Tamara Belt, Landscape Committee Chair

Tamara joined the Board in 2010 and is Vice Chair and Chair of the the Landscape Committee. She owns Hawthorne Garden Design, which specializes in high-end residential landscape design in the DC metropolitan region.
Before earning her degree in landscape design, Tamara was an environmental economist at the World Bank and the Inter-American Development Bank for over ten years, where she focused on projects in the environmental sector. She earned her Ph.D. in economics from the London School of Economics.
A native Spanish speaker and half-Colombian, Tamara also previously served as PTA co-chair at the Oyster-Adams Bilingual School. Tamara is married to Sean Greene, and they live in Woodley Park with their three children. She is delighted to be able to support the restoration of this neighborhood treasure.
Ann Brooke, Volunteer Landscape Designer

Ann Brooke has been designing and installing gardens, large and small, since 1987 — penthouses in New York City, Brooklyn brownstones, second homes and country estates in Connecticut, Massachusetts, Shelter Island and Colorado, schools in Brooklyn, and playgrounds in Colorado and New York. She recently relocated to Washington and is enjoying the opportunity to work in a new and more temperate environment. Ann grew up outside Sydney in a part of Australia full of lush, serene, sophisticated gardens whose English style had been adapted to a very different climate and landscape. Her landscape practice, Ann Brooke Landscape Design LLC, draws on that history of flexible and creative adaptation. Her volunteer work for Tregaron has included Shipman-inspired woodland garden design, tree planting plans, and supervising landscape installations.
Beth Kaplan, Volunteer Gardener Co-coordinator & Yoga Teacher

(Photo credit: Jennifer Packard)
Beth Kaplan is a yoga teacher and a devoted Tregaron neighbor. Since 2018, she has worked with Chris Powell to coordinate the on-the-ground work of Tregaron’s volunteer gardeners.
Beth is an archivist and a librarian. She has worked at MIT, the Kennedy Library, Iowa State University, the University of Minnesota, and, most recently, at George Washington University where she served as an associate dean. She left that position in 2018 to devote herself to teaching yoga full time.
Beth has taught at iconic DC locations including the National Gallery of Art, the National Zoo, the Phillips Collection, and the World Bank. She teaches classes in Tregaron’s Twin Oak Meadow in the summer and fall. Beth offers classes through her website, bethkaplanyoga.com.
Jennifer Packard, Volunteer Photographer
Jennifer Packard is a professional photographer who has a passion for nature photography. Inspired by her father’s service in the Navy in World War II, she served in the Navy Reserves for 10 years as a public affairs officer, documenting activities of the Navy around the globe. She now works as a freelance photographer in Washington, DC. Her work has been featured in many publications, including USA Today, NBC News, ABC Newspapers, Self.com, Navy Times, and Seabee Magazine.
Jennifer’s interest in nature photography began at a very young age, growing up in rural western New York State. By capturing the beauty of Tregaron, she hopes to inspire others to preserve the natural world and the open green spaces in our community.
Jennifer earned a BFA in Applied Media Arts/Photography and a Masters in Communication Studies from Edinboro University of Pennsylvania. View Jennifer’s portfolio here.
Christine Powell, Volunteer Gardener Co-coordinator
Chris has been involved with the Tregaron Conservancy since returning to DC in 2017. Before she moved to Nebraska to live on the prairie for a few years, she used to walk around the edges of the property, which was overgrown and rundown. When she returned to DC, she was amazed at the restoration that was happening and knew immediately she wanted to get involved. Now, Chris helps coordinate the on-the-ground work of the volunteer gardeners.
Chris retired a year ago as Chief of Staff of the National Park Service, which gave her more time to devote to Tregaron and her other volunteer endeavors. She has been a docent at the U.S. Botanic Garden for a decade, leading tours for the public and assisting with events. She is Board Chair of a small nonprofit animal welfare organization headquartered in Kabul, Afghanistan, and also tutors writing to adult immigrants through the Washington English Center. She serves on a Board committee for the Audubon Naturalist Society and is a member of their creek monitoring team.
Chris lives with her husband Bern and sister Bess, who are also Tregaron volunteers.
Shawn Siefers, Master Arborist

