Arboriculture & Urban Forestry 38(5): September 2012 Potential outcomes of the research discussed: * * * 239 enhancing coordination and cooperation with growers regarding best practices for the development of stock, especially for large planting projects development of state-specific standards for nursery stock opportunities for partnerships between arboricultural researchers, practitioners, and growers Future research priorities for investigating the roles of tree production and sales on tree growth and longevity were ranked in the following order: 1. 2. 3. 4. 5. 6. Investigate the importance of small, fibrous roots in a root ball, relative to tree growth and mortality rates. Species-specific root architecture issues should be studied. Genetic improvements in tree production should be sought. Identify rooting zones at transplant time. Determine the optimal planting depth for a given tree in typical urban conditions. Establish the extent to which circling roots can grow without causing irreparable damage to a tree. TOPIC #3: ROLES OF SITE DESIGN AND TREE SELECTION ON TREE GROWTH AND LONGEVITY For the third session of the symposium, the keynote presenta- tion, “Site Design and Tree Growth,” was provided by Susan Day, assistant professor in the departments of Horticulture and Forest Resources and Environmental Conservation at Virginia Tech. The roles of site design and tree selection on tree growth and longevity were further discussed in presentations by the follow- ing researchers: E. Thomas Smiley (Bartlett Tree Research Labo- ratory), “Growing Trees in an Urban Plaza Environment”; Alan Siewert and Stephanie Miller (Division of Forestry, Ohio Depart- ment of Natural Resources), “Urban Site Index for Urban Forest Planning”; and Jason Grabosky (Rutgers University), “An Orga- nizational Approach to Urban Tree Management and Longevity.” In summarizing the current state of the roles of site design and tree selection on the symposium’s second day, the need to predict ultimate tree performance was emphasized. One approach is examining the genetic and phenotypic characteris- tics of veteran trees that exhibit unusual longevity. Discussants at the roundtable session offered many comments and questions for further research on the ef- fects of site design and tree selection on urban tree health and survival. Researchers should develop partnerships with municipalities and tree planting groups, whether ad hoc neighborhood associations or established tree plant- ing nonprofit organizations, to share information on proven practices and to begin new research. Studies should be un- dertaken that investigate the relationship of economic and sociological variables to tree growth and survival. Research- ers also should take the initiative to integrate the results of their research into local tree ordinances. For example, if researchers know the best planting depths or soil condi- tions for trees in a parking lot, they should reach out to lo- cal communities to incorporate this information into their tree planting and maintenance practices. Participants also mentioned the need for further study into the architecture of root systems and potential advances toward improv- ing tree health and longevity through genetic engineering. Lastly, they acknowledged the need for development of a common language for effective communication between all stakeholders, and stated that this should be an imperative of the Urban Tree Growth and Longevity Working Group. Future research priorities for investigating the of site design and tree selection on tree roles growth and longevity were ranked in the following order: 1. 2. 3. 4. 5. Analyze or estimate the return on investment for different levels of site preparation. Determine the effects of storm water retention on tree health (bioretention). Investigate how planting type (i.e., bare root, field grown, and container) influences growth, survival rates, and costs of production, planting, and care. Increase the number of long-term studies of impacts of site design and tree selection on growth, longevity, and health. TOPIC #4: ROLES OF TREE AND SITE MANAGEMENT ON TREE GROWTH AND LONGEVITY James Clark, an ISA Certified Arborist and the Vice Presi- dent of HortScience, Inc., of Pleasanton, California, delivered the keynote presentation, “Making the Most of What Science Offers Us,” for the final session of the symposium. Research- ers and presentations for this fourth topic—the roles of tree and site management on urban tree growth and longevity— included Alessandro Pestalozza (Dendrotec, Monza, Italy), “Roadwork and Street Trees: The High Cost of Coexistence”; Alessio Fini (University of Florence, Italy), “The Effect of Repeated Pruning Cycles on Tree Structure and Physiology of Sycamore Maple Depends on Pruning Method”; Gary Wat- son (The Morton Arboretum), “Tree Planting Depth Impacts Growth”; and Nina Bassuk (Cornell University), “Rooting Vol- ume and Tree Growth Responses in the Urban Environment.” In summarizing the current state of research, it was noted that models and assessment methods must play an important role in future scientific studies. Demographic studies should include tree survival, mortality, and removal patterns. Re- searchers should examine species’ response to disturbances as well as specific management practices, such as the use of recycled water for irrigation. It was suggested that further study is needed on the relationship between wood decay and carbon sequestration. Of particular importance, the effective- ness of assessment tools must be verified. Forging partnerships between municipalities and researchers in academic settings was recommended. One recommendation was to establish an information clearinghouse on the roles of tree and site man- agement—perhaps following the International Tree Failure Database model wherein information is standardized for ease ©2012 International Society of Arboriculture Accurately predict tree performance for different ecosystem services, given differences in site conditions, species, management, and other variables.
September 2012
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