Ethnobotanical study of traditional herbal medicine in the multi-ethnic convergence zone of Northwestern, Guizhou, China

BACKGROUND: Traditional herbal medicine has played a vital role in human societies, contributing to health through both therapeutic and nutritional functions. This study aims to document the medicinal plants in the multi-ethnic areas of Guizhou Province, China, and quantitatively evaluate the diversity of traditional knowledge and its cultural significance. METHODS: We conducted field investigations with 103 respondents from 7 ethnic groups (including Han and six ethnic minorities) within the region, utilizing key informant interviews, semi-structured interviews, and participatory rural appraisal to systematically collect ethnobotanical knowledge. This included the types of medicinal plants, their parts used, traditional processing methods, indications, and application scenarios. Quantitative ethnobotanical indices, including National Cultural Significance Index (NCSI), Shannon-Wiener Index (H'), Simpson Index (D), and Sorenson Similarity Index (CS), were employed to evaluate herbal importance, diversity, evenness, and knowledge similarity among different villages and ethnic groups. RESULTS: A total of 200 medicinal materials (85 families, 169 genera) were recorded, with Fabaceae being the most represented family. They are mainly used to treat rheumatism and other common ailments, typically prepared as decoctions. Medicinal plant knowledge demonstrated high diversity and evenness across villages and ethnic groups (Shannon-Wiener indices ranging from 3.23 to 3.59, and Simpson indices from 0.0091 to 0.0186. The top three most frequently used species were Cynanchum auriculatum (HUF = 0.17), Lygodium japonicum (HUF = 0.16), and Pleuropterus multiflorus (HUF = 0.15). Taraxacum mongolicum holds the highest cultural significance (NCSI = 700). Intervillage and interethnic similarity showed low to moderate levels (Sorensen CS: 0.19 to 0.60 among villages; 0.31 to 0.62 among ethnic groups). Notably, only 45 species (22.5%) were shared across five or more villages, while 109 species (54.5%) were recorded in only one or two villages, reflecting a "limited similarity" pattern. The shared core resources mirror the fundamental role of the environment, while the ethnoculturally specific nature of the knowledge emphasizes the cultural shaping forces. CONCLUSION: These findings indicate that the internal diversity of traditional knowledge of medicinal plants in multi-ethnic areas is high, and there is "limited similarity" among villages and ethnic groups. The environment and culture jointly shape the formation of traditional medicinal knowledge. This research provides basic data for the protection and sustainable utilization of medicinal resources.