Semester

Fall

Date of Graduation

2005

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

James B. McGraw.

Abstract

American ginseng (Panax quinquefolius L.) is a long-lived, slow-maturing understory perennial herb found in eastern North American forests. The economic value of P. quinquefolius on the world market has remained strong for nearly 300 years. It has high economic and social value in the central Appalachians as well. Persistent harvest of ginseng combined with habitat loss has reduced populations in the wild, threatening the future of the species and its continued harvest. American ginseng was placed on the CITES Appendix II list in 1973 due to population declines. These concerns led to a series of studies investigating the population dynamics of ginseng in the center of its range. In the first study, I found that populations in the range center were projected to decline at a rate of 7 percent per year while those at the northern margin were projected to increase at a rate of 3 percent per year. The causes for the difference included significantly lower fertilities in the range center, and lower stasis and growth in all classes but growth from seedlings to 1-leaf plants in the populations in West Virginia. In the second study, the size structure of a wild population of ginseng was slow to recover following a fully destructive harvest, but the presence of seeds in the soil conveyed some resilience to the removal of all juvenile and adult plants from a site. In the third study, a seed bank viable beyond 20 months was documented for the first time for P. quinquefolius, indicating the need to restructure future demographic models to incorporate seed dormancy. In a series of harvester simulation studies, I found that harvester behavior dramatically impacts projected population growth rates of ginseng. By planting seeds at a depth of 2 cm, harvesters can reverse declining population growth rates. Current regulations for legal harvest in nearly three quarters (i.e., 71%) of the states in the range center are not adequate to protect P. quinquefolius in the long-term. This research led to the improvement of demographic models and documented the critical role that harvesters can play in maintaining healthy populations of wild ginseng.

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