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    Climbers' CornerTree Academy
    MondayTuesdayWednesday

    Urban Forestry through the Lens of Tree Growth and Longevity

    Summary

    The four papers below draw on large populations of trees in urban areas in order to model or characterize growth and survival given the biological, social, and environmental factors at play. The months and years following planting are a tenuous period in a tree’s life. The first two papers model replanting success in dramatically different environments (ranging from Sub-tropical to Temperate North America) from both biological and sociological perspectives. Most long-lived urban tree species that survive planting and become established in the landscape will experience some level of human-induced (i.e., construction) or environmental disturbance during their lifetime. The latter two papers identify conditions that contribute to mature tree mortality and/or failure. 

    Factors Influencing Urban Tree Planting Program Growth and Survival in Florida, United States    

      Andrew K. Koeser (Presenter), Edward F. Gilman, Maria Paz, and Chris Harchick    

    Planting projects with high mortality represent both an economic loss and ecological disservice once one accounts for the input and materials associated with tree production and installation. With many urban tree planting initiatives underway (including several higher profile million-tree endeavors), continual assessment is needed to gauge overall program success. Past planting projects funded by the Florida Forest Service (FFS) were revisited 2 to 5 years after installation to document tree survival. Additionally, various site (e.g., soil compaction, installed irrigation) and tree-related (e.g., species, nursery production method, initial size at planting) factors were noted to assess their impact on tree growth. Results, show that the overall survival percentage for the 26 sites (over 2350 trees) was high, with 93.6% of trees alive at the time of inspection. On-site irrigation played a significant role in tree survival and growth, especially for Magnolia grandiflora (97.7% survival on irrigated sites; 73.8% survival on non-irrigated sites). Findings from this work validate the effectiveness of current FFS program policies, which include required maintenance of tree quality (e.g., no die-back) within the first year after planting, and offer further insights regarding the impacts of season of planting and initial size of nursery stock on plant growth and development.    

         Explaining planted-tree survival and growth in urban neighborhoods using a social-ecological systems perspective: A study of recently-planted trees in Indianapolis (United States)    

      Jessica M. Vogt (Presenter),Shannon Lea Watkins, Sarah K. Mincey, Matthew S. Patterson, and Burnell C. Fischer    
    Tree-planting success in urban environments is not well understood. This presentation uses a data set of over 1300 trees planted in Indianapolis, Indiana (United States) to answer the question: What characteristics of trees, the biophysical environment, the community, and institutions predict survival and growth of trees in neighborhood tree-planting projects? We combine Ostrom’s social-ecological systems framework and the Clark et al. model of urban forest sustainability to inform the selection of variables that may influence tree outcomes. We use a probit model to predict tree survival, and multiple linear regression to predict tree growth rate, both with random effects at the neighborhood level. We find that tree characteristics more strongly influence tree growth than survival, and that characteristics of the biophysical environment, community, and institutions influence both survival and growth. Future research should continue to examine tree survival and growth in the context of the urban forest as a social-ecological system.  

    Urban Tree Longevity and Construction: Following a Milwaukee, WI, USA Street Tree Population    

    Richard J. Hauer (Presenter), Andrew K. Koeser, Kelly Norris, and Randy Krouse

     
    Urban trees face many stress factors linked to adverse site conditions, environmental extremes, and physical disturbances. These factors affect tree survival in urban areas. This presentation shows the impacts of construction on street tree longevity, growth, and condition. A street tree population in the city of Milwaukee, Wisconsin (United States) was followed for over 25 years with three assessments conducted in 1979, 1989, and 2005. In 1979, prior to street construction, baseline measurements of tree condition, tree size, tree species, and site attributes were made. These factors were measured again in 1989 and 2005 and comparisons were drawn between trees affected or spared by nearby construction activity. The effects of construction and other factors on tree longevity were determined with multivariate logistic regression. Cross validation showed our model was able to successfully predicted survival nearly 85% of the time. We found that: 1.) tree survival varied by species; 2.) trees were more likely to die as trunk diameter increased; 3.) as planting space width decreased in the tree lawn tree longevity decreased; and 4.) tree longevity decreased as tree condition decreased. Trees were twice as likely to die when exposed to redevelopment activities. Finally, results show a tree preservation program developed by Milwaukee in the mid 1980’s has led to less tree mortality and a lower reduction in tree condition when trees are subjected to construction compared to results before the tree preservation program.

