Wild American ginseng populations in the southern Appalachians may be negatively affected by climate change.
Gagnon, Daniel*,1, Rock, Janet2, Nantel, Patrick3, 1 Groupe de recherche en écologie forestière interuniversitaire, Montréal, QC2 Great Smoky Mountains National Park, Gatlinburg, TN3 Parks Canada, Hull, QC
ABSTRACT- Demographic analysis was conducted during 4 years in 2 populations (1998-2001) and 2 to 3 years in 4 populations (1999-2001) of Panax quinquefolius in Great Smoky Mountains National Park (Tennessee and North Carolina), yielding 13 transition matrices. Populations were comprised of between 90 to 200 plants, and occurred from 575 to 1280 m elevation. Objectives were to characterize demography, evaluate impacts of harvesting, and assess minimum viable population (MVP) size. Dormancy of large plants is confirmed for the first time in ginseng, with 8% (average) of all plants entering dormancy in any year, and a maximum of 29% of 4-leaved plants (largest size-class) in one population in 2000. Most dormant plants emerged after 1 year of dormancy (with a decrease in size), but 12% remained dormant for 2 years. Seed production was very low, declining from 1998 to 2000, averaging 10 seeds per 4-leaved plant (vs. average of 26 seeds in Canadian populations studied, 1986-1988). Population growth rates calculated from the matrices vary from 0.856 to 1.076 (mean = 0.997). Stochastic projections indicate that these populations are currently barely maintaining themselves and cannot tolerate any harvesting. Illegal harvests are a problem in Great Smoky Mountains National Park, where over 10,000 poached ginseng roots were confiscated during a 9-year period (estimated 1% of total illegal harvest). The determined MVP size of 510 plants, linked to low mean population growth rate, is larger than most existing populations, within or outside the park. Dormancy of large plants, small seed crops and low population growth rates appear related to droughts during 3 of 4 years of the study. Continued legal harvest pressure in the US (illegal in parks), increasing deer browse pressure in many areas (McGraw and Furedi (2005) Science), combined with likely climate change effects, will lead to the decline of American ginseng populations throughout the range of the species in the US and Canada.
Key words: Panax quinquefolius, minimum viable population size, non-timber forest product, CITES species
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