Forestry, Faculty of
DSpace
UBCV
Bassett, Corinne G.
Doctor of Philosophy - PhD
University of British Columbia
Urban forests are recognized as a nature-based solution providing myriad ecosystem services addressing the sustainability challenges faced by cities. This dissertation investigates disconnects between the practice of urban forest management and urban sustainability goals set by cities. Chapter 2 frames the dissertation, using the economic phenomenon of the “tyranny of small decisions” and the case of urban forestry. I argue that where social and ecological characteristics vary at fine scales, the so-called small decisions in natural resource management, and the people who make them, are critical underpinnings for achieving large-scale sustainability goals and must be considered in policy. In Chapter 3, I interviewed urban foresters from municipalities in the US and Canada (N=20) to understand current best practices and challenges for aligning street-level management decision-making with ecosystem service goals adopted by their cities. While specific ecosystem service goals did not influence day-to-day decision making, most urban foresters followed a “more, bigger trees” paradigm as a proxy for increasing the ecosystem services provided by city trees overall. Urban forestry was also not found to be well integrated in municipal strategic planning. In Chapter 4, I conducted a multi-city expert elicitation of urban foresters in Vancouver, BC, Canada, Washington, D.C., US, and Honolulu, HI, US, to identify links between management actions and urban sustainability goals, in the context of a hypothetical streetscape. I found that certain direct actions were needed to advance every goal, while other direct actions present tradeoffs. Finally, Chapter 5 shares the findings of a research synthesis focus group that highlighted two critical elements required to circumvent the paradigm suggested by the tyranny of small decisions and achieve larger urban sustainability goals that rely on urban forests: 1) site-scale direct management actions by urban foresters can support larger-scale sustainability goals and 2) urban foresters and other holders of specialized knowledge need to be empowered and supported to make these small-scale decisions. Urban forest management is currently disconnected from urban sustainability planning. Therefore, for cities to achieve ambitious sustainability goals, a broader effort focused on enabling site-specific management and cross-sector and interdisciplinary collaboration is essential.
BRIDGING GAPS IN URBAN FOREST MANAGEMENT TO ACHIEVE URBAN SUSTAINABILITY GOALS by Corinne G. Bassett B.A., Earth Sciences, The University of Pennsylvania, 2014 M.E.S., The University of Pennsylvania, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) June 2024 © Corinne G. Bassett, 2024 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Bridging gaps in urban forest management to achieve urban sustainability goals submitted by Corinne G. Bassett in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Forestry Examining Committee: Dr. Susan D. Day, Professor, Forest Resources Management, UBC Co-supervisor Dr. Cecil C. Konijnendijk, Professor, Forest Resources Management, UBC Co-supervisor Dr. Kai M. A. Chan, Professor, Resources, Environment, & Sustainability, UBC Supervisory Committee Member Dr. Jeanine Rhemtulla, Associate Professor, Forest and Conservation Sciences, UBC University Examiner Dr. Maged Senbel, Associate Professor, Community and Regional Planning, UBC University Examiner Additional Supervisory Committee Members: Dr. Lara Roman, Research Ecologist, United States Department of Agriculture Forest Service Supervisory Committee Member iii Abstract Urban forests are recognized as a nature-based solution providing myriad ecosystem services addressing the sustainability challenges faced by cities. This dissertation investigates disconnects between the practice of urban forest management and urban sustainability goals set by cities. Chapter 2 frames the dissertation, using the economic phenomenon of the “tyranny of small decisions” and the case of urban forestry. I argue that where social and ecological characteristics vary at fine scales, the so-called small decisions in natural resource management, and the people who make them, are critical underpinnings for achieving large-scale sustainability goals and must be considered in policy. In Chapter 3, I interviewed urban foresters from municipalities in the US and Canada (N=20) to understand current best practices and challenges for aligning street-level management decision-making with ecosystem service goals adopted by their cities. While specific ecosystem service goals did not influence day-to-day decision making, most urban foresters followed a “more, bigger trees” paradigm as a proxy for increasing the ecosystem services provided by city trees overall. Urban forestry was also not found to be well integrated in municipal strategic planning. In Chapter 4, I conducted a multi-city expert elicitation of urban foresters in Vancouver, BC, Canada, Washington, D.C., US, and Honolulu, HI, US, to identify links between management actions and urban sustainability goals, in the context of a hypothetical streetscape. I found that certain direct actions were needed to advance every goal, while other direct actions present tradeoffs. Finally, Chapter 5 shares the findings of a research synthesis focus group that highlighted two critical elements required to circumvent the paradigm suggested by the tyranny of small decisions and achieve larger urban sustainability goals that rely on urban forests: 1) site-scale direct management actions by urban foresters can support larger-scale sustainability goals and 2) urban foresters and other holders of specialized iv knowledge need to be empowered and supported to make these small-scale decisions. Urban forest management is currently disconnected from urban sustainability planning. Therefore, for cities to achieve ambitious sustainability goals, a broader effort focused on enabling site-specific management and cross-sector and interdisciplinary collaboration is essential. v Lay Summary As cities grow and the effects of climate change intensify, the needs of residents for healthy, safe, and sustainable neighborhoods becomes more critical. Urban forests (the trees and vegetation in cities) are essential to help cities face these challenges through shading hot streets, intercepting rainfall during storms and providing many other benefits. This dissertation investigates whether the decisions urban forest managers make, such as which trees to plant and how to care for them over their lifespan, are helping cities reach their sustainability goals. Without aligning these decisions, these important goals may not be achieved, even when significant resources are invested. This research found that day-to-day urban forest management decisions are disconnected from city sustainability goals, while at the same time finding that these decisions can have a significant impact on certain goals. Overall, the research uncovers the importance of small-scale tree management decisions in reaching critical, large-scale sustainability goals. vi Preface This dissertation is composed of one introductory chapter (Chapter 1) followed by three body chapters (Chapters 2, 3, 4), and a final synthesis chapter (Chapter 5). Chapters 2-5 have been written with the intent to publish in peer-reviewed journals. Thus, there is some repetition of background information from chapter to chapter to meet journal requirements and serve each journal’s audience. Additionally, though I am the lead author for each chapter, first-person plural pronouns were used throughout to represent the collaboration of co-authors on each manuscript. I conceived of the initial research objectives and scope of this dissertation, with the invaluable support and advising of my supervisory committee, Dr. Susan D. Day, Dr. Cecil C. Konijnendijk, Dr. Lara A. Roman, and Dr. Kai M. A. Chan. With this team of researchers, I initiated and applied for funding to establish a research-practice partnership and investigate the objectives. The project was named Street Tree Futures and is referenced throughout the dissertation. Throughout this project, an urban forestry practitioner advisory committee provided invaluable guidance; committee members included Dana Karcher, Rachel Holmes, Matt Spitsen, and Jordan Endahl. Chapter 2 was written with intent to publish as a perspective article in a peer-reviewed journal. I defined the research objectives, refined the outline, prepared the manuscript, and created the figures, supported by critical revisions from and discussions with Dr. Susan D. Day, Dr. Kai M. A. Chan, Dr. Cecil. C. Konijnendijk, and Dr. Lara A. Roman. vii Chapter 3 was written with intent to publish in a peer-reviewed journal. I defined the research objectives, prepared the manuscript, and created the figures, supported by critical revisions from and discussions with Dr. Susan D. Day, Dr. Cecil. C. Konijnendijk, Dr. Lara A. Roman, and Dr. Kai M. A. Chan. The methodology was defined with Dr. Susan D. Day, Dr. Cecil. C. Konijnendijk, and Dr. Lara A. Roman. Dr. Lorien Nesbitt, Jessica Quinton, and other members of the Urban Natures Lab also provided advising for the semi-structured interview methodology and analysis. The interview guide was tested with graduate students in Dr. Susan Day’s Urban Forest Ecosystems Lab and members of the Street Tree Futures practitioner advisory committee. Interviewee recruitment was aided by members of the Street Tree Futures research and practitioner advisory committees. Research assistant Chanel Yee aided in interview transcription editing, interview coding, and manuscript revision. Research ethics approval was obtained from the UBC Behavioural Research Ethics Board (certificate H22-02611). Chapter 4 was written with intent to publish in a peer-reviewed journal. I defined the research objectives and led the development of the methodology, data collection, data analysis, and manuscript preparation, supported by critical revisions from and discussions with Dr. Susan D. Day, Dr. Cecil. C. Konijnendijk, Dr. Lara A. Roman, and Dr. Kai M. A. Chan. The methodology, data collection, and analysis were conducted in consultation with Dr. Susan D. Day, Dr. Cecil. C. Konijnendijk, and Dr. Lara A. Roman. Dr. Victoria Hemming provided invaluable advising on expert elicitation methodology throughout the study. I supervised research assistants Angel Bao and Chanel Yee, who provided critical support in delivering the participatory workshops, creating the Qualtrics questionnaire, and developing figures and data visualizations. Members of Dr. Susan Day’s Urban Forest Ecosystems Lab, Dr. Lorien Nesbitt’s viii Urban Natures Lab, and the Street Tree Futures research and practitioner advisory committees tested and reviewed iterations of the questionnaire and workshop presentations. Research ethics approval was obtained from the UBC Behavioural Research Ethics Board (certificate H22-02863). Chapter 5 was written with intent to publish in a peer-reviewed journal. I defined the research objectives and led the development of the methodology, data collection, data analysis, and manuscript preparation, supported by critical revisions from and discussions with Dr. Susan D. Day, Dr. Cecil. C. Konijnendijk, and Dr. Lara A. Roman. Research assistant Chanel Yee supported the focus group planning and coordination. Research ethics approval was obtained from the UBC Behavioural Research Ethics Board (certificate H22-02863). ix Table of Contents Abstract ......................................................................................................................................... iii Lay Summary .................................................................................................................................v Preface ........................................................................................................................................... vi Table of Contents ......................................................................................................................... ix List of Tables ............................................................................................................................... xii List of Figures ............................................................................................................................. xiv List of Abbreviations ...................................................................................................................xv Acknowledgements .................................................................................................................... xvi Dedication ................................................................................................................................. xviii Chapter 1: Introduction ............................................................................................................... 1 1.1 Urban forestry ............................................................................................................. 4 1.2 Ecosystem services ..................................................................................................... 5 1.3 Linking urban forest management with urban sustainability ...................................... 8 1.4 Dissertation Overview .............................................................................................. 11 Chapter 2: From tyranny to hope: harnessing the power of small decision makers to achieve urban sustainability goals .......................................................................................................... 13 2.1 Summary ................................................................................................................... 13 2.2 Introduction ............................................................................................................... 14 2.3 The example of urban nature-based solutions .......................................................... 17 2.4 The importance of small decisions in achieving strategic goals ............................... 23 2.5 The hope of small decisions for urban sustainability ................................................ 27 Chapter 3: For the urban forest or the sustainability goals?: Alignments, conflicts, and the role of ecosystem services in site-level decisions and municipal planning ..................................... 29 x 3.1 Summary ................................................................................................................... 29 3.2 Introduction ............................................................................................................... 31 3.3 Methods..................................................................................................................... 36 3.4 Results ....................................................................................................................... 43 3.5 Discussion ................................................................................................................. 55 3.6 Conclusions ............................................................................................................... 63 Chapter 4: Aligning urban forest management actions with urban sustainability goals: A multi-city expert elicitation ................................................................................................................ 65 4.1 Summary ................................................................................................................... 65 4.2 Introduction ............................................................................................................... 67 4.3 Methods..................................................................................................................... 72 4.4 Results ....................................................................................................................... 86 4.5 Discussion ................................................................................................................. 98 4.6 Conclusions ............................................................................................................. 107 Chapter 5: Conclusion ............................................................................................................ 109 5.1 Introduction ............................................................................................................. 109 5.2 Summary of dissertation findings ........................................................................... 111 5.3 Process to synthesize dissertation findings ............................................................. 114 5.4 Reflections from the Street Tree Futures Research-Practice Summit .................... 115 5.5 Key contributions and significance to the research and practice of urban forestry 120 5.6 Strengths and limitations ......................................................................................... 124 5.7 Final thoughts ......................................................................................................... 125 References ...................................................................................................................................127 xi Appendices ..................................................................................................................................171 Appendix A Supplementary materials for Chapter 3 .............................................................. 171 Appendix B Supplementary materials for Chapter 4 .............................................................. 176 xii List of Tables Table 3.1 Participant inclusion criteria. The sampling approach targeted first municipalities meeting the below criteria, then participants employed at those cities meeting additional criteria. .............................................................................................................................. 38 Table 3.2 Employment and education background of semi-structured interview participants (n=20) by city population size. City population classifications: small < 100,000; 100,000 < medium > 700,000; large > 700,000. ............................................................................. 40 Table 4.1 Aggregated responses from all three metro areas (N=31) to question “Which actions are needed to significantly advance each scenario’s goal above all other goals?”, in the context of each hypothetical streetscape scenario and assumptions. ................................ 87 Table 4.2 Coded responses to each participant’s open-ended responses to the question “What are your main reasons for certainty?” Each response was assigned one certainty code and/or uncertainty code that most reflected their response. Subtotals for each goal reflect the number of participants who express certainty and/or uncertainty in their response. ........ 95 Table 4.3 Heat map of direct street tree management actions assigned a top three ranking in response to the question “Which actions present the greatest opportunities to advance each scenario’s goal?” across all participants (N=31). Each participant could pick and rank up to three actions per goal. ...................................................................................... 97 Table 5.1 Synthesized list of future research questions, building from results of the dissertation.......................................................................................................................................... 119 Table A.1 Examples of ecosystem service goals within adopted municipal plans with the potential for application of urban forests as a strategy to address such goals. The presence of goals such as the ones below made a municipality eligible for inclusion in this study.......................................................................................................................................... 171 Table A.2 Guide for semi-structured interviews with urban foresters at municipalities in the US & Canada, organized by section (Tracy, 2019). Questions were often slightly adjusted, or different follow-up questions may have been asked during the interview, in response to participant and conversation. .......................................................................................... 172 Table A.3 Examples of the integration of urban forestry and ecosystem services in adopted non-urban forestry specific municipal plans. Urban forests are being included in municipal plans as a strategy for a broad array of ecosystem service goals, and with varying specificity. ....................................................................................................................... 175 Table B.2 Summarized responses to open-ended response question: "Are there direct actions not listed and not referenced in the assumptions, that must be performed in order to advance this goal?" New direct actions described by more than one participant were summarized xiii in consistent language and included below. The numbered values represent the number of participants who described each direct action for a particular goal. Despite being out of scope for the question, the significant number of participants who described in-direct management actions and non-tree direct actions as needed to advance the goal led us to create categories for these actions, to show how important participants felt these actions were. ................................................................................................................................ 186 Table B.3 Responses to question “Which actions are needed to significantly advance each scenario’s goal above all other goals?”, in the context of each hypothetical streetscape scenario and assumptions. Each of the five sub-tables includes responses for one goal, separated by metro area. (See Table 4.1 for aggregated responses of all participants). . 188 xiv List of Figures Figure 1.1 The bodies of literature on urban forestry and ecosystem services (green boxes), and associated, relevant, themes explored within these bodies (points within boxes), which underpin the overall theme for this dissertation (blue box). This dissertation’s research is also enabled by themes which crosscut many disciplines (teal ovals). ............................... 3 Figure 2.1 How top-down policy solutions to the “Tyranny of Small Decisions” that are intended to reverse cumulative effects of individual actions can lead to minimizing local agency. Ignoring the opportunities at the site-scale misses out on creativity, self-organization, and new pathways. ................................................................................................................... 20 Figure 2.2 The wide range of factors required to decide what species to plant in a single place. Species selection is an example of a decision that cannot be done successfully without site-level information and high levels of expertise. .......................................................... 24 Figure 3.1 Map of cities with participating municipal employees. ............................................... 41 Figure 4.1 Phases of the street tree management life cycle (a) with simplified examples of how actions throughout the street tree management life cycle present opportunities to affect different ecosystem services, at the planning & design phase (b) and end of life phase (c). Photo credits: Corinne Bassett. ......................................................................................... 71 Figure 4.2 Overview of multi-city structured expert elicitation method for a qualitative elicitation. Pictures sized to obscure faces and protect the identity of participants. Photo credits: Chanel Yee. .......................................................................................................... 74 Figure 4.3 Hypothetical streetscape scenario context and assumptions to which participants were introduced in online introduction meetings. Next, in the questionnaire, they answered questions about direct management actions needed to advance five different goals within this context. ....................................................................................................................... 76 Figure 4.4 Expert elicitation participants were asked the same set of questions about each of the goals shown. ...................................................................................................................... 79 Figure 4.5 Box plots of certainty ratings (0-100%) of participants grouped by goal and metro area, in response to the question “Within the assumptions of this scenario, if all of your selected actions were taken, how certain are you that this goal could be significantly advanced in 20 years?” All 31 participants answered this question for each goal, five times total. ......................................................................................................................... 93 Figure 5.1 Conceptual framework of the dissertation’s research questions and associated chapters. .......................................................................................................................... 112 xv List of Abbreviations BC British Columbia DC District of Columbia HI Hawaiʻi UBC University of British Columbia US United States xvi Acknowledgements I acknowledge the UBC Vancouver campus, from which I conducted this research, is located on the traditional, ancestral, and unceded territory the xʷməθkʷəy̓əm (Musqueam) people. I am deeply grateful and privileged to have been given the opportunity to learn in and from this place. I thank those who continue to live on and care for this land and its trees. My dissertation is the product of collaboration, partnership, trust, and dedication, of so many people. First, to my supervisory committee—Susan Day, Cecil Konijnendijk, Lara Roman, and Kai Chan. You have been the dream team. You have continuously pushed me to be ambitious, pursue the most important questions, stay skeptical but also grounded, and make my work as robust and impactful as possible. Thank you for believing in me and for contributing your expertise and diverse perspectives which have so enriched this work, and my development as a scientist. Susan, I sincerely thank you for taking me on, as an aspiring social scientist, and guiding me through the interdisciplinary waters needed to produce this research. Your constant pursuit of excellence, and love of research and your students, continue to inspire me. I am so profoundly grateful for our relationship and collaboration. Cecil, I owe so much to your mentorship because without your encouragement I may not even have begun this journey in the first place. Your visions for urban forestry, your deep investment in your students, and your unwavering support have inspired and guided me from the start to the finish line. Lara, your dedicated mentorship—both professional and personal—over the last ten years has changed my life. You have shown me the kind of mentor I would like to be for others. Kai, you transformed my work and my perspectives on research on the values of nature in ways I could not have anticipated. Thank you for your kindness and support, I look forward to bringing all I have xvii learned from you to the field of urban forestry. To all of you—I look forward to continued collaboration to come. It was only possible to devote these years to my PhD research because of funding from the Social Sciences of Humanities Research Council of Canada (SSHRC) (Grant # 890-2020-0069) and the University of British Columbia (UBC). Thank you to the USDA Forest Service Los Angeles Urban Center for support through a fellowship and mentorship in my second year. Thank you also to the International Society of Arboriculture (ISA), Pacific-Northwest and Mid-Atlantic Chapters of the ISA, Arboriculture Research and Education Academy, and the Sustainable Urban Forests Coalition, for your support of student conference scholarships. I am so grateful for the support of my community of friends and fellow graduate students in the Urban Forest Ecosystems Lab (especially Laura Grant, Amy Blood, and Nelson Cheung) and Urban Natures Lab (especially Jessica Quinton, Kaitlyn Pike, Johanna Bock, and Daniel Sax). I would also like to sincerely thank Dr. Lorien Nesbitt for welcoming me as a contributing member of the Urban Natures Lab; the post-pandemic and post-maternity leave phase of my PhD would have been much more difficult without the UNL community. To my lab mates and dear friends Sophie Nitoslawski, Zhaohua Cheng, and Leila Todd—I am so grateful to have been on this journey with you, and that you charted a path to graduation that I could follow. Special thanks to Chanel Yee and Angel Bao for your hard work and spirit as research assistants in the Street Tree Futures project. Lastly, I feel so lucky to be part of the greater community of the Urban Forests Research Hub at the UBC Faculty of Forestry. Thank you to Dr. Tahia Devisscher for your generous leadership, mentorship, and for always bringing us all together. xviii Dedication To all the professionals working hard for trees and cities. To all my family and friends. You inspire me to do better and be better. 1 Chapter 1: Introduction Cities in Canada and the United States, as well as globally, have grown rapidly over the last half century and continue to expand (Seto et al., 2012). This widespread urbanization presents urgent need for novel solutions tailored for the unique contexts of urban communities and urban ecosystems that will address wide-ranging threats posed by both global concerns, such as climate change and biodiversity loss, and local concerns, such as neighborhood social cohesion and resilience to extreme weather (Espey et al., 2023; Grimm et al., 2008; Simkin et al., 2022). Urban forests, often defined as the communities of trees and associated vegetation in and around urban areas (Konijnendijk et al., 2006; Vogt, 2020), are increasingly being identified as solutions to these issues and, as such, are critical components of plans to advance cities towards urban sustainability goals. There is an increase in cities setting ambitious goals, and often framing such goals as ecosystem services such as climate change mitigation or habitat provision (Angelo et al., 2020; Hansen et al., 2015; Lam & Conway, 2018), services which ecosystems like urban forests can provide (McPhearson et al., 2014). However, existing evidence suggests there are major knowledge and implementation gaps in being able to successfully link urban forest management with desired outcomes to support urban sustainability (Andersson et al., 2021) and that there are misalignments between urban forestry and other sustainability policies, such as those intended to address climate change (Z. Cheng et al., 2021). Achieving the sustainability goals that urban communities need requires bridging disconnects in knowledge, policy, and management. The challenges to improving alignment of urban forestry with sustainability goals are substantial, yet there are numerous and valuable bodies of knowledge to build from. Tree management 2 actions can occur on different spatial and temporal scales of decision-making than those of urban planning and policy making (Borgström et al., 2006; Ossola et al., 2021). The urgency of the problems faced and the time and resources required to measure effects of management interventions on trees are also significant challenges (Hauer et al., 2020; Ko et al., 2015). Urban foresters, the professionals who specialize in planning and managing populations of urban trees, embody expertise and experience with trees over the course of their careers, as well as significant knowledge on the benefits of urban trees in their communities (Davies et al., 2017; O’Herrin et al., 2020). Through their positions planting and managing trees, urban foresters are key agents of change within urban ecosystems, often serving as a connection between operational management and stewardship activities and other fields dedicated to environmental issues highly connected to urban forestry, such as urban heat and stormwater. Yet, these professionals cannot manage trees in a vacuum; an interdisciplinary approach is needed to effectively conserve and grow urban forests for the social and environmental benefits that current and future urban residents need (Vogt et al., 2016). In this chapter, I provide context for my research by introducing the bodies of literature and key themes which underpin this dissertation (Figure 1.1). In my subsequent chapters, I build from the context I establish here and further review and synthesize literature on these themes. To begin, I introduce the state of knowledge on urban forestry, focusing on themes of the management and stewardship of urban forests, the professional identity of those who manage urban forests, and establishing urban forests as social-ecological systems. Next, I present the concept of ecosystem services, as a concept which has developed at the same time as the modern field of urban forestry, the themes of how ecosystem services are theorized to enable urban sustainability, the 3 potential of the concept to serve as a boundary object for transdisciplinary collaboration, and recent theoretical advances and limitations of ecosystem services. Then, I build from these ideas to link urban forest management and urban sustainability, introducing themes which crosscut many disciplines including operationalization (i.e. moving from theory to action), evidence-based decision making, and expert and stakeholder knowledge. In doing so, I will lay the foundation to the key gaps I seek to address through this dissertation’s research. Though this dissertation is first and foremost grounded in the rapidly growing and developing field of urban forestry, through the course of this research, I also seek to inspire and contribute more broadly to knowledge and methods needed to activate effective urban ecosystem management and improve environmental decision-making. Figure 1.1 The bodies of literature on urban forestry and ecosystem services (green boxes), and associated, relevant, themes explored within these bodies (points within boxes), which underpin the overall theme for this dissertation (blue box). This dissertation’s research is also enabled by themes which crosscut many disciplines (teal ovals). 