84 Appleton: Designing and Implementing Utility Line Arboreta reference and to highlight trees incorrectly sited under over- head distribution lines. Every few years, when these trees overgrow the lines, Dominion Virginia Power and Asplundh Tree Expert Company, a line-clearance contractor, use the trees for demonstrations of correct utility line-clearance prun- ing during HRAREC industry field days. DISCUSSION Small trees and overhead utility lines can coexist in aesthetic and nonhazardous combinations if size and maintenance re- quirements are considered when the trees are selected. The use of appropriately sized trees will significantly reduce power interruptions and outages, as well as line-clearance and tree removal costs. Regional tree selection trials, such as those being conducted in Pennsylvania and Virginia, greatly aid in the selection of trees compatible with overhead utility lines. Utility line arboreta, for the purpose of evaluating, showcasing, and promoting appropriate trees, can be estab- lished for a relatively low cost if grants are sought and part- nerships established. Although one of the three utility line arboreta presented here should be appropriate for almost any site on which de- velopment of a utility line arboretum might be desired, for development of any future utility line arboreta, several changes in our initial process are recommended. Where trees will be lined out in rows as in the HRAREC Utility Line Arboretum, spacing plants on 4.5 m (15 ft) centers within rows was often too close for full tree canopy spread develop and for maintenance activities around the trees. It is recom- mended that trees be spaced a minimum of 6.1 to 7.6 m (20 to 25 ft) apart within rows, with trees offset from each other in adjacent parallel rows. Adjacent rows should also be spaced a minimum of 6.1 m to 7.6 m (20 to 25 ft) apart. In addition, height is not the only dimension that needs to be considered when trees are selected for utility line arboreta. Many trees planted under overhead utility lines will be planted in strips between roads and sidewalks, as in the utility line arboreta along the two main streets in Abingdon, VA. Trees with broad spreads, such as flowering dogwood (Cor- nus florida) and Kwanzan cherry (Prunus serrulata), though their height may be appropriate, may be too wide for the location. In addition, because lower limbs will need to be removed (crown raising) to provide adequate clearance for pedestrians and vehicles, the appearance of many small trees may be ruined and their health stressed. Where horizontal landscape space is limited, small trees with more upright, columnar, or fastigiated forms are preferable. This selection criterion is being considered for all future trees to be trialed at Virginia utility line arboreta. Utility line arboreta, like any designed landscape feature, require far more than funding for initial development. A com- mitment must be made to ongoing maintenance and removal and replacement of trees as needed. As noted for the ©2006 International Society of Arboriculture HRAREC Utility Line Arboretum, many additional uses can be made for this type of landscape feature, often lending assistance with funding and maintenance. Multiple uses of utility line arboreta also increase community involvement and exposure. Information about the tree–overhead utility line conflict, conflict resolution options, and recommended trees and shrubs for easement plantings (USDA Hardiness Zones 6 to 8) are detailed in a Virginia Cooperative Extension publica- tion (Appleton et al. 2002) that is posted on and printable from the Internet (www.ext.vt.edu/pubs/trees/430-029/430- 029.html). With a grant from the National Urban and Com- munity Forestry Assistance Council (NUCFAC), the above publication was developed in template form, as well as tem- plates of a PowerPoint presentation and poster on utility line arboreta and utility line-compatible trees. In 2004 these ma- terials were distributed to all state urban forestry coordinators in the United States for regional customization and use and were posted to the website of Urban Forestry South Expo (www.urbanforestrysouth.org/Resources/Collections/ Collection.2004-10-22.0537/view). Additional information about this utility line arboreta proj- ect has been published in industry trade magazines (Appleton 2003, 2004; Appleton et al. 2003). Virginia MTRP recently launched a website (www.utilityfriendlytrees.org) where the above materials, and more, are posted. CONCLUSIONS The development of utility line arboreta is important to dem- onstrate to the public, to landscape designers and architects, and to municipalities that a wide variety of small trees and large shrubs, with either mature heights not exceeding the height of overhead utility lines or with growth rates that can help extend line-clearance cycles, are readily available in commercial nursery production in the United States. Many of the species we are evaluating and recommending, or similar species, are available worldwide, making the development of utility line arboreta feasible and appropriate wherever this tree–infrastructure conflict exists. Acknowledgments. This work has been supported by grants from the Virginia Department of Forestry, the Virginia Agricultural Council, and the National Urban and Community Forestry Assis- tance Council and by trees from J. Frank Schmidt & Son Company. LITERATURE CITED ANSI. 1997. National Electric Safety Code. ANSI C2. American National Standards Institute, New York, NY. Appleton, B. 2003. Utility room. American Nurseryman 197(3):41–45. ———. 2004. Trees: A threat to homeland security? Tree Care Industry 15(6):46–51.
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