Samuel Ma is a Hong Kong–based Consulting Arborist and recognized international trainer. He serves as Director, Consulting Arborist & Climbing Specialist of Kassod Arbor Tree Consultancy & Services Limited (Hong Kong) and EmCypress Arborist Consultancy Limited (Taiwan).

Samuel holds a BSc in Applied Biology from Hong Kong Baptist University. He is an ISA Board Certified Master Arborist (BCMA), Certified Tree Worker Climber Specialist, Tree Risk Assessment Qualified (TRAQ) professional and approved TRAQ Instructor, with professional qualifications in chainsaw operation and pruning.

Alongside his professional practice, Samuel is committed to arboricultural education and developing the next generation of arborists. He taught the Higher Diploma Programme in Tree Management and Conservation at the Hong Kong Institute of Vocational Education (IVE) and serves as a programme consultant for the Higher Diploma in Urban Forestry at HKU SPACE. His teaching emphasizes proper arboricultural practices, professionalism and safety.

Fluent in Cantonese, Mandarin and English, with conversational Japanese, Samuel has been invited by universities, professional institutes and industry organizations to deliver training, lectures and professional sharing across Hong Kong, Mainland China, Taiwan, Japan, Singapore, Malaysia, etc. Samuel has been actively involved in professional and industry development since 2013, including certification, tree climbing competitions and local qualification development. He has served as Convener of The Hong Kong Institute of Professional Arborists and contributed to Hong Kong’s Arboriculture and Horticulture Specification of Competency Standards. He is also an experienced tree climber, competition athlete and international judge.

Samuel’s contributions have been recognized by ISA through the M.F. Blair Award for Exceptional Contribution to Practical Arboriculture and the True Professionals of Arboriculture Award. His work combines practical arboriculture, education, technology and international collaboration to advance the profession in Asia and beyond.

Jessica serves as the Executive Director of the Sacramento Tree Foundation.  She fell in love with the Sacramento Tree Foundation’s holistic vision of urban forestry and prioritizes the organization’s goal of urban forestry from seed to slab, creating and cultivating an equitable urban forest through education and stewardship of trees in the Sacramento region.  She has a doctorate from Rutgers University and is a certified Project Management Professional. She previously worked at Casey Trees as the director of science and policy, overseeing community science, mapping, policy, partnerships, and land conservation.

Jessica has a passion for the urban forest, and her research has focused on developing and enhancing current urban forestry practices in order to better manage the urban interface. Growing up in New Jersey and spending her college years walking through Atlantic white cedar bogs, she wanted nature to be a daily experience, not a destination. Jessica has worked at the intersection of science communication and creation of long-lasting urban forestry policy.

She served as the chair of the conference program committee and the nominations and elections committee for the International Society of Arboriculture.  She was a board member for the Mid-Atlantic Chapter (MAC) of ISA and has served as President of AREA.  In her free time, you can find her reading, outside with her partner and two pups paddle boarding on the river, or hiking.

Lori Brockelbank has been involved in the arboriculture industry for 20 years, previously she worked as a forester for 8 years. She is an ISA Certified Arborist, Municipal Specialist,  Arborist Utility Specialist, TRAQ qualified, CTSP, and a Registered Consulting Arborist.

Lori previously volunteered for 13 years on the New York State International Society of Arboriculture Chapter. She served as the New York ISA Certification Liaison for 9 years, and as a liaison to the Tree Fund for 10 years; she additionally volunteered on the Tree Fund Board as Liaison Chair. She has participated in five Tour des Trees and is planning on riding again on future routes.

She is currently the President and has volunteered on the board for 17 years of the NYS Urban Forestry Council, which serves as an advisory board to the NYS DEC Urban Forestry Department and provides educational workshops and grant programs throughout NYS. She assisted the first Tree Campus USA Community College in NY to become recognized and continues to support them by teaching an Urban Forestry Internship in which students from a variety of disciplines and majors learn how they can become Lorax’s in their communities. She has presented at numerous Master Gardener Programs and Tree stewardship programs in Western New York. She was the keynote speaker for the Chautauqua Institution's annual Bird and Garden Club luncheon in which she shared her research on the many historical trees found on the grounds.

Lori holds a bachelor’s degree in Natural Resources from The University of New York Environmental School of Forestry and an Associate degree in social sciences from Jamestown Community College. She attended Municipal Forestry Institute in 2008 .

Beyond her passion for trees and plants, Lori enjoys working on her 161-year-old cider mill estate, spending time with her boys, cooking, hiking, gardening and learning homesteading skills. 