4 1.1 Urban forestry Urban forestry is defined as the field which manages, researches, and conserves trees and associated vegetation in urban and peri-urban areas (Gustavsson et al., 2005). These include trees on a continuum of urbanization and management intensity, from streets, to city parks and residential yards, to cemeteries and university campuses, to urban natural forests (Vogt, 2020). Urban forests, as part of urban ecosystems, are conceptualized as social-ecological systems, comprised of complex and inseparable interactions and relationships between people and nature (L. R. Johnson et al., 2021; Livesley, Escobedo, et al., 2016; Roman et al., 2018; Vogt, 2020). As a field of research and practice, it has emerged relatively recently and maintains strong ties to fields such as arboriculture, forestry, landscape architecture, and planning (O’Herrin et al., 2020). Members of the profession are cross-sectoral, working in governments, private companies, universities, non-governmental organizations, and other entities, to manage and conserve populations of urban trees (Day et al., 2022). The primary aim of the modern field of urban forestry is to serve and benefit urban communities (Konijnendijk et al., 2006; O’Herrin et al., 2023). Benefits from urban forests to urban communities, and society at large, are vast and varied and include mitigating urban heat, intercepting stormwater, providing habitat for wildlife, trapping air pollutants, beautifying and contributing to sense of place, and many more (Dobbs et al., 2011; Livesley, McPherson, et al., 2016). Likewise, mitigating the disservices and costs associated with urban forests is very important, especially through reduction of risk to people and property from falling branches or whole trees (termed “tree risk management” in the arboricultural industry) (Koeser, Hauer, et al., 2016; Roman et al., 2021). Balancing the provision of multiple benefits 5 provided by trees and associated vegetation with costs and risks is central to the management of urban forests (Hale et al., 2015; Roman et al., 2021). It is therefore not surprising that the rise of the ecosystem services concept, and the theoretical and analytical frameworks that support it, have been very influential in both urban forestry research and practice as well, resulting in a boom of research on the services and benefits of trees (Escobedo et al., 2019; Krajter Ostoić & Konijnendijk van den Bosch, 2015). However, despite much progress, the ways in which the mainstreaming of ecosystem services discourse affect decisions of urban foresters, and more importantly, how it can enable decisions which can contribute to urban sustainability goals is largely unknown. 1.2 Ecosystem services How researchers and practitioners employ the concept of ecosystem services, described as the processes by which people benefit from ecosystems, matters not just because of its implications for how people value nature, but because it influences which decisions are taken. Importantly, the understanding of the concept of ecosystem services is not static and continues to evolve since its original inception several decades ago (Daily, 1997). From the landmark Millennium Ecosystem Assessment in 2005, to the establishment of the International Panel on Biodiversity and Ecosystem Services (IPBES) in 2012 and its Global Assessment Report on Biodiversity and Ecosystem Services in 2019, the science of ecosystem services continues to evolve (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, 2019; Millennium Ecosystem Assessment, 2005). From its inception, it was envisioned as a mechanism for ecosystems to be included in the economic accounting processes that affect conservation and preservation (such as through influencing land development) (Daily et al., 2009, 2011). A widely adopted framework to create shared indicators is the cascade model, which describes a flow of 6 processes from ecosystems structure (e.g. trees) to functions (e.g. shade, transpiration) to services (e.g. cooling effect) to benefits to people (e.g. reduced heat stress), each component of which can be measured and monitored with indicators (Polasky, 2011; Potschin & Haines-Young, 2011). Such frameworks have provided a means to employ ecosystem services in diverse fields of conservation and environmental management, especially in the development of models to make the values of nature explicit. and improve decision-making in service of sustainability (Potschin-Young et al., 2018). In these ways, ecosystem services can also serve as a “boundary object,” a concept which provides shared language to connect separate fields and disciplines, and ideally overcome siloed decision-making and instead facilitate the setting of common sustainability goals (Abson et al., 2014; Carmen et al., 2018). However, despite strides in widespread uptake of the concept of ecosystem services in many sectors, it has also been widely critiqued for failure to accurately integrate social science, especially the cultural dimensions which shape all of human-nature relationships (Chan, Guerry, et al., 2012; Fish, 2011). Most critically, there are calls to incorporate social and cultural dimensions into ecosystem services in more fundamental and direct ways than the original frameworks proposed (Chan, Satterfield, et al., 2012; Fish et al., 2016; Pröpper & Haupts, 2014). Pröpper & Haupts (2014) are among those scholars proposing that there is a “culturality” of ecosystem services, that culture is the underlying foundation through which all ecosystem services are valued. There has also been much advancement in sustainability science towards other complementary or potentially alternative concepts, including the realm of understanding relational values, a category of values unique from intrinsic or instrumental values of nature, which encompass the value of human-nature relationships (Chan et al., 2016). The many 7 critiques of the concept of ecosystem services, ranging from the theoretical to the pragmatic to the ethical, even propelled the United Nations International Panel on Biodiversity and Ecosystem Services to propose a new term—nature’s contributions to people—as an umbrella concept and framework for research (Díaz et al., 2018). Nonetheless despite concerns, ecosystem services is still the dominant concept employed in North America, and globally, to describe the benefits of ecosystems and efforts continue to improve its usage to enable sustainability (Abson et al., 2014; Chan & Satterfield, 2020; Cueva et al., 2022; Thompson et al., 2024). In urban forestry, such conceptual critiques rarely enter professional discourse around ecosystem services and the concept has been thoroughly mainstreamed to describe the benefits of urban forests to cities. Significant studies include those by Silvera Seamans (2013) and Young (2010) which surveyed and interviewed nonprofit and municipal staff in the US and found that the perceived role of arborists and urban foresters had evolved to include the provisioning of ecosystem services in their professional duties (in a broad sense), beyond traditional duties such as managing tree health, public safety, and managing infrastructure conflicts. The development of i-Tree, a suite of urban forest environmental service assessment tools created by the United States Forest Service and private partners (Nowak, 2020), has been a major driver of the ecosystem services discourse within urban forest research and the software’s uptake is also strong evidence of the dominance of ecosystem services as a discourse among professionals. Many major cities in the United States and Canada have used i-Tree tools in analyses and assessment of their urban forest resources (Hauer & Peterson, 2016; Ordóñez & Duinker, 2013). Nonetheless, despite evidence of its mainstreaming in professional discourse, it has to date been 8 used primarily as an advocacy tool and remains to be fully operationalized and integrated into active management (Davies et al., 2017; Silvera Seamans, 2013; Young, 2013). 1.3 Linking urban forest management with urban sustainability Efforts to advance urban sustainability encompass many dimensions and sectors including, broadly speaking, environmental, social, and economic (Childers et al., 2014; Frantzeskaki et al., 2021). The framing of goals set at strategic levels of planning to increase the sustainability of cities have implications for the way other systems are integrated into such goals (Biddle & Koontz, 2014; Iwaniec et al., 2019). While urban forest management continues to advance in sophistication, there remain major gaps to inform changes in practice which can contribute to urban sustainability, including but not limited to the use of ecosystem services (e.g., as a framing for goals). The exploration of how to improve the use of ecosystem services to enable sustainability is often united by the term “operationalization,” defined as “the process by which concepts are made usable by decision makers” (Grêt-Regamey et al., 2017; Jax, Furman, et al., 2018). Efforts to operationalize ecosystem services include work towards conceptual, procedural, and methodological advancements, such as the development of principles to guide application, indicators which can be monitored, and tools to support decision-making (Daily et al., 2009; Jax, Furman, et al., 2018). Such efforts attempt to fulfill the promise of the concept of ecosystem services to enable progress towards sustainability, while critiques argue that solely relying on improving operationalization of ecosystem services could crowd out other pathways to sustainability (Chan & Satterfield, 2020; Turnhout et al., 2014). For example, both expert and stakeholder knowledge on local conditions and community needs is also necessary to enable better environmental decision-making, yet is often not effectively integrated into decision-making processes in many domains of sustainability (Morgan, 2014; Olazabal et al., 2021). 9 Nonetheless, ecosystem services are still promoted at high policy making levels as a framework to support evidence-based decision-making (Revesz & Prabhakar, 2023) and are key discourse to investigate the link between urban forest management and urban sustainability. Urban foresters are highly knowledgeable about the diverse benefits to society of the resource they manage and believe urban forests to be essential to fostering sustainable cities (Sax et al., 2020; Young, 2013). Nonetheless, in most regions there are common mismatches in scale between the existing evidence on the benefits of urban forests, issues that practitioners face in making urban forest management decisions, and the urban forest benefits that residents need (Borgström et al., 2006). Though urban foresters are called on to advance the implementation of the ecosystem services concept by research and the scientific literature (Roman et al., 2018), international meetings and summits (Vogt, 2015; World Forum on Urban Forests, 2018) and in management plans (Conway et al., 2019; Silvera Seamans, 2013), there appear to be no tools for practitioners that synthesize the effects of direct tree management actions on urban forest ecosystem services, specifically with practitioners as end users. Most areas of recent progress in orienting urban forest management towards ecosystem service goals seem to be in comparing canopy cover, tree species, or tree numbers with environmental data, such as heat and social data, to direct future planting (Norton et al., 2015; Selmi et al., 2020). Barriers to the creation of decision-support tools may include significant gaps in understanding the ecosystem service tradeoffs from urban forest management decisions (Hutt-Taylor et al., 2022) and in the explicit integration of the social and cultural dimensions of ecosystem service beneficiaries (Nesbitt et al., 2017). These gaps in the evidence base, and the lack of tools to help align decision-making with sustainability goals that cities are setting, suggest that research on the connections between 10 urban forest management and ecosystem service provision might help deliver the promised benefits of trees to urban communities. Fortunately, there are many paths to follow from peers in conservation and ecology who have engaged in large synthesis efforts to connect management with ecosystem services (e.g. Jax, Furman, et al., 2018; Tallis & Polasky, 2009). In particular, there are promising examples of harnessing expert knowledge to evaluate the potential impacts and tradeoffs of ecosystem management actions, through rigorous expert elicitation methods, in situations where time and resources are limited (Chrysafi et al., 2022; Kehoe et al., 2021; Martin et al., 2012; Schindler et al., 2014). For example, Schindler et al. (2014) engaged interdisciplinary experts in a process to rate a broad array of floodplain management actions on the expected positive, negative, or null, impacts on various ecosystem services. Kehoe et al. (2021) assembled a coalition to assess the effectiveness of management strategies on survival of species-at-risk of local extinction. In urban areas, especially those facing rapid development and increasing social-ecological pressures threatening human wellbeing, the urgency to deliver effective and sustainable solutions is high. Currently, urban forestry practitioners must weigh the wide ranging and sometimes conflicting messages of research on particular ecosystem services on their own. The processes through which urban foresters connect their operations to sustainability goals, and the challenges they face in doing so, are typically shared on an ad hoc basis through professional networks and have not been documented or synthesized. This research envisions a future where urban forest practitioners are empowered to weigh the impacts of their actions on ecosystem services through an evidence-based framework and be able to make the best decisions possible based on their own local conditions. Working towards this vision would not only improve the integration of urban 11 forestry into high-level decision making, but is also essential to achieving much needed sustainability goals for the benefit of society at large. 1.4 Dissertation Overview The overarching research question guiding my doctoral research is: How do direct, site-level urban forest management actions contribute to strategic-level urban sustainability goals? My doctoral work addresses this overall question through different dimensions by investigating the following sub-questions: 1. Why are site-level decisions important to achieving strategic-level sustainability goals, in the context of implementing urban nature-based solutions to achieve city goals? 2. What are the current challenges and best practices for aligning street-level urban forest management actions to contribute to sustainability goals, framed as ecosystem services? 3. How can urban foresters align their street tree management actions with specific urban sustainability goals? Chapter 2 puts forth the rationale for this thesis by synthesizing diverse bodies of literature in an argument-driven perspective. This chapter applies an economic phenomenon, “the tyranny of small decisions,” to the social and ecological problems facing urban areas. Site-level urban forest management actions, and those who make them, are posited as necessary ingredients to achieving urban sustainability goals. Chapter 3 establishes the current best practices and challenges of aligning site-level management actions with strategic-level goals in municipalities. Specifically, the relationship between street tree management decision-making and goals framed as ecosystem services are 12 explored through analysis of semi-structured interviews with 20 municipal urban foresters in the US & Canada. Chapter 4 investigates how direct street tree management actions differ in their contribution to specific sustainability goals and explores the consequences of how managing for goals such as increased canopy cover aligns with certain goals while misses opportunities to advance others. A multi-city expert elicitation was conducted with urban foresters, in which they selected and ranked actions needed and presenting the greatest opportunity to advance each of the five different sustainability goals, within a hypothetical streetscape scenario. Chapter 5 concludes the dissertation by synthesizing findings and describing implications for research and practice. This final chapter is framed by presenting the results of a Research-Practice Summit, consisting of urban forestry researchers and practitioners, held to synthesize results of earlier chapters. 13 Chapter 2: From tyranny to hope: harnessing the power of small decision makers to achieve urban sustainability goals 2.1 Summary Policy and planning aim to overcome the “tyranny of small decisions” to address the triple planetary threats of climate change, biodiversity loss, and pollution. However, top-down policies intended to prevent the accumulation of small decisions from undermining collective goods and public infrastructure have removed agency from individuals and caused unintended negative impacts on society. Urban areas are a critical context to examine the role of small decisions because of the extreme diversity and density of decisions and decision makers within them, their increasing growth worldwide, and their outsized ecological footprint on the world. We bring the economic concept of the tyranny of small decisions to the context of urban nature-based solutions, specifically, urban forestry initiatives, to show the power of small site-level decisions to support critical long-term social and environmental goals rather than being seen as only derailing them. In doing so, we argue that when social and ecological contexts vary at fine scales in ways that require place-based nuance in environmental management, policy makers and planners should seek to understand and support these small decisions, and promote solutions which harness the knowledge of ecological stewards in service of strategic goals. Failing to do so overlooks the power of human-nature relationships and specialized knowledge, missing opportunities to catalyze self-organization and creativity to propel cities towards sustainable futures. 14 2.2 Introduction Human society continues to struggle to manage Earth’s ecosystems to meet current and future societal needs and to mitigate the “triple planetary crisis” of climate change, biodiversity loss, and pollution (United Nations Environment Programme, 2021). In many cases, these massive, system-wide threats have been attributed to the cumulative effects of independent actors taking uncoordinated actions for their individual benefit—the so-called “tyranny of small decisions,” a concept articulated by economist Alfred E. Kahn in his essay of the same name (Kahn, 1966). In environmental policy, this logic can lead to top-down solutions which seek to control the decisions at the root of the identified tyranny, which though successful in certain cases at preventing specific outcomes, can also cause unforeseen negative impacts (Jacobs et al., 2007)— effectively trampling small decision makers (Laitos & Okulski, 2017; Patterson, 2023). In ecosystem management, and in the case we use in this perspective, urban forest management, making the correct management decision at the site-level can define the success of initiatives and must be made with hyperlocal information. Additionally, the autonomy to make such decisions is key to unleashing creativity and fostering people-nature relationships (Chan et al., 2017; Chapman et al., 2019; Stoneham et al., 2003). As leaders around the world are turning to nature-based solutions such as urban forests to serve as multi-functional tools to address goals as urgent and diverse as climate regulation, biodiversity conservation, public health and social cohesion (Croeser et al., 2021), and, as in urban forestry, new funding sources become available (Government of Canada, 2020; USDA, 2023), we believe it is timely and essential to examine the role of small decisions, and those who make them. 15 We propose that small decision makers who are already dedicated to achieving broad sustainability objectives and have critical knowledge on these decisions (i.e. “employed” or “volunteer” ecological stewards), should be uplifted and supported, in order to harness their small decisions in service of sustainability. To support our argument, we acknowledge and draw from diverse bodies of literature celebrating the knowledge and capacity of individuals and communities to take action towards conservation and sustainability, where they live and beyond. This recognition has been particularly evidenced by inclusion of individuals (or “resource-users”) as a core subsystem of Ostrom’s general framework for social-ecological systems, and the highlighting of characteristics of individuals such as “knowledge of the social-ecological system” and “importance of resource to users” as key variables influencing the capacity for them to self-organize to sustain the resource in question (Ostrom, 2009). Local ecological knowledge (including traditional and indigenous ecological knowledge) has long been known to be critical to effective ecosystem stewardship, yet often remains poorly integrated into policy and planning (Aswani et al., 2018; Yumagulova & Vertinsky, 2019). Advocates of the concept of planetary stewardship, which emphasizes the global responsibility of humanity toward the Earth's systems, show the need to connect individual stewardship with global goals (Steffen et al., 2011). There is established and growing understanding that positive, even transformational, change requires individuals and communities as critical partners (Chausson et al., 2023). Importantly, approaches which involve and empower individuals and communities in decision-making are as much about ethical and rights-based concerns as they are practical and pragmatic ways to achieve social-environmental goals intended to serve society at large (Jax et al., 2013). 16 Overcoming the tyranny of small decisions with top-down prescriptions risks replacing one source of tyranny with another by minimizing individual agency. In this article, we offer a new perspective on the tyranny of small decisions and argue that a more effective policy response to mitigate this tyranny is to harness the power of place-based, fine-scale knowledge of local decision makers in service of sustainability goals. We use the case of implementing urban nature-based solutions, specifically in urban forestry initiatives, to illustrate an approach to planning and policy making for cases where social and ecological contexts vary at fine scales, as they do in urban areas, that may also be broadly applicable to global environmental problems. Though there is considerable evidence on the benefits of co-management and co-production, research unfortunately still finds there are struggles in scaling up such arrangements in practice (Lemos et al., 2018; Razzaghi Asl & Pearsall, 2022). Nonetheless, improving the integration of small decisions into environmental policy is an urgent and practical necessity because (i) history and experience show there are decisions which cannot be made effectively at higher levels and must be made with local context and knowledge (Andersson et al., 2021), (ii) there are foundational relational and cultural processes which occur on the scale of individuals (Jax, Calestani, et al., 2018) and are broken down if the power to make them is stripped away, and (iii) top-down approaches prevent opportunities for the immense creativity and self-organization of communities which can arise at lower scales (Ostrom, 2009). Small decisions present a key inflection point where specialist expertise could be deployed. We argue that the power of small decisions can be redirected away from tyranny and instead directed towards advancing critical high-level goals, by supporting site-specific self-organization and investing in ecological stewards who are already working towards sustainability goals and targets. 17 2.3 The example of urban nature-based solutions The tyranny of small decisions can manifest in unique ways in urban systems because of the sheer number of “small decision makers” that exist across high proportions of private property managed under a diversity of governance arrangements (Colding et al., 2013; Ordóñez-Barona et al., 2021). In these contexts, decisions that can be easily pointed to as causes of widespread negative consequences, such as tree removals or development of individually-held parcels, are a clear target for policy makers to assert influence in the name of achieving a strategic-level goal (Aronson et al., 2017; Colding et al., 2013; Grose, 2010). However, in dense urban areas, even the decision to remove or plant a single tree occurs within a complex web of social-ecological processes which can vary at fine scales (Mincey et al., 2013). If local factors are not understood and acted upon, significant ramifications can occur, such as wasted resources (Nguyen et al., 2017), social and political backlash (Koeser et al., 2021), and missed opportunities. In urban policy, nature-based solutions are rapidly gaining traction and promoted as strategies which can accumulate to have positive system-wide effects such as mitigating stormwater flooding and supporting biodiversity (Nesshöver et al., 2017). Nature-based solutions encompass a diverse array of blue-green systems and interventions including, but not limited to, trees, woodlands, parks, green roofs, rain gardens, and constructed wetlands (Castellar et al., 2021). Researchers have called for nature-based solutions to be “scaled-up” with models and tools (Croeser et al., 2021; Pearsall et al., 2022). These interventions all require myriad small decisions to be made, which threaten the viability of each project and the potential to reach intended solutions. In addition, top-down nature-based policy solutions often still view small-scale environmental management decisions and those who make them as, at best, situations to be 18 controlled and harmonized in order to achieve wide-scale objectives, and at worst, a potential source of threatening tyranny to overcome. It is important to understand that these small yet influential decisions are not only made by private landowners and residents (the “resource-users,” as mentioned before per Ostrom’s framework for social-ecological system (Ostrom, 2009; Vogt, 2020)). They are also made and influenced by two groups of urban ecological stewards: (1) the array of professionals charged with managing public and institutional resources, such as land managers, horticulturalists, landscape architects, facilities personnel, and many more, and (2) volunteers who are dedicated to stewarding urban natural resources. Importantly, both these types of urban ecological stewards have higher levels of knowledge about the site-level ecosystem management decisions and are motivated to make choices which will result in pro-social and pro-environmental outcomes, that is to say, their motivations are likely in alignment with city sustainability goals. Specifically for urban forestry initiatives, urban foresters, who specialize in managing tree communities, and arborists, who focus on the management of individual trees (similar to the distinction between public health professionals and doctors) bring highly specialized expertise that is likely valuable for connecting local and high-level objectives (O’Herrin et al., 2023). As we will demonstrate, the assumption that uncontrolled local decision-making will lead to tyrannical outcomes overlooks the fact that the people who make these decisions are capable of seeing and acting beyond the scope of individual small-scale decisions. An example of the tyranny of small decisions in the urban forestry context is when widespread tree removals across the mosaic of properties and land ownerships results in overall decline in 19 urban tree canopy—‘death by a thousand cuts’ (Figure 2.1). To an individual landowner, the decision to remove a tree on their property is perceived as well within their rights, and even duties, as property owners. Reasons for removal include mitigating risk of the tree damaging property, perceived nuisances, a desire to use that space for building renovation or construction, and a preference to proactively remove unhealthy trees (Guo et al., 2019; Roman et al., 2022). Individual decisions by landholders to remove trees have slowed progress towards municipal goals to increase tree canopy cover. Such goals are often set because of the ecosystem services associated with canopy, like heat and stormwater flooding mitigation (C. Clark et al., 2020; Kronenberg et al., 2021). There are tensions in scale between resident and property owner decisions about tree management on private land, which may be rooted in specific concerns and desires, and municipal leaders’ goals for the public good (Nguyen et al., 2017; Pearsall et al., 2022). Two common solutions to this scenario of widespread tree loss have been municipal policies (such as ordinances or bylaws) to restrict removals, or initiations of massive new planting efforts (Chojnacky et al., 2020; Pike et al., 2021) (Figure 2.1). This can result in the unintended consequences of disgruntled residents and developers on one hand, and failed tree planting initiatives on the other. 20 Figure 2.1 How top-down policy solutions to the “Tyranny of Small Decisions” that are intended to reverse cumulative effects of individual actions can lead to minimizing local agency. Ignoring the opportunities at the site-scale misses out on creativity, self-organization, and new pathways. In the case of tree policies that regulate tree removals by individuals, these typically function by restricting the removal of trees based on size and/or species (Ordóñez-Barona et al., 2021). They have been found to be unpopular and can seem arbitrary when implemented at the site-level (Jones et al., 2013; Koeser et al., 2021; Zhang et al., 2007), as they often fail to understand and respect the contexts in which the small decisions were made in the first place (C. Clark et al., 2020). Despite studies repeatedly showing broad public support and affinity for urban green spaces (S. Miller & Montalto, 2019; Shackleton et al., 2018), residents and communities tend to have more place-based and nuanced views on their desires for their land or neighborhood (Riedman et al., 2022) and there is a difference between wanting to preserve trees in general, and wanting to preserve a specific tree that may be causing considerable negative impacts, i.e., 21 disservices (Roman et al., 2021). Nonetheless, many urban foresters and arborists believe that the public they serve hold generally negative opinions about trees, and believe they would remove fewer trees if there was better outreach and education to improve tree stewardship, indicating that professionals themselves believe there are alternative ways to prevent canopy decline which are currently underused (Kirkpatrick et al., 2013). However, policies restricting private tree removals tend to have very limited or strict roles (if any) for professionals to mediate or provide technical assistance to support tree retention decision-making, and these are generally not linked with efforts to improve tree stewardship (Ordóñez-Barona et al., 2021). This lack is not surprising, given that such tree-by-tree policies are incredibly costly and labor-intensive to enforce, challenging cities with typically already capacity-strapped urban forestry staff (Ordóñez-Barona et al., 2021). In the case of reacting to tree canopy loss with a major tree planting initiative, history again offers many examples of mayoral campaigns setting numeric tree planting targets (Eisenman et al., 2021). For example, in Honolulu, US, and in Vancouver, Canada, documented declines in canopy cover triggered new city tree planting initiatives (M. Cheng, 2021; Pawson, 2020). Massive urban tree planting initiatives often end in widespread tree mortality, even if comprehensively monitored (McPherson, 2014), or fizzle out due to changing mayoral administrations and priorities (Ding, 2022). Unfortunately, many new urban trees do not survive to maturity, with half typically dead by 15-18 years after planting (as found in a review of urban tree mortality studies, predominantly from the US, by Hilbert et al., 2019). Of course, urban tree plantings can succeed, but not without thorough consideration of the site context of each tree (including soil and climatic conditions, built infrastructure, and social infrastructure) and 22 dedicated maintenance—as labor-intensive as that may be to implement (Roman et al., 2015). There are also many examples of negative outcomes from failing to consider local social context in the implementation of top-down greening initiatives, including the many examples of expensive green infrastructure installations that end up underutilized or even vandalized and rejected by their communities (Pauleit et al., 2002). In cities undergoing gentrification, implementation of nature-based solutions has the potential to exacerbate gentrifying forces and contribute to community displacement pressures (Sax et al., 2022). For example, in response to a tree planting initiative in Detroit, US, although residents appreciated having trees in their neighborhoods in general, they were wary and even rejected new tree plantings due to a history of negligent maintenance practices and distrust of the city (Carmichael & McDonough, 2018). These examples underscore the need to define roles and support actors who understand not only the ecological context, but the social context (i.e. those with “knowledge of the social-ecological system” (Ostrom, 2009)) to insure tree planting initiatives accomplish stated goals without wasting resources and causing more harm than good. This type of social-ecological knowledge—including what to plant and where, how to maintain trees in the future, and how to engage with communities—is necessary for successful remedies to outcomes of the tyranny of small decisions. It is often held by local experts and community members and is not easily accessible by higher level actors and not practical to be written into policy with sufficient detail (Buijs et al., 2019). Small decisions made by local actors will be made whether or not they are intentionally connected with strategic goals. However, in describing problems with employing top-down solutions to the tyranny of small decisions, we are not in turn advocating for what might be simplified to a “free for all”, market-driven 23 approach to decision-making. Rather, we are arguing that site-level decisions can be aligned with strategic sustainability goals by integrating local expertise. The approach we believe is needed is more than merely a question of getting to know the area’s context in order to achieve buy-in, but of truly recognizing the value and expertise of the local actors (Pearsall et al., 2022). When attempting to reach social and environmental goals, policy makers may be better served by harnessing the power of small decisions, rather than trying to suppress them or work around them. 2.4 The importance of small decisions in achieving strategic goals The importance of small decisions can be considered to be two sides of the same coin: they are so essential that if ignored, programs will fail, and so valuable that if recognized, they present the path leaders need to achieve goals. Here, we outline three reasons why small decisions are both key to achieving strategic sustainability goals and why they require local knowledge and action, using examples from urban nature-based solutions, specifically urban forestry. We use these examples to make the case that the intricate dynamics of social-ecological interactions at local levels are critical to successful implementation of strategic policies, and that roles to support knowledge holders about these dynamics should thus be articulated and incorporated in policy making. 