     

    Failure of Boulevard Trees During Wind-Loading Events    

    Gary Johnson   

    Boulevard tree failures (i.e., full or partial windthrow failures at or below ground line) range from catastrophic and widespread losses to seemingly random and unpredictable events depending on the wind loading event. Wind loading events in the Mi range in velocity from 30 miles/hour (48 Km/hour) gusts or sustained winds to EF-5 tornadoes of greater than 190 miles/hour (305 Km/hour). The greater the wind velocity, the more likely are catastrophic tree losses, especially in root plate compromised landscapes such as boulevards (the planting area between public sidewalks and street curbs). However, when boulevard tree failures greatly exceed other landscape tree losses in the same area, predictable architectural, site, or compromised stability situations become suspect – especially from the perspective that they may be preventable to some degree.  

    A straight-line windstorm struck portions of the Minneapolis/Saint Paul metropolitan area of Minnesota (United States) on June 21, 2013, resulting in significant tree failures. A rapid assessment by the Department of Forest Resources, University of Minnesota suggested that the majority of the tree failures were in boulevards compared to parks and residential landscapes. From August through December, a detailed analysis of the fallen trees was conducted. Variables documented included: species, size, boulevard width, soil texture, soil compaction, recent (within five years) adjacent construction activities, and type of or construction work completed (e.g., sidewalk replacement, curb replacement, complete street and sidewalk infrastructure renewal). Results from this study offer two pragmatic perspectives: 1.) a protocol for collecting storm damage data pertinent to sustainable boulevard tree populations and 2.) a better tree selection and placement process for street tree designs for communities in regions prone to wind-loading events.

    Presenters

    Andrew K. Koeser is a Professor of Landscape Management at the University of Florida-Gulf Coast Research and Education Center near Tampa, Florida (United States) and an International Society of Arboriculture (ISA) Board Certified Master Arborist. Prior to working at the University of Florida, Andrew worked for five years at the ISA headquarters in Champaign, IL (United States) – starting as an intern and advancing to Science and Research Manager. He holds a Ph.D in Crop Sciences (Horticulture and Biometry emphases) from the University of Illinois at Urbana-Champaign, a M.S. in Natural Resources and Environmental Sciences from the University of Illinois at Urbana-Champaign, and a B.S. in Forestry (Urban Forestry Emphasis) from the University of Wisconsin – Stevens Point.

     
    Jessica M. Vogt is a doctoral candidate in Environmental Science (emphasis on Urban Ecology and Urban Forestry) at the School of Public and Environmental Affairs (SPEA) at Indiana University, Bloomington. Vogt is also a 2012 and 2013 Garden Club of America Urban Forestry Fellow.

    Richard Hauer is currently an Associate Professor of Urban Forestry at the University of Wisconsin-Stevens Point teaching courses in the urban forestry, nursery management and operations, woody plants, dendrology, and introductory forestry. He conducts research in tree biology, urban forest management, trees and construction, and ice storms and trees for nearly 20 years. Prior to coming to UWSP, Rich coordinated the Shade Tree Program at the Minnesota Department of Agriculture where he was responsible for the certification and training of over 900 tree inspectors statewide. He has worked in tree biology research, natural resource consulting, landscape maintenance, and as an arborist. He received a B.S. in Urban Forestry and Botany from the University of Wisconsin-Stevens Point, a M.S. in Tree Biology from the University of Illinois, and his Ph.D. in Urban and Community Forestry at the University of Minnesota. He has published over 90 papers in popular and peer-reviewed journals and presented over 200 professional presentations.      

    Gary Johnson is Professor and Extension Professor of Urban and Community Forestry in the Department of Forest Resources at the University of Minnesota, Twin Cities campus. Since 1992, Gary has conducted research and outreach in the areas of tree failures due to construction activities, wind-loading events, tree production and planting practices.

     

    Climbers' CornerTree Academy
    MondayTuesdayWednesday

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