American ginseng: COSEWIC assessment and status report: chapter 2

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Description

American ginseng, also known as ginseng (Panax quinquefolius L.), is a long-lived perennial herb 20 to 70 cm tall. It is composed of an elongated tap-root, bearing a spindly rhizome and an aerial stem ending in a whorl of palmately-compound leaves. The inflorescence is an umbel, found at the tip of the aerial stem, that originates from the center of the compound leaves. This feature distinguishes ginseng from similar associated species.

Distribution

Ginseng occurs in the United States from New England and Minnesota south to Louisiana and Georgia. In Canada, it occurs in southwestern Quebec and southern Ontario. It is considered to be rare or uncommon in most of its North American range. In Ontario, the species shows noticeable concentrations along the Niagara Escarpment and the eastern edge of the Precambrian Shield. In Quebec, the highest concentration of populations is found in Monteregian, south of Montreal. The species’ distribution range in Quebec has been reduced at its north-eastern limit.

Habitat

Ginseng requires rich, moist, undisturbed and relatively mature sugar maple-dominated deciduous woods in areas of circumneutral soil such as over limestone or marble bedrock. Colonies are often found near the bottom of gentle slopes facing south-east to south-west; a warmer microhabitat that is usually well-drained and species-rich. The forest canopy is dominated by sugar maple, white ash, bitternut hickory, and basswood.

General Biology

American ginseng is a long-lived forest perennial. Populations grow slowly and maintenance is firstly achieved through adult longevity. A plant takes several years to reach maturity. Sexual reproduction is the only reproductive means. An 18-month dormancy period is required for seed germination. Recruitment is reduced by seed predation and high seedling mortality (70-90%). 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. The Minimum Viable Population size for ginseng is estimated to be about 170 plants. Based on this criterion, there are only seven viable ginseng populations known in Ontario and 15 in Quebec.

Population Size and Trends

There are 139 records for ginseng in Canada, 65 in Ontario and 74 in Quebec. From 1996 to 1998, 20 previously-documented populations in Ontario were studied in detail: 25% of the 1988 sites had disappeared and 50% had declined. Harvesting was confirmed or suspected in 55% of the sites. Logging was suspected of causing declines in 25% of colonies investigated. Similar results were obtained from the 22 new sites surveyed in 1997 and 1998 (i.e. 27% extirpation). Seven viable populations are known in Ontario. The total plant count documented for the province is 8619, however, 70% were found in the two largest colonies. In Quebec, 74 ginseng occurrences are reported. Among the 59 locations surveyed since 1994, 10 populations have been extirpated (i.e. 17%) and most of the extant ones are small. Fifteen viable populations are presently known in the province, but nearly 50% of the 10 956 plants are found in two large colonies (only one is protected). In Quebec, ginseng is concentrated in the south, in the Monteregian region, the most developed and urbanized area of the province. As a consequence, most populations are small and dispersed in a fragmented landscape where habitat loss and degradation are high. Harvest has been observed in 15% of the sites sampled. Although there are 22 viable populations in Ontario and Quebec, none can be considered secure.

Limiting Factors and Threats

The main threats to ginseng are small population size, harvest, and habitat loss and degradation from clearing and logging. Small populations are highly vulnerable to environmental stochasticity, natural catastrophes and demographic stochasticity. Harvest affected 55% of surveyed sites in Ontario (nine were extirpated). Harvest severely reduces the colony reproductive potential. A 5% annual root harvest is sufficient to bring a viable ginseng population toward extirpation. Habitat loss and degradation are also a major threat for ginseng. Logging activities open the canopy and strongly modify the ecological parameters of a site (higher light intensity, lower soil moisture, introduction of invasive species, higher competition, intense grazing and higher seed predation). Logging contributed to the loss or decline of 25% of sampled sites in Ontario. In Quebec, seven populations were lost due to habitat loss and degradation. The severe ice storm in January of 1998 caused major damage to the forest canopy and may have a lasting negative impact on several ginseng colonies. Ginseng cultivation is a quickly expanding industry in Canada, the fourth ginseng producer in the world. Woodland cultivation is becoming increasingly popular, covering 1000 to 2000 acres in Ontario and 100 acres in Quebec. The habitat disturbances associated withsite preparation and maintenance (i.e. clearing, use of fertilizers and fungicides), the introduction of seed-borne pathogens that are common in commercial seeds, and the introduction of foreign genes by planting seeds from unknown sources, can have a significant impact on wild populations.

Existing Protection

American ginseng has been listed under Appendix II of CITES since 1973. It was designated “threatened” in 1988 by COSEWIC. Ginseng should soon be designated “espèce menacée” (i.e. the highest category under the Act) in Quebec, under the Endangered Species Act (bill 108). Export of wild roots is banned, but domestic sale and harvest are not regulated. Several populations of ginseng occur in protected areas. In Ontario, trails near at least two populations in protected areas have been relocated and one large colony threatened by a development was relocated to a protected area. Despite these measures, ginseng continues to decline. In Quebec, a conservation project for ginseng was initiated in 1994 at the Biodome of Montreal, to 1) characterize ginseng populations and their habitat; 2) develop micropropagation techniques for restoration purposes and 3) restore 10 depauperate populations. In 1997, a monitoring program was established in 10 key sites throughout the province and restoration efforts continue. Collaboration is also taking place with ginseng producers in the province.