2.4.1 Local factors determine functioning and benefits of natural systems Not only do trends occurring on global and regional scales affect natural systems, but numerous intricate human and biophysical factors at local scales influence both the functioning of and benefits from socio-ecological systems (Andersson et al., 2021). These factors are often too complex to be effectively addressed from higher decision-making levels alone. For example, 24 decisions regarding species selection for urban forestry projects require a deep understanding of site conditions, ecological interactions, and economic realities (Figure 2.2, see also Hilbert et al., 2023). The arborist’s mantra of “right tree, right place,” which promotes only planting species that meet place-based constraints and goals, requires a great deal of local knowledge and specialized expertise to follow and implement (Breyer & Mohr, 2023). Likewise, local social and ecological factors can determine which benefits are most readily provided by ecosystems and if beneficiaries are able to access them (Olander et al., 2018). Creating roles for qualified arborists and urban foresters in policy making would allow their specialized knowledge to ensure the right decisions are made. Investment in training for arborists and urban foresters on the connections between management actions and sustainability goals could also help bridge the site and strategic scales in planning. Figure 2.2 The wide range of factors required to decide what species to plant in a single place. Species selection is an example of a decision that cannot be done successfully without site-level information and high levels of expertise. 25 2.4.2 Local nature relationships and cultural values as motivations for individuals Small decisions made by individuals hold great importance as they tap into the deep and powerful connections between individuals and nature and provide further opportunity for connections within communities. The emerging field of study of relational values, a class of values distinct from intrinsic or instrumental values, highlights the significance of the emotional, cultural, and psychological bonds individuals form with their natural environment (Jax, Calestani, et al., 2018). These human-nature connections are formed at the level of individuals, reinforced and supported by greater cultural norms, form powerful building blocks for connecting communities, and represent irreplaceable relationships between people and nature at multiple, crossing, spatial scales. For example, an individual or community’s relationship with a tree, park, or forest, cannot simply be replaced with another tree, park, or forest. The physical labor required to steward urban nature requires taking many small actions—planting, watering, pruning, mulching, removing—and deepens site-scale relationships, while serving as a connection to both entire ecosystems (Jones, 2019) and their communities (Mincey & Vogt, 2014). By recognizing and nurturing models of stewardship which emphasize relationships to place, higher-level decision makers can harness the motivational and transformative potential that stems from the personal connections people have with nature (Campbell et al., 2022; Knibbe & Horstman, 2022). For example, urban biocultural stewardship transforms the notion of the separation of humans from nature in cities and emphasizes caring for whole networks of social-ecological relationships, rather than solely the care of natural resources (ʻĀina of Kaʻōnohi et al., 2023; McMillen et al., 2020). Cultivating relational values and fostering a sense of stewardship at the local level becomes instrumental in mobilizing collective action, fostering urban environmental stewardship, and achieving strategic goals (Chausson et al., 2023; Yazar & York, 2023). Creating deliberate roles for local “volunteer” ecological stewards, to include cultural 26 practitioners, in new programs and policy would allow for these motivated and knowledgeable individuals to contribute in valuable ways. 2.4.3 Space needed for local self-organization and creativity Rigid policies can counteract the forces needed for one of society’s most powerful tools for change: the power of self-organization (Meadows, 1997). By trampling actions at the local scale, for example, dictating requirements for landscaping, tree planting or care, decision makers not only risk forcing the wrong decisions for that site, but miss out on the potential for individuals to find creative solutions that align with both local and strategic goals. Two examples are the movements to safely preserve standing dead trees in the urban landscape for wildlife habitat (Hoek et al., 2017), and to grow fruit trees or gardens for home food production (Dawes et al., 2018). Both of these land uses would benefit from facilitation by individuals with specific skills and present unique benefits that align with community needs. Yet, these practices would not contribute as significantly to a tree planting or tree canopy cover goal as would planting large stature trees. Policies seeking to affect ecosystem management in service of strategic goals would do better to not presume to understand site-level conditions better than the site’s managers (the small decision makers), as has also been found to be a barrier to success in incentive programs such as payments for ecosystem services schemes (Chan et al., 2017; Chapman et al., 2019). Instead, they should seek to design supports that can enlist the creativity and knowledge of such small decision makers (Stoneham et al., 2003). 27 2.5 The hope of small decisions for urban sustainability The stakes are high: nature-based solutions are being relied upon by policy makers and even regulators to achieve strategic sustainability outcomes. The literature we synthesized here from urban forestry, and urban nature-based solutions broadly, presents warning calls and lessons learned that are necessary to consider in future work, especially about the costs of failing to understand and honor site-level factors as well as local decision makers and stakeholders in environmental policy and planning. The tyranny of small decisions presents a narrative whereby many individually made decisions at small scales cause unintended and negative societal consequences. However, this same story can be flipped. Acknowledging that small decisions have power and potential for significant effects at higher scales is the first step to seeing the opportunities they present. Practically speaking, small decisions that impact environmental outcomes will be made, and are already being made. Management and policy approaches can ensure that small decisions support critical long-term social and environmental goals rather than being seen as only derailing them. We propose that new approaches to remedying the tyranny of small decisions should start with renewed focus on enabling the creativity of those ecological stewards already employed to implement broader policy objectives, and those enlisted to help, those with “knowledge of the social-ecological system” (Ostrom, 2009). In the case of urban forestry, urban foresters at municipalities are already trying to manage their resources for multiple and strategic benefits—they are on “the same team” as those seeking to advance broad sustainability objectives (Chapter 3). Yet, the profession lacks recognition and appreciation, even within urban sustainability planning (O’Herrin et al., 2020). When their expertise is not consulted, new policy solutions 28 which seek to utilize urban forestry, such as tree planting initiatives, can be ungrounded and unrealistic (Sousa-Silva et al., 2023). As new initiatives to scale up nature-based solutions come to center stage (Croeser et al., 2021), especially those seeking to remedy the tyranny of small decisions, we urge policy makers and planners to consider the people and knowledge needed to make these plans come to fruition and avoid missed opportunities. In sum, we propose that small decisions and the people who make them are not a source of tyranny to overcome but are instead necessary ingredients to further progress towards strategic goals. We issue a call to action to the environmental science and policy communities, especially those focused on urban sustainability and urban planning, to acknowledge and honor decisions that need to be made at local levels and the individuals who are responsible for making them. We argue that the complexity and variation of the social-ecological context of cities necessitates increased attention and that the opportunity to harness small decisions and the knowledge and creativity of small decision makers is too great to ignore. Failure to prioritize small-scale decisions and those who make them can result in wasted resources and missed opportunities to achieve our cities’ critical social and environmental goals. 29 Chapter 3: For the urban forest or the sustainability goals? Alignments, conflicts, and the role of ecosystem services in site-level decisions and municipal planning 3.1 Summary Cities around the world are setting goals and creating plans to alleviate mounting, diverse problems such as stormwater flooding, extreme heat, food insecurity, and disappearing wildlife habitat. While there is robust evidence on how trees address these issues, it is unclear how urban forestry is being used to meet city goals, and if ecosystem services framings and goals affect how urban foresters think about their responsibilities and site-level decisions. In this study we ask, what are the current challenges and best practices of urban foresters for aligning site-level management actions to contribute to city-level ecosystem service goals? We interviewed 20 urban foresters with responsibility for managing street trees, employed at small, medium, and large municipalities across the United States and Canada. Targeted municipalities had (1) one or more adopted ecosystem service-related goals and (2) an advanced urban forestry program. All participants considered managing for ecosystem services to be part of their job, but many were uncomfortable selecting specific ecosystem service goals as their top priority. Participants articulated that their choices (e.g., what species to plant, whether/how to remove dying trees) could influence the type and magnitude of ecosystem services provided. Nevertheless, they mostly did not view ecosystem service goals as driving day-to-day decision-making, which focused on tree health and public safety. We found participants’ perspectives largely aligned with a paradigm aiming for “more, bigger trees” with the justification that this would deliver increased ecosystem services in a general sense. We posit urban foresters as guided by a shared 30 sense of the greater purpose of urban forestry to serve urban communities, which yields actions usually aligning but sometimes conflicting with specific city goals. 31 3.2 Introduction The ability of city leaders to mitigate rising urban temperatures, improve stormwater management, and generally provide healthy and safe neighborhoods in the face of many mounting environmental threats will have serious impacts on the health and wellbeing of urban residents. Cities are thus adopting ambitious plans to address an array of serious sustainability and resilience concerns (Keith et al., 2023; Stone et al., 2012). Many of these plans rely, in part, on urban forests—the communities of trees and associated vegetation in urban areas—as a nature-based solution. However, in spite of their urgency, it is uncertain whether these plans will result in their desired and needed outcomes (Stone et al., 2012) and, furthermore, if urban forest management is sufficiently aligned with them to effectively contribute to their success. Initial evidence suggests a lack of alignment between urban forestry and sustainability goals, such as those set forth in climate action plans (Z. Cheng et al., 2021). While urban foresters are typically highly knowledgeable and care deeply about the benefits to society of the resource they manage, it is largely unknown how or if these professionals connect their management decisions to the broader sustainability goals of their city (Ordóñez et al., 2019a). Here, we investigate the connections between goals adopted in city plans, specifically those framed as ecosystem services, and decision-making of urban foresters in the United States (US) and Canada. In doing so, we explore the discrepancies, contradictions, and alignments between sustainability goal setting and site-level natural resource management, and how these relationships are impacted by municipal employees’ own understanding of how to best serve their cities. 32 3.2.1 From concept to practice: Operationalization of ecosystem services in urban planning Ecosystem services are broadly defined as the benefits to people from natural ecosystems (Daily, 1997; Millennium Ecosystem Assessment, 2005). In the US and Canada, scientific and professional discourses of both urban planning and urban forestry have been strongly influenced by the rise of the concept of ecosystem services (Lam & Conway, 2018; McPhearson et al., 2014). The concept is used in diverse types of municipal plans, from comprehensive land use plans (Cortinovis & Geneletti, 2019; Thompson et al., 2019) to more targeted plans such as those concerning climate adaptation or urban heat (Keith et al., 2023). Urban forestry programs also have their own suite of planning documents, often labeled as urban forest management plans (or UFMPs), in which ecosystem services are often a dominant framing and justification for management (Ordóñez & Duinker, 2013). Initially promoted as a way to justify and communicate the values of natural ecosystems (Costanza et al., 1997), the concept of ecosystem services is now frequently applied in the development of ecosystem management objectives or goals (Arkema et al., 2015; Hansen & Pauleit, 2014). Two differing uses of the concept—as a tool for both advocacy and ecosystem management—have emerged which can have different consequences (Daily et al., 2009; Matzek & Wilson, 2021). Ecosystem management actions have been shown to present tradeoffs and synergies in the provision of multiple ecosystem services (Chan et al., 2006; Naidoo & Ricketts, 2006; Nelson et al., 2009). Scholars have called for more effective ways to integrate ecosystem services into urban plans to manage these tradeoffs (Cortinovis & Geneletti, 2019; Thompson et al., 2024) as a way to move from ecosystem service theory to practice and thus operationalize the concept. The drive to operationalize ecosystem services in the planning process is related to the potential of the concept to serve as a boundary object, a concept which can connect siloed 33 disciplines around shared language, and facilitate decisions towards goals which benefit society as a whole (Abson et al., 2014; Carmen et al., 2018). Challenges found in operationalization include overcoming differing understandings of ecosystem services (Carmen et al., 2018), the tradeoff between standardizing terms and indicators and losing flexibility (Steger et al., 2018), and the tendency to undervalue cultural benefits, which are difficult to quantify (Chan, Satterfield, et al., 2012; Daniel et al., 2012). These challenges are critical to overcome in sustainability planning, as goal specificity has been associated with positive environmental outcomes across different types of plans (Biddle & Koontz, 2014). The ecosystem service cascade model (Polasky, 2011; Potschin & Haines-Young, 2011), one of the most adopted frameworks for the concept of ecosystem services, envisions flows from ecosystems to people, captured by a cascade of processes from ecosystem structure (e.g. canopy cover) to function (e.g. transpiration) to service (e.g. cooling effect) to benefit (e.g. reduced incidence of heat strokes) to value (e.g. health care savings). Ecosystem structures can have multitudes of functions, services, and benefits, each with their own possible proxy indicators; thus, framing objectives as ecosystem services such as “reduce urban heat”, contrasts with goals related to ecosystem structure, such as “preserve large trees” and impacts the actions required to align with such goals (Olander et al., 2018). It is in large part because of the broad ability of the concept of ecosystem services to connect different systems via ecosystem processes that the concept has been promoted as having potential to connect siloed disciplines, such as urban forestry, with other fields, such as stormwater management or climate science (Abson et al., 2014; Thompson et al., 2024). In urban forestry specifically, intergovernmental collaboration and coordination has also been put forward as a path to achieve goals, strengthen 34 programs (Ordóñez et al., 2020), and overcome current isolation from other disciplines (Vogt, 2018). However, it is not well understood if the mainstreaming of the concept of ecosystem services in ecosystem services in urban forestry (Silvera Seamans, 2013; Young, 2013) facilitates cross-disciplinary work, and can thus aid practitioners in aligning decisions with more holistic, strategic sustainability goals. 3.2.2 Ecosystem services in urban forestry Simultaneous to the recent rise of the concept of ecosystem services has been the development of urban forestry as a standalone profession (O’Herrin et al., 2023). Urban foresters include professionals who work in many sectors, including governments (primarily municipal), private industry and consulting, non-governmental organizations, and academic and educational institutions (Day et al., 2022). The professional identity of urban foresters, while still being defined, is uniting around a shared mission to manage trees and forests in urban areas as an essential service to society (O’Herrin et al., 2020). Broader research has found that professions can promote the development of “group-based values” amongst their members, which can influence their decision-making and priority setting (Breed, 2022). In urban forestry, training for professionals emphasizes that their central role is to maximize the ecosystem services of trees in order to benefit society (O’Herrin et al., 2020; Roman et al., 2021). How this shared mission influences the management decisions of urban foresters is critical to understanding the alignment of their decisions with city goals. Though urban foresters are very familiar with the concept of ecosystem services and even see it rising in importance in their field, initial inquiries suggest that they do not employ a formal 35 ecosystem service-based approach in their management, that is, the concept has not been operationalized beyond advocacy to use in directing decision-making (Davies et al., 2017; Young, 2013). Goals in urban forest management instead tend to be related to ecosystem structure, such as increasing tree abundance, health, or species diversity (to address socioecological resilience, see Huff et al., 2020), rather than specific ecosystem services (Roy et al., 2017). Managing disservices, especially the risk of damage to people and property from falling trees and branches through regular inspection and pruning, termed tree risk management, also typically takes high priority (Hauer & Peterson, 2016; Koeser, Hauer, et al., 2016). A systematic literature review of empirical studies on the views of municipal urban forest managers identified a need to further understand the relationships between decision-making processes and program objectives (Ordóñez et al., 2019a). Furthermore, the popularity of i-Tree, an ecosystem services modeling suite developed by the USDA Forest Service (Nowak, 2020), and the rise in cities adopting plans with ecosystem service goals (Angelo et al., 2020; Thompson et al., 2019), suggest that urban forest management objectives could be changing and warrant investigation. Additionally, there is strong evidence that decisions throughout the urban tree management life cycle present tradeoffs in provision of multiple ecosystem services and minimization of disservices (Roman et al., 2021)—spanning design (Bruner et al., 2023), planting (Bodnaruk et al., 2017), maintenance (McPherson et al., 2015), and eventual end of life and removal (Dickie et al., 2014). Thus, the alignment of urban forest management decisions with city goals is important to understand as these decisions can significantly impact the ecosystem services provided by urban forests and their contribution to sustainability and the benefits received by urban residents. 36 3.2.3 Study scope and research questions Achieving the many sustainability goals that cities are setting requires the alignment of decision-making at multiple levels. We address this fundamental challenge to urban sustainability through an investigation of urban forest management, and the role of the concept of ecosystem services in facilitating alignment of strategic goals and site-level decisions. To do so, we investigated cities working towards ecosystem service goals, as evidenced by their inclusion in any adopted municipal plan. The scope was narrowed to street trees for comparability across cities because the trees which municipalities manage vary significantly in type from natural forest patches to manicured parks to streets. For purposes of this research, we refer to ecosystem service goals as goals framed around increasing services that urban ecosystems have been shown to provide. We investigated the following research questions: 1. To what extent do urban foresters align their street tree management with specific ecosystem service goals in their municipalities? 2. What do urban foresters consider as the current challenges and best strategies in aligning street-level decisions to contribute to ecosystem service goals in their municipalities? 3.3 Methods 3.3.1 Approach We conducted semi-structured expert interviews to investigate specialized knowledge within the field of urban forestry, as well as to uncover both explicit and implicit understandings, opinions, and preferences (Döringer, 2021). Study design and analysis followed an “iterative phronetic approach” (Tracy, 2019). This is a reflexive and inductive approach which allows researchers to 37 not only construct theory but also to inform and guide practice and action. This study was part of Street Tree Futures, a multi-year research-practice partnership led and advised by a committee of researchers and practitioners. 3.3.2 City and participant selection To meet our objective of investigating best practices, we interviewed urban foresters employed at an array of cities in the US and Canada, varying in population and geographic location, with particularly advanced urban forestry programs and adopted ecosystem service goals (see below criteria). An initial list was created utilizing two recently published lists of cities with urban forest management plans in the US (Grant et al., 2022) and Canada (Z. Cheng et al., 2021). Additional municipalities known to have advanced urban forestry programs were added by the co-authors and the Street Tree Futures project practitioner advisory committee, composed of members of urban forestry NGOs and private industry organizations with national reach in the US and Canada. The initial list was then evaluated against inclusion criteria (Table 3.1) to create a list of eligible cities, using information from city websites and online searches. A final list of 54 eligible cities was categorized and sorted by country, geographic area, and population. A random number generator was used to assign an outreach order, spread across the categories, with the goal of achieving evenness in representation and removing bias from the selection process. Potential eligible participants at each of the 54 eligible cities were identified by city website searches, recommendations of the project’s research and practitioner advisory committees, and through requests for recommendations via contacts at urban forestry departments found on city websites. The goal in recruitment was to identify employees with both 38 managerial and operational duties i.e. those involved in operational decision-making about street trees and in enough of a leadership position to participate in their city’s planning processes (Table 3.1). Table 3.1 Participant inclusion criteria. The sampling approach first targeted municipalities meeting the below criteria, and then participants employed at those cities who met additional criteria. Municipality inclusion criteria ● Located in the US or Canada ● An advanced urban forestry program indicated by having two out of three of the following: (i) an urban forest management plan or similar strategy document published within ten years of the study start (Jan 2013- Jan 2023), (ii) Tree City USA (Arbor Day Foundation, 2024b) or Tree City of the World recognition (Arbor Day Foundation, 2024a), (iii) a full or partial street-tree inventory ● At least one formally identified ecosystem service goal within an adopted municipal plan such as those related to climate change mitigation, urban heat, stormwater management, biodiversity, or human health, with the potential for application of urban forests as a strategy to address such goals (see Appendix A; Table A.1 for examples) ● The authority to manage street trees under its jurisdiction Participant inclusion criteria ● Responsible for making decisions, or significantly informing the decisions, about municipal street trees in at least one (but preferably most) of the following phases: planning/design, planting, maintenance, and/or removal ○ Example titles include terms such as: manager, director, chief, lead, combined with either urban forestry or arboriculture ● At least five years’ work experience in relevant fields ● Employed at their current city for at least 6 months (i.e., familiar enough to speak on how decisions are made there) Prospective participants from the first 20 cities from the order created by the random number generator were emailed. They were asked to sign a consent form and schedule a one-hour interview within two weeks, after which a follow-up email was sent. When initial contacts did not respond to follow up emails, additional prospective participants from remaining eligible cities were contacted, aiming for evenness with respect to population and geographic region. 39 Twenty participants were interviewed, each employed at a different city. Cities ranged in population and geographic area (Table 3.2; Figure 3.1). Most participants employed in parks and recreation, or public works departments were in positions where they directed staff performing street tree maintenance (performed by crews on staff or by contractors), though their interaction with this level of activity varied based on city size. Participants employed in planning departments were more often involved in street tree management via code enforcement of tree ordinances/bylaws or development plan approval, though these participants strongly identified as urban foresters and were engaged with the tree maintenance procedures in their cities. All participants were employed at municipalities whose official names contained the term “city,” regardless of size. For brevity, we will thus use the term “city” throughout this paper. 40 Table 3.2 Employment and education background of semi-structured interview participants (n=20) by city population size. City population classifications: small < 100,000; 100,000 < medium > 700,000; large > 700,000. City size Small (n=7) Medium (n=8) Large (n=5) Department Count % Count % Count % Parks and Recreation 5 71.4 4 50.0 3 60.0 Public Works 0 0.0 3 37.5 1 20.0 Planning 2 28.6 0 0.0 0 0.0 Forestry 0 0.0 1 12.5 0 0.0 Transportation 0 0.0 0 0.0 1 20.0 Education level Masters 2 28.6 2 25.0 2 40.0 Bachelors 5 71.4 5 62.5 2 40.0 Likely Bachelors 0 0.0 1 12.5 1 20.0 Time in urban forestry (years) <= 10 years 2 28.6 1 12.5 1 20.0 11-20 years 1 14.3 3 37.5 1 20.0 >= 21 years 3 42.9 1 12.5 3 60.0 Not mentioned 1 14.3 3 37.5 0 0.0 Time employed at city (years) <= 5 3 42.9 4 50.0 1 20.0 6-20 3 42.9 2 25.0 2 40.0 >= 21 1 14.3 2 25.0 2 40.0 41 Figure 3.1 Map of cities with participating municipal employees. 3.3.3. Interviews Semi-structured interviews were organized into four sections. In order, these were opening (ex. “What are your primary responsibilities and tasks in your current role?”), generative (ex. “Do you think it is part of your position’s job duties to manage trees for any specific ecosystem services?), directive (ex. “In your decision-making, how important is this [ecosystem service] goal compared to your previously stated street tree management objectives?”) and closing sections (ex. “In an ideal world, what do you think are the best practices for cities to align street tree management actions to contribute to city-level ecosystem service goals?”) (Tracy, 2019) (see Appendix A; Table A.2 for complete interview guide). 42 All interviews were conducted by the lead author, who was a doctoral student with prior professional experience working in urban forestry and arboriculture and serving in leadership positions at professional organizations. The interviewer positioned themselves as a “co-expert” (Döringer, 2021), and began interviews by briefly introducing their background in the field and journey to the chosen research questions, establishing a rapport that could be characterized as both peer-to-peer and expert-to-student. Twenty interviews of 34 to 100 minutes (with most lasting around 60 minutes) were conducted and recorded via video-conferencing software (Zoom, 2024) in February and March of 2023. Interviews were transcribed using Otter.ai Pro 2023 (Liang & Fu, 2023) after which produced transcripts were manually edited for comprehension (e.g. mis-transcribed words, speaker assignment). 3.3.4. Analysis Analysis followed an iterative phronetic approach, chosen for its suitability for research closely tied to a pre-identified research question or problem and intending to “shed light on an issue or open a path for possible social transformation” (Tracy, 2019). The lead author conducted primary (or “open coding”) and secondary cycles of code development, which led to an initial codebook of themes. Through memo-writing by the lead author, the process of refining codes was guided by iterative, continuous reflection on the themes which recurred in the data and the dialectical relationships and tensions between those themes and the original research questions (Srivastava & Hopwood, 2009; Tracy, 2019). 43 Comparison coding then was conducted with a second coder (also a co-author), where both coders analyzed two randomly selected transcripts using the initial codebook, and together further refined it through in-depth discussion of agreements and discrepancies. This final shared codebook was then utilized by both coders to independently code remaining transcripts (n = 18), with one coder coding odd numbered transcripts, and the other coding even ones. The coders frequently conferred with each other to refine or add to the codebook as necessary. All analysis was conducted in NVivo 14 (NVivo, 2023). As a result of the analysis, we offer the frequencies of participant interviews in which themes were found to give insight into their relative prominence amongst our interviewees. However, this qualitative methodology is not designed to assess the frequency of specific opinions within a sample population, so it is important not to over-interpret or project conclusions based on the numeric frequency of certain codes. Coding matrix queries were conducted in NVivo to explore the frequencies of codes across participant and city factors (Table 3.2), however no notable trends were found and are thus not reported in the Results section. 3.4 Results 3.4.1 Context of municipal street tree management In the openings of interviews, participants described being tasked with managing and balancing many complex objectives at multiple levels. In this section, we describe their perception of the objectives driving their management decisions from their positions at the intersection between high-level strategic thinking and plan making, and detailed operational responsibilities, such as managing service requests from residents and equipment needs. 