a more comprehensive set of criteria and performance due to the limited application of the approach to achieving ur- indicators by which to measure urban forest management suc- ban forest sustainability. When first published, the paper showed cess. It is important to note that the criteria and indicators-based promise by providing objectives that spanned a range of urban (C&I) urban forest management approach described in this paper forestry issues and enabled managers to focus their efforts and can be applied by communities of any size, even with the most frequently limited budgets. More than a decade later, few urban limited of budgets. While local circumstances differ, urban for- forest management plans or programs are informed by these cri- ests everywhere face similar challenges, from limited community teria and indicators, making the tracking of progress difficult and involvement, to invasive species, to inadequate growing spaces, potentially resulting in missed opportunities and misallocation just to name a few. Criteria and indicators provide a standardized of resources. By expanding the list of criteria and indicators and set of performance measures that can relate to urban forests any- modifying others to shift the focus towards more easily quantifi-
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able results, it is hoped that this assessment framework may once • Tree habitat: Uncertainty about the availability and quality again become a leading model to be taken up by urban forest stew- of growing space for new trees. ards interested in building livable and sustainable communities. • Land and tree tenure: A high proportion of the urban forest is under private ownership, placing a disproportionate reli- Canopy Cover ance upon landowners to maintain and expand the urban All too often, urban forest management programs are driven by forest. the need to increase urban forest canopy cover. Setting canopy • Financial considerations: Budgetary and resource implica- cover goals has many implications, including the associated tions for the long-term maintenance required to support ag- need for increased tree planting and the long-term resources re- gressive tree establishment goals. quired to manage the expanding urban forest. The following dis- cussion on targets for canopy cover provides some context for policy makers and managers, and further justifies the need for a Ideally, an assessment of a community’s potential canopy broader approach to urban forest assessment and management. cover capacity, such as the USDA Forest Service’s Urban Tree The advantage of measuring canopy cover is that it is a sim- Canopy (USDA Forest Service 2010) and Forest Opportunity ple, intuitive indicator of the extent of the urban forest. However, Spectrum assessment, should be conducted before any mean- measuring only canopy cover does not provide information about ingful targets are set. Similar methods have also been developed other essential parameters required to effectively manage and by Kenney (2008), Wua et al. (2008), Kirnbauer et al. (2009), sustain a community’s urban forest. For example, canopy cover and Monear and Hanou (2010). A high-quality potential canopy provides no indication of the species diversity of the forest, no cover assessment should not only provide an indication of avail- measure of the condition of forest resources, and no indication able plantable spaces, but also take into consideration aboveg- of the age or size class distribution of the trees making up the round growing space for future canopy expansion, current and urban forest. A popular target for urban forest canopy cover rec- future land uses, regional climate and soils, and other key vari- ommended by American Forests is 40% (30% in arid regions) ables that may affect tree growth and longevity. While effective (American Forests 2009). While ambitious and desirable, for a tree establishment is important, it is only part of a strategy for variety of reasons this figure may be unattainable in many urban sustainable urban forest management. The protection and main- centers, and difficult to attain in others. Setting overly ambitious tenance of the existing trees that form the community’s urban canopy cover targets can unduly focus urban forest management forest canopy is critical. Additionally, the importance of plan- activities on tree planting. This could be to the detriment of other ning for, and adequate funding of, tree maintenance and pro- strategic and more comprehensive approaches to management. tection throughout the life of the trees cannot be overstated. Also, canopy cover measurements alone are unable to provide In recognition of the significant limitations of using tree an estimate of the carrying capacity of any particular part of a com- canopy cover as a strategic objective for urban forest manage- munity. For example, a commercial area may have a canopy cover ment, the study authors suggest an alternative means for setting of 10%, and this may be all that the area can support due to a high and achieving management targets through the use of twenty-five proportion of hard surface cover. Another part of the community criteria and indicators for urban forest sustainability. The con- may be dominated by light industry and also exhibit 10% canopy cept of canopy cover is included as only one of these criteria. cover, but with the potential to support significantly more. Mea- suring canopy cover alone tells us little of this possible variation Criteria and Indicators of Urban Forest and does not reflect potential regional differences (Sanders 1984). Management Success Without a clear