Virginia Round-leaf Birch

Betula uber

Description

The Virginia round-leaf birch, Betula uber, is a deciduous tree with dark, smooth bark separated into thin plates. It has hairless twigs and foliage, and nearly circular toothed leaves about 1 in (2.5 cm) long. It grows to about 30 ft (10 m) in height and can live 50 years or more. Seed production is believed to be cyclical, with abundant fruits and seeds appearing every three to four years. Leafing out and flowering of mature trees occurs late April to early May. Fruits are mature by mid-October, and seeds are dispersed in January and February.

Originally listed as Endangered in 1978, the species was reclassified to Threatened status in 1994 thanks to the ongoing success of recovery efforts that established, over a decade-long period, 20 additional populations resulting in a dramatic increase in subadult trees.

Habitat

The Virginia round-leaf birch grows along the banks of a small mountain stream at an elevation of 2,700 ft (821 m). The habitat vegetation is characterized as a highly disturbed second-growth, transitional forest of oak-pine and maple-beech-birch associations. Flood plain species, such as elm and cottonwood may also be present.

The climate is relatively cool and moist with an annual rainfall of 48 in (122 cm). Soils are stony colluvium, strongly acidic and highly permeable. The round-leaf birch depends on some disturbance, such as fire or cutting, to maintain itself, as it cannot compete with more long-lived and shade resistant species. Shade forestalls the establishment of seedlings, believed to germinate in mid-June.

Distribution

This species of birch is considered endemic to mountainous southwestern Virginia. It has existed in the wild for at least 60 years with characteristics passed from parent to offspring without losing integrity. It is related to Betula lenta and is similar in nearly all ways except for its round leaves. The birch was originally reported along Dickey Creek, although specimens are not now known from that site. Botanists now believe the original reports of populations there may have been erroneous; the collection is thought to have been confused with the Cressy Creek population.

Virginia round-leaf birch was rediscovered in 1975 along the banks of Cressy Creek near Sugar Grove, Virginia. When first surveyed, the population consisted of 14 adult trees and 26 saplings, but by the fall of 1988, only four adult trees and several seedlings remained. Three of these trees are on private property, while the fourth is on adjacent U.S. Forest Service land. Cultivated stocks of round-leaf birch have been established at Reynolds Research Center in Critz, Virginia, and at the National Arboretum in Washington, D.C.

Thanks to dedicated recovery efforts, however, the species population has increased exponentially in the past 15 years. By 1994, an additional 20 populations had been established, increasing the total subadult population to more than 1,400 trees, and sparking the reclassification of the species from Endangered to Threatened.

Threats

Vandals have repeatedly destroyed trees and seedlings at the Cressy Creek site, presumably because of fear that the federal government will use the trees as a reason to intrude on the rights of local landowners. Competition from encroaching vegetation has limited the tree's ability to recover from these depredations.

Conservation and Recovery

To encourage natural regeneration, canopy cover was removed in 1981 to expose mineral soils at two sites close to fruiting trees. About 80 seedlings sprouted in 1982. About 50 seedlings died, probably due to encroaching plants or to browsing white-tailed deer and rabbits. Despite close observation, additional seedlings were vandalized in 1983 and 1984, and by 1985 only two of the 80 seedlings remained. In 1984, the Nature Conservancy purchased a 36-acre parcel bordering Cressy Creek, directly adjacent to the wild population. This land was in turn purchased by the U.S. Forest Service in 1986, and has been managed ever since as potential habitat for the tree.

Recovery strategies for the Virginia round-leaf birch have focused on establishing a healthy stock of cultivated saplings and then transplanting trees to new, less exposed locations. In 1984, 480 seedlings were transplanted to Forest Service lands from stock cultivated at the Reynolds Research Center. Five additional sites of 40 trees each were established in 1985 using three-year-old seedlings. By 1994, a total of 20 new populations had been established, increasing total populations to more than 1,400 trees.

The National Arboretum has cultivated a number of round-leaf birches and distributed seedlings to public and private nurseries in the United States, England, Belgium, and West Germany. As the Cressy Creek site is consistently vandalized and transplants on Forest Service property have reportedly suffered from vandalism, botanists have been unwilling to hint at the location of other transplanted trees. The cultivation and transplantation effort has already succeeded in bringing this species back from the edge of extinction, and the marked success of recovery efforts, moving the species from Endangered to Threatened status by 1994, makes it likely that the tree could be delisted altogether in the near future—perhaps even sooner than the target delisting date of 2010 projected in the 1990 Fish and Wildlife Service revised recovery plan update for the species.

The Recovery Plan calls for the species to be delisted after the existence can be documented of ten self-sustaining populations, defined on the basis of having each produced through natural regeneration, 500 to 1,000 individuals standing more than 6 ft (2 m) tall.

Contact

U.S. Fish and Wildlife Service
Division of Endangered Species
300 Westgate Center Drive
Hadley, Massachusetts 01035
http://northeast.fws.gov/

References

Hayden, W. J., and S. M. Hayden. 1984. "WoodAnatomy and Relationships of Betula uber." Castanea 49:26-30.

Sharik, T. L., and R. H. Ford. 1984. "The Current Status of the Virginia Round-Leaf Birch, Betula uber (Ashe) Fernald." Annual Progress Report. U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.

U. S. Fish and Wildlife Service. 1986. "Virginia Round-Leaf Birch Recovery Plan." U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.

U. S. Fish and Wildlife Service. 1990. "Virginia Round-Leaf Birch Revised Recovery Plan Update." U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.