PARENT SESSION
Oral Session # 36: Rare, Threatened, and Endangered Species I: Plants.
Presiding: H Balbach
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 204.

Demography of central populations of American ginseng.

McGraw, James^*,1, Furedi, Mary Ann¹, ¹ West Virginia University, Morgantown, WV

ABSTRACT- American ginseng is being harvested from natural populations throughout the central part of its range. Previous demographic studies at the northern range margin suggested that levels of harvest typically seen were unsustainable there. Over a two year period, we censused 27 natural populations containing over 3000 individuals spread over four states in the central part of the distribution. Using population projection matrix models, we determined individual, regional, and overall population growth rates. Overall, in 2001-2, populations were found to be expanding slightly (= 1.0427). In the two states with the largest harvest rates, contrasting population growth rates were found: Kentucky populations were found to be expanding, on average ( = 1.0846), while West Virginia populations were declining slightly ( = 0.9781). The cause of these differences is not clear, however Kentucky populations appeared to have higher rates of seed production (albeit lower germination rates) than West Virginia populations. Another difference is that West Virginia populations were browsed by deer at high rates. Further demographic simulations showed that the fate of seeds is particularly important for ginseng population growth rates, and this represents two very important management opportunities. First, the ripeness of seeds at the time of harvest was shown to significantly affect subsequent germination; harvest prior to full seed ripening can drive population growth rates below 1 (declining populations). Thus, it is exceedingly important that the onset of the harvest season occur after completion of seed ripening. Presently, there is very little data to suggest current harvest seasons are optimally timed. Second, the disposition of seeds by the harvester is critical to population growth. Harvesters can dramatically influence population growth and viability if they are encouraged to (a) harvest only seed-producing plants, (b) leave seeds in the population, and (c) plant the seeds 2 cm deep to enhance subsequent germination.

Key words: American ginseng, demography, harvest