Shawn Siefers is certified as a Master Arborist through the International Society of Arboriculture, and has been involved in the Arboriculture field since 1999. He has worked for The Davey Tree Expert Company (formerly The Care of Trees), a sustainable tree care service, since 2003, where he specializes in tree health care, a skill he brings to his work with Tregaron. Shawn has also brought his expertise to a wide range of institutions, including a number of campuses such as Georgetown University, Washington International School, Sidwell Friends School, Georgetown Visitation, and Maret School. He has also provided tree care services for the National Cathedral. Shawn is affiliated with a number of professional associations, including the Maryland Arborist Association, and consults for the City of Gaithersburg. He holds degrees in Forestry from Allegany College of Maryland and the University of Maryland.
Glenn Stach, RLA, LEED AP, Consulting Preservation Landscape Architect & Planner
Glenn Stach has been dedicated to cultural landscape preservation for over 20 years. Glenn has a proven record of sustaining and enhancing the historic legacy of significant landscapes through design and planning. Glenn obtained his degree from Virginia Tech, and has since managed projects in landscape architecture, historic preservation, and urban design for clients such as the Central Park Conservancy, the James Monroe Birthplace and Biltmore Estate. His Washington DC-based projects have included Meridian Hill Park, St. Elizabeth’s Hospital and the World War I Memorial.
Before Glenn started his firm, he was employed by Heritage Landscapes, the Vermont-based preservation planning firm that authored Tregaron’s Cultural Landscape Report. Glenn has served on the Board of Directors of The Cultural Landscape Foundation, which has recognized Tregaron as a notable destination. The Conservancy is delighted to have Glenn’s expertise and guidance in renewing and recapturing the beauty and integrity of the historic Platt/Shipman landscape.
Judith B. Tankard, Independent Historian of Landscape Design

Judith Tankard is a landscape historian, preservation consultant and author. She is a frequent lecturer on landscape history and a noted expert on Ellen Biddle Shipman. She is the author of The Gardens of Ellen Biddle Shipman (Sagapress/Library of American Landscape History, 1996), which introduced a new generation of garden lovers and historic landscape enthusiasts to Shipman’s pioneering achievements. In response to the popularity of Tankard’s book and its role in catalyzing preservation and renewal of Shipman’s gardens, the Library of American Landscape History has published an updated edition, Ellen Shipman and the American Garden (University of Georgia Press/LALH, 2018), a winner of the 2019 John Brinckerhoff Jackson Book Prize.
Judith lives in Boston, Massachusetts. She taught landscape design at Radcliffe Seminars for many years and was the founding editor of the Journal of the New England Garden History Society. She currently serves on the Stewardship Council of The Cultural Landscape Foundation. Judith lectured at Tregaron in 2012 and periodically advises the Conservancy on Shipman’s landscape designs.
James Whelan Wohlgemuth, Former Chair
Jim Wohlgemuth served on the Board continuously from the Conservancy’s founding through spring 2018, and from 2015 to February 2018 as Chair. A native of Chicago, Jim has lived in Washington DC for over 30 years. He began his professional career as a marketing representative for the E&J Gallo Winery in Denver, Colorado. He then moved to Washington DC in 1983 and began working in securities for Dean Witter Reynolds. From 1987 to 2009 Jim was a managing director at Alex Brown and Sons and its successor companies. He is currently a managing director at Morgan Stanley Private Wealth Management in Washington DC. Jim serves on the Finance Committee and advises the Conservancy on its endowment investment strategy.
Jim received his MBA from The George Washington University and a bachelor of arts in political science from Colorado State University. He and his wife, Caroline, live and raised their four sons in Woodley Park, a half-block from Tregaron.
Susie Zimmermann, Marketing and Communications
Susie brings 30-plus years of marketing and communications experience to the Conservancy. She currently provides services to nonprofits, federal contractors and other businesses through her consulting firm, Channel Z Marketing. From 2009 to 2018, she served as Director of Communications at Bullis School in Potomac, Maryland. Earlier in her career, Susie managed marketing communications programs for organizations including the National Institute of Standards and Technology, Americorps and the Peace Corps.
Susie is a graduate of the University of Virginia and is originally from Atlanta. She served on the Conservancy’s board from 2017 to early 2020. She recently moved to New York City from Cleveland Park but remains active in supporting the Conservancy’s communications efforts.