understanding of several factors that The concept of using criteria and indicators as sustainable for- ultimately determine canopy cover, setting meaning- est management tools originates from the 1994 meeting of the ful targets is a significant challenge. There are some fac- Working Group on Criteria and Indicators for the Conservation tors beyond the control of urban forest managers that and Sustainable Management of Temperate and Boreal Forests in may render canopy cover estimates unreliable, including: Geneva, Switzerland, as part of the Montréal Process. Since then, • Mortality rates: Little information is available about base- many sets of criteria and indicators of sustainable forest man- line tree mortality rates in urban forests (Nowak et al. agement have been developed around the world. For example, 2004). the Canadian Council of Forest Ministers has published Criteria • Climate change: The potential impacts of climate change and Indicators of Sustainable Forest Management in Canada: in general, and extreme weather events more specifically, National Status 2005 (Canadian Council of Forest Ministers are difficult to predict. 2006) to underscore the applicability of the C&I approach to • Invasive insects: The potential impacts of invasive alien more traditional production-based forest management planning. insects are difficult to predict but could have significant Urban forest managers must be able to clearly identify where impacts. For example, Humble and Allen (2004) note that specific goals or targets have been met and when adaptations to many invasive insects have been detected adjacent to the management approaches appear to be necessary. Assessing suc- port of Vancouver, British Columbia, Canada, illustrating cessful urban forest management therefore also requires clearly that continued vigilance is imperative and that tree mortal- defined targets, or criteria, and specific performance indicators ity rates must be considered with caution. of success. The performance indicators enable measurement of progress towards the achievement of the key objectives for each • In-fill development/intensification: In established residen- criterion, which in turn permits the ongoing evaluation of suc- tial neighborhoods, in-fill development can be expected to cess in implementing the community’s urban forest strategy. contribute to further losses of mature tree canopy.
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More than a decade ago Clark et al. (1997) pro- from Farrar (1995), Kershaw (2001), Lauriault (1989), Leopold posed a set of tools to reflect the specific issues concern- (2003), Petrides (1972), and Rushforth (1999). If an extensive ing urban forestry, and provided a list of criteria and in- tree inventory is available, this could inform the development of dicators for urban forest sustainability that considered: maximum DBH values. Ideally, DBH data could be pooled at a • the vegetation resource regional level (i.e., across municipalities). Maximum urban tree • the community framework, and DBH values may not be immediately available; however, once developed, RDBH will provide quantifiable targets for tree size • the resource management approach. and distribution across the community. Additionally, it enables managers to determine whether urban trees are able to reach Each criterion includes a key objective and performance indica- their genetic potential for a given species, which is largely de- tors describing low, moderate, good, and optimal levels of perfor- pendent on the condition of the planting site and other factors. mance. In a subsequent paper, Clark and Matheny (1998) surveyed Maintaining a diverse species mix (species diversity) is a critic- a sample of 25 U.S. municipalities and scored their performance al way to promote a healthy and resilient urban forest (Santamour in terms of urban forest sustainability using the criteria and indica- 1990). Maintaining species diversity is a function of the number tors matrix. General findings from the survey responses suggested of species present, as well as how those species are spatially dis- that, on average, communities scored 49 of a maximum 80 points. tributed across the community. Therefore, this original criterion In the following pages, the authors of the current study build was further divided into two distinct criteria and key objectives: upon several of the criteria and indicators developed by Clark et al. 1) species suitability, to establish a tree population suited to the (1997), and provide more detail in a number of areas to better posi- urban and regional environment, and 2) species distribution, to tion C&I as tools for strategic urban forest management planning. establish a genetically diverse population of trees throughout the urban forest. Tree species suitability can be based on regionally- The Vegetation Resource specific guidelines, such as those provided in the Council of Tree Clark et al. (1997) provided four criteria for success in managing the and Landscape Appraisers’ regional supplements, which take into urban forest vegetation resource: 1) canopy cover, 2) age distribu- account concerns such as adaptability to local climate, and man- tion of trees in the community, 3) species mix, and 4) native vegeta- agement needs. In the absence of such guidelines, a municipal- tion. Suggested here are two additional criteria to be incorporated ity can develop its own species suitability index, based on local into strategic urban forest management planning: 5) the condition expert opinion. While Clark et al.’s (1997) performance indica- of publicly owned trees, and 6) publicly owned natural