Importance Indices in Ethnobotany

Abstract

Measuring the "importance" of plants and vegetation to people is a central concern in quantitative ethnobotany. A common tool to quantify otherwise qualitative data in the biological and social sciences is an index. Relative cultural importance (RCI) indices such as the "use values" developed by Prance et al. (1987) and Phillips and Gentry (1993a, 1993b) are applied in ethnobotany to calculate a value per folk or biological plant taxon. These approaches can provide data amenable to hypothesis-testing, statistical validation, and comparative analysis. The use of RCI indices is a growing trend in ethnobotanical research, yet there have been few attempts to compile or standardize divergent methods. In this review, we compare RCI indices in four broad categories and present a step-by-step guide to some specific methods. Important background topics are addressed, including ethnographic methods, use categorization, sampling, and statistical analysis. We are concerned here only with "value" as a non-monetary concept. The aspiring and veteran researcher alike should find this paper a useful guide to the development and application of RCI indices. IntroductionThe scientific rigor of ethnobotanical research has increased dramatically in the past two decades due to the adoption of quantitative methods (Phillips 1996). By and large, ethnobotanists have recognized and responded to the need for research based upon hallmarks of the scientific method, including testable hypotheses, reproducible methods, and statistical measures of variation. A primary challenge in this quantitative trend is how to produce values that are reliable and comparable measures of less tangible qualitative data. Borrowing from the social sciences and ecology, considerable advances have been made through the development and application of relative cultural importance (RCI) 1 indices that produce numerical scales or values per plant taxon (Alexiades & Sheldon 1996, Kvist et al. 1995, Lykke et al. 2004, Martin 2004, Phillips & Gentry 1993a, 1993b, Phillips et al. 1994, Phillips 1996, Prance et al. 1987, Reyes-García et al. 2006a, Turner 1988).The application of RCI indices in ethnobotany began during the late 1980s. Boom (1990) determined the percentage of plants used by Panare indigenous informants within a 1 hectare forest plot in Venezuela. His research was an important starting point for quantitative inter-cultural comparisons of plant knowledge. Recognizing that not all uses are equal, Prance et al. (1987), applied weighted indices of 1.0 for "important" uses and 0.5 for "minor" uses. This approach was aimed at capturing relative degrees of "importance", but did not address informant variation. Gentry and Phillip's (1993aPhillip's ( , 1993b) publication on RCI "use values" was a watershed event in quantitative ethnobotany. These last authors evaluated variation among informants based upon use-citation frequencies, considering each as a statistical "event."Since the methods of Prance et al.

Floristic Features, Distribution, and Ethnobotany of Plants Gathered and Used by Local People from the Mediterranean Forest in Northern Jordan

“…The third indicator calculated was Uses Totaled, in which the uses of each species are summed and ranked (Hoffman & Gallaher 2007).…”

“…This index was calculated to rank the recorded plant species based on their claimed relative effectiveness following Friedman et al (1986) as follows: FL = (I p / I u ) × 100 where I p is the number of informants who mentioned the use of a particular species for a particular purpose and I u is the total number of informants who mentioned the plant for any use. Species that were mentioned by only one informant were not included in the FL% calculations.The third indicator calculated was Uses Totaled, in which the uses of each species are summed and ranked (Hoffman & Gallaher 2007).Detrended Correspondence Analysis (DCA) was chosen as a multivariate method for ordination. DCA was performed using CANOCO for Windows 4.5 (ter Braak & Smilauer 2002).…”

Local Uses of Native Plants in an Area of Caatinga Vegetation (Pernambuco, NE Brazil)

“…The Spearman correlation coefficient was employed to compare the species citations offered by the men and women interviewed. The use-value technique was chosen as it is considered objective, reproducible, and appropriate for statistical analyses (Hoffman & Gallaher 2007).…”

Conservation and Ethnobotanical Knowledge of a Hmong Community in Long Lan, Luang Prabang, Lao People's Democratic Republic

“…Designing appropriate use categories is important to any ethnobotany study (Hoffman & Gallaher 2007). Ethnobotanical knowledge was expressed in many different ways in Long Lan: e.g., medicine, food, spiritual practices, stories, legends, folklore, rituals, and customary laws.…”

“…Use categories were determined, in part with the respondents, after the initial review of the study area to offer insights about the level of importance and the level of use, a crucial step (Hoffman & Gallaher 2007) that reflects the variety of ways in which knowledge is expressed (e.g., cookbooks, stories, legends, folklore, rituals, songs, cultural rules, and laws).…”