Novel ethnobotanical indices of harvesting pressure and vulnerability to supply disruption reveal conservation priorities across five communities in the Nimba Mountains, Guinea

Abstract

Background: Classic ethnobotanical indices such as UV, RFC, and CI capture the cultural importance of plant species but overlook the vulnerability of communities to resources shortages and the extent of destructive harvesting pressure. This pilot study aimed to validate three new indices, to quantify the dependence of five communities in the Nimba Mountains on plant resources and identify conservation priorities.

Methods: Three indices were developed: the harvesting-pressure index (C’), the use-dependence index (UD), and the supply-disruption vulnerability index (Am), built using the Analytic Hierarchy Process (AHP). A matrix combining Use value (UV) and C’, together with the Jenks threshold and IUCN status, was used to rank conservation priorities.

Results: A total of 77.7% of species are used in traditional medicine. Garcinia kola and Alchornea cordifolia had the highest UV values (0.26) and the strongest C’ scores (155 and 90), with 46.3% and 60% of their uses being destructive, respectively. Garcinia kola and Xylopia aethiopica are classified as Conservation Priority 1. The Am index ranged from low in Doromou (0.141) to critical in Zouguepo (0.927), with Serengbara (0.779) classified as having very high vulnerability. Zouguepo combines high medicinal dependence (55.8%), near-universal daily use (99.5%) and low species richness (35 species). UD was the dominant driver of Am (ρ = 0.90; p = 0.03).

Conclusions: The C’, UD and Am indices provide an empirical, reproducible framework for prioritising conservation under data-limited conditions. As an exploratory pilot tool, their validation at a larger scale remains a priority avenue for further work.

Keywords: Ethnobotany; Analytic Hierarchy Process; Nimba Mountains; harvesting pressure; community vulnerability; conservation; indices; Guinea.