110 Kenney et al.: Criteria and Indicators for Strategic Urban Forest Planning and Management More than a decade ago Clark et al. (1997) pro- posed a set of tools to reflect the specific issues concern- ing urban forestry, and provided a list of criteria and in- dicators for urban forest sustainability that considered: • the vegetation resource • the community framework, and • the resource management approach. Each criterion includes a key objective and performance indica- tors describing low, moderate, good, and optimal levels of perfor- mance. In a subsequent paper, Clark and Matheny (1998) surveyed a sample of 25 U.S. municipalities and scored their performance in terms of urban forest sustainability using the criteria and indica- tors matrix. General findings from the survey responses suggested that, on average, communities scored 49 of a maximum 80 points. In the following pages, the authors of the current study build upon several of the criteria and indicators developed by Clark et al. (1997), and provide more detail in a number of areas to better posi- tion C&I as tools for strategic urban forest management planning. The Vegetation Resource Clark et al. (1997) provided four criteria for success in managing the urban forest vegetation resource: 1) canopy cover, 2) age distribu- tion of trees in the community, 3) species mix, and 4) native vegeta- tion. Suggested here are two additional criteria to be incorporated into strategic urban forest management planning: 5) the condition of publicly owned trees, and 6) publicly owned natural areas. Fur- ther proposed is a revision to the original canopy cover criterion. Clark et al. (1997) suggested that the key objective in man- aging canopy cover is to achieve a climate-appropriate degree of tree cover within the community, yet the performance in- dicators presented only track increasing levels of sophistica- tion in assessment or technological input. As such, there is a disconnect between the key objective and the indicators avail- able to urban forest managers to evaluate the success of their management strategies. Suggested here is a revised perfor- mance indicator, relative canopy cover, which allows for a quantifiable comparison between actual canopy cover and the maximum potential cover within a community (Appendix 1). In other words: Relative Canopy Cover = Canopy Cover Potential Canopy Cover The application of this criterion is, of course, predi- cated on the availability of a measure of the carrying cap- acity or potential canopy cover, as discussed previously. In terms of tree age distribution, the original key objective was to build to provide for an uneven age distribution city-wide and at the neighborhood level. The initial indicators proposed by Clark et al. (1997) focused on the methods of assessing tree age distribution, but did not provide actual age class targets at differ- ent performance levels. The revised indicators introduce the con- cept of relative diameter (RDBH) as a more meaningful target. RDBH is the ratio between a tree’s measured diameter at breast height and the maximum diameter for its species. Species specific maximum DBH values can be derived from the literature and/ or local experience. For example, in southern Ontario, Canada, a database has been developed based on maximum DBH values ©2011 International Society of Arboriculture from Farrar (1995), Kershaw (2001), Lauriault (1989), Leopold (2003), Petrides (1972), and Rushforth (1999). If an extensive tree inventory is available, this could inform the development of maximum DBH values. Ideally, DBH data could be pooled at a regional level (i.e., across municipalities). Maximum urban tree DBH values may not be immediately available; however, once developed, RDBH will provide quantifiable targets for tree size and distribution across the community. Additionally, it enables managers to determine whether urban trees are able to reach their genetic potential for a given species, which is largely de- pendent on the condition of the planting site and other factors. Maintaining a diverse species mix (species diversity) is a critic- al way to promote a healthy and resilient urban forest (Santamour 1990). Maintaining species diversity is a function of the number of species present, as well as how those species are spatially dis- tributed across the community. Therefore, this original criterion was further divided into two distinct criteria and key objectives: 1) species suitability, to establish a tree population suited to the urban and regional environment, and 2) species distribution, to establish a genetically diverse population of trees throughout the urban forest. Tree species suitability can be based on regionally- specific guidelines, such as those provided in the Council of Tree and Landscape Appraisers’ regional supplements, which take into account concerns such as adaptability to local climate, and man- agement needs. In the absence of such guidelines, a municipal- ity can develop its own species suitability index, based on local expert opinion. While Clark et al.’s (1997) performance indica- tors track only the scope of assessment and inventory technology, the current revision encourages urban forest managers to account for species diversity at a level of detail (i.e., neighborhood level) not available through aggregate tree inventory data, thereby mak- ing this criterion better suited to long-term strategic planning. The present study differentiates between intensively managed parts of the urban forest and extensively managed woodlands – that is, areas where individual trees are managed under arboricultural techniques as opposed to areas that are managed en masse using techniques more closely related to silviculture. While these various components together form the urban forest, the authors feel that it is critical that the unique approaches to management required in each are clearly recognized in the development of inventories and man- 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- vate ownership, and municipal resources are used to support the relatively small component of the canopy on public land (e.g., street trees). Therefore, the condition of intensively managed, publicly owned trees—with the key objective of a detailed un- derstanding of the condition and risk potential of all public trees—is an important new criterion that can be used to evaluate the success of forest management and support strategic planning. In communities with significant natural areas, a similar cri- terion is suggested in addition to the previous—publicly owned natural areas, which are primarily extensively managed. A de- tailed understanding of the ecological functions and struc- tures, as well as information about public use of these areas, represents a significantly more sophisticated articulation of practical management concerns to support strategic planning. Finally, the use of native species on public or private land may represent an important objective for sustainable urban forest man- agement. While Clark et al.’s (1997) criteria and performance in- dicators are still generally robust, the current study expands on the
May 2011
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