Tim Walsh is Vice President of Safety & Training for The Townsend Company, LLC, where he provides executive leadership for safety, training, and workforce development across vegetation management, tree care, and related operations throughout the United States.

Tim is currently completing his Ph.D. in Industrial Engineering and Safety, with research focused on ergonomics, human performance, and the physiological and ergonomic demands of arboricultural climbing systems. He expects to complete his doctoral work in 2026. He also holds a Master of Science in Ergonomics from the University of Massachusetts Lowell and both Master of Science and Bachelor of Science degrees from the University of Wisconsin–Stevens Point.

He is a Certified Utility Safety Professional (CUSP), Certified Treecare Safety Professional (CTSP), ISA Certified Arborist, and ISA Certified Tree Worker Climber Specialist.

Tim currently serves as Treasurer of the International Society of Arboriculture Board of Directors, a position he has held for the past year. He is also a Past President of the Utility Arborist Association (UAA) and has held numerous leadership positions within UAA, including chairing its Safety and Professional Development Committees. In recognition of his contributions to the utility arboriculture profession, Tim received the UAA Will Nutter Silver Shield Award in 2022.

Tim has been extensively involved in the development and revision of the Z133 Safety Requirements for Arboricultural Operations. He has served as a voting member of the Z133 Accredited Standards Committee (ASC) and has participated in numerous task groups supporting revisions to the standard, including serving as a task group chair. His involvement in standards development spans multiple revision cycles and reflects a longstanding commitment to advancing worker safety and professional practice within arboriculture.

His broader industry involvement includes participation in the National Occupational Research Agenda (NORA) Safety Workgroup and service on the Tree Care Industry Magazine Editorial Advisory Committee. He has contributed to industry education and research initiatives, provided input to state and federal agencies on worker-safety issues, and helped develop training programs supporting implementation of the Z133 standard.

Throughout his career, Tim has been an active educator, researcher, and industry speaker. He has more than three decades of experience in arboricultural climbing and rigging education and regularly presents on safety, human performance, standards, and utility vegetation management at national and regional industry conferences. 

Dr. Asia Dowtin is an Associate Professor of Urban Forestry in the Michigan State University Department of Forestry. Her work explores the relationships that exist between urban forest structure, spatial context, and water and nutrient cycling in metropolitan areas. Through this work, she aims to broaden our understanding of the influence that species composition, related physical tree traits, and surrounding land use have on urban forest function and ecosystem service provision. A major goal of Dowtin's work is to utilize this knowledge to inform the development of urban forest management plans, specifically aspects of these plans that are intended to optimize the yield of ecosystem services provided by urban trees. Her research and editorial contributions have been published in Urban Ecosystems, Urban Forestry and Urban Greening, Forest Ecology and Management, Science, Journal of Environmental Management, Journal of the American Water Resources Association, and IMPACT (the American Water Resources Association Magazine). She has secured more than $1.6 million (USD) through competitive grant funding to support her research and program development initiatives. Her work at Michigan State University includes research, teaching, and extension related to urban and community forestry. Her extension efforts largely focus on building municipal capacity for urban forest management and creating inclusive educational and workforce development programming for K-12 and college students, in addition to a diverse array of adult learners. 

She is a member of the National Urban and Community Forestry Advisory Council, TREE Fund Board Trustees, International Society of Arboriculture – Michigan Chapter Executive Board, Michigan Urban and Community Forestry Council, Women’s Forest Congress Advisory Council, Sustainable Forestry Initiative/Project Learning Tree Education Operation Committee, Green Communities Leadership Institute Core Leadership Team, Michigan State University Campus Arboretum Committee, and US Endowment for Forestry and Communities Inclusion Council. She previously served on the Sustainable Forestry Initiative Urban and Community Forestry Standard Development Task Group and currently serves as an Associate Editor of Arboriculture & Urban Forestry. She holds a B.S. in Meteorology from the State University of New York College at Oneonta, and an M.S. and Ph.D. in Physical Geography from the University of Delaware.

John Coles is employed as the Senior Tree Officer to the Royal Court of Norway. He is responsible for the management and maintenance of the historic tree population that grows on the Royal estates. The largest of these areas being The Royal Palace Park in central Oslo. John has also worked part time as an arboricultural tutor and climbing instructor at Norway’s only government arborist school.
 
