The Use of “Use Value”: Quantifying Importance in Ethnobotany

The Use of “Use Value”: Quantifying Importance in Ethnobotany. Use value (UV) is an index widely used to quantify the relative importance of useful plants. It combines the frequency with which a species is mentioned with the number of uses mentioned per species, and is often used to highlight prominent species of interest. However, high-UV species are often disproportionately cultivated species, with wild-collected plants ranking lower. To better understand this pattern, and to determine if it is present in the broader ethnobotanical literature, we reviewed an array of papers with results on UV and cultivation status, and we analyzed in depth data from two large ethnobotanical studies in the Republic of Georgia in the Caucasus. In addition to looking for differences in UV by cultivation status, we compared the two best-populated categories of use (medicinal and food uses) and the components of UV (relative frequency of citation and number of uses mentioned per species). We found that UV was higher in cultivated plants than wild plants in both the Caucasus datasets and the 17 studies overall. Medicinal plants did not exhibit this trend, as medicinal wild plants had marginally higher UV than medicinal cultivated plants. Relative frequency of citation had a substantial effect on UV, in contrast to number of uses mentioned for a given plant. In sum, UV seems subject to some obscured biases which are important to consider in the context of each study.