Evidence for decline in stature of American ginseng plants from herbarium specimens

American ginseng (Panax quinquefolius L.) has been harvested from the wild to supply the Asian herbal market for more than 200 years. As a CITES Appendix II listed species, ginseng trade has been monitored since 1975 and evidence for no detrimental effects of harvest is required annually by the US government. One kind of evidence gathered to gauge harvest effects has been mean root size and age, however the short-term nature of the data set limits possible inferences. In this study, 915 herbarium specimens from 17 herbaria were aged and measured to extend the time-transect to 186 years. Nine of 11 size-related traits showed statistically significant declines, most of this change occurring since ca. 1900. Multivariate analyses confirmed the overall decline in plant size. Age of herbarium specimens did not significantly decline during the same interval. Plants collected from northern populations did not decline in size, while plants from midwestern, Appalachian and southern states showed sharp declines in stature. Assuming herbarium specimens are representative of a consistent portion of natural populations, either direct or indirect effects of environmental change or human harvest could explain the rapid change in ginseng stature. Understanding the implications of such plant stature changes will require examining the effects of size on harvest probability and reproduction in the context of population viability analyses. (C) 2001 Elsevier Science Ltd. All rights reserved.