He has been an ISA Certified Arborist for more than 20 years and is TRAQ qualified.John’s strong interest in practical arboriculture has led to his involvement in several ISA committees over the years. He has served on both the ITCC and ETCC operations committee as well as the ITCC rules committee and international safety committee.
 
John is a past Chairperson of the ISA Norway Chapter and a former ITCC and ETCC competitor. He is a current member of the ISA Board of Directors.

Kevin K. Eckert is President, Managing Director and Chief Consulting Arborist of Arbor Global USA and Arbor Global Hong Kong Ltd. (AG). AG provides arboriculture and urban forestry consulting, training, tree management and expert witness services to diverse clients throughout the United States, Hong Kong, Asia, Australia, Central and South America, and around the Pacific Rim. Because of his love of trees and tree work, Kevin continues to climb and conduct tree management work on occasion for select trees. 

Kevin has served within the arboricultural industry for over 45 years. He is an International Society of Arboriculture (ISA) Board Certified Master Arborist and is a very active leader within the profession currently serving as a member of the Western Chapter ISA Board of Directors and its past President, Hong Kong Urban Forestry Advisory Panel, Director of Trees For Honolulu’s Future and President of Smart Trees Pacific, an NGO supporting urban and community forestry. He has received numerous awards from professional associations, government and private organizations for his extensive education work and leadership in arboriculture. 

Kevin is an Instructor and Mentor for many programs including ISA’s Tree Risk Assessment Qualification, climbing and lift aerial rescue, Chainsaw safe operation, tree felling, Electrical Hazard Awareness Program (EHAP), Certified Arborist and Certified Tree Worker preparation, and occupational safety for tree workers and the arboriculture industry. He has served as a lecturer in Arboriculture at the Hong Kong University SPACE program and the University of Hawaii. 

Kevin developed and is the Master Instructor for the UpSkill California Utility Vegetation Management Pre-inspector training program offered at colleges throughout California. This program is designed to build industry capacity in qualified, limited visual tree risk inspectors focused on minimizing the incidence of wildfires caused by trees in power lines. 

His ultimate goal is to build a legacy of students, colleagues and sustainable urban and wildlands forests that will enhance the human and natural environment through safe, healthy trees for current and future generations. 

Tristan Fields is a consulting arborist and landscape architect based in Seattle, Washington, and the owner of Land Meets Water LLC (LMW)—a woman-owned micro-consultancy specializing in municipal arboriculture, tree risk assessment, and sustainable design integration. Her work focuses on reconciling infrastructure development with long-term canopy health, helping cities, engineers, and designers plan around trees using ISA Best Management Practices and ANSI A300 standards. Beyond her consulting practice, Tristan served as Secretary of the Pacific Northwest Chapter ISA and currently sits on the Washington Community Forestry Council.  

Dedicated and experienced arborist, trainer, and board member with over 15 years in the arboriculture industry. Accomplished tree climber and international tree climbing champion, highly skilled in advanced rope techniques (SRT/MRS), spikes, and MEWPs. Certified specialist trainer and assessor with extensive experience delivering hands-on instruction in climbing, chainsaw use, wood chipper operation, and pesticide application—always with a strong focus on safety, performance, and environmental awareness. 

In addition to fieldwork, I bring a deep background in organizational leadership, volunteer coordination, budget management, and technical standards development. I have served on national and international boards, led large-scale professional events, and contributed to educational and policy initiatives across Europe. Known for cross-cultural collaboration, member engagement, and a passion for raising industry standards, I combine technical excellence with strategic vision and a strong commitment to arboriculture’s future.

Rebecca Johnson is the founder and principal owner of Arborholic, LLC, a consulting arborist firm with a focus on outreach and education, working to improve tree care across the central Texas region and beyond. Rebecca facilitates the Austin Certified Arborist® prep course, which has provided education to over 500 arborists and enthusiasts and counting.

Rebecca is a true arborholic. She is addicted to helping trees and the people who care for them. Her goal in life is to see arboriculture become a safer, more inclusive industry. Rebecca enjoys educating fellow arborists and the general public by speaking at professional conferences, homeowner events, and one-on-one discussions. She spent almost a decade serving on the ISA Texas Chapter board of directors first as Editor of their newsletter, then through their leadership track from Vice President to Past President. One of her proudest achievements was bringing the Women's Tree Climbing Workshop to Texas for the first time and continuing to support this program locally. In addition, she facilitates a monthly "Women in Trees" chat, which serves as a sounding board for challenges and celebrates the successes of women in the industry. She was recognized with the 2020 ISA President's Award for her work with Women in Arboriculture.