areas. Fur- tors track only the scope of assessment and inventory technology, ther proposed is a revision to the original canopy cover criterion. the current revision encourages urban forest managers to account Clark et al. (1997) suggested that the key objective in man- for species diversity at a level of detail (i.e., neighborhood level) aging canopy cover is to achieve a climate-appropriate degree not available through aggregate tree inventory data, thereby mak- of tree cover within the community, yet the performance in- ing this criterion better suited to long-term strategic planning. dicators presented only track increasing levels of sophistica- The present study differentiates between intensively managed tion in assessment or technological input. As such, there is a parts of the urban forest and extensively managed woodlands – that disconnect between the key objective and the indicators avail- is, areas where individual trees are managed under arboricultural able to urban forest managers to evaluate the success of their techniques as opposed to areas that are managed en masse using management strategies. Suggested here is a revised perfor- techniques more closely related to silviculture. While these various mance indicator, relative canopy cover, which allows for a components together form the urban forest, the authors feel that it is quantifiable comparison between actual canopy cover and the critical that the unique approaches to management required in each maximum potential cover within a community (Appendix 1). are clearly recognized in the development of inventories and man- In other words: agement plans as well as in some aspects of the criteria and indicators. Typically, the majority of trees in an urban forest are in pri- Relative Canopy Cover = Canopy Cover vate ownership, and municipal resources are used to support the Potential Canopy Cover relatively small component of the canopy on public land (e.g., street trees). Therefore, the condition of intensively managed, The application of this criterion is, of course, predi- publicly owned trees—with the key objective of a detailed un- cated on the availability of a measure of the carrying cap- derstanding of the condition and risk potential of all public acity or potential canopy cover, as discussed previously. trees—is an important new criterion that can be used to evaluate In terms of tree age distribution, the original key objective the success of forest management and support strategic planning. was to build to provide for an uneven age distribution city-wide In communities with significant natural areas, a similar cri- and at the neighborhood level. The initial indicators proposed by terion is suggested in addition to the previous—publicly owned Clark et al. (1997) focused on the methods of assessing tree age natural areas, which are primarily extensively managed. A de- distribution, but did not provide actual age class targets at differ- tailed understanding of the ecological functions and struc- ent performance levels. The revised indicators introduce the con- tures, as well as information about public use of these areas, cept of relative diameter (RDBH) as a more meaningful target. represents a significantly more sophisticated articulation of RDBH is the ratio between a tree’s measured diameter at breast practical management concerns to support strategic planning. height and the maximum diameter for its species. Species specific Finally, the use of native species on public or private land may maximum DBH values can be derived from the literature and/ represent an important objective for sustainable urban forest man- or local experience. For example, in southern Ontario, Canada, agement. While Clark et al.’s (1997) criteria and performance in- a database has been developed based on maximum DBH values dicators are still generally robust, the current study expands on the
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public policy aspect of native species establishment, and suggests lic and administrative perceptions of management itself. Clark et that the degree of public policy support for native species use in al. (1997) suggested nine criteria and key objectives for success- intensively- and extensively managed areas is an important per- ful urban forest resource management: 1) citywide management formance indicator. The importance of project-appropriate use of plan, 2) citywide funding, 3) city staffing, 4) assessment tools, native species is also highlighted. Nonnative plantings may be 5) protection of existing trees, 6) species and site selection, 7) more appropriate in circumstances where poor growing conditions standards for tree care, 8) citizen safety, and 9) recycling. In ad- or limited space could prevent any native species from reaching dition to several new criteria, the proposed changes to the origi- their full genetic potential, or may significantly limit their longev- nal criteria and key objectives are to improve their application to ity. The issue of plant invasiveness similarly are considered as well. strategic urban forest management and planning (Appendix 3). Optimal urban forest management will always account for project- Although the importance of a routinely-updated and com- specific considerations in tree establishment activities. While in- prehensive tree inventory is addressed in the original assess- vasive plants should generally be discouraged, in some scenarios ment tools criterion, there was no distinction made between (i.e., away from natural areas), even potentially invasive trees may a tree inventory and a canopy cover inventory. An optimal tree be preferable to no