44 3.4.1.1 Street tree management objectives All participants were asked about the most important objective that drives street tree management decision-making. The most important street tree management objectives described were urban forest health and growth (n=11), tree risk and public safety (n=9), and serving the public (n=8). Many participants were unable to choose a single objective as most important in all situations, and described their main objectives as blending tree health, risk management, and benefit provision. “Keeping trees alive and providing benefits, safely, for as long as possible.” (P13) “The objective is to keep the public safe, that’s first and foremost. But then also to keep our urban forests healthy.” (P2) 3.4.1.2 Job duties towards a specific ecosystem service After discussing street tree management decision-making processes in depth, the interviews shifted into a broad conversation about ecosystem service goals. When asked if it was part of their job duties to manage trees for any specific ecosystem services, just over half said no, not directly, but that they manage for ecosystem services broadly (n=11), while the other half of respondents said yes, often highlighting several services they were focused on (n=9). “It is my opportunity, and in many cases, my pleasure to manage trees for their ecosystem benefits. It is not necessarily my responsibility, or within my power, to manage the full range of environmental benefits that trees and ecosystems can provide.” (P19) “Yes, I would say for sure stormwater mitigation. Working with our interdepartmental partnerships in stormwater mitigation is a huge goal.” (P11) 45 3.4.2 Strategies and challenges to align street tree management with specific city ecosystem service goals To respond directly to the research questions, we coded only those strategies and challenges which participants specifically connected to aligning street tree management with specific city ecosystem service goals. The coded strategies and challenges in this section include both approaches that participants were actively using in their own cities, and their ideas for what could work for cities in general. However, in addition to the coded strategies and challenges, participants brought up many strategies and challenges in street tree management generally. At times it was difficult for the coders to distill specific strategies to align street tree management with specific ecosystem service goals, because participants often seemed to view any actions to improve tree health and longevity as being in alignment with these goals. This difficulty led to the development of the themes which are explored in the subsequent subsection. 3.4.2.1 Strategies to align street tree management with specific city ecosystem service goals Nearly all participants described strategies to align site design and species selection (n=18) with specific city ecosystem service goals and using data or tools to support those decisions (n=18). For example, the Tree Equity Score, a spatial index of socio-environmental factors (American Forests, 2024), was frequently referenced as a potential strategy to align new tree plantings with a city’s goals to reduce urban heat and better serve low-income communities. “We try to overlap goals. So, if we have a low-income area that is also stormwater susceptible, that will be a priority planting area.” (P11) “First, it’s going back to GIS and like ‘hey, is this an area of high need of trees, based on all the factors, low canopy, high urban heat, underserved neighborhood?’” (P1) 46 Factors within their municipality were also seen as fundamental, including support from elected officials (n=14) and the alignment of existing urban forest plans and policies (n=14). Regular, formal, or informal communication with other city staff, including building inter-departmental relationships, was also described as a key to advancing their city’s ecosystem service goals (n=13). “There's a lot of change going on in local government, now that the city council just adopted a new climate lens, which will factor into all decisions made within city purchasing, prioritization of projects, all these things.” (P3) “I just met with our transportation engineers yesterday about, in our big intersections, finding ways to slow traffic, pull out impervious surfaces, put in trees and other vegetation to help with the heat island effect and to collect stormwater, and all these other things. So, yeah, it’s in every single department here.” (P13) About half of participants described partnership with an organization specializing in a specific ecosystem service goal (n=11), either internally, such as their city’s water department, or externally, such as an NGO focused on food security, as a strategy. Enabling community stewardship and support (n=12) was also seen as key to reaching goals. “There’s a group called [city name] Urban Gardens [...] and we’re actually starting to plant apple trees and other things.” (P10) “We partner and support each other with the department of utilities who handle stormwater. […] on one hand, I'm working with a tree, but I'm promoting a goal that is actually somebody else's goal.” (P19) 47 Another strategy was to follow models from other cities (n=7), for example, through utilizing design specifications for trees in new projects geared towards a specific ecosystem service. Strategies like allocating funding (n=10) or creating a new staff position (n=5) described ways to direct work towards one specific goal or another. Nonetheless, for almost all participants, their program’s current goals to improve urban forest health and protect public safety remained the top priority. 3.4.2.2 Challenges to align street tree management with specific city ecosystem service goals The challenges to align street tree management with specific city ecosystem service goals were in many ways the “other side of the coin” of the strategies previously described. While departmental collaboration had been previously described as a strategy, departmental silos were a frequently described challenge to advancing ecosystem service goals in UF management (n=10). Institutional arrangements, and the position of urban forestry within them (e.g. in a parks department, public works, or planning department) also affected priorities. “From a park management standpoint, I mean, we do manage for culture, and you know, pollinator friendly, all those kinds of things. But that’s, um, like a park maintenance priority, that’s not really an urban forestry priority.” (P3) Insufficient resources, such as funding (n=14) and problems with staffing (n=11) were also commonly cited challenges. “We’re not in a position to have a lot of discretion in what or how we’re making decisions, because we have a very finite amount of resources. So, you know, we have to do what makes sense in every situation. Sometimes that doesn’t match with our overarching ecosystem goals.” (P3) 48 “I know what I want out there, I know what the Climate Action Plan is asking for. Money is usually the biggest problem.” (P20) Many also described their current operational procedures for street tree management as not allowing for strategic decision-making (n=9). For example, being solely service request-based (which was a common but not universal set up) also affected their ability to take on higher level objectives. “So, in urban forestry, the way I’m set up as a maintenance organization, is not well geared to track overall climate change or the benefits of the trees I’m planting or maintaining. So, I would be poorly suited to meet the requirements and restrictions of [climate mitigation specific funding].” (P19) Current knowledge and prevailing preferences of both city staff and the public were also seen as challenges by some interviewees. While some described their cities’ desire for new, perhaps “flashier,” strategies to reach goals such as pop-up parks or new capital improvement projects, instead of investing in maintenance of existing trees as an impediment (n=5), inertia was also brought up as preventing changes to their programs (n=3). A lack of evidence-based guidelines on how to align their management with particular ecosystem services was also described (n=4). For example, one participant described not knowing of any local guides for which species were best suited to help achieve specific objectives. However, the most common challenges related to the built environment limiting street tree management choices (n=17). For example, harsh growing conditions (e.g. insufficient growing space, compacted soil) limit the survival potential of many native trees, thus making it infeasible to plant them in service of a biodiversity goal. 49 Competing land use priorities (n=9), such as whether to develop land for new housing vs. preserve native habitat, were reported as limiting street tree management choices and efforts to achieve ecosystem service goals by reducing available space for existing and new trees. A particular challenging example of competing priorities was in considering the role of urban forestry in reaching biodiversity goals for cities in non-forested biomes: “Parks and Rec is really big on natural grasses [...] We're a novel ecosystem within the ecoregion of shortgrass prairie [...] so, the push isn't to plant more trees, the push is actually to return it back to its original state. I go home with a lot of headaches sometimes because on one hand politicians want trees, trees, trees, but then it's like, like the old saying, don't listen to what they say, but watch what they do. So, they say trees, trees, trees, but they're pushing for more natural landscapes.” (P10) 3.4.3 Perceptions of ecosystem services, street tree management, and city goals Complexities related to the concept of ecosystem services strongly influenced participants’ perception of whether their work aligned with city ecosystem service goals, and even more fundamentally, how they viewed the objectives of the urban forestry programs they managed. The following four themes were constructed to describe the current paradigm of street tree management and alignment with municipal sustainability plans as reflected by these interviews. 50 3.4.3.1 Understanding of urban forest ecosystem service provision All 20 participants had high familiarity with the concept of ecosystem services and were well versed in the many possible benefits of urban trees. Participants repeatedly emphasized that their job was to increase the longevity of trees (n=15), grow trees of larger stature (n=12), and grow more trees (n=10), and that these outcomes would all result in “more” ecosystem services. “Maximize the size of tree that you can get in any appropriate location. Because when you're doing that, you're inherently setting yourself up at least for maximum ecosystem benefits when you're following right tree, right space, all those things and also planting as many trees as you possibly can in those spaces” (P3) This was often expressed through the idea that managing for overall tree health and increased canopy coverage would ultimately result in more ecosystem services (n=14), and thus, actions taken to increase these structural goals were aligned with ecosystem service goals. “When I said I focus on canopy coverage, that's going to hit all the climate goals about heat island effect, about stormwater retention, about habitat.” (P19) At the same time, participants also articulated how street tree management choices could result in different ecosystem services (n=8), especially through species or site selection. They also described how certain urban forest types were better at providing, or designed to provide, different ecosystem services (n=12), for example, describing that the main roles of street trees were to provide shade and beauty for pedestrians while natural forested areas in city parks were better for providing wildlife habitat. 51 3.4.3.2 Role of the ecosystem services concept in street tree management Participants primarily described using ecosystem services as a justification for funding and existence of their street tree management programs (n=15) by, for example, advocating for their budget to city leadership or using ecosystem services to make the case for tree preservation to the public. Over half described having an ecosystem service assessment and valuation, either using i-Tree (Nowak, 2020), or through a tree inventory software tool with embedded ecosystem service estimates. Most believed that describing—and even better, quantifying—the benefits of trees was the best way to gain support for urban forest management. “When you talk about tree quantities, and even canopy cover percentages, as, you know, the sort of measurables, it just gets lost for people. Like, people don't give a shit whether you have a 25 or 35% canopy cover percentage, right. But if you tell them that we were able to, you know, offset a million-and-a-half dollars worth of carbon, or, you know, here is the impact that we've had on our stormwater management system, or you know, some of these other sort of ways to tell our story, that's where the real benefit of that stuff is.” (P16) An advocacy strategy of describing one specific ecosystem service to get the attention of a specific audience also frequently came up in the interviews (n=12). Nonetheless, there was notable tension between understanding that street tree management actions could affect specific services or disservices, and whether and to what degree decisions should, or could, be aligned with a specific benefit, and beneficiaries thereof. 52 “P2: I think if we’re gonna sell it to folks, maybe public health is the way to do it. Because if you basically say, like, listen, your grandchild is going to have asthma. Do you want that to happen? Most people, I would like to think, would say no, right? So, how about we plant a bunch of trees and take care of the existing ones that we have? Interviewer: Do you think that would, then, make you choose species with less allergens? P2: Yeah. I guess that’s a good point. There’s a lot of checks and balances there.” When it came to aligning street tree management decisions with a specific benefit, many said explicitly that ecosystem services were not considered directly in their typical decision-making processes (n=10). Participants on the whole, however, acknowledged that choices they make could affect alignment with a specific benefit goal. “I don't go out every day, looking at ‘Oh, how can I sequester this carbon longer?’ That's, I mean, it's a mutual, happy, coincidental benefit that comes along with all of the tangible everyday benefits that the residents get that they don't think about.” (P13) “[Our i-Tree ecosystem service assessment] is not really for management decisions. That’s more for budgeting, public information. I don’t think we use it when deciding where to plant a tree or which tree to plant.” (P6) When asked to compare the importance of a street tree management objective related to increasing canopy or tree health with an ecosystem service goal they previously described as very important to their city, most stated that their street tree objective was more important, but still believed it would align with city ecosystem service goals, at least broadly. “Oh, it'd be planting within our neighborhoods just because the byproduct of doing that will help to mitigate stormwater.” (P11) 53 However, even if their overall program goals were focused on metrics of urban forest structure such as canopy cover, many also could describe situations where ecosystem services were used to direct management choices (n=14). These were mostly related to managing sites with specific needs, such as sidewalks needing shade for pedestrians, or a riparian area in need of native species for local wildlife. At the city scale, ecosystem services were used to direct management choices usually only at the stage of prioritizing new plantings within certain neighborhoods with specific needs. “I’ve highlighted the site suitability for different metrics. So, you know, living below poverty level, high urban heat island effect, low tree canopy, looking at the health index, [...] and pulled those census blocks out [...] So that map, I’m actually including in the RFP, and asking the consultant to specifically identify potential tree planting sites in those census blocks.” (P17) 3.4.3.3 Role of street trees in city ecosystem service goals Participants described the role of street trees, and urban forests broadly, in city ecosystem service goals, and the plans which contained them, in a number of ways. When asked about specific plans in their cities, they described important roles (n=8), such as playing key parts in specific strategies, to minor roles (n=4), like being mentioned but not receiving sufficient attention, to not being mentioned at all (n=2). “I've been involved with the development of that plan. It certainly discusses trees, but I don't think there's specific targets for trees within the [Vision Zero plan to eliminate traffic-related mortalities]. Just some narrative around, you know, the benefits of having a nice green streetscape, reducing traffic speeds and things like that.” (P18) 54 However, some expressed dismay over arbitrary tree-related objectives being set that were unrealistic or not evidence-based, or not supported by city practices (n=6). “...I just feel like it's lip service at its finest, because, you know, all we're really doing is counting how many trees we're planting. And you know, that really isn't a great proxy for anything at all because, you know, half of them are gonna die anyways, and we don't really know how it's advancing our goals, right?” (P16) 3.4.3.4 Role of city ecosystem service goals in street tree management Despite sharing a range of perceptions on the role of street trees in their city’s sustainability plans, participants frequently described the ecosystem service goals within these municipal sustainability plans as having a small influence on their decisions (n=7). Ecosystem services were either not related to their day-to-day operations, or many competing priorities prevented them from adhering to one plan or another. The type of plan, the legal authority of that plan, and the funding allocated by that plan influenced how much it affected their management decisions. “...We do refer to the Climate Action Plan, [...] but overall, like, from a day-to-day standpoint, it's just trying to get more trees in more spaces.” (P20) The term “guide” recurred frequently in reference to how they viewed municipal sustainability plans, such as climate action plans, especially in describing them as a flexible guide to follow, especially when useful or practical for their own urban forestry goals (n=7). 55 “...I don't use them as my Bible [...] my focus is health of trees, health of the urban forest, you know, keeping what we have as long as we can [...] I think the benefit of that is, is providing what we need for those goals [...] my goal is the forest, their goal is they want these things to happen. But I just use that as like guides.” (P20) Participants also viewed city ecosystem service goals, and the plans that contained them, as having a role in garnering recognition, political and public support, and funding, for their programs (n=8). “I mean, sure, that goes in any grant application I’m working on. It definitely comes into play, like, I got funding from a different department to create this assistant position from water quality.” (P7) “I’m hoping that through the Climate Change Action Plan review we can maybe find opportunities for more funding for maintaining our forest.” (P8) 3.5 Discussion In the discussion, we address our initial research questions by explaining how our interviews show the limited extent to which urban foresters align their street tree management decisions with adopted, specific, ecosystem service goals in their municipalities. Overall, we discuss how ecosystem services as a concept are still typically used more as a justification for overall urban forest management, and that we find urban foresters adopt a “more, bigger, trees” paradigm in their management. We synthesize literature which supports how this approach may align with certain priority goals which cities are advancing and miss opportunities to advance others. We discuss how urban foresters can be split between advancing the stated objectives of their own 56 programs and the strategic level priorities of their cities—and how this tension gets to the heart of the purpose of urban forestry, and more broadly, urban ecosystem management, in cities. 3.5.3 Extent of alignment of street tree management with municipal ecosystem service goals Participants could describe cases where their decision-making was intentionally aligned with a particular ecosystem services goal, however, their programs were typically aligned with achieving tree-specific (or ecosystem structure) management objectives, such as increasing tree cover and reducing risk of tree failure. Participants who believed their programs were aligned with ecosystem service goals thought this because they believed their goals to increase the abundance and health of their urban forests in general would necessarily contribute to the ecosystem service goals in their city’s plans. The finding that urban foresters typically prioritize tree-specific goals over ecosystem service goals provides critical context to understanding participants’ views on aligning their programs with so-called “other” city goals. While urban foresters agree that urban forests provide many diverse ecosystem services, and believe that their responsibilities include increasing such provision, any work to tailor programs towards specific ecosystem service goals is often perceived as “extra” or “additional” to the core function of their jobs. It is significant that the mainstreaming of rhetoric around ecosystem services in urban forestry (Silvera Seamans, 2013; Young, 2013) has not resulted in the widespread uptake of using specific ecosystem services to direct management and operations. This is true despite evidence of the integration of urban trees into municipal plans as strategies for specific goals (Appendix A; Table A.3). Given that our sample only included cities who had adopted ecosystem service goals, we think it is reasonable 57 to expect that most urban foresters in the US and Canada do not align management with specific ecosystem service goals. While it is relatively simple to grasp the overall concept of ecosystem services—that ecosystems, such as urban forests, provide benefits to human well-being—the process of operationalizing this concept is much more challenging (Carmen et al., 2018). Major challenges found in other environmental fields include developing shared understandings of the concept and finding common methods to assess ecosystem services (Ainscough et al., 2019; Jax, Furman, et al., 2018). Our participants did not describe these specific challenges. They were remarkably united around an understanding that urban forests provided a broad swath of essential benefits, and that increasing tree numbers, improving tree health, and generally adding canopy cover would necessarily result in more of such benefits. There was also no disagreement on ways to assess ecosystem services; by far the most dominant ecosystem service assessment tool referenced was i-Tree. Other software mentioned by participants actually utilized i-Tree models for ecosystem services estimation, such as TreeKeeper, a tree inventory and workflow tool (Davey Tree, 2024) and the Tree Equity Score, which though focused on characterizing distributional equity of canopy cover, uses i-Tree to estimate the benefits of increasing tree cover (American Forests, 2024). When it came to operationalizing ecosystem services in a more targeted way, such as through aligning decisions with a particular ecosystem service goal, participants seemed generally less familiar or practiced at discussing management in such a way, with the notable exception of using spatial indicators of ecosystem services need to direct tree planting. This mirrored evidence 58 from a large European survey (Ainscough et al., 2019) finding that environmental management practitioners, broadly, do not see ecosystem services as useful in supporting decision-making, in sharp contrast to the perception of the usefulness of the concept among ecosystem services researchers. Urban foresters seem to use the language and metrics of ecosystem services opportunistically to enable their work, including their site-level decisions, especially if mainstreamed in their cities. However, overall, they do not believe their management exists to serve one particular ecosystem service or another and are instead guided by their sense of the greater purpose of urban forestry. 3.5.4 Best strategies and current challenges in aligning street-level decisions to contribute to municipal ecosystem service goals The ecosystem service goals that cities are setting are broad, important, and ambitious (Appendix A; Table A.1 & A.3). Our analysis indicated that governance factors, such as staffing, insufficient funding, and departmental silos, were the primary challenges to municipal urban foresters faced in alignment with such goals. Even their institutional arrangement (e.g. their department) or structure of their current operational procedures (e.g. being service request-based in some instances) were barriers to strategically aligning with specific ecosystem service goals. These challenges are, for the most part, expected, as they have been identified as barriers to program improvement by previous research (Davies et al., 2017; Ordóñez et al., 2020), and it is difficult to parse challenges to tree survival from those that influence the benefits of those same trees. Problems with insufficient funding and staffing make it yet more imperative for cities to use wisely what resources do exist, and to align spending with the most critical goals. 59 Almost all urban foresters described decisions in the pre-planting phase of management—choosing what species to plant and where to plant them—as top strategies to further align their management with city ecosystem service goals. This alignment was greatly facilitated by spatial analysis and decision-support tools, and participants expressed demand for new tools which could further aid them. Beyond the ecosystem services from trees alone, there is also a need to support professionals in comparing the potential of trees and other interventions to achieve holistic city objectives, such as increasing housing supply or planting natural landscapes (Angelo et al., 2022). An original intention of operationalizing ecosystem services in urban planning and urban ecosystem management is to serve as a boundary object, uniting disparate disciplines in common goals and common terminology (Steger et al., 2018; Thompson et al., 2024). Yet, there are very few tools which can aid practitioners in aligning urban planning decisions with city ecosystem service goals, and challenges with integrating those existing tools into their processes (Tefera et al., 2024). Several participants described feeling a duty to be the voice for trees in the planning process, in the face of competing priorities at their city placing pressure to use land for other purposes, including purposes to meet sustainability goals like increasing native landscaping or housing density. Instead of feeling a sense of abdication of duty or failure and wasting effort and resources to prevent the removal of trees for the sake of a project needed to serve cities through means other than trees, it could be possible to use ecosystem service goals to help municipal units understand their part and relationships in a greater strategic collaboration. Our results support that urban forest management can be tailored to advance specific goals, and that urban foresters have the knowledge and access to a field that is rapidly advancing in professionalism 60 (O’Herrin et al., 2023). However, in absence of the strategies highlighted in this paper to facilitate alignment with a particular ecosystem service goal, such as allocated funding and collaborative partnerships, urban foresters will likely default to managing for public safety and an oversimplified “more, bigger trees” approach. 3.5.5 Goal alignment, missed opportunities, and potential disservices from the “more, bigger trees” approach Our results show that the way professionals understand mechanisms of ecosystem service provision can affect their decision-making. In the case of urban foresters in the US and Canada, we found the widespread belief that “more, bigger trees” would virtually always lead to more ecosystem services, in a general sense, and that this understanding was used to justify their urban forestry program objectives. This paradigm is rooted in ideas such as the “large tree argument,” which posits that large stature trees should be prioritized because, in many cases, they offer more per tree benefits to society (USDA Forest Service, 2004), as well as the broader “Trees are Good” campaign, promoted by the arboricultural industry (Roman et al., 2021). Management paradigms like these, while never perfect, can be important and useful heuristics to prevent decision-making from being paralyzed by the infinite complexity of the real world (Levine et al., 2015). The prevalence of the “more, bigger trees” paradigm suggests it is an example of the adoption of a group-based value by a profession (Breed, 2022), in this case, among urban foresters in the US and Canada. This paradigm may give professionals a shared mission as well as facilitate their translation of tree-specific objectives from the city-scale, like setting canopy cover goals, to the site-scale, like planting larger specimens wherever possible. 61 Striving for “more, bigger trees” does align with certain critical ecosystem service goals. Larger stature trees provide a greater cooling effect (Rahman et al., 2020), intercept more stormwater (Dowtin et al., 2023), sequester and store more carbon (Nowak & Crane, 2002), provide critical habitat to urban wildlife (Stagoll et al., 2012), and even serve as unique historical and cultural attachment points (Lavy & Zavar, 2023). However, there are additional actions to consider for all of these goals, such as consideration of species traits like crown structure and density, leaf texture, or nativity status (Castro-Díez et al., 2019; Dowtin et al., 2023; Farrell et al., 2022), which could be employed to increase each ecosystem service but would not necessarily be considered if only marching towards, for example, a canopy cover goal (Tran et al., 2020). In addition, there are important situations where following this approach not only misses the mark but can pose significant management costs or contribute to ecosystem disservices. One benefit where simply managing for “more trees” without place-based nuance may exacerbate disservices, is with respect to air quality, a frequently promoted benefit. Streets with a canyon-like form can create worse air quality conditions when they are fully planted with tall and wide canopied trees as the trees can decrease air flow and trap pollutants (Eisenman et al., 2019); in this context, fewer trees with increased spacing can mitigate this negative effect (Abhijith et al., 2017). Another often touted benefit is that more trees can make cities safer. However, dense trees can also affect fear of crime (Jansson et al., 2013), and have been associated with facilitating crime, because they can obstruct lines of sight (though primarily with vegetation at eye-level, while presence of taller trees is associated with reduced crime rates) (Lin et al., 2021). Similarly, a focus on only “bigger trees” misses unique benefits provided by smaller stature species. Many trees valued for fruit and flowers tend to be small stature, and are 62 highly demanded by residents for food production, cultural value, and aesthetic appeal (Nguyen et al., 2017). Small stature trees can also provide significant benefits which align with city ecosystem service goals while accommodating space constraints from built infrastructure (e.g. utilities). Indeed, street tree systems in some US cities have been shifting away from large-stature trees to small-stature trees to avoid the ecosystem disservices associated with tree-utility conflicts (Magarik et al., 2020; Roman & Eisenman, 2022). The “more, bigger trees” paradigm is a somewhat blunt instrument that does not accommodate situations needing a more nuanced consideration of desired benefits and the actual beneficiaries, as well as site-specific tradeoffs across different services, or between services and disservices. We believe a significant finding of this research is that urban foresters across the US and Canada are guided, and united, by their own sense of the purpose of urban forestry, which mostly aligns but is in some cases in contradiction with the objectives set by city leaders. We posit their perception of the purpose of urban forestry is mediated by the development of the professional identity of urban foresters around shared values (Breed, 2022; O’Herrin et al., 2023), and grounded in management paradigms backed the urban forestry scientific community (USDA Forest Service, 2004). Ecosystem services as a concept (and accompanying metrics and language) are used when they align with this purpose, which is, broadly, to grow healthy forests which serve urban communities. 63 3.5.6 Limitations Our interviews did not focus on a specific type of planning document or specific type of ecosystem service goal. Different plans are imbued with different types of authority depending on the governance context of a municipality. Future research on the alignment of urban forest management decision-making could reveal advantages of utilizing different administrative mechanisms over others, as well as investigate the degree of genuine collaboration and communication across municipal departments in the planning process. Because we sought to draw general conclusions across a profession, the results are also limited by small sample sizes for specific regions, for example, we were unable to recruit participants from the Canadian prairies or maritime provinces. The results are also likely most relevant in the US and Canada, as it has been recognized that municipal organization and the role of urban foresters at municipalities takes very different forms around the world (Ordóñez Barona et al., 2023; Yao et al., 2019). Study results should be compared with other social and ecological contexts, rather than assumed to be representative. However, there are likely important parallels to be drawn at a wider scale as the concept of ecosystem services, and demand for tools like i-Tree, is certainly impacting the research and practice of urban forestry around the world (Riondato et al., 2020; Wu et al., 2019; Xie et al., 2023). 3.6 Conclusions The sustainability goals that cities are working towards are not trivial, rather, they will significantly impact the quality of life of urban residents, mortality rates and the burdens of disease (Jackson et al., 2013). How cities frame their goals (as ecosystem services or otherwise) and work to align their many programs, including urban forestry, will influence the progress of 64 cities towards such goals. The role of an urban forester is becoming increasingly more important as a link between high-level sustainability planning and the management decisions and operations which shape urban ecosystems. We found that in urban forestry, the adoption of ecosystem service goals by cities does not result in substantial changes in day-to-day decision-making. On the other hand, the “more, bigger trees” paradigm adopted by urban forest professionals can both aid in alignment with certain city ecosystem service goals and cause missed opportunities or unintended disservices. It is also important to note that urban foresters expressed a desire for new tools and evidence to support better alignment with ecosystem service goals, as well as more collaboration with other professionals like urban planners, stormwater managers, etc. The disconnects we identified present missed opportunities to align the limited resources that exist for managing natural resources, such as urban forests, to advance the most needed goals for cities' needs, and thus progress towards more sustainable cities. 