In addition to her current board service with ISA, Rebecca is an accreditation auditor for TCIA - helping companies improve through advice on standard documents and safety practices and helping them interpret OSHA and ANSI standards. She also takes this as a chance to talk with the workers in the field to find out what draws them to work with trees and what could improve their careers.

She is an ISA Certified Arborist®,  a TCIA Certified Treecare Safety Professional (CTSP) and Qualified Trainer, Tree Risk Assessment, Texas Oak Wilt and Wildfire Risk Reduction Qualified, and has a degree in Forestry from Oklahoma State University.

Steve is the Lead Consultant, GIS Director, and Outreach Coordinator for Great Lakes Urban Forestry, a midsize consulting firm based in the west suburbs of Chicago. He is also currently the ISA CoR Representative from Illinois, as well as the co-Chair of the Illinois Arborist Association’s Advanced Training Program, and is on the American Society of Consulting Arborist’s Editorial Committee.

Steve graduated from the University of Oregon in 2004 with a major in Environmental Science and a double minor in Biology and Geography. He has also been the President of the Illinois chapter of ISA, the 2nd largest single state chapter in the United States. He chaired the Advanced Training program in Illinois, a one-of-a-kind training program, and has helped countless Arborists advance their careers by teaching courses and assisting with course material preparation. Steve is also a member of the Urban Forest Strike Team, where he leads crews after storm events and prepares risk management reports for the state Department of Natural Resources. He is currently in the ISA’s QIAP program to become a TRAQ Instructor.

Steve has spoken across the country on topics ranging from hard science (GIS in Urban Forestry) to soft skills (Public Relations in Arboriculture) at events up to and including the ISA International conference. He also donates a significant amount of time to advancing the Arboricultural industry in his free time, teaching classes as a volunteer for the Openlands TreeKeepers program, the Illinois Arborist Association’s Certified Arborist Prep courses, Chicago Region Tree Initiative’s Urban Forestry Basic Training, and the Indy Tree Stewards in Indiana, among others. He is passionate about expanding our industry and growing it to its full potential and was picked to be part of the Steering Committee / Sector Partnership as an advisor for creating the 1st ever Arborist Apprenticeship program in Illinois.

A true believer in the power of the profession, Steve enjoys spending a lot of time in the woods recreationally hiking and learning more about plants and rare ecosystems. He also maintains his love of music, and plays the bass guitar with a bunch of lousy garage bands you’ve never heard of, and hopefully never will.

Carlos Llanos is a returning board member and is professionally trained in forestry engineering. He is skilled in the management of environmental and community project formulation, planning and operation of preventive forest maintenance projects in electrical networks, reforestation, forest harvesting, management of hydrographic accounts, urban forestry (pruning, felling, blocking, transfers, injection, fertilization, etc.), landscape design, forest, inventories, forestry, environmental education, environmental impact assessment, technical training in soils and plant health. He has dedicated years to promoting best practices and advancing the science of arboriculture in Latin America.  

Lauren Marshall, an ISA Certified Arborist, professional Landscape Architect, and Fellow, American Society of Landscape Architects, is an innovative, flexible, and resilient leader who believes in collaborative problem solving, cultivating the strengths of others, and listening before acting. In her current role as the Director of Landscape Restoration at the Arbor Day Foundation, Lauren leads the development of innovative, equity-driven programs through strategic partnership cultivation and industry research. Lauren's prior roles at the U.S. Forest Service, including serving as a Legislative Affairs Specialist and in national leadership roles in Urban & Community Forestry, integrated policy analysis with practical solutions, fostering collaboration and catalyzing significant investments in our nation's forests.

Lauren has been active in service and leadership roles in the natural resources sector for more than a decade. Since 2020, she has served as a Board Member for Nature Sacred and served on the Committee on the Environment for the City of Takoma Park, Maryland from 2013 to 2017. Lauren's role as a leader on the Presidential Management Fellows Board at the U.S. Forest Service from 2013 to 2019 and her service on the Green Communities Leadership Institute Steering Committee from 2020 to 2023 underscore her passion for fostering leadership development within the environmental sector.

Holding a Ph.D. from the University of Maryland, Lauren's research focused on community co-design of vacant land economic systems demonstrates her commitment to merging environmental stewardship with community led design. She also holds a Master's in Landscape Architecture from the University of Michigan and a Bachelor of Science in Plant Science from Cornell University.