trees at all. Conversely, in growing conditions in inventory provides complete data for the entire public tree re- proximity to natural areas but where no noninvasive trees will like- source (generally excluding natural areas) and a sample-based ly thrive, it may be preferable to forego tree establishment entirely. inventory of private trees. In combination with a GIS-referenced In addition to the new criteria proposed here, the study canopy cover inventory, based on aerial or satellite imagery, the authors believe that these developments based upon Clark optimal level of inventory data will allow for both micro and et al.’s (1997) original criteria and indicators for man- macro-level tree resource management and strategic planning. aging the urban forest vegetation resource provide a Clark et al. (1997) suggested that optimal citywide man- more robust foundation for strategic planning, by setting agement planning must cover both public and private prop- more easily quantifiable targets as indicators of success. erty—urban trees make no distinction between land tenure, yet tenure may have significant effects upon the health of in- dividual trees and the canopy as a whole. No major modifica- The Community Framework tion to this criterion are suggested, but the importance of stra- In a truly sustainable urban forest, all members of a community tegic planning for all components of the urban forest through must cooperate to share the responsibility for tree resource man- a comprehensive, multi-tiered plan with clearly defined vi- agement. Clark et al. (1997) proposed seven criteria to assess the sion and goals, stakeholder input, and built-in mechanisms for strength of the community framework for urban forest sustain- adaptive management, are emphasized. Similarly, no chan- ability: 1) public agency cooperation, 2) involvement of large pri- ges to the municipality-wide funding criterion are suggested, vate and institutional landholders, 3) green industry cooperation, other than to emphasize the importance of long-term strategic 4) neighborhood action, 5) citizen-municipality business interac- budgeting that extends well beyond simple tree establishment. tion, 6) general awareness of trees as a community resource, and The number of municipal employees involved in urban for- 7) regional cooperation. On the whole, the original criteria and est management is not a sufficient indicator of the adequacy of indicators are highly applicable for urban foresters to evaluate the city staffing. Furthermore, the optimal number of urban for- success of their forest management activities relative to the com- estry personnel will vary among communities, making staffing munity framework. However, the study authors do suggest sev- targets an inappropriate benchmark. A better criterion would eral changes, as described below and summarized in Appendix 2. address the training, skill, and experience of the staff. It is sug- In terms of public agency cooperation, it is important to distin- gested that a sustainable and optimally managed urban forest guish between types of municipal interdepartmental cooperation. requires a broader range of skills and experience than can be Revised performance indicators, which range from “conflicting provided by arborists or other professional tree care staff alone. goals” among departments (as in Clark et al. 1997) to formal Therefore, the importance of a multidisciplinary management interdepartmental working teams on all municipal projects, dis- team entrenched within a dedicated municipal forestry unit are tinguish between project-specific and organization-wide formal highlighted. Such a team would optimally combine the tree cooperation, and allow urban forest managers to track incremen- care skills of arborists with the planning, modeling, and eco- tal progress in reform of administrative structures and procedures. logical background of professional foresters and ecologists to A frequent obstacle to community cooperation around sustain- develop and implement successful strategic management plans. able urban forest management is a lack of awareness of trees as a It is recognized that species and site selection is an important community resource. Clark et al. (1997) suggest that an optimal consideration in tree establishment, but the Clark et al. (1997) key indicator of success is a community that recognizes the environ- objective and indicators for this criterion make little provision for mental and economic contributions made by the urban forest. integrated establishment planning to achieve strategic goals and While the study authors agree, it is also suggested that the com- the community vision. Therefore, the study authors propose this munity must be aware of the numerous social benefits provided criterion be modified to highlight tree establishment planning and by tree cover, thereby broadening the potential extent of the total implementation, with the objective of renewing and expanding the supportive political constituency—a worthy undertaking to ensure urban forest through a comprehensive tree establishment program long-term sustainable urban forest management and public health. driven by increasing canopy cover, species diversity, species distri- bution and maximizing tree growth and longevity. These proposed The Resource Management Approach indicators make explicit the connections between the data source The resource management approach set of criteria and indicators supporting establishment planning (tree inventory) and desired concerns not only physical resource management but also pub- biological outcomes on a site and aggregate (canopy cover) level.