65 Chapter 4: Aligning urban forest management actions with urban sustainability goals: A multi-city expert elicitation 4.1 Summary Cities are setting ambitious plans to achieve critical urban sustainability goals such as reducing urban heat, mitigate flooding during storms, and conserving biodiversity. Urban forests, defined as the trees and associated vegetation in urban and peri-urban areas, are key components of urban ecosystems which contribute to such goals. Current paradigms of urban forest management typically prioritize managing for increased tree canopy cover or similar goals that are often viewed as proxies for increased ecosystem service provision, in a general sense. However, urban foresters, the professionals with responsibility to manage urban forests, are increasingly faced with the complex challenge of managing for new goals related to ecosystem services, biodiversity, or people-nature relationships, as cities increasingly set strategic goals centered on such outcomes, without robust management approaches or guidelines to follow. In this study we ask: How can urban foresters align their street tree management actions with specific urban sustainability goals? We conducted a structured expert elicitation of urban forest professionals in three cities: Vancouver, British Columbia, Canada, Honolulu, Hawaiʻi, US, and Washington, DC, US. Participants assessed the impacts of forty direct management actions on five goals (1) canopy cover increase and tree risk reduction, (2) urban heat reduction, (3) people-nature relationships, (4) wildlife habitat, and (5) stormwater interception and infiltration. While certain actions (such as in the mature tree maintenance phase) were selected as needed to advance every goal, experts identified numerous actions which aligned with one or several goals, but not all. Actions within the pre-planting phase, specifically site selection and species 66 selection, presented the greatest opportunities to advance specific goals, suggesting that aligning this phase with city sustainability goals is critical. Participants were highly confident in being able to notably advance all goals through street tree management and were more confident in being able to advance the goals of increasing canopy cover while reducing tree risk and urban heat reduction, possibly because these goals more closely align with traditional canopy cover goal setting. This research underscores the necessity of considering site-level actions to advance strategic sustainability goals, while also revealing the complexity of the task that professionals are charged with in making site-level decisions. Our findings further motivate the need for further research and tools to help support professionals in their decision-making. 67 4.2 Introduction The rapid growth of cities in the United States and Canada over the last half century, as well as globally, demands urgent action to conserve urban nature to achieve sustainability goals for the wellbeing of urban residents (Colding et al., 2020; Seto et al., 2012). The fields of urban ecology and urban sustainability are likewise rapidly developing as linked disciplines of research and practice needed to inform action in cities’ complex networks of social, ecological, and built infrastructure systems (Frantzeskaki et al., 2021; Wu, 2014). Urban forests, often defined as the communities of trees and associated vegetation in urban areas (Konijnendijk et al., 2006), play a key role in urban ecosystems through providing a wide range of critical services including heat island mitigation, stormwater interception, and wildlife habitat provision (Roy et al., 2012). The social and cultural benefits of urban forests, many derived from people-nature relationships, can also be important drivers of stewardship and conservation, though they often elude quantification efforts (Chan et al., 2016; Nesbitt et al., 2017). Managing urban forests for such benefits requires skilled application of both general and context-specific knowledge, including understanding the impacts of management strategies on specific ecosystem services and the spatial and temporal scale of that service provision, all of which have been identified as crucial research needs (McPhearson et al., 2016). Previous research indicates that urban foresters—important change agents and knowledge holders in urban ecosystem management through their role influencing urban forest management (O’Herrin et al., 2023)—largely focus their efforts on maximizing tree canopy while minimizing disservices as a blanket approach to provisioning ecosystem services (Walters & Sinnett, 2021; Chapter 3). However, there is reason to believe that urban forest management actions differ in their impacts on different ecosystem services, and understanding these differences is critical to successful multi-objective management. In this study, we present a 68 multi-city, scenario-based expert elicitation to identify points of influence for a key agent of change in urban ecosystems, in our case, urban foresters, to align decision-making with urban sustainability goals. The many challenges and needs of urban areas necessitate a multi-objective approach to ecosystem management (Almeter et al., 2018; Hale et al., 2015). In multi-objective management, it is important to first define objectives, identify management options, and characterize the effect of management options on each objective in order to eventually assess tradeoffs (Bradford & D’Amato, 2012). In the US and Canada, many cities are adopting broad arrays of goals related to climate adaptation and human health (Turner et al., 2022), resilience (Fitzgibbons & Mitchell, 2019), and advances in the field of urban sustainability science which promote strong connections between people and urban ecosystems (Frantzeskaki et al., 2021). These goals encompass efforts to increase ecosystem services, such as those that urban forests provide to humans, to mitigate ecosystem disservices, and even to recognize the relationships between people and place that are required for urban sustainability, adding to the complexity of the task that urban foresters are tasked with. Multi-objective management of urban forests for urban sustainability requires deliberate consideration of this broader array of goals, and the identification of suitable management options for such goals. In urban forestry, management options vary along a gradient of intensity from urban forested natural areas, which are often managed at the stand level, to street trees or individual trees in yards or parks, which are often intensively managed at the individual tree level (Vogt, 2020). Management of these individual trees focuses primarily on tree survival and health (Hauer & 69 Peterson, 2016), and is characterized by cycles of human-led planting, care, and then removal. Though cities expressly point to urban forests as a critical tool for achieving these goals (Croeser et al., 2021), urban foresters lack support, evidence, and capacity to tailor their management accordingly (Chapter 3). Urban foresters already must already weigh many layers of complexity in making each decision. Furthering multiple urban sustainability goals through management of urban forests requires identifying clear links between specific urban forest management actions and specific urban sustainability goals, as well as identifying possible tradeoffs, to support urban foresters in an already nearly impossible balancing act. Advances in research on this topic include characterizing the effects of different urban forest types (e.g. street trees vs. parks) on different ecosystem services (Elliott et al., 2020) or effects of urban forest management actions on single ecosystem service goals, such as which species should be selected to improving air quality, heat mitigation, or stormwater mitigation (Dowtin et al., 2023; Eisenman et al., 2019; Rahman et al., 2020). Most of the research on urban forest management and ecosystem services has focused on actions within the planning and design phase of the urban tree management cycle (Almeter et al., 2018; Bodnaruk et al., 2017), but there is a pressing need to examine effects of actions throughout the full street tree management life cycle on the diverse range of urban sustainability goals cities are adopting (Figure 4.1a). Lack of understanding of needs and costs of the full tree life cycle has been found to be a limiting factor to improved urban forest management, identified as a barrier to community participation in tree planting (Riedman et al., 2022) and to the proper investment by municipalities (Koeser, Vogt, et al., 2016). Overall, there is a scarcity of research examining the full tree life cycle, and to the 70 best of our knowledge, there are no prior studies linking multiple ecosystem services to management decisions throughout the tree life cycle. Crucially, decisions made later in the cycle can also affect ecosystem services and disservices. For example, decisions in the mature tree management and end of life phases can affect not only the risk trees pose to people and property within their fall zones, but also affect their contribution to wildlife habitat (Fröhlich & Ciach, 2020; Figure 4.1b and c). Analyses of the carbon footprint of urban trees, which examine the climate change mitigation potential of urban trees from beginning to end of the life cycle, have shown different emissions from management actions in different phases (McPherson et al., 2015; Petri et al., 2016). It is important to understand the impacts of all site-level actions needed for urban forest management if cities aim to rely on urban forests to help achieve urban sustainability goals. Furthermore, direct management actions (e.g. tree planting, pruning, and removal) make up significant portions of municipal urban forestry budgets (Hauer & Peterson, 2016) and have potential to affect human health and wellbeing. Understanding these links can affect how we align actions with broader sustainability goals and could influence the allocation of resources towards using urban trees as a solution for such challenges. Additionally, as not all actions will result in the same outcomes everywhere, there is a need for multi-city research which can compare differences in needs between different contexts to understand which management recommendations can be generalizable, and which are context dependent (McPhearson et al., 2016). 71 Figure 4.1 Phases of the street tree management life cycle (a) with simplified examples of how actions throughout the street tree management life cycle present opportunities to affect different ecosystem services, at the planning & design phase (b) and end of life phase (c). Photo credits: Corinne Bassett. In urban forestry research, time and resources are significant barriers to conducting a field-based, multi-city study which could compare the effects of a multitude of management options available on multiple goals. Expert elicitation is frequently used in many fields, including conservation and natural resources management, to answer and understand research questions where data are absent or insufficient and where conducting field experiments may not be feasible due to time or resources (Martin et al., 2012). Such methods have also been used to elicit expert judgment on the outcomes of management interventions on complex systems, generating results that can inform policy and decision-making (Kehoe et al., 2021; Schindler et al., 2014; Singh et al., 2017). 72 Our broad aim is to investigate how cities could align site-level natural resource management decisions with critical sustainability goals. Specifically, our research question is: how can urban foresters align their street tree management actions with specific urban sustainability goals? To address this question, we set the following research objectives: 1. Determine if suites of actions needed for typical urban forest management goals (i.e. canopy cover and risk mitigation) differ from those needed for other urban sustainability goals. 2. Identify which direct actions are linked with which specific urban sustainability goals. 3. Identify points of influence in the street tree management cycle where urban foresters could advance specific urban sustainability goals. In this study, we selected three metro areas in the US and Canada and conducted an expert elicitation to address these objectives. As part of expert elicitation, we also ascertained the degree of certainty that participants held in their responses and underlying reasons for certainty. We discuss possible tradeoffs and synergies in managing for urban sustainability goals, including those framed as ecosystem services and disservices, and how findings could inform generalizable and context-specific management recommendations. 4.3 Methods 4.3.1 Approach We applied a Delphi approach, wherein expert participants independently answer a set of questions, participate in a discussion-based calibration process, then individually revise their estimates following the discussion (Figure 4.2). Our method was inspired by the structured steps 73 outlined in the IDEA protocol (Hemming et al., 2018) but differed in that our study had qualitative aims (e.g., Cawson et al., 2020). Though expert knowledge can be both biased and limited (Morgan, 2014), following principles of structured elicitation, such as those described in the IDEA protocol (Hemming et al., 2018) can help improve accuracy of results, identify and mitigate biases, and qualify results by assessing confidence of the experts in their elicited judgments. We took a qualitative approach because of the nature of the research questions to establish links or isolate key factors, and because qualitative elicitation is often a necessary precursor to a quantitative elicitation (S. French, 2022). We used scenarios in this qualitative elicitation because they can elicit creativity and overcoming of “real world” obstacles, provide mutual ground for productive discussion and identification of new connections, and enable creative visioning about the future (Wollenberg et al., 2000). This study was part of Street Tree Futures, a multi-year research-practice partnership in the US and Canada led and advised by a committee of researchers and practitioners. 74 Figure 4.2 Overview of multi-city structured expert elicitation method for a qualitative elicitation. Pictures sized to obscure faces and protect the identity of participants. Photo credits: Chanel Yee. 4.3.2 Metro areas and participants To respond to the need to produce knowledge which could generate both generalizable and context-specific recommendations, we selected metro areas with three contrasting climatic and ecological characteristics, yet, which shared similar streetscape forms within their regions. Vancouver, British Columbia, Canada, is situated within the Pacific maritime climate and temperate rainforest, characterized by rainy winters and warm, dry, summers (Beck et al., 2018). The metropolitan area (referred to as Metro Vancouver) includes 23 local authorities, with a total population of 2.64 million and land area of 2,878 km2 (Statistics Canada, 2023). Washington, DC, US, is situated within the temperate Eastern deciduous forest, characterized by hot, humid, summers (Beck et al., 2018). The metropolitan area (referred to as the National Capital Region) includes the city of Washington, District of Columbia, two counties in the state of Maryland, and 75 five counties and four cities in the state of Virginia, with a total population of 5.22 million and land area of 6,063 km2 (US Census Bureau, 2023). Honolulu, Hawaiʻi, US, is a tropical city with zones spanning from tropical savannah to arid and hot (Beck et al., 2018). The City & County of Honolulu is a city-county merger representing the entire island of Oʻahu with a total population of 995,638 and land area of 1,545 km2 (US Census Bureau, 2022). Importantly, the urban forestry professionals and arborists in these three metro areas are united by training and experience, credentials, professional organizations, such as the International Society of Arboriculture, and linked North American paradigms of urban forest management (Day et al., 2022). Members of the study team had extensive connections with the professional communities in these metro areas, allowing for successful identification of experts and knowledge of local contexts. 4.3.3 Pre-elicitation In the pre-elicitation phase, steps consisted of developing and defining (i) research questions, (ii) scenario context and assumptions, (iii) goals, (iv) list of direct management actions, followed by (v) creating and testing the questionnaire, and (vi) recruiting eligible participants. The steps in this phase were conducted in consultation with the Street Tree Futures project’s committee of researchers and practitioners (Figure 4.2). In developing the scenario context and assumptions (Figure 4.3), particular care was taken to develop a hypothetical streetscape that allowed for the answering of the research question, and that would be salient, credible, and legitimate to urban foresters across the US and Canada, for future application of results (Rounsevell & Metzger, 2010). The scenario assumptions were 76 designed to create a “mostly perfect world,” removing sources of uncertainty that are threats to basic tree survival. This included the removal of ecological threats, such as invasive pests, and social threats such as vandalism or mower damage, to allow the isolation of factors upon which urban foresters have the most control. Figure 4.3 Hypothetical streetscape scenario context and assumptions to which participants were introduced in online introduction meetings. Next, in the questionnaire, they answered questions about direct management actions needed to advance five different goals within this context. 77 The hypothetical streetscape is characterized by a plantable public right-of-way, in which the urban forester has authority to plant and manage trees, bordered by a public pedestrian sidewalk and privately owned low-rise development. This street form is found in all three metro areas. It was critical to choose a form that represented a “sweet spot” between the typical constraints urban foresters face, so that the scenario was close to real life circumstances, and parameters that gave participants ample space and authority, so they could exercise many different management options in considering the sustainability goals. Streetscape designs can vary significantly and impact the types and sizes of trees which can grow primarily due to above and belowground space constraints, the authority to perform management due to property lines and municipal codes, and the way that residents interact with street trees, such as due to sidewalk placement. The steps of selecting management goals and generating a list of direct management actions were informed by results from a prior study wherein semi-structured interviews were conducted with urban foresters working at municipalities across the US and Canada to understand their street tree management priorities and strategies to align direct management actions with ecosystem service goals (Chapter 3). We developed our suite of goals following common principles in scenario development, such as adhering to a decision-making context that is sufficiently familiar to participants that they will be able to provide constructive inputs, but choosing conditions that are flexible and distinct enough to stimulate creativity and critical thinking, including the crafting of scenarios with somewhat “extreme outcomes” to free participants from real world constraints (Wollenberg et al., 2000). 78 Each goal was developed to consist of a thematic title and a specific management objective (Figure 4.4). Critically, each goal represented a qualitative target to advance towards with benefits relevant to residents of the street in question. Though trees can provide services at many spatial scales (e.g. the benefit of food provision at a local scale vs benefit of climate change mitigation at a global scale), the goals were designed to keep the scale of benefit provision constant between scenarios. Goal 1 Canopy & Risk Reduction was designed to represent the typical priorities of municipal urban forestry programs—to increase canopy cover and reduce risk from falling branches or whole trees. “Tree risk rating” refers to results of a Level 2 risk assessment following the International Society of Arboriculture’s Best Management Practices for Tree Risk Assessment, which assigns a risk rating of low, moderate, high, or severe, after consideration of likelihood of failure, likelihood of impact, and consequences of impact, and is a widely known industry standard in arboriculture and urban forestry (Koeser, Hauer, et al., 2016). While the first goal (shorthand: Canopy & Risk) was developed to represent a typical or “business as usual” type goal, the subsequent four goals (shorthands: Heat, People-Nature, Wildlife, and Stormwater) were developed to represent important priorities often featured in city sustainability plans and which could require contrasting management strategies when compared with Canopy & Risk. Additionally, Heat, Wildlife, and Stormwater, represent goals fitting a typical definition of ecosystem services wherein ecosystems provide services to humans in a unidirectional relationship, while People-Nature represents a relational approach to urban sustainability, wherein people and nature are united through more reciprocal and irreplaceable relationships. 79 Figure 4.4 Expert elicitation participants were asked the same set of questions about each of the goals shown. The questionnaire consisted of five questions, asked for each of the five goals. In the first question, “Which actions are needed to significantly advance each scenario’s goal above all other goals?” participants considered a suite of 40 direct street tree management actions, which were intended to constitute actions an urban forester could take throughout the street tree management life cycle. This suite of actions was developed by first constructing an initial list from results of interviews with urban foresters in Chapter 3 and from the literature on urban forest management (Lilly et al., 2022; R. W. Miller et al., 2015). Then, direct actions deemed as required by policy, such as notifying utilities prior to digging, and actions obviously required for tree survival in all scenarios such as watering, were removed from the list and added to the set of scenario assumptions. The final list of actions was reviewed by members of the Street Tree Futures research and practice advisory committees. To ensure that the choice to not select an option was intentional and not indicative of a missing value, participants were required to check at least one action or “None of these options” per phase. The second question, “Are there direct 80 actions not listed and not referenced in the assumptions that must be performed in order to advance this goal?” was open-ended and the only non-required question. In the third question, “Within the assumptions of this scenario, if all of your selected actions were taken, how certain are you that this goal could be significantly advanced in 20 years?” participants indicated their response by dragging a slider on a horizontal scale of 0-100%. The slider was labeled with 0% as “With the actions I selected, I do NOT believe this goal will be significantly advanced in 20 years,” 50% as “Coin toss,” and 100% as “With the actions I selected I believe this goal WILL be significantly advanced in 20 years.” In the fourth question, “What are the main reasons for your level of certainty?” participants wrote brief open-ended responses. In the fifth question, “Which actions present the greatest opportunities to advance each scenario’s goal?”, participants were asked to pick up to three actions from a list populated with the actions they had selected in the first question and drag them into a box in ranked order of importance to the goal. The questionnaire was hosted on Qualtrics, Version July 2023, Provo, UT. The final questionnaire (Appendix B, Supplementary material B.1) underwent several iterations of testing by study team members and external urban forest professionals. Research ethics approval was obtained through the University of British Columbia Behavioural Research Ethics Board (Approval Certificate #H22-02863). We aimed to recruit participants with significant expertise related to street tree management and urban forest ecosystem services, who as a group would represent a diversity of perspectives and experiences on these topics. As the professional identities of those who manage and influence the management of urban trees is varied and multidisciplinary (O’Herrin et al., 2020), and individuals communicate their expertise through the use of credentials from several disciplines 81 (Day et al., 2022), we did not require any specific professional or academic credentials as signifiers of expertise. We asked prospective participants to self-define their eligibility to participate based on the following criteria (i) interested in and knowledgeable of diverse benefits of trees or ecosystem services, (ii) significant experience with street tree management, (iii) currently in role where they manage or inform management of street trees in the city’s metro area, and (iv) two or more relevant credentials (professional credentials or degrees). Initial letters of contact with attached project overviews were sent via email to participants at key urban forestry organizations in each city who met the above eligibility criteria. Contacts were also asked to recommend other eligible individuals in their metro area, who the project team then also reached out to. A target was set to recruit 10-15 participants per city, with a minimum of eight participants, based on recommendations from the IDEA Protocol (Hemming et al., 2018) and evidence that there are only minimal gains from having groups larger than 6-12 in size (Cooke & Goossens, 2004; Rowe & Wright, 2001). Participants were not given monetary incentives, but benefits to participation described in recruitment included networking with their peers and documentation of participation to receive credit towards maintaining professional credentials. The final participant totals for each cohort were: Vancouver, BC (n=11), Washington, DC, (n=11) and Honolulu, HI (n=11). Participants’ years of experience in urban forestry ranged from 3-49, with an average of 15 years and a median of 12 years. 77.4 % (n=24) were ISA Certified Arborists, 74.2% (n=23) held the ISA Tree Risk Assessment Qualification, and 90.3% (n=28) held a relevant professional credential other than an academic degree. Participants reported their 82 highest level of education completed as PhD 12.9% (n=4), master’s degree, 35.5% (n=11), bachelor’s degree, 45.2% (n=14), associate’s degree 3.2% (n=1), and high school diploma 3.2% (n=1). Over all 31 participants, 16 self-identified as male, 14 self-identified as female, and 1 preferred not to disclose. 4.3.4 Elicitation The elicitation consisted of online introduction meetings, completion of the questionnaire (Round 1), in-person workshops, and a final completion of the same questionnaire (Round 2), all of which took place from June–September 2023. The same elicitation method was followed in each of three metro areas and participants were informed of the existence of the other two areas, but cohorts were managed and conducted independently from each other. The identities and opinions of participants were only shared within each city cohort. All materials, such as recruitment and informational materials, were the same for each city. The same introductory presentation was given to each cohort and included an overview of the study’s purpose and methods and a demonstration questionnaire. To retain the independence of participants prior to completing the first questionnaire, participants were given opportunities to ask questions related to definitions of terms and the study logistics but were asked to not discuss anything that might give away their expert opinions on the subjects at hand. Participants were emailed the questionnaire immediately upon the ending of the meeting and were asked to complete it as soon as possible, or within two weeks at the latest. In-person workshops were scheduled to occur within 1-2 months of the introduction meetings. The Washington, DC, metro area workshop had to be rescheduled to 2.5 months after the introduction meeting because of an extreme windstorm which required most of the participants to attend to emergency clean-up efforts. 83 Prior to the in-person workshops, reports of results of the Round 1 questionnaires were produced and shared via email with each cohort prior to the in-person workshops. Participants were each assigned and informed of their random codename (e.g. “HNL_1,” “DC_1,” or “YVR_1”) and responses were only identified via codename in each city’s report, so that each participant could locate their own Round 1 responses in relation to the rest of the group, while still retaining their anonymity. Following the IDEA protocol, and general principles of expert elicitation, the primary goals of the workshops were to discuss the questions of the Round 1 questionnaire and in doing so, investigate sources of uncertainty, clarify ambiguous terms, and explore underlying reasonings behind participants’ responses to Round 1. Importantly, the goal of discussions was not to force or even work toward consensus, but rather to share knowledge between participants and improve collective responses in the final Round 2 questionnaire. Facilitators centered the workshop discussions on the first and fifth questions of the questionnaire—the actions needed and presenting the greatest opportunity to advance each goal. Participants were instructed to consider their selected actions as part of a management program that would be implemented regularly throughout the hypothetical 20-year time span. Facilitators promoted critical thinking through tactics such as probing assumptions underlying statements and use of “coherence checks,” such as asking participants to consider counterfactuals (e.g. “if this action wasn’t taken, could this goal still be advanced?”) (Rowe & Wright, 2001). 84 The lead author took on the role of facilitator and led participants through discussions first of the overall scenario context and assumptions, followed by a deep dive into each of the five goals of the questionnaire (Figure 4.4). The discussion of each goal was structured as follows: independent reflection, small group discussion (groups of three), full group discussion, and final independent reflection. This structure was designed to mitigate “anchoring bias”—the phenomena where group-based decision-making tends to be overly influenced by the first idea or information presented prior to making a judgment (Furnham & Boo, 2011)—by allowing all participants to reflect and take notes, prepare to share them with the group, then share in small groups, a greater number of ideas were encouraged and shared. Participants also changed seats so that the composition of the small groups were different for each discussion round. Research assistants aided with notetaking throughout the workshops. In final reflection, participants were encouraged to take as specific notes as possible in their workbooks to assist them in completing the Round 2 questionnaire at the end of the day. Notes were also taken during discussion by the research team. Participants were also asked to complete an optional, anonymous survey to share any reflections on their experience in the study. 4.3.5 Post-elicitation Following expert elicitation methodology, the Round 2 questionnaire was treated as the final results of the elicitation. Overall, a descriptive and comparative approach to analysis was deemed most appropriate for this primarily qualitative and categorical data, especially given the interdependencies between responses to check-all-that-apply and ranked choice questions, and because while participants filled out the questionnaires privately, the discussion phase of the 85 elicitation was designed for participants within cohorts to learn and influence each other’s final answers. We calculated descriptive statistics (e.g. frequencies, percent in favor) and created graphical visualizations (e.g. heat maps, summary tables, and box plots) using IBM SPSS Statistics, version 29, and R Statistical Software, version 4.3.0 (R Core Team, 2023). Additional direct management actions offered by participants in the second question were consolidated into consistent language and summarized (more details in Appendix S2: Table S1). In the fourth question, reasons for certainty described by participants for each scenario were coded following an inductive and deductive process (Tracy, 2019). This process began with a round of open coding from a full reading of all responses, after which a set of codes were developed to describe the main reasons for certainty and uncertainty. All responses were then coded deductively using this set of codes, with only one code assigned to each response per list of certainty or uncertainty codes (see Results, Table 4.2). For example, the response "Soil remediation aids tremendously in stormwater management" (YVR_12) was only assigned the certainty code of “Belief actions will advance goals,” while another response "We can manage for some wildlife like song birds on the street but most wildlife is going to need a forest or at least a forest patch" (DC_13) was assigned a certainty code of “Belief actions will advance goals” and an uncertainty code of “Street trees limited in advancing goals.” In instances where multiple reasons for certainty or uncertainty were given, only the most prominent was chosen to represent that response. 