The geography of wild American ginseng in North Carolina, USA: a comparative study of four capability analysis methods

Abstract Wild American ginseng is the root component of a family of plants called Panax, and it grows mainly in the understory of the eastern deciduous forests in North America. The growing market for wild American ginseng in Asia along with the scarcity of this plant in the wild due to rising illegal harvest have been simultaneously pushing up the price of American ginseng in the market, increasing incentives further for illegal harvest of this soon-to-be-extinct species. This paper studies the geography of wild American ginseng to identify the spatial distribution of the suitable habitat of this plant in the wild and provides advice on what conditions are required and what regions are suitable for cultivating it in farms, introducing an alternative to the wild American ginseng to decrease the harvesting pressure on its wild counterpart. By employing four popular geospatial methods, including the Binary Screening method, the Ordinal Ranking method (both Graduated Screening and Addition-of-Factors methods), and the Weighted Linear Combination method, this paper carries out a capability analysis and mapping for wild American ginseng in North Carolina (NC). After building the models, they are validated by using the data of the known locations of wild American ginseng plants in NC. Developing these models helps in gaining a more comprehensive understanding of where the plant naturally grows and sheds light on how government agencies can more effectively and more efficiently plan for law enforcement activities to better protect this plant from illegal harvest. The general pattern of our results suggests that western NC counties such as Jackson, Haywood, Transylvania, Henderson, Cherokee, and Ash are some of the most suitable geographical areas for wild American ginseng to grow. The results of our model validation analysis, along with the comparison of our models' predictions to the observed occurrences of wild American ginseng in nature, indicate that the Binary Screening method’s predictions align with almost 96% of the reported observations in nature. This suggests that the influential natural factors necessary for wild American ginseng are more of complementary factors to each other than being substitutes, meaning that they all must exist in the environment for it to grow, and it could not be that the lack of one natural factor can be compensated by the abundance of another natural factor.