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Also proposed here is a new criterion of tree habitat suit- ing challenge at first. Although most criteria can be easily assessed ability. The suitability of the habitat will not only be deter- with minimal analysis, several C&I depend upon somewhat more mined by the growing environment but also by the desired sophisticated analyses or detailed information. However, com- functions trees should perform at any given site. The key ob- munities that may lack the resources to conduct such assessments jective for this criterion is that municipal tree establishment should not overlook the importance of these criteria; instead, they programs ensure that all publicly owned trees are planted on should consider any current shortfalls as opportunities to set fu- sites where the above- and belowground conditions will maxi- ture strategic objectives and management or budget priorities. mize current and future benefits. In an optimal situation, all Urban forest managers must also recognize the flexible nature planting sites will be assessed for soil volume and quality, of many of the proposed C&I. Even though several performance and provisions for matching species with their sites or amend- indicators are based on discrete thresholds (for example, see rela- ing sites to suit the desired tree species will be implemented. tive canopy cover), others are open to more subjective interpre- Although tree establishment is an effective part of increasing tation. For instance, “adequate” funding or staffing to optimize the extent of the urban forest, the adherence to professional stan- urban forest management will differ greatly among communities; dards for tree care of existing trees is equally important, if not a metropolis with more than one million residents will surely de- more so. Following the proposal of two new vegetation resource fine adequacy far differently than a rural village. The strength of criteria concerning public and private trees, it is recommended that the approach outlined in this paper lies in the fact that urban forest the original standards for tree care criterion be divided to reflect managers in both types of communities, regardless of any other the different management requirements of intensively- and exten- factors, can use the same set of criteria and indicators to assess and sively managed trees. Maintenance of publicly owned, intensive- track their progress toward true urban forest sustainability. Com- ly managed trees on a cyclical basis will ensure the maximization munities, and particularly their politicians and senior management of benefit provision and tree longevity over time, reducing future staff, need not fear scoring in the lower range of assessment; low- costs and potential liability from tree failure. Management plan- er scores simply highlight opportunities for future improvements. ning and implementation in extensively managed natural areas is While criteria and indicators are useful tools for evaluating ex- an analogous criterion for natural areas, and optimal implemen- isting management practices, the use of C&I in this capacity alone tation would ensure the protection and enhancement of natural does not guarantee successful sustainable urban forest manage- structures and functions. These two new criteria, adapted from ment. An adaptive plan or framework reflecting a community’s Clark et al.’s (1997) original tree protection criterion, reflect the commitment, vision, and goals, and enabling strong links between importance of integrated policy mechanisms, while facilitating these and daily on-the-ground operations, is equally important. strategic planning by distinguishing between public, intensively The updated criteria and indicators presented here have been managed resources and more extensively managed natural areas. successfully incorporated into a long-term strategic urban forest As a greater share of urban forest benefits is derived from management plan for the Canadian municipalities of Oakville large-stature and well-established trees, the protection of existing (Urban Forest Innovations and Kenney 2008), Burlington (2010) trees is a key criterion for successful management. No major and Ajax, Ontario (in press), and are being used as a model modifications are recommended to either the criterion or the indi- for the development of similar plans in other municipalities. cators, but the study authors do stress the importance of con- The applicability of criteria and indicators as a powerful tool for sistent enforcement of tree protection policies, coupled with urban forest management was recognized more than a decade ago, effective deterrents to prevent offenses from first occurring. yet policymakers and managers continue to overlook their poten- Finally, it is proposed that the criterion of citizen safety, supported tial to ensure the long-term provision of urban forest benefits in any by relative indicators in Clark et