86 4.4 Results Overall, we found notable differences in management actions seen as needed to advance the five goals. There was also high agreement in responses across metro areas, with notable exceptions for certain actions and goals. Results are qualified by participants' certainty ratings, which were on the whole very positive, but showed highest certainty in being able to advance Canopy & Risk, and least certainty in being able to advance People-Nature. 4.4.1 Actions needed to significantly advance each goal Overall, the need for direct management throughout the street management cycle to “significantly advance each scenario’s goal above all other goals” (as phrased in the questionnaire) was strongly supported (Table 4.1). Certain actions were seen as needed for all or some goals, while others were only needed for one goal. Suites of actions considered as needed for Canopy & Risk appear to be more similar to Heat and Stormwater than People-Nature and Wildlife. There is indication of a possible tradeoff when actions were selected as needed for only one or some goals but not all, however, we did not ask about negative relationships between actions and goals. Below, we breakdown results of the questionnaire’s first question by management phase (Table 4.1) and include descriptions of these results for each metro area (for full results by metro area, see Appendix B, Table B.2). 87 Table 4.1 Aggregated responses from all three metro areas (N=31) to question “Which actions are needed to significantly advance each scenario’s goal above all other goals?”, in the context of each hypothetical streetscape scenario and assumptions. % of participants (N=31) Phase Direct management action Goal 1 Goal 2 Goal 3 Goal 4 Goal 5 Canopy & Risk Urban Heat Reduction People- Nature Relationships Wildlife Habitat Stormwater Interception & Infiltration Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 19.4 6.5 38.7 6.5 9.7 32.2 siting trees in every available planting space 93.5 100 32.3 93.5 96.8 67.7 None of these options 0.0 0.0 35.5 6.5 0.0 35.5 Plant species with x characteristic native to region 19.4 9.7 38.7 83.9 6.5 77.4 edible food (humans) 3.2 0.0 54.8 3.2 0.0 54.8 food source to native wildlife 6.5 3.2 48.4 87.1 0.0 87.1 aesthetic interest-flowers, foliage, bark, etc. 6.5 0.0 96.8 6.5 0.0 96.8 cultural significance to residents 9.7 0.0 96.8 3.2 3.2 96.8 drops leaves seasonally (deciduous) 22.6 25.8 9.7 35.5 25.8 25.8 retains leaves year-round (evergreen) 22.6 25.8 12.9 35.5 54.8 41.9 small mature size 38.7 22.6 32.3 45.2 35.5 22.6 medium mature size 61.3 61.3 32.3 48.4 58.1 29.0 large mature size 100 96.8 29.0 54.8 100 71.0 spreading or vase shaped growth habit 80.6 80.6 12.9 32.3 54.8 67.7 columnar or pyramidal shaped growth habit 22.6 12.9 9.7 19.4 19.4 12.9 round or oval growth habit 67.7 48.4 12.9 29.0 35.5 54.8 palm species 0.0 0.0 6.5 0.0 3.2 6.5 None of these options 0.0 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 0.0 0.0 3.2 0.0 3.2 3.2 variety of species by size (small, medium, large) 25.8 25.8 35.5 54.8 41.9 29.0 variety of species within previously selected characteristics 87.1 90.3 90.3 93.5 83.9 9.6 None of these options 6.5 6.5 6.5 0.0 6.5 6.5 88 Site preparation remediate soil compaction 93.5 93.5 71.0 87.1 100 29.0 test soil and amend accordingly 67.7 58.1 54.8 41.9 61.3 25.8 None of these options 3.2 0.0 19.4 12.9 0.0 19.4 Planting inspect nursery stock quality 100 93.5 83.9 74.2 74.2 25.8 stake for stability 51.6 32.3 51.6 29.0 29.0 22.6 add mulch ring with berm 45.2 48.4 51.6 45.2 61.3 16.1 prune root ball prior to planting 22.6 19.4 19.4 16.1 19.4 6.5 None of these options 0.0 0.0 12.9 6.5 3.2 12.9 Young tree maintenance perform structural pruning for young trees 100 80.6 87.1 45.2 71.0 54.8 maintain mulch ring 38.7 38.7 54.8 38.7 67.7 29.0 None of these options 0.0 9.7 6.5 22.6 3.2 22.6 Mature tree maintenance prune on a cycle (once every 5-7 years) 51.6 35.5 45.2 6.5 25.8 45.1 prune by resident request 9.7 3.2 87.1 6.5 6.5 83.9 prune in response to storm damage 58.1 29.0 67.7 16.1 22.6 51.6 prune for clearance 41.9 29.0 58.1 6.5 12.9 51.6 prune deadwood 45.2 25.8 58.1 12.9 19.4 45.2 prune as needed to mitigate risk 100 45.2 64.5 32.3 22.6 77.4 assess for plant health care needs and treat accordingly 71.0 67.7 67.7 48.4 61.3 22.6 None of these options 0.0 12.9 0.0 35.5 29.0 35.5 End of life remove trees when invasive non-native species (even if healthy) 6.5 0.0 6.5 29.0 0.0 29.0 remove trees when tree risk assessment rating exceeds moderate risk level 74.2 25.8 51.6 12.9 12.9 61.3 remove trees when declining and likely to die within inspection cycle 67.7 51.6 51.6 16.1 45.2 51.6 remove trees when completely dead 67.7 87.1 77.4 32.3 80.6 54.8 retain standing snags at safe height 3.2 0.0 12.9 54.8 6.5 54.8 retain stumps 0.0 0.0 3.2 29.0 19.4 29.0 None of these options 3.2 6.5 3.2 9.7 9.7 6.5 Note: Cells are colored on a graded scale from 0-100%. Min-Max Range is the difference between the min and max percentage across all five goals for that action, where a higher value (darker color) indicates an action was highly needed to advance one goal but not another and may present a tradeoff. 4.4.1.1 Space tree planting sites by… Almost all 31 participants selected “siting trees in every available planting space” as needed to advance Canopy & Risk, Heat, Wildlife, and Stormwater. Participants were split between all options for tree spacing on People-Nature and varied by metro area. For People-Nature, 89 participants from DC still mostly selected “siting trees in every available planting space” as needed, while none from Honolulu and only two from Vancouver did. 4.4.1.2 Plant species with x characteristic Across all species characteristics, there was most agreement among all participants that planting species of “large mature size” was needed to advance Canopy & Risk, Heat, and Stormwater. This was followed by needing to plant species with “aesthetic interest - flowers, foliage, bark, etc.” and “cultural significance to residents” for People-Nature, and “native to region” and “food source to native wildlife” for Wildlife. For People-Nature, more participants identified “native to region,” “food source to native wildlife,” and “edible food for humans” as needed, notably with participants in Honolulu slightly more likely to select “native to region” and “edible food for humans,” and DC more likely to select “edible food for humans.” No one selected palm trees for any of the five goals, except for one participant each from DC and Vancouver for People-Nature. 4.4.1.3 Plant trees that are of x species mix There was widespread agreement that planting a “variety of species within previously selected characteristics” was needed to advance all five goals. “Variety of species by size (small, medium, large)” had moderate support, mostly due to more selections from Honolulu participants. Almost no participants thought it was needed to plant “no variety in species (i.e. all same species)” to achieve any of the five goals. 90 4.4.1.4 Site preparation There was widespread agreement on the need to “remediate soil compaction” to advance all goals, especially Canopy & Risk, Heat, and Stormwater. About half of participants thought it was needed to “test soil and amend accordingly,” with no notable differences by metro area or goal. 4.4.1.5 Planting There was widespread agreement on the need to “inspect nursery stock quality” prior to planting, however fewer participants from Vancouver selected this for Wildlife and Stormwater. Approximately half of participants selected “add mulch ring with berm” for all goals, due mostly to participants from Vancouver who nearly unanimously selected it for all goals. Almost no participants from Honolulu selected “add mulch ring with berm” for any goal (in the Honolulu workshop, participants described the current quarantine on moving mulch or wood chips to prevent the spread of the invasive coconut rhinoceros beetle). 4.4.1.6 Young tree maintenance There was widespread agreement on the need to “perform structural pruning” during young tree maintenance, across all goals except for Wildlife. Like in the Planting phase, “maintain mulch ring” was favored across goals much more by participants from Vancouver than DC and Honolulu. 91 4.4.1.7 Mature tree maintenance Mature tree maintenance needs varied across goals and metro areas, with pruning related actions being selected as needed more for Canopy & Risk and People-Nature than for the other scenarios. “Prune on a cycle (once every 5-7 years)” received almost no selections from Honolulu participants, for any goal. All three workshops included at least some discussion of resident interest in pruning of trees on their street, and the opportunities that arose for engaging with residents while inspecting and pruning trees. 4.4.1.8 End of life Reasons to initiate removal varied across goals, with reasons related to risk management selected somewhat more for Canopy & Risk than for other goals. “Remove trees when completely dead” was selected as needed by most participants for all goals but Wildlife. For Wildlife, participants selecting “retain standing snags at safe height” and “retain stumps” were mostly from Vancouver, and some from DC, with only one from Honolulu. In the workshops, participants discussed the need to remove dead street trees to continue the street tree management cycle and plant new trees which could go on to provide more benefits. 4.4.1.9 Additional direct actions needed Participants generally seemed to think that the list of direct actions included in the first question was comprehensive, based on the limited range in responses to the follow-up question asking if there were any additional direct actions needed for a particular goal that were not listed in the question or referenced in the assumptions (see Appendix B, Table B.1 for a complete list of responses). Of these, additional direct actions suggested for multiple goals included: interplant 92 large trees with small understory trees (suggested for Canopy & Risk (n=1), Wildlife (n=4), and Stormwater (n=2)) and plant species with characteristics such as high leaf area index (suggested for Heat (n=1) and Stormwater (n=3)). Notably, across all scenarios, participants from Honolulu stated a preference for pruning on a shorter cycle, such as 1-3 years, than the 5-7 year cycle specified in the original list, aligning with a discussion during the Honolulu workshop that most urban trees in Hawaiʻi grow too fast for a 5-7 cycle to result in safe conditions. Of the nine total Honolulu participants, eight wrote in this suggestion for Canopy & Risk. Participants understood the scope of the study to include only direct, tree-based actions, however, answers to this open-ended question revealed how important participants believe indirect and non-tree-based actions to be in achieving certain goals. For People-Nature, many participants ignored the question parameters and wrote in detailed examples related to community engagement and education as needed to advance the goal (n=18), which would be considered “indirect actions” and outside of the scope of this study. For Heat, Wildlife, and Stormwater, though not asked for, participants provided examples of non-tree direct actions they believed were also needed, such as changing the built infrastructure or changing the ground vegetation. 4.4.2 Certainty of advancing each goal and underlying reasons Participants rated their certainty that their previously selected actions would “significantly advance each scenario’s goal above all other goals” on a sliding scale of 0-100% (Figure 4.5). For all five goals, the median certainty ratings were over 50%, indicating that on the whole, participants believed these goals could be significantly advanced with direct tree management. 93 Considering all 31 participants, Canopy & Risk had the highest median certainty rating, 88%, while People-Nature had the lowest, 65%. Wildlife and Stormwater had the widest ranges between min and max rating (91% and 96%, respectively) and largest standard deviations (20.8 and 22.2, respectively). Certainty ratings showed more alignment by metro area for Canopy & Risk, Heat, and People-Nature. Participants from Honolulu had notably lower certainty ratings for Wildlife and Stormwater. Figure 4.5 Box plots of certainty ratings (0-100%) of participants grouped by goal and metro area, in response to the question “Within the assumptions of this scenario, if all of your selected actions were taken, how certain are you that this goal could be significantly advanced in 20 years?” All 31 participants answered this question for each goal, five times total. Across all goals, participants’ reasons for their certainty ratings, given in an open-ended response question, mostly reiterated or described their belief that the actions they selected would advance 94 the goal in question, coded as “Belief actions will advance goal.” Some referenced their education or experience. A few said that the assumptions of the scenario parameters removed sources of uncertainty that would make them think a goal was less achievable in the real world, but that allowed them to have increased certainty within the hypothetical scenario. More responses in People-Nature were coded with reasons for uncertainty, in alignment with lower certainty ratings of being able to advance that goal with direct management alone (Table 4.2; Figure 4.5). There were not notable differences in frequencies of codes between participants of different metro areas. 95 Table 4.2 Coded responses to each participant’s open-ended responses to the question “What are your main reasons for certainty?” Each response was assigned one certainty code and/or uncertainty code that most reflected their response. Subtotals for each goal reflect the number of participants who express certainty and/or uncertainty in their response. Frequency of participants (N=31) Goal 1 Canopy & Risk Goal 2 Urban Heat Reduction Goal 3 People-Nature Relationships Goal 4 Wildlife Habitat Goal 5 Stormwater Interception & Infiltration Certainty codes Belief actions will advance goal 22 20 12 16 16 Experience 4 4 0 5 0 Scenario assumptions removed sources of uncertainty 3 2 0 1 0 Education 0 0 1 0 1 Subtotal 29 26 13 22 17 Uncertainty codes Complex/difficult 4 1 5 1 3 Street trees limited in advancing goal alone 0 0 3 5 5 Environmental factors 3 2 0 4 3 Need for indirect actions 0 1 8 0 0 Not enough information or knowledge 0 1 2 2 4 Social factors 1 0 6 0 0 Factors specific to their metro area 0 0 0 3 0 More scientific research needed 0 1 0 0 0 Subtotal 8 6 24 15 15 Note: Responses where the participant wrote "N/A" or similar, were coded as "N/As" and omitted from this table. 4.4.3 Points of influence to advance each goal Results indicate that each goal requires actions that are common across all goals, and actions that are unique to that goal. Specifically, there were actions presenting greater opportunity to influence specific goals, and management phases during which urban foresters could influence 96 the advancement of goals by considering these actions (Table 4.3). “Siting trees in every available planting space” was the direct action ranked as presenting the greatest opportunity to advance most goals. In addition to receiving the most cumulative top three rankings, it received the most first place rankings of any action (n=17 for Canopy & Risk, n=25 for Heat, and n=17 for Stormwater). Actions presenting the greatest opportunity to advance Canopy & Risk, Heat, and Stormwater, were broadly more in line with each other, while People-Nature and Wildlife each had different groupings of top ranked actions. By phase, actions within the planning and design phase presented the greatest opportunity to advance specific goals. Within the planning and design phase, species selection appeared to be the most important choice for urban foresters to influence goals in the hypothetical streetscape, as actions within “Plant species with x characteristic” received more rankings cumulatively than the “Space tree planting sites by…” and “Plant trees that are of x species mix” categories. After comparing rankings for each action by metro area, cities were relatively aligned, with a few notable exceptions. Virtually all DC participants (91%) ranked “native to region” among the three most important actions for Wildlife, compared to only 22% of Honolulu participants and 36% of Vancouver participants. Meanwhile, 54% of Vancouver participants ranked “retain leaves year-round (evergreen)” for Stormwater, compared to 0% of DC participants and only 11% of Honolulu participants. 97 Table 4.3 Heat map of direct street tree management actions assigned a top three ranking in response to the question “Which actions present the greatest opportunities to advance each scenario’s goal?” across all participants (N=31). Each participant could pick and rank up to three actions per goal. # of respondents assigning a top three ranking (N=31) Goal 1 Goal 2 Goal 3 Goal 4 Goal5 Phase Direct management action Canopy & Risk Urban Heat Reduction People- Nature Relationships Wildlife Habitat Stormwater Inter cep. & Infil. Total # of ranks for all goals, per action Total # of ranks for all goals, per phase Planning & design Plant species with x characteristic large mature size 17 19 1 2 16 55 food source to native wildlife 0 0 2 24 0 26 aesthetic interest - flowers, foliage, bark, etc. 0 0 23 0 0 23 cultural significance to residents 0 0 22 0 0 22 spreading or vase shaped growth habit 4 9 0 0 6 19 native to region 0 0 1 16 0 17 retains leaves year-round (evergreen) 0 1 1 0 7 9 Space tree planting sites by… siting trees in every available planting space 23 30 3 20 27 103 siting one tree for every building 2 0 3 0 1 6 Plant trees that are of x species mix variety of species within previously selected characteristics 3 9 4 11 7 34 variety of species by size (small, medium, large) 3 4 3 3 2 15 329 Mature tree maintenance prune as needed to mitigate risk 13 1 2 0 0 16 assess for plant health care needs and treat accordingly 4 4 2 2 1 13 prune by resident request 0 0 12 0 0 12 41 Site preparation remediate soil compaction 6 6 2 4 21 39 39 Young tree maintenance perform structural pruning for young trees 7 4 1 1 1 14 14 Planting inspect nursery stock quality 4 2 1 0 0 7 7 End of life retain standing snags at safe height 0 0 0 5 0 5 5 Note: Cells are colored on a graded scale from 0-31. Heat map is organized by listing phases in descending order of importance (i.e. total # of ranks for all goals, across actions of that phase). Nine actions which each received fewer than five total rankings across all goals were omitted from this table. 98 4.5 Discussion 4.5.1 Certain goals are more aligned than others Overall, we found strong evidence that street tree management actions can be aligned to substantially advance specific urban sustainability goals. In response to our first research objective, the results show that suites of actions needed for typical urban forest management goals (i.e. canopy cover and risk mitigation) have both broad overlap as well as notable differences from those needed for goals framed as specific urban sustainability goals. In particular, actions known to highly impact the survival of newly planted trees past the young tree maintenance phase (also known as the establishment phase), such as inspecting nursery stock prior to planting and performing structural pruning (Gilman et al., 2015; Ryder & Moore, 2013), were deemed essential nearly across the board. Though there was broad overlap in actions needed for most goals (Table 4.1), the actions presenting the greatest opportunity for each goal differed more starkly (Table 4.3). Specifically, we found strong evidence that actions needed for to increase canopy cover while reducing tree risk (Canopy & Risk) aligned most with actions needed to mitigate urban heat (Heat) and increase stormwater interception and infiltration (Stormwater) (Tables 4.1 and 4.3). Most of these actions were also needed to foster people-nature relationships (People-Nature) and increase wildlife habitat (Wildlife), with notable exceptions related to selecting species characteristics and mature tree maintenance. Extensive literature strongly supports the alignment of increasing canopy cover with the provision of both the ecosystem services of heat mitigation (Alonzo et al., 2021; Krayenhoff et al., 2020) and stormwater interception and infiltration (Berland et al., 2017; Selbig et al., 2022). These are often united through studying the effect of increased leaf area index (Dowtin et al., 2023; Rahman et al., 2020), as also found in studies based on the commonly used i-Tree software, comprising a 99 suite of tools for estimating urban forest ecosystem services developed by the USDA (Nowak, 2020). Nonetheless, despite these similarities, our evidence shows that managing for goals framed as changing ecosystem or biophysical structure (e.g. increasing canopy cover) requires different strategies compared with goals framed as ecosystem services or social-ecological relationships, and next look to an investigation of the specific actions which can cause these different outcomes. 4.5.2 Actions linked with specific urban sustainability goals With respect to the second research objective, we find that some actions with the widest divergences in participant response were in planting species with specific characteristics needed for People-Nature (i.e., aesthetic interest or cultural significance) and Wildlife (i.e., native to region or a food source to native wildlife), which were selected for those goals alone (Table 4.1). On the whole, these results imply that aligning urban forest management with any of the other goals could miss the opportunities to advance People-Nature or Wildlife through planting species with these characteristics. For example, one could more quickly achieve a canopy cover goal through planting fast-growing non-native tree species, even though those trees may not be ecologically appropriate (Dickie et al., 2014). Multi-objective management requires deliberate choosing of actions that align with each goal at hand (Bradford & D’Amato, 2012). Although we identified a suite of direct actions that aligns with each of the goals examined in this study, more research is required to fully develop management recommendations for specific urban sustainability goals. In some cases, experts identified barriers to implementing certain actions or gaps in research-based knowledge. In particular, they indicated relatively more 100 uncertainty about People-Nature and Wildlife, which may mirror gaps or uncertainty in the literature or perhaps illustrate inherent tradeoffs. For example, when considering People-Nature many participants in the workshops described that individual residents and diverse populations formed connections with many types of trees in ways that were difficult for them to predict. Experts related that fruit trees, for example, are often divisive—with some residents demanding more fruit trees and others demanding their removal. Literature on this subject has found that though the typical narrative aligns with most people liking trees with aesthetic or food production traits more, this can vary, as relationships people form with trees can be deeply personal and reflect a range of values, including those informed by cultural identity and personal past experiences, and influence perceptions of services and disservices (Barona et al., 2023; Fernandes et al., 2019). Nonetheless, the selection of many diverse actions (such as many different species characteristics and pruning strategies) by participants indicate a potential diversity of pathways to foster stronger relationships between residents and street trees. These results, that relationships between residents and trees on their street are different depending on the types of people and trees (and that urban foresters recognize this well), align with the growing body of literature on relational values (Chan et al., 2018), which puts forth that, like all relationships, people-nature relationships can change depending on the entities involved, and that one (e.g. person or tree) cannot be replaced without changing the relationship (Eyster et al., 2023). Literature on people-nature relationships is emerging as powerful area to understand human behavior and unlock pro-environmental behavior (Jax, Furman, et al., 2018), and our results both contribute to this body of knowledge and indicate there is great opportunity for research which could inform further activation of tree stewardship and urban sustainability. 101 While People-Nature brought up questions related to serving diverse human populations, Wildlife required considering how to support diverse native wildlife populations. In the workshops, experts described many barriers to managing for habitat in the real world, even if within the parameters of the hypothetical scenario they believed that actions such as planting native species could support native wildlife. In Honolulu, participants expressed that it was so unlikely for native birds to be found on streetscapes that they were even hesitant to try to manage for this goal in the context of the hypothetical expert elicitation, especially combined with their experience that many native tree species fail to thrive in the typically poor and non-native soils along developed streets. Issues related to suitability of native species for streetscapes were also raised in Vancouver, but from a different angle. Though participants agreed planting native species could support native wildlife in general, participants also voiced concerns that the dominant tree species in native forests of Metro Vancouver include Douglas fir (Pseudotsuga menziesii), western red cedar (Thuja plicata), and western hemlock (Tsuga heterophylla), all of which can grow to exceptional heights and sizes (50-100m), were not appropriate for most streetscapes because of their great needs for space and soil volume (British Columbia Ministry of Forests, 2024). It is also highly possible that participants only selected actions that they were familiar with. For example, discussion in the DC workshop revealed uncertainty among participants about the difference in annual stormwater interception ability between deciduous and evergreen trees, which could have influenced responses. This points to the need for more empirical research, and dissemination of such research on trait-based functions of urban trees (Dowtin et al., 2023; Farrell et al., 2022; Paquette et al., 2021). Thus, while our results describe actions which can be linked to specific goals in general, these results should be connected with 102 other sources of evidence and knowledge of local social and ecological factors to inform practice. 4.5.3 Points of influence for specific goal in the street tree management life cycle With respect to our third research objective, we find actions in all phases of the street tree management cycle are needed no matter the goal at hand (e.g. street trees require active management), however participants identified actions in the planning and design phase as presenting the greatest opportunities to influence which goals are most advanced. There were also notable opportunities to advance goals later in the cycle that should not be ignored, such as increasing stormwater infiltration through site preparation actions like remediating soil compaction and reducing tree risk (i.e. minimizing an ecosystem disservice) through mature tree maintenance actions. That the planning and design phase had the actions considered the greatest opportunities for advancing specific urban sustainability goals was not surprising, especially given the amount of literature focusing on actions in this phase (e.g. Almeter et al., 2018; Bodnaruk et al., 2017; Esperon-Rodriguez et al., 2022). The results also show the high importance of species selection when siting options are limited, as the parameters of this study (linear streetside plantings) limited creativity in siting of trees in order to reduce variables. If this study were repeated in a different setting where practitioners could direct urban tree placement, such as yards, parks, institutions, we would expect site selection to present greater opportunities to advance goals, given the growing body of literature finding significant effects from modeling differences in ecosystem services such as heat regulation from site-level tree placement decisions (Abram et al., 2022; Hwang et al., 2015). Future management planning could benefit from considering the unique opportunities to influence different goals in different phases. 103 4.5.4 Untangling differences between contexts We tried to anticipate as many differences in management needs between the three metro areas as possible in development of the study design to be able to assess actions with which all participants would be familiar. For example, we expected that appropriate street tree species would differ substantially between the three metro areas, and thus took a trait-based approach to the suite of species selection actions in the questionnaire. However, as anticipated, unexpected differences in context-based management needs still arose. One notable example clearly affected the study results for Canopy & Risk: while all 31 participants said it was needed to “prune as needed to mitigate risk,” only 16 participants, none from Honolulu, said “prune on a cycle (5-7 years)” was needed. Meanwhile, eight out of nine Honolulu participants wrote in answers that pruning on a shorter cycle, such as 1-3 years, was needed to advance Canopy & Risk. This suggests that had the questionnaire been phrased differently, such as “pruning or inspecting trees on a locally appropriate cycle,” 24 or more participants may have supported this action for Canopy & Risk. The recommendation to prune trees on an approximately 5 year cycle is widespread in temperate cities, and originates from seminal research from Milwaukee, Wisconsin, which determined this an optimal cycle length to reduce tree risk and overall maintenance costs (R. W. Miller & Sylvester, 1981). Inspection and pruning cycles are critical components of mature tree maintenance to identify health issues, promote strong tree architecture, and mitigate risk to residents from dead or dying tree parts, yet they are expensive and as a maintenance line item, do not receive as strong support from city leaders as do exciting tree planting initiatives (Koeser, Hauer, et al., 2016; Vogt, 2015). In sum, mature tree maintenance activities such as proactive inspection and pruning are essential to achieving most goals across all metro areas, with a notable exception for supporting wildlife habitat (likely specifically for species reliant on tree cavities, such as in Kane et al., 2015). 104 Although participating experts were broadly aligned on actions needed to achieve each of the goals, we identified differences across metro areas in certain key areas. We suspect these differences are a product of likely differences in local knowledge bases and training which interact with local social and ecological needs and conditions. For example, the ban in place at the time of writing on moving mulch in Honolulu due its ability to transport the invasive coconut rhinoceros beetle (Oryctes rhinoceros) not only rightly resulted in expert participants not recommending mulching, but based on discussions in the workshop, seemed to also be paired with less experience and knowledge of with the potential benefits of mulching compared to participants in DC and Vancouver. Similarly, all Vancouver participants recommended retaining standing snags for Wildlife (Appendix B, Sub-table B.3.4), perhaps because of a movement in the professional tree care community of the Pacific Northwest to preserve habitat for cavity-nesting wildlife (B. French et al., 2020; Wildlife Dangerous Tree Committee of British Columbia, 2019), which seems not to have taken hold in DC. A comparable wildlife movement in the tree care community in Hawaii created guidelines for the only native bird species that is found to nest in street trees, manu-o kū (Gygis alba), which was reflected in the discussions and subsequent responses of the Honolulu participants (manu-o kū lays directly lays eggs in crooks of branches of street trees and does not seem to discriminate between trees based on nativity status) (Bassett et al., 2022; Liu et al., 2019). This idea of regional knowledge bases may be a factor in the varying certainty ratings between metro areas as well. For example, in the DC area, urban foresters are frequently involved in stormwater management discussions (perhaps in part due to region wide efforts to protect the Chesapeake Bay watershed, see Kimball et al., 2014), while urban foresters in Honolulu described being disconnected from stormwater management 105 issues, due to barriers including disciplinary silos. However, though our results illuminate interesting and novel instances of difference between our included cities, we were overall relatively surprised at the high level of agreement in this study between participants of different metro areas. 4.5.5 Applications to multi-objective management for urban sustainability We believe our study represents an important contribution towards the multi-objective management of urban forests for urban sustainability goals. Our results present a step forward in tailoring phase-specific management plans in multi-objective management of urban forests, however, this should be done with consideration for local factors, emerging literature on effects of management actions, and sustainability goals not included in this study. Additionally, despite being frequently reminded that this study was limited to direct street tree management actions, participants continuously pointed out many strategies to advance goals through indirect management actions, like fostering people-nature relationships through community outreach and education, or non-tree actions, like increasing stormwater retention capacity through engineered green infrastructure. This contributes to the idea that urban forest management cannot advance urban sustainability through trees alone, and that there are likely powerful benefits that could accrue when urban foresters connect with other disciplines, communities, and practices (Campbell et al., 2022; ʻĀina of Kaʻōnohi et al., 2023; Vogt et al., 2016). Our results should also thus be considered within the context of managing urban forests as complex social-ecological systems within dynamic and changing urban areas. 