COSEWIC Assessment and Update Status Report on the American Ginseng in Canada
The life history strategy of American ginseng is typical of a long-lived forest perennial. Populations grow slowly, remains close to the equilibrium (i.e. growth index (l) remain close to “1.00”; Charron, 1989). Population maintenance is firstly achieved through adult longevity (Charron and Gagnon, 1991). An individual takes several years to reach seed-producing stage (the only method of reproduction). Since seed production is closely linked to plant size, large three- and four-leaved plants produce most of the seeds in a colony. Seed predation by small rodents is often severe, significantly reducing recruitment potential in the wild (pers. observ.). Seedling mortality is high, reaching 70-90% in northern populations (Charron et Gagnon, 1991). According to Lewis and Zenger (1982) who studied ginseng in Missouri, a seed has only a 0.55% chance of reaching maturity. Such a conservative life history strategy explains the high sensitivity of ginseng to harvest.
Recent studies of ginseng populations in Quebec have demonstrated that colonies below a certain size threshold (minimum viable population size or MVP) are likely to become extirpated (probability exceeds 5% over 100 years) in the long term (Nantel, et al., 1996). The MVP for ginseng is estimated to be about 170 plants (Nantel, et al., 1996). Based on this criterion, there are only seven viable populations known in Ontario and 15 in Quebec.
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