al. (1997), be modified to include indi- size of community. Contemporary urban forest professionals can- cators in absolute terms in a program of comprehensive tree risk man- not only monitor and adjust policies determined by others. Ideally, agement. To move beyond the “low” performance level, this criterion they will be leaders in decision-making processes, and at a mini- requires the presence of at least a sample-based inventory with gener- mum be active participants in urban forest management planning. al tree risk information, highlighting the importance of strategic man- The set of criteria and indicators for urban forest sustainability pre- agement based on sound data concerning the urban forest resource. sented here can aid in the planning process by guiding an analysis of strengths, weaknesses, opportunities, and threats. They can also serve as a nucleus, around which a long-term strategic urban forest CONCLUSION management plan can be designed, and against which a series of In this paper, the reasons canopy cover alone cannot provide an milestones progress through the implementation of the plan, which accurate representation of the structure, health, and function of can be measured. Because urban forest management and planning is an urban forest were discussed, along with why overly ambi- complex, these C&I can also serve as a concise yet comprehensive tious canopy cover targets, unless accompanied by more com- communications tool for managers charged with explaining their prehensive criteria, may in fact be detrimental to urban forest challenges to politicians, other professionals, and the general public. sustainability. More importantly, however, is the presentation The paper by Clark et al. (1997) represents the seminal work of an updated framework of criteria and indicators. Building for the growing dialogue about sustainable urban forest manage- upon the foundation laid by Clark et al. (1997), these criteria ment. The authors’ framework of key objectives, criteria, and per- and indicators will help managers, policy makers, and other formance-based indicators for urban forest management success stakeholders to move beyond thinking about their urban forests recognized the dynamic and multi-faceted nature of urban forests, as two-dimensional entities described solely by canopy cover. and provided a promising tool for the development of citywide Assessing a community’s relative performance in each of the urban forest management planning. However, years later, the rel- twenty-five proposed criteria and indicators may seem like a daunt- ative success or failure of urban forest management in communi-
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ties across North America is still far too often measured by canopy tion, testing, evaluation and introduction. Proceedings of the seventh cover alone. It is hoped that the expanded and updated criteria and conference of The Metropolitan Tree Improvement Alliance (MET- indicators presented here provide a more comprehensive, strategic, RIA), June 11–12, 1990, The Morton Arboretum, Lisle, Illinois. and sustainable context for urban forest management planning. Urban Forest Innovations, and W.A. Kenney. 2008. Urban forest stra- tegic management plan for the Town of Oakville 2008-2027. Retrieved May 1, 2009.
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publicly-
all
of
Key objective climate-appropriate Achieve of tree cover, degree community-wide aged for uneven Provide citywide distribution as well at the neighborhood level. suitable for the urban and adapted environment environment. to the regional diverse genetically a Establish tree population citywide as well at the neighborhood level. Detailed understanding of the condition and risk trees. Detailed understanding of the ecological structure and function of all areas. natural owned publicly Preservation and Preservation enhancement of local natural biodiversity. TION r ESOU CE a Optimal canopy The existing equals 75%–100% cover of the potential. 25% of the tree population is in each of four RDBH classes.
considered suitable for the area. No species represents more than 10% of the entire tree population at the neighborhood level. Complete tree inventory that includes detailed ratings. The ecological structure and function of all publicly- natural areas are owned documented and included in the citywide GIS.
The use of native species The use of native is required on a project- appropriate basis in both and extensively intensively managed areas; invasive species are recognized and prohibited. THE VEGET THE r S FO TO a L. 1997). Good canopy The existing equals 50%–75% cover of the potential. No RDBH class represents more than 50% of the tree. population
are of species considered suitable for the area. No species represents more than 10% of the entire tree population citywide. Complete tree inventory that includes detailed and type of The level public use in publicly- natural areas is owned documented.
