American ginseng is a widespread but uncommon understory herb of the eastern deciduous forest. Ginseng is America's premier wild harvested medicinal plant species, annually worth millions of dollars in supplemental income to thousands of rural Appalachian diggers. The wild harvest supplies Asian market demand for the plant's putative broad-spectrum herbal properties. Recent medical research suggests that ginseng may treat diabetes, lower obesity, and boost the immune system. Conservation of natural ginseng populations is mandated by its listing on the Convention on International Trade in Endangered Species (CITES) Appendix II, however detailed demographic data are needed to place management of the species on solid scientific ground. The proposed LTREB project will extend long-term, detailed censusing and demographic modeling of 30 geographically distributed populations of ginseng containing an aggregate of more than 4000 individuals.
This project will provide crucial information about how perturbations in the environment affect the long-term prognosis for wild ginseng populations. This analysis will be shared with three stakeholder groups with strong interests in ginseng conservation biology: other scientists, managers/policymakers, and the general public. A conservation fellowship will be created for a Ph.D. student to train them in data curation, population matrix modeling, and outreach. A second graduate student and two undergraduate interns will receive summer support to assist with the project.
The purpose of this project was to use long-term demographic censusing of wild American ginseng populations to evaluate risks to viability of natural populations over the coming century. American ginseng is America's premiere wild harvested plant species. Harvested for the past three centuries to supply the Asian traditional medicine market, the species provides important supplementary income to rural residents, particularly in Appalachia, where unemployment is high. In addition, ginseng hunting connects rural residents to healthy, diverse forests to a degree no other plant does. The tradition of ginseng harvest is deeply rooted in Appalachian culture, and knowledge of this plant, among many other wild harvested species, is an important part of the cultural heritage of the region. Conservation of this species is therefore not just preservation of a plant, but also conservation of a way of life and conservation of the thread that connects people to the land. Through twice-annual censusing of 30 representative natural populations in 7 states, our goal is to sample nearly 500 'population-years' of data. This will allow us to detect patterns in directional changes affecting ginseng populations as well as allow us to detect rare occurrences which may be equally important. In the first five years of this project, we evaluated several factors thought to affect ginseng population viability: (1) harvesting, (2) overbrowsing by white-tailed deer, (3) invasive species, and (4) climate change. With respect to harvesting, we showed that compliance with current law governing harvest is inadequate to protect the species. However 'stewardship' harvesting can be done sustainably. We recommended specific changes to states managing ginseng harvest. Three out of four of the largest harvest states (WV, KY, TN) have now changed their laws to promote more stewardship oriented harvesting as a direct result of our research. We also showed that harvest affects the process of 'natural' selection in wild populations, such that dwarfing of adult plants is expected over time. Overbrowsing by deer has effects on ginseng populations of comparable magnitude to harvest. In areas with large deer populations, lower population viability suggested imminent extinction of almost all populations over the coming century. Simulated reductions of deer browse prevented such extinction. Because ginseng is not a 'preferred' plant for deer, we expect such results could be widely applicable to other understory herbs. Invasive competitive plant species had relatively small effects on ginseng. One herb (garlic mustard) and one tree (Tree-of-heaven) were investigated in terms of their effects, and neither showed strong negative effects, although seedlings of ginseng were affected by garlic mustard. Studies of response to inter-annual climate variation showed clear patterns of local adaptation, such that the expected directional warming of climate over time will negatively affect ginseng - not just in the south, but in the middle of its range, and farther north, as well. Accompanying experiments strongly suggested this local adaptation pattern was not due to temperature, per se, but instead due to indirect effects of temperature. The continued long-term censusing of many populations over time has led to an unprecedented data set on this uncommon to rare medicinal plant species. Future studies focusing on landscape level change, and conservation solutions to the problems facing species such as ginseng will further the value of the dataset to the wider scientific community and to the public. The PI has made numerous efforts to publicize the scientific findings for the benefit of peer scientists, policymakers and the public, including developing a data sharing policy and plan, an informational web site, and producing two highly viewed YouTube videos.
