Barcroft Bog: Home to Two Rare Natural Communities
Lying along Four Mile Run in Arlington County, Virginia, Barcroft Park contains two of the most unusual plant communities remaining in the immediate DC-area. These two communities are growing right next to each other, and they are sometimes referred to collectively as the “Barcroft Bog.” But ecologically, they are distinctly different places.
One of these communities is a magnolia bog, which lies at the base of a steep, forested slope. Several groundwater seeps in the slope feed the bog below, keeping it wet, but usually not flooded, all year round. The bog’s herb layer includes sphagnum mosses (Sphagnum spp.), sedges (Carex spp.), and slender wood oats (Chasmanthium laxum). Among the bog’s woody plants are several species uncommon in the DC area, for example: swamp azalea (Rhododendron viscosum), dangleberry (Gaylussacia frondosa), swamp-haw (Viburnum nudum), poison sumac (Toxicodendron vernix), and sweetbay magnolia (Magnolia virginiana), from which the magnolia bog community takes its name.
The bog has been recognized by the Virginia Department of Conservation and Recreation as a “critically rare and endangered” plant community. (Note that the designation applies to the plant community as a whole—not to the individual species that compose it.) The Barcroft magnolia bog is thought to be one of only ten such sites remaining in the mid-Atlantic.
Barcroft’s other unusual plant community, a seepage swamp, lies just downslope from the bog. Here, the water forms standing pools, except during the driest part of the year. In and around the pools, skunk cabbage (Symplocarpus foetidus) dominates the herb layer. Above it grows willow oak (Quercus phellos), red maple (Acer rubrum), black gum (Nyssa sylvatica), and river birch (Betula nigra). This community has been recognized as “uncommon to rare.”
Nearby development has reduced the size of both the magnolia bog and the seepage swamp. Development has also affected the area’s unusual hydrology. But Arlington County has a detailed management plan to keep the surviving portions of both communities in good condition. The Earth Sangha participated in that plan in 2005, by helping to replant an abandoned baseball field adjoining the sensitive natural areas. The planted field will eventually become a protective “buffer forest.”
We were invited into the project by Arlington County Naturalist Greg Zell, who asked us to supply planting stock from our Wild Plant Nursery, because we propagate exclusively from local, wild, native-plant populations. The use of such material is a standard best practice in ecological restoration because that helps to maintain the genetic variety and local character of the species planted—and on a site as sensitive as this, Greg was especially interested in insuring that extraneous material would not be introduced.
Where to Find More Information
To see our plants being put in and a few photos of the bog, view the Barcroft Bog slide show. For recent activities on sites described in the Special Places page, look at the Special Places News.