Threats to Wild American Ginseng
American ginseng is North America's most valuable wild collected medicinal plant. Because of ginseng's slow and intricate biology, and the demand for this important herb, in addition to other local and large scale threats, the challenge that wild American ginseng faces is growing every year.
Local scale threats constitute a direct and tangible challenge to local populations and individual plants. For instance, regular deer browsing might keep a wild population from growing larger for various reasons. Large scale threats affect American ginseng on a broader regional scale. In depth research has shed light on just some of these effects, and show wild American ginseng to be a slow opportunist in the way that it adapts to changes in environment.
Local Threats Large-scale Threats Extinction Vortex
Local Threats to Wild American Ginseng
Local scale threats constitute a challenge to plants and populations in many ways. For instance, regular deer browsing causes adult plants to shrink from one year to the next, and reduces reproductive output, until ultimately, seed production is insufficient to replace plants lost to mortality. One or more unsustainable harvests from a population can have a major lasting impact. Because of wild American ginseng's long and complex life cycle, recovery from major events can take many years, or even decades. Research on the identified threats to wild American ginseng has brought up the following threats to the persistence of this species:
American ginseng harvest can lead to sustained declines in population sizes, even when done in accordance with current regulations. Stewarding the population, on the other hand, can help grow ginseng populations.
2) Overbrowse by White-tail Deer
White-tailed deer abundance has exploded due to the removal of top predators, habitat fragmentation, and wildlife management policy. Overbrowse of the understory by deer may lead to extirpation and eventual extinction of some species, including American ginseng.
Both climate change and forest habitat alterations are influencing the distribution and survival of key animal species that disperse American ginseng seeds. For example, the wood thrush, a key disperser of American ginseng seeds, has declined precipitously over the last 50 years.
Invasive, non-native plant species can quickly outcompete native species, transforming diverse native communities into dense, low-diversity stands.
Wild American ginseng can cross-pollinate with cultivated ginseng that was planted in the wild. The resulting offspring may do poorly compared to truly wild plants due to a genetic makeup maladapted to natural environmental conditions.
Large-scale Threats to Wild American Ginseng
Large-scale threats affect American Ginseng on a regional scale, as opposed to individual populations and plants. Broad sweeping practices like timber harvest, mountaintop removal and climate extremes like canopy damage and species decline, continue to pose a major threat to the forests, ecologies and wild American ginseng's specialized habitat.
American ginseng is adapted to local climatic conditions, and research has indicated that deviations from these conditions reduce population growth. As local climates change, the ginseng populations are left vulnerable.
7) Habitat Loss
Be it through agriculture, development, surface mining or a host of other activities, land use conversion removes critical ginseng populations and their habitat, leading to local extirpation.
The alteration of forest habitat through both natural and man-made disturbances can elicit a diverse, complex suite of responses from understory species depending on disturbance the type, intensity, duration, and scale.
In other words...
Conservation of ginseng is challenging because wild populations are exposed to many different threats. Indeed, any one population could experience 2, 3, or 4 of these threats, simultaneously pushing the population ever closer to an "extinction vortex" - essentially a black hole, which nudges small populations toward inevitable extirpation.
Ginseng leaves showing too much sun exposure.
Photo credit: batcavebotanicals.com
Extirpation vs. Extinction
Ginseng consists of many thousands of small populations across its broad range. Loss of an individual population is termed ‘extirpation’. If the pace of extirpation is greater than the rate of formation of new populations, the species is headed toward extinction, which is defined as the loss of ALL populations of a species. Evidence suggests that ginseng is headed in this direction, albeit slowly.
Extinction Vortex by McGraw: adapted from
Wild American Ginseng: Lessons for Conservation in the Age of Humans (2020)
Many rare species consist of very few populations, so they are teetering on the edge of extinction all the time. Extinction of a species like ginseng, with its many populations, would take much longer as the threats cause higher rates of extirpation than would naturally occur. To conserve a species such as ginseng, at least a subset of all populations needs to be protected from threats. Nature preserves (for example National Parks and Forests, State Parks and Forests, etc.) are critical; places where human influences are reduced in deference to the habitat requirements of native plants and animals existing in an intact, fully functioning ecosystem. As Henry David Thoreau wrote:
“In wildness is the preservation of the world”.