106 4.5.6 Limitations Overall, outcomes from expert elicitation as a method are limited by knowledge of the expert participants and common biases, which can include overconfidence and reliance on cognitive heuristics (Morgan, 2014). In constructing the elicitation, although we attempted to achieve a balance between asking questions that could open new areas of inquiry as well as match the knowledge of urban foresters, our participants themselves acknowledged significant differences in their depths of understanding on topics within the elicitation in workshop discussions and in the questionnaire (Table 4.2). The scope of our study was as comprehensive as possible in terms of inclusion of considered management actions and diversity of sustainability goals, within the limits of managing participant fatigue. We were also limited to subject areas we expected urban forest professionals to have a deep understanding of, which did not include emerging topics of importance such as the role of greenspace in human health (Pinto et al., 2022) or topics with considerable complexity and uncertainty in the literature, such as the relationship of trees and air quality (Eisenman et al., 2019). Because of this, study results could also serve to guide future science dissemination and professional education, for topics where expert knowledge may seem not to reflect the state of the science. To meet the goal of generating results generalizable beyond the study metro areas, both goals and actions were framed broadly. Though our study design was limited to only three metropolitan areas, we also see this as a feature of the novelty of the study, as most expert elicitations either combine participants from many locations into one cohort, e.g. through virtual discussion processes, or are limited to considering a single location. This meant that despite careful adherence to consistent communications and facilitation procedures, participants from each cohort will have had different experiences in the influential discussion phase of the 107 elicitation. Future research could more fully investigate factors identified within each of these metro areas to understand practices within a specific region and could investigate regions not included in this study. Using these results to inform practice and policy will require considering the assumptions within our hypothetical scenario, including but not limited to the considerable costs of individual tree management such as watering trees in establishment, threats from climate change and invasive pests undermining knowledge of suitable species, and limited soil volume and quality in most streets. 4.6 Conclusions Our study offers a comprehensive, qualitative, evaluation of street tree management actions in relation to a selection of commonly targeted urban sustainability goals. We find that managing for widely adopted canopy cover goals could result in missed opportunities to advance other important sustainability goals and that there is more alignment in management approaches for certain goals than others. Additionally, it is critical to support the entire street tree management cycle in order to advance all goals using street trees, but that each phase presents different opportunities to advance different goals. These findings can lay the foundation for future quantitative studies, such as through suggesting inputs for future modeling and highlighting areas to advance quantification efforts on the effects of management actions on outcomes, all of which can contribute to better assessment of tradeoffs to inform multi-objective management for urban sustainability (Bradford & D’Amato, 2012; Rounsevell & Metzger, 2010). Experts can be a valuable source of insights to inform practice, such as through evaluating management options (Hagerman & Satterfield, 2014), and to inform further research, such as identifying inputs for environmental modeling (Krueger et al., 2012). In this study, we found expert elicitation to be an 108 expedient and fruitful exercise with positive benefits to the production of generalizable knowledge, and to the participants themselves. Given changing cities and climates, it would not be possible to test the number of variables considered in this study over a 20-year horizon. Still, the findings should be taken as a whole and integrated with local knowledge and emerging, relevant, research. We present evidence that site-level management decisions must be made deliberately to successfully use urban forests as a nature-based solution for urban sustainability goals. 109 Chapter 5: Conclusion 5.1 Introduction After decades of building momentum from advancements in research and practice, there are many signs that the field of urban forestry is at the brink of entering into a new era. The increased recognition of the essential services urban forests provide to society is resulting in increased demands on the professionals who manage them, and triggering much needed advances in professionalization (O’Herrin et al., 2023). Research and technology to aid in the management and assessment of urban forests is likewise rapidly advancing (Nitoslawski et al., 2019), paired with advances in understandings of the relationships between urban forests and dimensions of human and ecosystem well-being (Barron et al., 2019; Pataki et al., 2021). The social dimension of urban forestry is likewise emerging to take centerstage in research and practice, especially in the understanding of how historic tree management practices have resulted in environmental inequities (Locke & Grove, 2016) and how current and future work can serve to remedy injustices (Nesbitt et al., 2018). At the same time, related fields of study, including on the concept of ecosystem services (Daily & Ruckelshaus, 2022; Díaz et al., 2018) and paradigms and definitions of urban sustainability (Frantzeskaki et al., 2021; Wu, 2014) have rapidly advanced; how these advances will affect urban forestry and its role in cities remains to be seen. In their defining 1997 paper, Clark et al., stated “while we may be able to describe the desired functions of a sustainable urban forest, we cannot yet design the forest to optimize them” (J. R. Clark et al., 1997). Much progress towards this goal of linking human action and subsequent urban forest function has been made since then, and this dissertation builds upon this body of work. Using street trees as the connecting element to explore how changing the management of one system of interest can affect the future sustainability of not just urban forests, but cities, this 110 dissertation takes a critical look at the current paradigms of urban forest management in the US and Canada and asks how they could be changed to further urban sustainability. The foundation to all of this momentum fueling the growth in the science and practice of urban forestry are the paired, evidence-based, expectations that (1) trees do and will continue to provide essential benefits to cities (Dobbs et al., 2014; Roy et al., 2012) and (2) professionals can increase such benefits through skilled management (O’Herrin et al., 2023; Ordóñez et al., 2020; Östberg et al., 2013). Nonetheless, to fulfill these expectations, there are major gaps in understanding which types of management align with which goals. There is also a dearth of evidence to support professionals in aligning their decision making with sustainability goals, related to critical issues like climate change adaptation or biodiversity conservation (Hutt-Taylor et al., 2022). My doctoral work directly contributed to these gaps through the establishment of a multi-year grant-funded research project titled Street Tree Futures, led by a team from the University of British Columbia and composed of interdisciplinary urban forestry researchers and practitioners from Canada and the United States. This dissertation is the result of studies from Street Tree Futures, all of which investigate the nexus between urban forest management and benefit provision, specifically, how to operationalize urban forestry in service of sustainability goals. I, and the teams I had the opportunity to work with in Street Tree Futures, established current paradigms in urban forestry practice and advanced understanding on the role of site-level decision making in urban ecosystem management in service of specific sustainability goals During the course of this work, two major initiatives arose which provide unprecedented funding for urban forestry in North America, amplifying the need for timely and relevant evidence to 111 inform practice. In the US, the Inflation Reduction Act allocated US$1.5 billion for urban and community forestry over ten years, with at least 40% of the funds targeted for disadvantaged communities under the Biden Administration’s Justice40 initiative (USDA, 2023). In Canada, the 2 Billion Trees initiative was announced to fund tree planting on rural, suburban, and urban land through afforestation and restoration (Government of Canada, 2020). These “once in a generation” resources will support the planting of millions of trees and management decisions which stand to significantly shape the urban forests for the next century, and beyond. While urban foresters often cite budget constraints as a top barrier to improving their programs (Ordóñez et al., 2019b), recipients of these new funds have the chance to tackle ambitious plans and apply the most advanced procedures in service of their goals. In this context, understanding the impacts of urban forest management decisions is incredibly timely to make the best use of these opportunities and ensure they lead to improved urban conditions. In this dissertation’s conclusion, I aim to synthesize previous chapters and highlight key findings for research and practice to more strategically mobilize urban forests as solutions to specific sustainability goals and make the most of available resources. More broadly, I hope to situate urban forest management, and the professionals who hold urban forestry expertise (i.e. urban foresters), within the context of urban ecosystem management and describe how they can be better operationalized for urban sustainability. 5.2 Summary of dissertation findings This dissertation was guided by an overarching research question: “How do site-level urban forest management actions advance strategic-level urban sustainability goals?” Street trees were chosen as the focal unit of analysis, as the most generalizable and comparable unit across North 112 American cities and the component of urban forests typically the most intensively managed by urban foresters, though connections are made to urban forest management issues as a whole. From the outset, to complement my doctoral supervisory committee composed of interdisciplinary urban forestry and sustainability researchers, I established an advisory committee of cross-sector urban forestry professionals to inform and advise the project (who were also the advisory committees for Street Tree Futures). Three components were designed to address different dimensions of this question, followed by a fourth component to synthesize the previous components (this conclusion chapter) (Figure 5.1). Figure 5.1 Conceptual framework of the dissertation’s research questions and associated chapters. The first component addressed the sub-question (1) “Why are site-level decisions important to achieving strategic-level sustainability goals, in the context of implementing urban nature-based solutions to achieve city goals?” This perspective piece framed the main themes of the project 113 and justified the importance of small decisions in achieving urban sustainability goals (Chapter 2). The economic concept of the tyranny of small decisions was used as a foil. Instead of framing small decisions only for their potential to undermine sustainability goals (Kahn, 1966; Odum, 1982), we use the concept to show the power of small decisions and those who make them, and the untapped potential of ecological stewards to harness these decisions towards urban sustainability. Using urban forestry initiatives as a case study, the article illustrated the potential of small decision makers to drive widespread change and argued for a more integrative approach that empowers local specialist expertise to more effectively achieve sustainability goals. The second component addressed sub-question (2) “What are the current challenges to, and best practices for, aligning street-level urban forest management actions to contribute to sustainability goals that are framed as ecosystem services?” (Chapter 3). This study explored and established the current state of how urban foresters in the US and Canada conceptualize the alignment between their street tree management decisions and strategic sustainability plans set in their cities. Urban foresters at cities with adopted sustainability goals framed as ecosystem services, though able to articulate management tradeoffs for specific ecosystem services, were found to not use these goals in day-to-day decision-making about street trees. Instead, their priority was on goals related to biophysical structure, such as increasing canopy cover or reducing risk of tree failure. This was predicated on the widespread paradigm that managing for “more, bigger trees” results in more ecosystem services overall, which we posit is a good proxy for certain goals but misses opportunities for others. 114 The third component addressed sub-question (3) “How can urban foresters align their street tree management actions with specific urban sustainability goals?” (Chapter 4). This study established links between which direct street tree management actions could influence five urban sustainability goals (related to canopy cover and tree risk, heat mitigation, people-nature relationships, wildlife habitat, and stormwater management) through a structured expert elicitation in Vancouver, Honolulu, and Washington, D.C. Opportunities to advance specific goals were identified, particularly through actions in the pre-planting phase such as site and species selection. The results of Chapter 4 established not only that site-level management actions can be linked with specific goals, but that these actions are needed and present key opportunities to deliver such goals. This conclusion chapter represents the fourth component (4) and aims to synthesize the main academic contributions from the dissertation and envision implementation strategies for research and practice of urban forestry. To launch this synthesis process, I share reflections from a semi-structured focus group discussion conducted as part of the Street Tree Futures project to reflect on findings of the earlier components. Then, I describe key contributions and significance to the research and practice of urban forestry, strengths and limitations, and final conclusions. 5.3 Process to synthesize dissertation findings To guide the synthesis of this dissertation, I turned to the literature on research synthesis to follow a deliberate and transparent process (Wyborn et al., 2018). Research synthesis entails selecting and distilling the “information overload” posed by original research studies and translating findings into information matching the needs or context of decision makers (Dicks et 115 al., 2014). Synthesis methodologies can range from systematic or scoping literature reviews, to structured decision-making processes, to focus groups and expert consultation, all of which range in time and resources required to execute as well as credibility of created outputs (Dicks et al., 2017). In the process of synthesis, the new outputs can be greater than the sum of its original parts, as the inter- and trans-disciplinary teams of subject matter experts who typically conduct synthesis activities (and are considered to be best poised for these tasks) can have a strong hand in shaping outputs based on their own expertise, pointing to the need for transparency (Dicks et al., 2017). Who is considered an “expert” necessarily shapes the outcomes of research synthesis through the inclusion and exclusion of different types of knowledge (Burgman et al., 2011). In this synthesis, I relied on the research and practice advisory committees of Street Tree Futures project, which included representation from the university, government, private industry, and non-profit sectors—the most prominent sectors leading urban forestry. I brought these members together in the Street Tree Futures Research-Practice Summit to gather the diverse and expert perspectives of our team and to provide a process for generating the foundations for the synthesis process. 5.4 Reflections from the Street Tree Futures Research-Practice Summit The Research-Practice Summit was held in October 2023, after completion of data collection and analysis of the prior project components, to synthesize overall findings and discuss implications for future research and practice. This summit took the form of a semi-structured focus group discussion. I led and facilitated this meeting, and the participants were three members of the Street Tree Futures research committee, two members of the professional advisory committee, one facilitator, and one notetaker. First, the problem statement of apparent disconnect between 116 small decisions and strategic goals was presented and framed (as described in Chapter 2). This was followed by three focused discussions. The topics for the three focused discussions were (1) findings of Chapter 3, semi-structured interviews with urban foresters, (2) findings of Chapter 4, expert elicitation, and (3) synthesis and implications of findings for research and practice of urban forestry. The reflection prompt for discussions (1) and (2) was “From these results, what is one thing that you think is very significant? What is one thing that you think that is missing?” and the final reflection prompt for discussion (3) was “Please share one future direction or application of these results for research in urban forest management and the practice of urban forest management.” Each discussion took the structure of a short presentation of previous findings, independent reflection in response to open-ended question prompts, sharing of reflections in randomized order, followed by open discussion, and final written reflections by participants on collected note cards. The primary themes of the written reflections of participants were summarized and augmented with detailed notes taken during the focus group and are described below. 5.4.1 “Us vs. them”: gaps between urban forestry and allied fields Research-Practice Summit participants were most struck by the disconnects between urban forest management and city ecosystem service goals that municipal urban foresters expressed (Chapter 3). These were summed up by an “us vs. them” or “my goals vs. their goals” mentality and the recurrent themes of needing to overcome departmental silos and increase collaboration. Some summit participants were disappointed, but not too surprised, with one participant reflecting “I feel as if not much progress has been made on the idea that the person in charge of trees operates in a vacuum.” There was agreement on the need to understand ways to connect 117 urban foresters with so-called “other goals,” and not just tree-focused goals through, for example, exploring governance arrangement processes to include urban forestry within broader planning, and having mechanisms for goal accountability. Future research could also consider the impact of the type and structure of municipal plans and degree to which urban forestry is integrated in such plans. Sharing success stories, such as cases where urban foresters were given a seat at the table in the planning process and how that affected outcomes for urban forest management and city ecosystem goals, was an idea for inspiring future action. 5.4.2 Management actions can be linked with specific ecosystem service goals The findings of the expert elicitation study (Chapter 4) were overall perceived to have high application for urban forestry practice and as foundations for future research. As one summit participant wrote, the identification that “some actions clearly serve multiple services, and other actions are more specific.” Identifying actions as fundamental to tree health and longevity, for example, structural pruning for young trees, or as needed to advance specific services, for example, retaining dead trees for wildlife habitat, could aid in evaluation of tradeoffs and synergies of ecosystem services presented by management. However, because of the “mostly perfect world” assumptions in the expert elicitation scenarios, there were questions as to how the findings would fit in real world situations, where issues such as conflicts with built infrastructure, budget constraints, and limited and/or poor-quality soils, are major constraints. Some links found were thought to be more novel and represent a shift in thinking among urban forest professionals, especially the potential of a range of mature tree maintenance actions to support people-nature relationships and potential alignment between actions to support wildlife habitat and people-nature relationships. 118 Summit participants commented both on the difference in how expert elicitation participants responded to the hypothetical scenario and in the results of the elicitation themselves. For example, the expert elicitation results present strong evidence that urban foresters can link specific actions with specific ecosystem services, while the results of the interviews showed that urban foresters can do this to a degree, but preferred a focus on structural goals, such as canopy cover. Summit participants observed alignment in the results of the two studies in that expert elicitation participants were more confident their actions could advance a canopy cover and tree risk reduction goal, than they were in advancing other ecosystem service goals. 5.4.3 Implications for research and practice The summit finished with a discussion of the overall findings of the project and their implications for research and practice of urban forest management. Barriers to using Street Tree Futures study results to improve alignment of urban forest management with city-wide sustainability goals included needing additional information to (1) translate generalized findings to specific social and ecological contexts and (2) understand the local governance arrangements in different cities. For example, participants discussed that it was likely that plans imbued with more authority, monitoring, incentives, or enforcement mechanisms, or plans created through deeper engagement processes, could have more alignment between urban forest management and specific goals. The challenges to alignment identified in Chapter 3, such as departmental silos and need for decision-support tools, were brought up as key areas to focus on in future research and practice. Most participants believed the linkages between actions in goals identified in Chapter 4 represented a substantial synthesis of knowledge which could significantly advance 119 practice. However, because of the many assumptions in the hypothetical scenarios used in this study (especially the removal of typical barriers such as budget constraints and infrastructure conflicts) Research-Practice Summit participants wondered how results could be applied in real world scenarios. They also saw a need to consider other ecosystem services or disservices, such as those related to human health, like reducing allergens or trapping particulate matter, which are critical wellbeing challenges in cities. Overall, participants suggested new avenues for academic research that could build from the results of Street Tree Futures, which we synthesized into a list of future research questions (Table 5.1). These were primarily related to understanding and quantifying the impacts of site-level management on sustainability outcomes, and the relationships between managing for tree health and enabling community tree stewardship. In the near term, results could inform outreach and education efforts, such as increasing awareness on which actions impact which ecosystem services and supporting communication between urban forestry and other departments, institutions, and professions, working towards urban sustainability goals. Using results to serve as foundations for best practices or decision-support tools, combined with locally relevant information, could provide a path to substantially improve urban forest management decision-making. Table 5.1 Synthesized list of future research questions, building from results of the dissertation. Research questions 1. How do other stakeholders (e.g. private residents, institutions) align their direct urban forest decision-making with specific urban sustainability goals? 120 2. Does increasing the visibility of tree maintenance to the public impact human relationships with trees? 3. Which actions lead to the most benefits, in resource constrained environments? 4. How much impact could be made on a given goal by aligning site-level actions? 5. What are the barriers to aligning actions with specific sustainability goals (e.g. governance, measurability)? 6. What is the relationship between tree health and each sustainability goal? 7. How do current tree management best management practices align with different sustainability goals? 8. How should professionals adapt practices to align with goals in their cities? 5.5 Key contributions and significance to the research and practice of urban forestry Aligning site-level management decisions with strategic level sustainability goals would present a paradigm shift for urban forestry. For one, this research opens up new avenues for further research to consider how actions throughout the street tree management life cycle can be mobilized for sustainability, where most current research is typically focused on “what to plant where,” furthering the neglect of other phases of management also needed to achieve strategic goals (Almeter et al., 2018; Bodnaruk et al., 2017). Furthermore, this dissertation contributes to understanding of the purpose of urban forestry and how management paradigms can support this purpose. Typical narratives inside the professional and research communities often describe understandings of the benefits of trees as ways to advocate for further tree preservation and planting (Chapter 3). Through a structured expert elicitation (Chapter 4), we found managing for increased canopy cover to require similar suites of actions as the other goals, and to be a close proxy for urban heat and stormwater mitigation especially. We also identified actions that this goal does not incentivize, such as the planting of native or fruit bearing species. Our findings also suggest that the framing of strategic goals—whether intended to change ecosystem structure 121 (e.g., a canopy cover goal), increase provision of an ecosystem service (e.g., heat regulation or stormwater interception), or foster people-nature relationships (e.g. encourage bonds between residents and trees)—resulted in different management strategies. These complement literature finding that the framing of goals can significantly impact subsequent management (Biddle & Koontz, 2014) and that engaging with relational values can elicit different sets of viewpoints and actions (Chapman et al., 2019; Eyster et al., 2023). Overall, we have identified key points of influence in the street tree management life cycle where specific sustainability goals should be considered as a part of decision-making (such as through intentional species selection prior to planting, and mature tree management decisions later in the cycle to enable longevity). All together, these key points identified in Chapter 4 present new pathways to overcome the disciplinary silos identified as a barrier in Chapter 3 through articulating strategies to align urban forest management with strategic sustainability goals usually thought of as belonging to other disciplines, such as stormwater management or wildlife conservation. These pathways to align actions with specific goals build off of research that already supports this work, such as through more intentional site and species selection in new plantings (Bodnaruk et al., 2017). We propose that these pathways be used to connect urban foresters with other disciplines and leaders steering urban sustainability efforts. However, to truly value what interviewees referred to as “other goals” at their city, i.e. ecosystem service goals including climate change mitigation, urban heat reduction, etc., (Chapter 3), a shift in thinking is needed, to see trees as more than a natural asset managed in a vacuum, and instead as part of the social-ecological system of cities which support and improve the wellbeing of human and non-human residents (Keeler et al., 2019). 122 However, working with other disciplines, even so-called “allied” professions like planning or landscape architecture, is extremely limited not only by the capacity and willingness of urban foresters, but by the capacity and willingness of other disciplines to engage with urban foresters. Even basic awareness of the existence of urban forestry and its potential to be mobilized in service of other objectives is a major barrier. A striking example of this that hits close to home is a recent study by researchers from UBC’s School of Community and Regional Planning and the Sauder School of Business (Yumagulova & Vertinsky, 2019). The authors conducted an analysis of knowledge systems for urban resilience in the Metro Vancouver region, specifically related to flood risk, and contend that cities need to move beyond “engineering supremacy” and towards models that support multiple knowledge systems and collaborative governance. As a researcher in urban forestry, and urban ecosystems systems broadly, at an institution home to one of the largest urban forestry research and educational programs in the world (which frequently collaborates with the planning school), I hoped to see in this analysis even small nods to the role of natural systems, or even urban forests specifically, in mitigating flood risk as supported by decades of research (Berland et al., 2017; Coville et al., 2022; Dowtin et al., 2023). However, no such mentions of any nature-related terms were made, despite the aim of the paper to promote collaboration and interdisciplinarity. In highlighting this example, I do not intend to lay fault or negative blame about the individual authors or other researchers in these communities, many of whom do incorporate nature-based solutions in their approaches to urban sustainability (e.g., Conger & Chang, 2019). However, the article is nonetheless representative of how urban forestry, and urban ecology as a whole, can easily be overlooked and left out of broader 123 discourses in urban sustainability, exemplifying the disconnects which were encountered in this dissertation and related literature (Ordóñez, 2021; Vogt, 2018). Nonetheless, the gaps must be bridged. The rise of concepts such as ecosystem services (and more recently, the concepts of green infrastructure and nature-based solutions) have substantially moved the needle on “telling the story” of how urban forests contribute to cities and support the wellbeing of residents and progress towards sustainability (Escobedo et al., 2019). As awareness increases of not just the nature in and of cities, but of the need for nature for cities (Pickett et al., 2016), urban foresters, as key agents of change within urban ecosystems, need to be prepared to likewise adapt their management to target the present and future needs of cities. New funding sources, such as the Inflation Reduction Act and Bipartisan Infrastructure Law in the US, and the 2 Billion Trees Initiative in Canada, present opportunities not just to advance the scale and sophistication of new urban forestry programs, but to raise the profile of, and attract attention to, the field. Theoretical advances in understanding the benefits of nature to people are likewise rapidly expanding in other fields, such as evolutions of the concept of ecosystem services to better include cultural values, and the introduction of the umbrella concept of nature’s contribution to people (Díaz et al., 2018), which remain underexplored in urban forestry. Unfortunately, the interdisciplinary nature of urban forestry research can pose challenges to finding the significant funding required for long term research—leading some academics to describe their work as stuck in a “permanent ‘pilot study’ mode” (Sustainable Urban Forests Coalition, 2023). Overall, although there is overwhelming evidence substantiating the myriad benefits urban forests provide to society, to truly operationalize urban forestry in service of sustainability goals, research is needed to inform evidence-based frameworks to aid professionals 124 in simplifying the complexity of the real world and aligning actions with goals. This dissertation specifically contributes to this aim by showing the power of site-level decisions to achieve or undermine strategic goals (Chapter 2), establishing the main barriers to aligning street tree management with ecosystem service goals (Chapter 3), and providing a qualitative assessment of the key points of influence for different goals throughout the street tree management life cycle (Chapter 4). 5.6 Strengths and limitations This research was strengthened by a diversity of cases, incorporating perspectives from cities of varying sizes and diverse social and ecological contexts across the United States and Canada, including cities underrepresented in the literature such as Honolulu. This broad scope enhances the generalizability of the findings to urban areas within these countries. An important limitation is that results are rooted in the assumption that urban foresters possess valuable knowledge on the connection between their actions and the provision of a multitude of ecosystem services. Researchers may find the expertise of urban foresters to be behind the state of the science concerning the specific mechanism of provision of certain benefits. The scope of this dissertation was also limited in focus on direct management, and while appropriate to the questions being asked, could not thoroughly consider the likely very influential context of the social and governance contexts of such actions (M. L. Johnson et al., 2019). The focus on street trees also aided in comparability between sites, but limits applications of results to other components of the urban forests with different management regimes e.g. parks or urban natural forests (Pregitzer et al., 2019). 