The National Big Tree Program’s Measuring Guidelines Working Group and Eligible Species Working Group encompass a diverse committee of experts who assist the national program by addressing some of the tough questions inherent in crowning champion trees, from updating taxonomy and nomenclature to reviewing measuring guidelines and presenting new measuring techniques.

Eligible Species Working Group Members

Measuring Guidelines Working Group Members

Mark Grueber
Mark Grueber is an urban forester for the Missouri Department of Conservation, where he provides information on technical and urban forestry, green design and arboriculture to various government agencies, nonprofit organizations and planners. Grueber works to promote and increase awareness of the many benefits of healthy forests to the citizens of Missouri, assists landowners with sound management and ecological restoration and conducts workshops on increasing healthy urban forest canopy.

He has held various positions throughout the state of Missouri and played an integral role in the development of Forest ReLeaf of Missouri, where he has served on the board of directors since the organization’s inception in 1995. He was named the Urban Conservationist of the Year in 2008 and the Tree Advocate of the Year in 2012. Grueber says his love for trees began at an early age, as his mother would take him outdoors and identify trees with him.

Grueber is a certified arborist and proctor with the International Society of Arboriculture and a master gardener and naturalist instructor. He is also an official measurer for the national, state and St. Louis champion tree programs. He received his bachelor’s degree in forest management from the University of Missouri.

Edward Hedborn
Edward Hedborn is the manager of plant records for Illinois’ The Morton Arboretum, where he maintains the life history of every plant grown by the arboretum and makes the information available to staff, visitors, researchers and the green industry. Hedborn also verifies plant nomenclature, identifies plants in collections and the plant clinic, updates the arboretum’s online web catalog along with the herbarium and maintains the geographic information system. He works with the plant records assistant to ensure the inventory of all living collections and that plants are labeled appropriately.

In his free time, Hedborn gives back to the community by helping out with local Boy Scout troops. He has advised more than 82 Eagle Scout projects and one Girl Scout Gold Award service project. He is the recipient of a District Award of Merit, Silver Beaver Award and William T. Hornaday Gold Badge for service in conservation and ecology. He also teaches botany for the arboretum and the Associated Colleges of the Chicago Area (A.C.C.A.).

Hedborn received a bachelor’s degree from Illinois’ North Central College and a master’s degree in biology from Northeastern Illinois University.

Dr. John R. Seiler
Dr. John R. Seiler is an alumni distinguished professor at Virginia Polytechnic Institute and State University (Virginia Tech) and currently holds an endowed chair — named in honor of the Honorable and Mrs. Shelton H. Short, Jr. — in the Department of Forest Resources and Environmental Conservation.

In January 1985, he joined the faculty in the Department of Forestry at Virginia Tech, where he researches the effects of various environmental impacts on tree biology and growth. With his graduate students, he has published more than 90 referred articles on the subject. In the past, he has researched water stress, acid rain, ozone and elevated CO2 effects on forest trees. His most recent research is investigating the role that managed tree ecosystems can play in sequestering atmospheric CO2.

Dr. Seiler has taught a wide variety of classes including dendrology (tree identification), forest biology, silviculture, forest fire management, plant water relations, advanced forest ecology and tree physiology, and he teaches an online course called Forest Ecology and Dendrology for Educators that was designed for public school biology teachers to take during the summer months. Dr. Seiler and his colleagues have also developed a wide array of multimedia teaching tools, including the Woody Plants in North America DVD, to aid students in learning tree identification and forest biology and most recently released a smart phone app that has quickly become the most widely downloaded tree identification app. Dr. Seiler and his team have won numerous state, national and international teaching-related awards. Throughout his career, he has been involved in curriculum development at the department, college and university levels.

He received bachelor’s degrees in forest science and environmental resource management and a master’s degree in forest biology from The Pennsylvania State University and a doctorate degree in tree physiology from Virginia Tech.

Don Bertolette
Don Bertolette is the state coordinator for the Alaska Big Tree Program, serves on the National Big Tree Committee and acts as an ex-officio member and full-time member on the Measuring Guidelines Working Group.

Bertolette started his forestry career in 1967 and has worked at such agencies as the Bureau of Land Management, the U.S. Forest Service and the National Park Service. He retired in 2007 from the Grand Canyon National Park Service Science Center, where he served as a restoration forester and vegetation program manager, overseeing 150,000 acres of forested ecosystems.

Bertolette received his bachelor’s degree in forest resources management at Humboldt State University and a master’s degree in forestry, with a specialization in remote-sensing, from the University of Massachusetts-Amherst. He has also received training in Fire Area Growth Simulation Modeling (FARSITE) and preparation in ecological restoration.

Robert T. Leverett
Robert T. Leverett is the co-founder and executive director of the Native Tree Society, an organization devoted to the scientific research, modeling, measurement, education, advocacy and general enjoyment of forests and trees. He is also the co-founder and president of Friends of Mohawk Trail State Forest, a federally recognized nonprofit partner to the state forests and parks of the Commonwealth of Massachusetts.

As one of the developers of sine-based and other trigonometric methods for measuring tree dimensions for the Native Tree Society, Leverett conducts advanced tree measuring workshops for champion tree measurers. He has been recognized by the Massachusetts Natural Heritage Program as the discoverer of more than 50 old-growth stands in Massachusetts and has authored numerous articles on old-growth forests and tree measuring. Leverett has also co-authored a number of books, including Sierra Club Guide to Ancient Forests of the Northeast, Eastern Old-growth Forests, Prospects for Rediscovery and Recovery and Stalking the Forest Monarchs: A Guide to Measuring Champion Trees.

He is a recipient of the 1993 Conservation Award from New England Wild Flower Society, the 2010 Citizen Conservation Award from the Springfield, Mass., Naturalist Club and the Massachusetts Audubon Society’s highest Citizen Conservation Award. He is the principal architect of the Ancient Eastern Forest Conference Series and has also served as a nature interpreter for numerous environmental organizations.

Leverett served as an adjunct instructor in computer science at American International College and at Holyoke Community College for 24 years. He originally studied electrical engineering for three years before receiving a bachelor’s degree from the Georgia Institute of Technology in industrial management and engineering. Leverett completed graduate studies in economics at South Dakota State University and business administration and computer science at the University of Wyoming.