Sharing ethnobotanical knowledge in traditional villages: evidence of food and nutraceutical “Core Groups” in Bali, Indonesia

The island of Bali has several aga (indigenous) villages that have survived despite the pressures of an intense tourist industry and agricultural changes. A rich ethnobotanical culture persists, but the meaning of differences in traditional ethnobotanical knowledge (TEK) remains under-explored. We analyzed information obtained from interviews of inhabitants from diverse villages on food and nutraceutical plants to identify plant patterns, i.e., relevant plant groups with species sharing a similar occurrence. Through cluster analysis, we identified 12 main groups of species and found that species were grouped based on traditional knowledge and the use each community made of plants on the whole, and not on growth forms nor on specific uses. The frequency distribution of species clusters showed a bimodal trend, with several groups present only in few villages, and a few groups present in almost all villages. The latter are defined as “core groups” and represent the shared TEK of each aga community. Other “satellite species groups” embodied in the local TEK were related to small isolated communities. Cultural erosion caused by modernization, with the consequent fragmentation of information, was judged to be one of the main causes of increasing TEK heterogeneity.