The use of native species The use of native is encouraged on a project- appropriate basis in both and extensively intensively managed areas; invasive species are recognized and their use is discouraged. OM C L ark ET C ommunity F ramework a PTED F r a ND PE r FO M NCE INDIC ( a D Moderate canopy The existing equals 25%– cover 50% of the potential. RDBH class Any represents between 50% and 75% of the tree population. Performance indicators 50% to 75% of trees are of species considered suitable for the area. More than 75% of trees No species represents All trees are of species more than 20% of the entire tree population citywide. Establish a tree population Sample-based inventory indicating tree condition Publicly owned natural Publicly owned areas identified in a “natural areas survey” or similar document.
use of native Voluntary species on publicly and lands; privately-owned species are invasive recognized.
a NDED C r ITE I
Low canopy The existing equals 0%–25% cover of the potential. DBH Relative Any (RDBH) class (0%– 25% RDBH, 26%– 50% RDBH, etc.) represents more than 75% of the tree population.
system. The condition system. trees are of species considered suitable for the area. than five Fewer species dominate the entire tree population citywide. No tree maintenance or risk assessment. Request based/reactive is in place. and risk level tree condition ratings. tree condition and risk potential of the urban forest is unknown. No information about natural publicly owned areas.
No program of integration.
APPENDIX 1. E XP
canopy Relative cover Age distribution of trees in the community Criteria managed Species suitability Less than 50% of
Species distribution Condition of publicly owned trees (trees Publicly owned intensively) natural areas (trees managed e.g., extensively; ravine woodlands, lands, etc.) vegetation Native
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Kenney_May11.indd 114 4/26/2011 3:34:14 PM Arboriculture & Urban Forestry 37(3): May 2011 115 O rk Key objective Insure all city department cooperate with common goals and objectives. embrace citywide goals and through specific objectives resource management plans. The green industry operates standards professional high with and commits to citywide goals and objectives. At the neighborhood level, cooperate and understand citizens in urban forest management. community interact for the benefit of the urban forest. understands public general The the role of urban forest. for cooperation and Provide groups. regional and communities Optimal Municipal policy implemented by formal interdepartmental/ teams working interagency on all municipal projects. tree comprehensive management plans (including funding). Shared vision and goals including the use of professional standards. All neighborhoods organized and cooperating. a tree board with staff coordination. Urban forest recognized as vital to the community’s social, and environmental, economic well-being. planning, Regional coordination, and/or management plans. interaction among neighboring THE COMMUNITY F ra ME w r S FO TO a L. 1997). OM C L ark ET ramework C ommunity F ramework Good Informal teams among departments and or agencies implementing common goals on a project-specific basis. for by landholders. Incentives trees. of private preservation Specific cooperative arrangements, such as purchase certificates for “right tree in and Citywide coverage interaction. cooperation. acknowledged Trees environmental, as providing social, and economic services. planning Regional are functioning and the right place.” a PTED F r a ND PE r FO M NCE INDIC ( a D Performance indicators Moderate no Common goals but cooperation among agencies. to advice available landholders. General cooperation among nurseries, tree care companies, etc. Isolated or limited number of active groups. constituencies. seen as important Trees to the community. Communities share vehicles. similar policy is in effect. a NDED C r ITE I Low Conflicting goals among departments and or agencies. departments and/or No cooperation of among segments the green industry. No adherence to industry standards. No action. Conflicting goals among constituencies. No interaction among seen as a Trees problem, a drain on Informal and/or general budgets. Communities interaction, such as Formal independently. All constituencies in the APPENDIX 2. E XP municipality- Criteria Public agency cooperation of Involvement and private large institutional land Ignorance of issues. holders Educational materials and Green industry cooperation Clear goals for tree resource Landholders develop Neighborhood action landholders private Large Citizen- business interaction General awareness of trees as a community resource Regional cooperation cooperate
©2011 International Society of Arboriculture
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CH a O a PP r condition, and risk assessment. assessments resolution High potential and existing the of for the cover canopy entire community. and implement Develop forest urban comprehensive a private for plan management and public property. adequate maintain and Develop citywide a implement to funding plan. management forest urban and train adequate Employ to implement citywide staff urban forestry plan. ensured is renewal forest Urban tree comprehensive a through by driven program establishment diversity, species cover, canopy and species distribution objectives. trees are All publicly owned planted in habitats that will maximize current and future to the site. benefits provided Key Key Objective of the Complete inventory tree resource to direct its management, including age species mix, tree distribution,
GEMENT a Sampling of tree cover using aerial photographs or satellite imagery included in citywide GIS. multi-tiered plan for Strategic intensively- public and private forest and extensively-managed resources accepted and implemented with adaptive management mechanisms. and public Adequate private funding to sustain maximum urban forest benefits. Multi-disciplinary team within the urban forestry unit. establishment is directed Tree from a tree by needs derived and is sufficient to inventory meet canopy cover objectives criterion, cover (see canopy Appendix 1). All trees planted in sites with adequate soil quality and space and growing quantity, their genetic to achieve potential. Optimal of Complete inventory trees publicly owned and sample-based inventory trees of privately-owned included in citywide GIS.