125 I also acknowledge the limitations inherent in the synthesis process of this conclusion, which requires making selective choices about which findings to emphasize and thus is subject to the inherent biases of authors, though I attempted to mitigate this earlier in the chapter by making the process transparent. Finally, while the papers contribute valuable insights applicable to the US and Canada, the transferability of these findings to other countries may be more constrained, due to differences such as local governance arrangements and ecology. 5.7 Final thoughts In many ways every component of this dissertation has been a work of evidence synthesis—I have drawn on diverse bodies of literature and perspectives of many experts, and my analysis has sought to develop generalizable findings for which can be operationalized in service of real societal needs. Though I present key novel contributions to this effort, I also know this is just the beginning. In that light, I present three main recommendations from this research. 1. Advance research to characterize and quantify the relationships between management actions and urban sustainability goals (such as through funding investigations of the questions in Table 5.1) 2. Break down “us vs them” barriers to integrate urban forests into holistic urban ecosystem management, and advancement towards strategic urban sustainability goals 3. Look to other fields, such as advances in the science of ecosystem services, to advance pluralistic understandings of the benefits of urban trees and the people-nature relationships that underpin and propel stewardship. 126 Ecosystem management decisions, such as those arising in urban forestry, are nearly always made with insufficient information. While an idealized pathway for evidence-supported decision making may rest upon systematic review of all available evidence, it is also common for single studies, or selections of studies, to have outsized impact on decisions or official guidelines (Dicks et al., 2014; Haynes, 2001). I recommend that if seeking to apply these results, for example, in tailoring actions for a specific sustainability goal, that any direct findings be applied in combination with local and expert knowledge, especially subject matter experts. It is not realistic or possible for every urban forester to become an expert on the complex mechanisms of benefit provision for the many possible benefits that city residents need, nor is it possible for experts in subjects as diverse as hydrology, microclimate regulation, wildlife ecology, and sociology to understand the complexities of urban forest management. Coalitions with diverse knowledge bases are therefore perhaps the only pathways to integrate scientific evidence with local conditions to support the decision-making we need. 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Ecosystem service Example of ecosystem service goal Climate change mitigation "Reduce GHG emissions 80% below 1990 levels by 2050, with a long-term goal of becoming a net zero community" (p. 6). City of Mississauga. (2021). Climate Change Action Plan Progress Report. https://www.mississauga.ca/wp-content/uploads/2020/09/30164812/Mississauga-Climate-Change-Action-Plan-Progress-Report-2021.pdf Stormwater “Goal 4: Leverage stormwater investments to help manage future flood risk from extreme rain and sea level rise. Future investments can alleviate flooding throughout the city” (p. 13). City of New York. (2021). New York City Stormwater Resiliency Plan. https://www.nyc.gov/assets/orr/pdf/publications/stormwater-resiliency-plan.pdf Urban heat "N-1.4: Implement heat island mitigation strategies though development. Evaluate development codes for opportunities to encourage or require urban heat island mitigation strategies as part of new development or redevelopment." (p. 57). Kansas City. (2022). Climate Protection and Resiliency Plan. https://www.kcmo.gov/home/showpublisheddocument/9912/638112897582470000 Biodiversity “Explore incentives for and encourage developers to integrate natural biodiversity features (e.g. trees, wetlands) into development; Incorporate a Biodiversity Checklist (Appendix G) that will require developers to achieve a specified biodiversity target, but permit flexibility in how this can be achieved.” (p. 85). City of Surrey. (2014). Biodiversity Conservation Strategy. https://www.surrey.ca/sites/default/files/media/documents/Surrey_BCS_Report.pdf Human health "Maximize the role of parks and recreation in promoting healthy communities and lifestyles." (p. 164). City of Austin. (2018). Imagine Austin Comprehensive Plan. https://www.austintexas.gov/sites/default/files/files/Imagine_Austin/IACP_2018.pdf 172 Table A.2 Guide for semi-structured interviews with urban foresters at municipalities in the US & Canada, organized by section (Tracy, 2019). Questions were often slightly adjusted, or different follow-up questions may have been asked during the interview, in response to participant and conversation. Section Questions Opening 1.1 To begin, can you tell me briefly about your job history in urban forestry and how long have you worked in this field (urban forestry or arboriculture)? 1.2 How long have you been a [position title] at [City of____]? 1.3 What are your primary responsibilities and tasks in your current role? 1.4 To get an idea of the size of your program… 1.4a Do you have specific trees or a specific geographic area that you have authority over? 1.4b How many trees? 1.4c How large an area? 1.4d How many people are employed in urban forestry at your city? How many report to you? 1.5 What is your position’s authority over decision making for these trees? 1.5a Does the city have full responsibility over all street tree management, or is that shared with anyone, such as adjacent property owners? Generative 2.1 Specifically thinking about physical, or maintenance actions, what actions do you or your staff take in this phase? For example, we’re interested in hearing about things like species selection, but not communication with a resident: 2.1a Pre-planting phase, such as species selection, siting where trees will be planted 2.1b Planting phase 2.1c Maintenance phase 2.1d What are the differences between management decisions made about young vs mature trees? 2.1e End of life, old trees, and removal phase 2.2 When a decision needs to be made about street trees, what management objective or objectives is most important in deciding what to do? 2.3 Do you have any questions about this definition [Participant prompted with a definition of ecosystem services]? 2.4 Do you think it is part of your position’s job duties to manage trees for any specific ecosystem services? 2.5 Given this definition, are you aware if your city has any goals related to ecosystem services like these, of any type? If so, what are they? (if yes, aware of some goals) 2.5a What kind of documents or plans is that goal/are each of those included in? Urban forest planning documents, like a management plan or strategy? Climate action plan, municipal plan, resilience strategy? 2.5b Do you know how these goals got incorporated into these documents? Can you tell me about it? (If haven’t heard of the plan they mentioned) 173 2.5c Can I follow up to ask for a copy of the management plan or strategy? 2.5d What kind of input did you have in these plans? (if no, not aware of any ecosystem service goals) 2.5e I have done some web searches and found some goals and plans I’d like to ask you about (refer to list) 2.5d Have you heard of this goal or plan before? (if the goal or plan explicitly mentions trees): Do you know how these goals got incorporated into these documents? Can you tell me about it? Directive 3.1 To recap, we talked about [list the goals talked about] that your city has set. Overall, which of these goals is most important to manage for, in your position? Do you have the most responsibility to manage for? 3.1a Why is that? 3.1b Do you use any specific strategies to achieve that goal? What are they? 3.2 How important is this goal compared to street tree management objectives you talked about before? (prompt with the objective that was mentioned before, e.g. risk management) 3.3 Now, using the example of the goal that was most relevant to your work, I want to talk really specifically about street tree management strategies. Part of my research is about bringing together all the possible ways that we adjust or change, in one way or another, the benefits of trees. So that when cities set goals, we can better align management to actually achieve those goals. Does that make sense? 3.4 Thinking back to the street tree management actions you talked through at the beginning, let’s talk through this together: 3.4a Which decisions in the pre-planting phase could increase that benefit from street trees and help achieve that city goal? 3.4b Which decisions in the planting phase could increase that benefit and help achieve that city goal? 3.4c Which decisions in the young tree maintenance phase could increase that benefit and help achieve that city goal? 3.4d Which decisions in the mature tree maintenance phase could increase that benefit and help achieve that city goal? 3.4e Which decisions in the “end of life” phase could increase that benefit and help achieve that city goal? 3.5 Overall, do you think that street tree management in your city are aligned with the city’s ecosystem service-related goals that we have discussed? 3.5a What do you do to align operations in urban forestry to the city-wide goals we discussed before? 3.5b Is there any particular data or tool that helps to do so? Does it assist in management decision making? 3.5c What are the obstacles and challenges to doing so? 3.5d Is there any information gaps you or your staff think you need to know how to manage trees for these city goals? 3.5e Do you feel like there is a goal that you don’t know how to align to help achieve? 174 Closing 4.1 In an ideal world, what do you think are the best practices for cities to align street-level urban forest management actions to contribute to city-level ecosystem-service goals? 4.1a What are barriers to implementing these best practices? 4.1b What would help cities be able to do this better? 4.2 Before we close, do you have any final thoughts to share about city-wide ecosystem service goals and street tree management? 4.3 That is the end of my questions! What did you think of this interview and my questions? Any feedback? 175 Table A.3 Examples of the integration of urban forestry and ecosystem services in adopted non-urban forestry specific municipal plans. Urban forests are being included in municipal plans as a strategy for a broad array of ecosystem service goals, and with varying specificity. Ecosystem Service Example Climate change mitigation “Adopt energy efficiency and tree planting requirements to ensure rental housing is contributing to public health concerns associated with climate change" (p. 14). City of Iowa City. (2020). Acceleration Iowa City’s Climate Actions. https://www.iowa-city.org/WebLink/0/edoc/1944166/100%20Day%20Report%20-%20approved%20April%202020.pdf Stormwater “Use trees, vegetation, green stormwater infrastructure, amended soils, green roofs, and other low-impact development features to meet drainage needs and reduce the impacts of development." (p. 133). City of Seattle. (2020). Seattle 2035 Comprehensive Plan: Managing Growth to Become an Equitable and Sustainable City 2015-2035. https://www.seattle.gov/Documents/Departments/OPCD/OngoingInitiatives/SeattlesComprehensivePlan/CouncilAdopted2020.pdf Urban heat “Goal 18: Establish a robust urban tree canopy and implement strategies to mitigate the UHI effect” (p. 36). City of Louisville. (2013). Sustain Louisville: Louisville Metro Sustainability Plan. https://louisvilleky.gov/sustainability/document/sustainlouisvillepdf Biodiversity "Increase Biodiversity in Public Landscapes[...] Recommendation: Promote diverse and native plant species by requiring their use on city-owned property, including buildings, parks and sidewalks" (p. UE 1). City of New York (n.d.). NYC Green Codes Task Force: Full Proposals. https://www.nyc.gov/html/gbee/downloads/pdf/urban_ecology.pdf Human health "P5.2 Develop more nature playgrounds and nature play features in parks. Create more opportunities to advance the physical and mental health benefits of children's play and exploration in nature." (p. 48). City of Surrey. (2018). Parks, Recreation & Culture Strategic Plan. https://www.surrey.ca/sites/default/files/media/documents/PRCStrategicPlan.pdf 176 Appendix B Supplementary materials for Chapter 4 Supplementary material B.1 Street Tree Futures Expert Elicitation Questionnaire Participants completed this questionnaire twice during the expert elicitation. The questionnaire was hosted on Qualtrics, and has been revised, reformatted, and abbreviated to increase readability. Differences between this supplement and the Qualtrics questionnaire are described in red font next to each change. Dear participants, Welcome to the questionnaire! In this questionnaire, we would like you to answer a set of questions related to managing a hypothetical streetscape in your region. Your contribution is highly valuable and will help us develop effective strategies for urban tree management. Approximate time: 20-30 minutes Instructions: Answer all the questions in each scenario before proceeding to the next one. Complete the questionnaire in one sitting, if possible. However, if you need to pause and return, your progress will be saved as long as you use the same device and browser. For best display and user experience, use a device with a larger screen, such as a computer or tablet. Thank you for taking the time to participate in our survey. If you have any questions or concerns, please feel free to contact [email address redacted]. Sincerely, The Street Tree Futures Research Team 177 178 Contact information Please fill out the following information. Your name and identity will be kept confidential when results are shared with other participants and anyone beyond the research team, as described in the consent form. We ask for your name here so we are able to identify responses for logistical reasons (e.g. in case of duplication, need to re-share link with you). Full name: Metro Area: Scenario Context & Assumptions *This is the context for all 5 scenarios. You will be able to refer to this text on each page. Imagine yourself as a manager responsible for planning all street tree management on a hypothetical street in your region for the next 20 years. The street has a sidewalk and low-rise development, with buildings that are approximately 1-3 stories tall. In this mostly perfect world, you have full control over the trees adjacent to the sidewalk (pictured below). 179 Within these scenarios, you should assume the following will be true: • Each action you select is in comparison to not doing the actions at all • Actions will be performed according to industry standard • Trees will not be removed by events such as vandalism, new construction, extreme storms, or pest invasions • Newly planted trees will be watered through establishment and as needed for survival • Urban form will not change (street, pavement, buildings will remain the same with reasonable maintenance) • Species planted will be adapted for any change in hardiness zone projected in 20 years due to climate change. 180 Remember! The goal of this study is to isolate the actions which directly impact the management goal of each scenario. 181 Scenario 1: Canopy & Risk Reduction Goal: Increase canopy coverage, while keeping tree risk rating for all trees to moderate (or lower). Q1.1 Which of these actions are needed to advance this goal over all other goals? Check all that apply for each phase of management. Remember you are trying to advance this specific goal over a 20 year period for this hypothetical streetscape in your region. 182 183 Q1.2 Are there direct actions not listed and not referenced in the assumptions, that must be performed in order to advance this goal? ________________________________________________________________ Q1.4 What are the main reasons for your level of certainty? ________________________________________________________________ 184 The actions listed under “Items” and ranked under “Opportunities…” are included as an example of how the question would look after being filled out by a participant. 185 The same five questions posed for Scenario 1 were repeated exactly for Scenarios 2-5. Here are the following Scenario themes and goals, as presented to participants in the questionnaires. Scenario 2: Urban Heat Reduction Goal: Pedestrians are able to walk comfortably during the hottest time of day during the hot season. Scenario 3: People-Nature Relationships Goal: Residents develop a strong and personal connection with trees on this street. Scenario 4: Wildlife Habitat Goal: Increase the abundance and diversity of species of native wildlife who use these street trees for habitat. Scenario 5: Stormwater Interception & Infiltration Goal: This street can experience a storm with no stormwater runoff. 186 Table B.2 Summarized responses to open-ended response question: "Are there direct actions not listed and not referenced in the assumptions, that must be performed in order to advance this goal?" New direct actions described by more than one participant were summarized in consistent language and included below. The numbered values represent the number of participants who described each direct action for a particular goal. Despite being out of scope for the question, the significant number of participants who described in-direct management actions and non-tree direct actions as needed to advance the goal led us to create categories for these actions, to show how important participants felt these actions were. Goal Management Type Direct Action DC HON. VAN. TOTAL Goal 1 Canopy and Risk Reduction Space tree planting sites by… interplant large trees with small understory trees 1 0 0 1 interplant for succession 1 0 1 2 Mature tree maintenance inspect on a cycle 2 1 0 3 prune on a cycle (1-3 yrs) 0 8 0 8 Goal 2 Urban Heat Reduction Plant species with x characteristic high leaf area index 1 0 0 1 Mature tree maintenance prune on a cycle (1-3 yrs) 0 4 0 4 Non-tree direct action change built infrastructure 0 1 1 2 ground vegetation 0 0 1 1 Goal 3 People-Nature Relationships Plant species with x characteristic match neighborhood aesthetic 0 0 3 3 Mature tree maintenance prune on a cycle (1-3 yrs) 0 2 0 2 Indirect action community engagement and education 8 7 3 18 Goal 4 Wildlife Habitats Space tree planting sites by… interplant large trees with small understory trees 1 0 3 4 Mature tree maintenance prune on a cycle (1-3 yrs) 0 1 0 1 Non-tree direct action change built infrastructure 0 0 1 1 ground vegetation 2 0 2 4 woody debris 1 0 1 2 predator control 0 2 0 2 Goal 5 Stormwater Interception & Infiltration Space tree planting sites by… interplant large trees with small understory trees 1 0 1 2 Plant species with x characteristic rough bark 3 0 1 4 high leaf area index 1 1 1 3 more pubescent leaves 2 0 0 2 high water uptake 2 2 0 4 187 Mature tree maintenance prune on a cycle (1-3 yrs) 0 2 0 2 Non-tree direct action change built infrastructure 1 4 1 6 ground vegetation 0 2 1 3 188 Table B.3 Responses to question “Which actions are needed to significantly advance each scenario’s goal above all other goals?”, in the context of each hypothetical streetscape scenario and assumptions. Each of the five sub-tables includes responses for one goal, separated by metro area. (See Table 4.1 for aggregated responses of all participants). Sub-table B.3.1 Goal 1 Canopy & Risk participants by metro area (%) Phase Direct management action Total (n=31) DC (n=11) Hon. (n=9) Van. (n=11) Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 19.4 9.1 33.3 18.2 24.2 siting trees in every available planting space 93.5 90.9 100.0 90.9 9.1 None of these options 0.0 0.0 0.0 0.0 0.0 Plant species with x characteristic native to region 19.4 36.4 11.1 9.1 27.3 edible food (humans) 3.2 0.0 11.1 0.0 11.1 food source to native wildlife 6.5 0.0 11.1 9.1 11.1 aesthetic interest - flowers, foliage, bark, etc. 6.5 0.0 22.2 0.0 22.2 cultural significance to residents 9.7 0.0 22.2 9.1 22.2 drops leaves seasonally (deciduous) 22.6 0.0 22.2 45.5 45.5 retains leaves year round (evergreen) 22.6 9.1 22.2 36.4 27.3 small mature size 38.7 27.3 88.9 9.1 79.8 medium mature size 61.3 45.5 88.9 54.5 43.4 large mature size 100.0 100.0 100.0 100.0 0.0 spreading or vase shaped growth habit 80.6 45.5 100.0 100.0 54.5 columnar or pyramidal shaped growth habit 22.6 9.1 55.6 9.1 46.5 round or oval growth habit 67.7 45.5 88.9 72.7 43.4 palm species 0.0 0.0 0.0 0.0 0.0 None of these options 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 0.0 0.0 0.0 0.0 0.0 variety of species by size (small, medium, large) 25.8 18.2 66.7 0.0 66.7 variety of species within previously selected characteristics 87.1 90.9 88.9 81.8 9.1 None of these options 6.5 0.0 0.0 18.2 18.2 Site preparation remediate soil compaction 93.5 90.9 100.0 90.9 9.1 test soil and amend accordingly 67.7 63.6 77.8 63.6 14.2 None of these options 3.2 9.1 0.0 0.0 9.1 Planting inspect nursery stock quality 100.0 100.0 100.0 100.0 0.0 stake for stability 51.6 9.1 77.8 72.7 68.7 add mulch ring with berm 45.2 36.4 11.1 81.8 70.7 prune root ball prior to planting 22.6 36.4 22.2 9.1 27.3 189 None of these options 0.0 0.0 0.0 0.0 0.0 Young tree maintenance perform structural pruning for young trees 100.0 100.0 100.0 100.0 0.0 maintain mulch ring 38.7 27.3 22.2 63.6 41.4 None of these options 0.0 0.0 0.0 0.0 0.0 Mature tree maintenance prune on a cycle (once every 5-7 years) 51.6 45.5 11.1 90.9 79.8 prune by resident request 9.7 0.0 0.0 27.3 27.3 prune in response to storm damage 58.1 18.2 77.8 81.8 63.6 prune for clearance 41.9 0.0 77.8 54.5 77.8 prune deadwood 45.2 0.0 77.8 63.6 77.8 prune as needed to mitigate risk 100.0 100.0 100.0 100.0 0.0 assess for plant health care needs and treat accordingly 71.0 54.5 88.9 72.7 34.4 None of these options 0.0 0.0 0.0 0.0 0.0 End of life remove trees when invasive non-native species (even if healthy) 6.5 9.1 0.0 9.1 9.1 remove trees when tree risk assessment rating exceeds moderate risk level 74.2 72.7 66.7 81.8 15.1 remove trees when declining and likely to die within inspection cycle 67.7 72.7 77.8 54.5 23.3 remove trees when completely dead 67.7 45.5 66.7 90.9 45.4 retain standing snags at safe height 3.2 0.0 0.0 9.1 9.1 retain stumps 0.0 0.0 0.0 0.0 0.0 None of these options 3.2 0.0 11.1 0.0 11.1 190 Sub-table B.3.2 Goal 2 Urban Heat Reduction participants by metro area (%) Phase Direct management action Total (n=31) DC (n=11) Hon. (n=9) Van. (n=11) Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 6.5 0.0 22.2 0.0 22.2 siting trees in every available planting space 100.0 100.0 100.0 100.0 0.0 None of these options 0.0 0.0 0.0 0.0 0.0 Plant species with x characteristic native to region 9.7 18.2 0.0 9.1 18.2 edible food (humans) 0.0 0.0 0.0 0.0 0.0 food source to native wildlife 3.2 0.0 0.0 9.1 9.1 aesthetic interest - flowers, foliage, bark, etc. 0.0 0.0 0.0 0.0 0.0 cultural significance to residents 0.0 0.0 0.0 0.0 0.0 drops leaves seasonally (deciduous) 25.8 18.2 0.0 54.5 54.5 retains leaves year round (evergreen) 25.8 0.0 44.4 36.4 44.4 small mature size 22.6 9.1 55.6 9.1 46.5 medium mature size 61.3 18.2 100.0 72.7 81.8 large mature size 96.8 100.0 88.9 100.0 11.1 spreading or vase shaped growth habit 80.6 54.5 88.9 100.0 45.5 columnar or pyramidal shaped growth habit 12.9 0.0 33.3 9.1 33.3 round or oval growth habit 48.4 27.3 66.7 54.5 39.4 palm species 0.0 0.0 0.0 0.0 0.0 None of these options 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 0.0 0.0 0.0 0.0 0.0 variety of species by size (small, medium, large) 25.8 9.1 55.6 18.2 46.5 variety of species within previously selected characteristics 90.3 100.0 88.9 81.8 18.2 None of these options 6.5 0.0 0.0 18.2 18.2 Site preparation remediate soil compaction 93.5 100.0 88.9 90.9 11.1 test soil and amend accordingly 58.1 54.5 66.7 54.5 12.2 None of these options 0.0 0.0 0.0 0.0 0.0 Planting inspect nursery stock quality 93.5 100.0 100.0 81.8 18.2 stake for stability 32.3 9.1 44.4 45.5 36.4 add mulch ring with berm 48.4 45.5 11.1 81.8 70.7 prune root ball prior to planting 19.4 27.3 33.3 0.0 33.3 None of these options 0.0 0.0 0.0 0.0 0.0 Young tree maintenance perform structural pruning for young trees 80.6 100.0 100.0 45.5 54.5 maintain mulch ring 38.7 27.3 22.2 63.6 41.4 None of these options 9.7 0.0 0.0 27.3 27.3 prune on a cycle (once every 5-7 years) 35.5 63.6 0.0 36.4 63.6 191 Mature tree maintenance prune by resident request 3.2 0.0 0.0 9.1 9.1 prune in response to storm damage 29.0 9.1 55.6 27.3 46.5 prune for clearance 29.0 0.0 55.6 36.4 55.6 prune deadwood 25.8 9.1 55.6 18.2 46.5 prune as needed to mitigate risk 45.2 27.3 66.7 45.5 39.4 assess for plant health care needs and treat accordingly 67.7 63.6 77.8 63.6 14.2 None of these options 12.9 0.0 0.0 36.4 36.4 End of life remove trees when invasive non-native species (even if healthy) 0.0 0.0 0.0 0.0 0.0 remove trees when tree risk assessment rating exceeds moderate risk level 25.8 9.1 55.6 18.2 46.5 remove trees when declining and likely to die within inspection cycle 51.6 72.7 55.6 27.3 45.4 remove trees when completely dead 87.1 81.8 100.0 81.8 18.2 retain standing snags at safe height 0.0 0.0 0.0 0.0 0.0 retain stumps 0.0 0.0 0.0 0.0 0.0 None of these options 6.5 0.0 0.0 18.2 18.2 192 Sub-table B.3.3 Goal 2 People-Nature Relationships participants by metro area (%) Phase Direct management action Total (n=31) DC (n=11) Hon. (n=9) Van. (n=11) Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 38.7 27.3 66.7 27.3 39.4 siting trees in every available planting space 32.3 72.7 0.0 18.2 72.7 None of these options 35.5 9.1 33.3 63.6 54.5 Plant species with x characteristic native to region 38.7 36.4 55.6 27.3 28.3 edible food (humans) 54.8 54.5 55.6 54.5 1.1 food source to native wildlife 48.4 63.6 33.3 45.5 30.3 aesthetic interest - flowers, foliage, bark, etc. 96.8 90.9 100.0 100.0 9.1 cultural significance to residents 96.8 90.9 100.0 100.0 9.1 drops leaves seasonally (deciduous) 9.7 9.1 0.0 18.2 18.2 retains leaves year round (evergreen) 12.9 9.1 22.2 9.1 13.1 small mature size 32.3 18.2 22.2 54.5 36.3 medium mature size 32.3 18.2 22.2 54.5 36.3 large mature size 29.0 36.4 11.1 36.4 25.3 spreading or vase shaped growth habit 12.9 18.2 11.1 9.1 9.1 columnar or pyramidal shaped growth habit 9.7 18.2 0.0 9.1 18.2 round or oval growth habit 12.9 18.2 11.1 9.1 9.1 palm species 6.5 9.1 0.0 9.1 9.1 None of these options 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 3.2 9.1 0.0 0.0 9.1 variety of species by size (small, medium, large) 35.5 36.4 55.6 18.2 37.4 variety of species within previously selected characteristics 90.3 100.0 88.9 81.8 18.2 None of these options 6.5 0.0 0.0 18.2 18.2 Site preparation remediate soil compaction 71.0 72.7 88.9 54.5 34.4 test soil and amend accordingly 54.8 54.5 44.4 63.6 19.2 None of these options 19.4 27.3 11.1 18.2 16.2 Planting inspect nursery stock quality 83.9 81.8 88.9 81.8 7.1 stake for stability 51.6 27.3 55.6 72.7 45.4 add mulch ring with berm 51.6 54.5 11.1 81.8 70.7 prune root ball prior to planting 19.4 27.3 33.3 0.0 33.3 None of these options 12.9 18.2 11.1 9.1 9.1 Young tree maintenance perform structural pruning for young trees 87.1 90.9 88.9 81.8 9.1 maintain mulch ring 54.8 54.5 11.1 90.9 79.8 None of these options 6.5 9.1 11.1 0.0 11.1 prune on a cycle (once every 5-7 years) 45.2 36.4 0.0 90.9 90.9 193 Mature tree maintenance prune by resident request 87.1 100.0 66.7 90.9 33.3 prune in response to storm damage 67.7 45.5 88.9 72.7 43.4 prune for clearance 58.1 45.5 77.8 54.5 32.3 prune deadwood 58.1 45.5 66.7 63.6 21.2 prune as needed to mitigate risk 64.5 54.5 88.9 54.5 34.4 assess for plant health care needs and treat accordingly 67.7 63.6 77.8 63.6 14.2 None of these options 0.0 0.0 0.0 0.0 0.0 End of life remove trees when invasive non-native species (even if healthy) 6.5 9.1 0.0 9.1 9.1 remove trees when tree risk assessment rating exceeds moderate risk level 51.6 63.6 66.7 27.3 39.4 remove trees when declining and likely to die within inspection cycle 51.6 54.5 66.7 36.4 30.3 remove trees when completely dead 77.4 54.5 88.9 90.9 36.4 retain standing snags at safe height 12.9 27.3 11.1 0.0 27.3 retain stumps 3.2 9.1 0.0 0.0 9.1 None of these options 3.2 9.1 0.0 0.0 9.1 194 Sub-table B.3.4 Goal 4 Wildlife Habitat participants by metro area (%) Phase Direct management action Total (n=31) DC (n=11) Hon. (n=9) Van. (n=11) Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 6.5 0.0 22.2 0.0 22.2 siting trees in every available planting space 93.5 100.0 88.9 90.9 11.1 None of these options 6.5 0.0 11.1 9.1 11.1 Plant species with x characteristic native to region 83.9 100.0 55.6 90.9 44.4 edible food (humans) 3.2 0.0 0.0 9.1 9.1 food source to native wildlife 87.1 90.9 66.7 100.0 33.3 aesthetic interest - flowers, foliage, bark, etc. 6.5 0.0 11.1 9.1 11.1 cultural significance to residents 3.2 0.0 11.1 0.0 11.1 drops leaves seasonally (deciduous) 35.5 18.2 11.1 72.7 61.6 retains leaves year round (evergreen) 35.5 18.2 11.1 72.7 61.6 small mature size 45.2 36.4 44.4 54.5 18.1 medium mature size 48.4 36.4 55.6 54.5 19.2 large mature size 54.8 45.5 55.6 63.6 18.1 spreading or vase shaped growth habit 32.3 27.3 44.4 27.3 17.1 columnar or pyramidal shaped growth habit 19.4 9.1 22.2 27.3 18.2 round or oval growth habit 29.0 27.3 44.4 18.2 26.2 palm species 0.0 0.0 0.0 0.0 0.0 None of these options 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 0.0 0.0 0.0 0.0 0.0 variety of species by size (small, medium, large) 54.8 36.4 55.6 72.7 36.3 variety of species within previously selected characteristics 93.5 90.9 88.9 100.0 11.1 None of these options 0.0 0.0 0.0 0.0 0.0 Site preparation remediate soil compaction 87.1 81.8 88.9 90.9 9.1 test soil and amend accordingly 41.9 45.5 44.4 36.4 9.1 None of these options 12.9 18.2 11.1 9.1 9.1 Planting inspect nursery stock quality 74.2 81.8 100.0 45.5 54.5 stake for stability 29.0 0.0 55.6 36.4 55.6 add mulch ring with berm 45.2 36.4 11.1 81.8 70.7 prune root ball prior to planting 16.1 18.2 33.3 0.0 33.3 None of these options 6.5 0.0 0.0 18.2 18.2 Young tree maintenance perform structural pruning for young trees 45.2 63.6 66.7 9.1 57.6 maintain mulch ring 38.7 36.4 0.0 72.7 72.7 None of these options 22.6 9.1 33.3 27.3 24.2 prune on a cycle (once every 5-7 years) 6.5 0.0 11.1 9.1 11.1 195 Mature tree maintenance prune by resident request 6.5 0.0 0.0 18.2 18.2 prune in response to storm damage 16.1 0.0 33.3 18.2 33.3 prune for clearance 6.5 0.0 22.2 0.0 22.2 prune deadwood 12.9 0.0 44.4 0.0 44.4 prune as needed to mitigate risk 32.3 9.1 55.6 36.4 46.5 assess for plant health care needs and treat accordingly 48.4 27.3 77.8 45.5 50.5 None of these options 35.5 63.6 0.0 36.4 63.6 End of life remove trees when invasive non-native species (even if healthy) 29.0 54.5 11.1 18.2 43.4 remove trees when tree risk assessment rating exceeds moderate risk level 12.9 0.0 44.4 0.0 44.4 remove trees when declining and likely to die within inspection cycle 16.1 0.0 55.6 0.0 55.6 remove trees when completely dead 32.3 0.0 77.8 27.3 77.8 retain standing snags at safe height 54.8 45.5 11.1 100.0 88.9 retain stumps 29.0 18.2 11.1 54.5 43.4 None of these options 9.7 27.3 0.0 0.0 27.3 196 Sub-table B.3.5 Goal 5 Stormwater Interception & Infiltration participants by metro area (%) Phase Direct management action Total (n=31) DC (n=11) Hon. (n=9) Van. (n=11) Min-Max Range Planning & design Space tree planting sites by... siting one tree for every building 9.7 0.0 22.2 9.1 22.2 siting trees in every available planting space 96.8 100.0 100.0 90.9 9.1 None of these options 0.0 0.0 0.0 0.0 0.0 Plant species with x characteristic native to region 6.5 9.1 0.0 9.1 9.1 edible food (humans) 0.0 0.0 0.0 0.0 0.0 food source to native wildlife 0.0 0.0 0.0 0.0 0.0 aesthetic interest - flowers, foliage, bark, etc. 0.0 0.0 0.0 0.0 0.0 cultural significance to residents 3.2 0.0 11.1 0.0 11.1 drops leaves seasonally (deciduous) 25.8 36.4 0.0 36.4 36.4 retains leaves year round (evergreen) 54.8 36.4 22.2 100.0 77.8 small mature size 35.5 45.5 44.4 18.2 27.3 medium mature size 58.1 45.5 100.0 36.4 63.6 large mature size 100.0 100.0 100.0 100.0 0.0 spreading or vase shaped growth habit 54.8 45.5 77.8 45.5 32.3 columnar or pyramidal shaped growth habit 19.4 9.1 22.2 27.3 18.2 round or oval growth habit 35.5 18.2 66.7 27.3 48.5 palm species 3.2 0.0 11.1 0.0 11.1 None of these options 0.0 0.0 0.0 0.0 0.0 Plant trees that are of x species mix no variety in species (i.e. all same species) 3.2 0.0 0.0 9.1 9.1 variety of species by size (small, medium, large) 41.9 36.4 66.7 27.3 39.4 variety of species within previously selected characteristics 83.9 100.0 88.9 63.6 36.4 None of these options 6.5 0.0 0.0 18.2 18.2 Site preparation remediate soil compaction 100.0 100.0 100.0 100.0 0.0 test soil and amend accordingly 61.3 45.5 77.8 63.6 32.3 None of these options 0.0 0.0 0.0 0.0 0.0 Planting inspect nursery stock quality 74.2 81.8 100.0 45.5 54.5 stake for stability 29.0 0.0 44.4 45.5 45.5 add mulch ring with berm 61.3 63.6 22.2 90.9 68.7 prune root ball prior to planting 19.4 27.3 33.3 0.0 33.3 None of these options 3.2 9.1 0.0 0.0 9.1 Young tree maintenance perform structural pruning for young trees 71.0 72.7 77.8 63.6 14.2 maintain mulch ring 67.7 72.7 22.2 100.0 77.8 None of these options 3.2 0.0 11.1 0.0 11.1 197 Mature tree maintenance prune on a cycle (once every 5-7 years) 25.8 18.2 0.0 54.5 54.5 prune by resident request 6.5 0.0 0.0 18.2 18.2 prune in response to storm damage 22.6 0.0 44.4 27.3 44.4 prune for clearance 12.9 0.0 33.3 9.1 33.3 prune deadwood 19.4 0.0 44.4 18.2 44.4 prune as needed to mitigate risk 22.6 0.0 44.4 27.3 44.4 assess for plant health care needs and treat accordingly 61.3 36.4 77.8 72.7 41.4 None of these options 29.0 45.5 11.1 27.3 34.4 End of life remove trees when invasive non-native species (even if healthy) 0.0 0.0 0.0 0.0 0.0 remove trees when tree risk assessment rating exceeds moderate risk level 12.9 0.0 33.3 9.1 33.3 remove trees when declining and likely to die within inspection cycle 45.2 54.5 55.6 27.3 28.3 remove trees when completely dead 80.6 72.7 88.9 81.8 16.2 retain standing snags at safe height 6.5 0.0 22.2 0.0 22.2 retain stumps 19.4 36.4 11.1 9.1 27.3 None of these options 9.7 9.1 0.0 18.2 18.2
Thesis/Dissertation
eng
Forestry
Vancouver : University of British Columbia Library
Attribution-NonCommercial-NoDerivatives 4.0 International
Graduate
Day, Susan D. (Susan Downing), 1963-
Konijnendijk, C. C. (Cecil C.)
Bridging gaps in urban forest management to achieve urban sustainability goals
Text