Randall ("Randy") H. Miller is Director of Research and Development at Eocene Environmental group (formerly CNUC). He is responsible for conducting utility vegetation management research (UVM), providing subject matter expertise to utility vegetation management programs across North America, and provides expert witness testimony in vegetation management litigation.

Randy served as Arborist at Medinah Country Club in Medinah, Illinois; Wasatch Front Community Forester for Utah State Lands and Forestry; and as an Area Forester and System Forester/Director of Vegetation Management for PacifiCorp, an electric utility serving California, Idaho, Oregon, Utah, Washington and Wyoming. He holds a BS degree in Horticulture from the University of Wisconsin - Madison and an MS in Urban Forestry from the University of Wisconsin - Stevens Point. Miller has been an ISA member since 1986 and is an ISA Certified Utility Specialist™ and ISA Board Certified Master Arborist®, tree risk assessment qualification (ISA TRAQ).

Randy has over 35 years of continuous volunteer service to arboriculture and urban forestry non­profit organizations. In addition to his ISA Board service; he has served on the ISA Certification Test Committee,  Journal of Arboriculture and Urban Forestry Editorial Board, and on the ISA Appeals and Awards Committees. Outside of the ISA, he has been Chair of the TREE Fund Board of Trustees, President of the Utility Arborist Association (UAA), Chair of the Edison Electric Institute Vegetation Management Task Force and President of the Oregon Community Forest Council.

Randy has been recognized as the ISA 2005 R.W. Harris Authors Citation award recipient; and received the 2007 UAA President's Award, 2013 UAA Education Award 2022 UAA Utility Arborist Award;  2007 Pacific Northwest Chapter President's Award, 2008 Utah Chapter Distinguished Service Award, 2017 Utah Chapter ISA Lifetime Achievement Award, and the 2026 TREE Fund Ken Ottman Volunteer Award. He has over 100 published writing credits, including the ISA Integrated Vegetation Management Best Management Practices and, as coauthor with Geoff Kempter, Utility Arboriculture: The Utility Specialist Certification Study Guide. Randy is an accomplished speaker and has delivered hundreds of presentations on arboricultural, urban forestry and utility vegetation management topics. He is an eleven-time Tour des Trees rider and has raised over $70,000 for the TREE Fund.

Caitlyn Pollihan serves as CEO and Executive Director for the International Society of Arboriculture (ISA).  She began her role as Executive Director in 2017, with the Board adding the CEO title in 2020 to better reflect Caitlyn’s leadership responsibilities. During her tenure Caitlyn has successfully led the organization’s relocation to Atlanta, GA US, initiated the modernization of ISA systems and operations, and has increased the global connectivity and accessibility of the association.

Prior to joining ISA, Caitlyn served as the executive director of the Council of Western State Foresters (CWSF) and the Western Forestry Leadership Coalition (WFLC). In this role, she facilitated the development of the organization’s strategic goals and agendas and worked with members and CWSF/WFLC staff to ensure the organization’s success. Prior to this role, Caitlyn was the CWSF/WFLC governmental affairs director where she was instrumental in the creation of key legislation and educating members and partners on legislative proposals and national policy with western implications.

Caitlyn previously served as the staff vice president for government and environment affairs for the Home Builders Association of St. Louis and Eastern Missouri. In this role, she worked on state and local legislative initiatives, green building programs, and helped create and implement a ground‐breaking approach to building site safety inspections with the Occupational Safety and Health Administration. 

Caitlyn participates in several coalitions and committees, such as the Sustainable Urban Forestry Coalition Steering Committee, the i-Tree Executive Committee, and previously served on numerous public policy committees and was an appointed member of the National Advisory Committee for Implementation of the National Forest System Land Management Planning Rule.

Caitlyn holds a bachelor’s degree in contemporary media and journalism/public relations from the University of South Dakota and a master’s degree in organizational communication from the University of Missouri‐St. Louis. She has a Certificate in Nonprofit Organization Management from the US Chamber of Commerce Foundation’s Institute for Organization Management and has earned the Certified Association Executive (CAE) credential, the highest professional credential in the association industry.

Roger Rankine is an arboricultural consultant and business leader with more than two decades of combined experience across arboriculture, business management, and corporate leadership. As the Managing Director and Principal Consulting Arborist at Independent Arboricultural Services and ArbSupplies, Roger oversees a diverse range of operations spanning vegetation assessments, risk analysis, expert witness reporting, plant health care programs, and advanced diagnostic techniques. His work extends across Queensland and nationally, where he has served as an expert witness in numerous notable arboricultural legal cases involving local councils and private entities.