Living plant collections play an important role in conserving plant biodiversity. Public gardens and arboreta collect and cultivate threatened tree species to learn about and safeguard important sources of tree genetic diversity. One threatened American tree species, Quercus oglethorpensis (Oglethorpe oak), is being grown and protected at The Morton Arboretum and other institutions.
Quercus oglethorpensis is an endangered species native to the southeastern United States. It is threatened by land-use changes, competition, and chestnut blight. The sparse distribution covers a linear distance of about 950 km (approximately 590 miles), including several disjunct populations potentially harboring unique genetic diversity or adaptive variation. Protected populations in the Bienville National Forest (Mississippi), Oconee National Forest (Georgia), and Sumter National Forest (South Carolina) are regularly monitored and managed through a combination of techniques including burning and selective clearing.
Several additional populations were recently discovered in Alabama, primarily along rights-of-way or on private land where they should be considered vulnerable or at risk of extirpation. One documented population in Sumter County (Alabama) has already been lost to land clearing or logging. Traditional techniques such as seed banking are insufficient for ex situ conservation of Quercus oglethorpensis due to the recalcitrant nature of the seeds. However, the species has been shown to be suitable for cultivation across a wide area of the United States and can be conserved ex-situ in the living collections of arboreta and botanical gardens.
In 2015, through a joint venture between the USDA Forest Service and the American Public Gardens Association, seed and/or samples of scion wood were collected from populations of the species in Mississippi, Alabama, Georgia, and South Carolina and were propagated at The Morton Arboretum. In 2017, they were distributed to five arboreta and botanical gardens: the Chicago Botanic Garden (Glencoe, IL), Starhill Forest Arboretum (Petersburg, IL), the Holden Arboretum (Willoughby, OH), the Donald E. Davis Arboretum of Auburn University (Auburn, AL), and Moore Farms Botanical Garden (Lake City, SC). All have Nationally Accredited Plant Collections™ certified by the Plant Collections Network of the APGA. Through cultivation in these arboreta and botanical gardens, genetically diverse and representative germplasm of Quercus oglethorpensis will be preserved and potentially can be used in future reintroduction efforts.
Toward the end of 2017, a second phase of the project was attempted. Scouting was completed in the Bienville National Forest (Mississippi) and Caldwell Parish, Louisiana. Many trees were located, though most had not produced acorns that season. Additional collecting efforts will be undertaken in hopes of bringing this germplasm into cultivation as well.
To view the complete report, please visit publicgardens.org.