The Native Arboretum project is located at the Marie Butler Leven Preserve, in the McLean section of Fairfax County. The project began in 2004, and is based on an agreement between the Fairfax County Park Authority, which owns the Preserve, and the Earth Sangha. The aim of the project is to transform the Preserve into an extensive collection of plants native to the greater Washington, DC, region. The collection will not include all species native to the DC Metropolitan area, but it will represent the full spectrum of the region’s flora—trees, shrubs, vines, and herbaceous plants.
Our objective is to create a living botanical library. The Native Arboretum will be a public resource for building ecological literacy, and for creating a stronger mandate for conservation.
When our project started, the Preserve was well on its way from being a small but diverse native forest to becoming a large invasive thicket. Since then we have made substantial progress, but the Preserve remains heavily infested by invasive alien plants; we have had to fight the invasives for just about every square foot of area restored.
If you’re interested in volunteering at our Native Arboretum site, please check our Field Schedule for upcoming volunteer opportunities.
In 2016, with the support and guidance of Dranesville District Supervisor John W. Foust, the Earth Sangha and the Fairfax County Park Authority entered into an agreement to renovate the old Leven House on the Preserve grounds. The Earth Sangha has signed a 10-years lease to use the house in order to better assist with the management of the grounds. The Earth Sangha is responsible for renovating the house for this purpose. The preservation of the house concluded in June 2017.
The Native Arboretum project is large, long-term, and complex. To keep the agenda manageable, we have broken the work down into a set of more or less independent project modules, each focused on a particular area. As is apparent from the descriptions that follow, project activities are almost entirely variations on two basic themes: controlling invasive alien plants and reintroducing appropriate native plants. All of the reintroduced natives are local-ecotype stock, produced at our own Wild Plant Nursery (and at the raised beds at the Preserve itself). All of our stock is grown from seed, spore, or cuttings that we ourselves collect, with permission, from local natural areas.
The Rain Garden
In collaboration with the Fairfax County Park Authority, the Northern Virginia Soil and Water Conservation District, and the McLean Citizens Foundation, we helped create a rain garden along the northern edge of the Preserve in 2005. The garden should act like a giant sponge, absorbing stormwater run-off from about an acre of the surrounding terrain, filtering the water, and releasing it gradually into adjacent soil. Unfortunately, the garden is not draining properly, so the Park Authority and Soil-and-Water are planning to install a better drain. Once that is done, the garden should help stabilize Pimmit Run, the local stream.
The Kirby Road Border
The narrow band of trees along Kirby Road, on the west side of the Preserve, was densely infested with various invasive alien vines and shrubs — and with one “native invasive,” black locust, a large, fast-growing tree that suckers readily (that is, it produces additional stems from its roots) and that can readily dominate disturbed areas. Since 2006, we have been pushing back against the invasives and the black locust. Currently, our focus is on suppressing black locust and managing the "curtain" of shrubs and vines along the inner edge of the border. Much of this curtain is invasive.
The Native Pollinator Garden
In 2005, we replaced a dense thicket of invasives — primarily multiflora rose (a large, spiny shrub) and mile-a-minute (a spiny, annual vine) — with a long, forest-edge garden that includes many native herbaceous and woody plants attractive to native butterflies, moths, bees, and other nonpest insects. Since the initial planting, we have continued to remove invasives from this section, adjust the planting, and add more natives.
The Southern Forest
The forest in the southern section of the Preserve is mostly on drier soil than the forest in the gorge drainage and the plant community here is less diverse. This section is densely infested with various invasive alien shrubs and vines. The most common invasive shrubs are multiflora rose and Amur honeysuckle; among the vines are mile-a-minute (along the forest edge), oriental bittersweet, porcelainberry, Japanese honeysuckle, English ivy, and wintercreeper euonymus. There is also at least one invasive alien tree in this area: white mulberry. We started working in this area in 2010.
The Native Pollinator Forest
Behind the pollinator garden, there is a little patch of forest that extends past the old barn foundation and up to the house lawn. This area is being cleared of invasive alien vegetation. We started working here in 2006. Most of the invasives had been suppressed, but we will have to continue weeding in this area for many years to come. We are also doing some planting to enrich forest composition.
The Gorge and Pond
In the eastern section of the forest, there is a little gorge that has been cut by a spring that runs into a seasonal pond near the Preserve’s eastern boundary. The gorge drainage contains many naturally-occurring native groundlayer plants—a feature that distinguishes this part of the park from just about all the other parts. But these native groundlayer herbs (nonwoody plants) are intermingled with various invasives, and over the long term, the invasives are likely to displace the natives. A further complication in this area is its steep slopes, which are very susceptible to erosion. Under these conditions, the only safe way to remove the invasives is through careful hand-weeding, followed by a little judicious planting as the need arises. We started work in this area in 2008.
Meadows are among the most diverse plant communities in our region. As more and more meadows are lost, the plant and animal species that depend on these communities are becoming less and less common. The Preserve's main field, now mowed only once or twice a year, is home to a meadow project that we started in 2013. We plowed a section of the field and planted natives there. Our plants are doing well but we need to maintain the site through continual hand-pulling of invasives.
Banner: Witchhazel in bloom at the Marie Butler Leven Preserve. Photo by Chris Bright.