a L. 1997). THE r ESOU CE M a N r S FO TO OM C L ark ET Sampling of tree cover using Sampling of tree cover aerial photographs or satellite imagery. plan for Comprehensive intensively- publicly owned and extensively-managed forest resources are accepted and implemented. increase in urban forest benefits. Certified arborists and professional foresters on professional with regular staff establishment is Tree directed by needs derived from a tree inventory. Community-wide guidelines are in place for the of planting improvement sites and the selection of suitable species. for net Funding to provide development. Good Complete inventory trees of publicly owned and sample-based inventory of privately-owned trees. a PTED F r M anagement Approach ( a D a ND PE r FO M NCE INDIC Visual assessment. Visual Existing plan limited in scope and implementation. urban forest. existing No training of staff. existing establishment occurs Tree on an annual basis. species are considered Tree in planting site selection. Funding to optimize Resource Resource Performance indicators Moderate Complete or sample-based of publicly- inventory trees. owned a NDED C r ITE I No inventory. No plan. management. No staff. establishment Tree is ad hoc . planted without Trees consideration of the site conditions. Funding for reactive Low No inventory. APPENDIX 3. E XP Canopy cover cover Canopy inventory Citywide management plan wide funding City staffing establishment Tree planning and implementation habitat Tree suitability Municipality- Criteria inventory Tree
©2011 International Society of Arboriculture
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CH a O maximize
to
a PP r Key Key Objective trees are All publicly owned The benefits derived from The benefits derived trees are ensured large-stature by the enforcement of municipal wide policies. The ecological structure and function of all publicly- natural areas are owned protected and, where appropriate, enhanced. longevity. safe. are trees owned publicly All and future benefits. Tree health Tree benefits. future and maximum ensure condition and GEMENT a Optimal All mature publicly owned risk ratings; abatement eliminating program is in effect one week from confirmation of hazard potential. municipal wide Integrated policies that ensure the protection of trees on public land are and private consistently enforced and supported by significant deterrents. plan in effect Stewardship for each publicly owned natural area focused on sustaining the ecological structure and function of the feature. Complete tree inventory that Complete tree inventory year cycle. All immature year cycle. trees are structurally pruned. THE r ESOU CE M a N r S FO TO a L. 1997). OM C L ark ET Good trees All publicly owned maximum of one month from trees public and private with enforcement. for each publicly owned public natural area to facilitate use (e.g. hazard abatement, trail maintenance, etc.). failure risk ratings; failure abatement program is in effect eliminating hazards within a confirmation of hazard hazards within a maximum of potential. Policies in place to protect plan in effect Stewardship Complete tree inventory which includes detailed tree includes detailed tree failure on a cycle longer than on a cycle years. five a PTED F r M anagement Approach a ND PE r FO M NCE INDIC ( a D Resource Resource Performance indicators Moderate trees are Publicly owned abatement program system. public trees. public to facilitate in effect use (e.g., hazard abatement, trail maintenance). general tree risk information. Request- Policies in place to protect Reactionary stewardship Sample-based tree including inventory reactive basis. No reactive systematic (block) pruning. a NDED C r ITE I Low No maintenance of system. The system. policy. plans or implementation in effect. remediation program. Request based/reactive condition of the urban forest is unknown. risk based/reactive No tree protection No stewardship No tree risk ONTINUED. E XP APPENDIX 3. C ONTINUED. Criteria Maintenance of publicly owned, trees. publicly owned on a request/ maintained are systematically maintained trees are maintained on a five- maintained protection policy development and enforcement natural areas management planning and implementation Tree Publicly owned Tree risk Tree management assessment/ intensively intensively managed trees
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