Bio-cultural traits and cultural keystone species, a combined approach: an example of application about plants used for food and nutraceutical purposes in Aga Villages in Bali, Indonesia

Wild and semi-wild plants are factual resources for a local community when they satisfy its needs. According to the bio-cultural approach, these plants and associated knowledge help define the cultural identity of each community, and ethnobotanical plants constitute a particular facet of the cultural relationships between people and nature. By referring to the concept of Cultural Keystone Species (CKS), a group of species considered in the same way within a community represents a homogeneous biocultural trait. We tested the hypothesis that the CKS model and the related index, the Identified Cultural Importance (ICI) of species, could be useful tools to culturally define and describe groups of species as bio-cultural traits. As a dataset to test this hypothesis we considered the wild and semi-wild plants used for food and nutraceutical purposes in 13Agavillages in Bali. Data were collected through an ethnobotanical study in 2014. A multivariate analysis method based on the Fuzzy Set Theory was used to perform quantitative analyses to find clusters of plants. The Graph Theory was instead applied in order to detect trajectories and similarity gradients in the system of groups of species. The results confirmed that groups of species can be considered as biocultural traits, spreading within a cultural area in different ways and conveying information about their relationship with the native culture. The ICI index and CKS concept helped us to interpret the bio-cultural traits in terms of their cultural salience, considering them as general descriptors of the bio-cultural system of a community according to bio-cultural diversity and Traditional Ecological Knowledge. In the case of the Bali Aga villages, the partition of species showed 11 groups, and several species resulted of relevant cultural importance. Among them, Arenga pinnata(Wurmb) Merr. can be considered a CKS.