Table of Contents Robert T. Fahey, Margaret B. Bialecki, and David R. Carter Tree Growth and Resilience to Extreme Drought Across an Urban Land-use Gradient ................ 279 Abstract. Understanding the response of urban forests to extreme climatic events, such as drought, will be essential to predicting impacts of climate change on the urban tree canopy and related ecosystem services. This study evaluated variation in tree growth and drought resis- tance (growth during drought) and resilience (growth in period following drought) across four land-use categories (built, transporta- tion, park, and semi-natural forest) and four species (Acer saccharum, Gymnocladus dioicus, Liriodendron tulipifera, and Pinus strobus) at The Morton Arboretum in suburban Lisle, Illinois, U.S. Tree growth and resistance to drought both varied as an interaction between land- use and species (F15, 100 not vary across species and land-uses. In this study, individual tree species responses to drought varied across land-uses, illustrating the dif- ficulty of predicting the reaction of urban forests to projected increases in the frequency of extreme climatic events. Tree growth response to drought varied even across the relatively narrow range of growing conditions studied here. Investigation of a broader range of sites, encom- passing the full urban forest continuum, would likely demonstrate even greater variation in tree response to extreme climatic events. Key Words. Climate Change; Drought; Growth; Gymnocladus dioicus; Land-use; Liriodendron tulipifera; Pinus strobus; Resilience; Urban Forest. = 5.25, p < 0.001; F15, 100 Chris A. Martin and Jean C. Stutz Tree Health in Phoenix, Arizona, U.S. .......................................................................................... 286 Abstract. Two studies of tree diversity, visual health, and mortality in the Phoenix, Arizona, U.S. metropolitan basin were conducted as part of the Central Arizona Long-Term Ecological Research project. For one study, tree diversity, mortality, and visual health were deter- mined in 2010 at 204 sites, encompassing both the Phoenix metropolitan basin and in the surrounding Sonoran Desert. In another study, records of tree visual health and mortality were taken during the winter months (2003–2007) at 65 non-residential sites across an urban to rural gradient. Average tree mortality rates were 4.2% per annum. Crown condition was rated as very good or good for the major- ity of trees. Poor pruning practices and abiotic injuries, such as trunk sunscald, were observed on 70% and 23%, respectively, of trees in non-residential areas. Disease and pest problems were detected in 41% of urban trees, including wood decay, Verticillium wilt, sooty can- ker, and ash decline. Based on these data, researchers suggest that urban forest health in Phoenix is being negatively impacted by exten- sive wounding of trees, particularly in non-residential settings, possibly caused by excessive crown manipulation through pruning. Key Words. Arizona; Phoenix; Tree Diversity; Tree Mortality; Urban Forest; Urban Heating. Lara A. Roman, E. Gregory McPherson, Bryant C. Scharenbroch, Julia Bartens Identifying Common Practices and Challenges for Local Urban Tree Monitoring Programs Across the United States .............................................................................................................. 292 Abstract. Urban forest monitoring data are essential to assess the impacts of tree planting campaigns and management programs. Local practitio- ners have monitoring projects that have not been well documented in the urban forestry literature. To learn more about practitioner-driven moni- toring efforts, the authors surveyed 32 local urban forestry organizations across the United States about the goals, challenges, methods, and uses of their monitoring programs, using an e-mailed questionnaire. Non-profit organizations, municipal agencies, state agencies, and utilities participated. One-half of the organizations had six or fewer urban forestry staff. Common goals for monitoring included evaluating the success of tree planting and management, taking a proactive approach towards tree care, and engaging communities. The most commonly recorded data were species, con- dition rating, mortality status, and diameter at breast height. Challenges included limited staff and funding, difficulties with data management and technology, and field crew training. Programs used monitoring results to inform tree planting and maintenance practices, provide feedback to indi- viduals responsible for tree care, and manage tree risk. Participants emphasized the importance of planning ahead: carefully considering what data to collect, setting clear goals, developing an appropriate database, and planning for funding and staff time. To improve the quality and consistency of monitoring data across cities, researchers can develop standardized protocols and be responsive to practitioner needs and organizational capacities. Key Words. Citizen Science; Forest Inventory and Analysis; i-Tree; Monitoring; Survey; Tree Mortality; Tree Planting. = 2.42, p = 0.005). Resilience of tree growth to extreme drought was generally high and did ©2013 | International Society of Arboriculture | ISSN:1935-5297
November 2013
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