Cultural importance indices: A comparative analysis based on the useful wild plants of southern Cantabria (northern Spain)

This paper compares four indices based on informant consensus. Each index aims to assess the cultural significance of plant species and is suitable for statistical testing of different hypotheses. For the comparison, we used data concerning plants traditionally used in the Campoo area of southern Cantabria in northern Spain. Our results show a positive and significant correlation between the number of uses (NU) and the frequency of citation (FC) of the species. It seems to be a general rule that the more versatile a plant, the more widespread its usefulness. In addition, NU is highly influenced by the number of use-categories in the study. Consequently, an objective index must rely on FC more than NU. We propose the use of the cultural importance index (CI), which is defined as the summation of the informants' proportions that mention each of the uses of the species. The CI index is highly correlated with FC and, although it also considers diversity of use, each use-category is conveniently weighted by the number of informants mentioning it. Despite the use of cultural significance indices being questioned, we believe that indices based on in-depth, semi-structured interviews are still very useful for compilation studies of passive knowledge, such as most ethnobotanical works conducted in the last three decades in Europe.