Conserving the roots of trade: Local ecological knowledge of ethnomedicines from Tanga, Tanzania markets

Abstract

This dissertation is based on research with healers, vendors, harvesters, and consumers of medicinal plants in a botanically rich, economically poor area where conservation, livelihoods, and health are key concerns. It examines biological and social factors related to the knowledge, procurement, and use of medicinal flora, and considers whether focusing on locally important plants and places can promote larger conservation goals. Methods include: 79 semi-structured interviews on medicinal plant acquisition; 28 market inventories of >250 ethnospecies; 74 local ecological knowledge (LEK) surveys on nine medicinal species; 112 semi-structured household interviews and inventories of home gardens; and 13 focus groups to validate, expand, and return findings. Twenty key species were identified on the basis of their 25% prevalence rate among vendors' stocks and vendors nominating them as important. These are primarily bark and roots of non-cultivated, locally harvested, native trees. Seventeen are widely distributed and found in areas that range from highly anthropogenic to relatively undisturbed, and three are comparatively vulnerable. They are Warburgia stuhlmannii (proposed as endangered due to its limited distribution in Coastal Forests) and Ocotea usambarensis and Morella salicifolia, two montane species which are primarily harvested in forest reserves. While quantitative LEK survey analyses show no significant differences in knowledge among social groups (based on role, gender, experience, age), qualitative analyses indicate that healers have a greater understanding of and adhere more to harvesting pre- and proscriptions. Culturally based and ecologically based knowledge are significantly correlated, but knowledge and behavior are not necessarily consistent with each other. The marketplace is a central locus for knowledge transmission and this transmission is influenced by market demands and motivated by opportunities to supplement livelihoods. The dissertation concludes that phytomedicine harvest is not presently a threat to conservation in Tanga, but the availability of these plants may be limited in the future. This is indicated by local observations of shrinking medicinal plant habitats and populations, and a growing demand for commercial species that are wild harvested but not cultivated. The findings underscore the value of plant medicines to local people's health, livelihoods, and culture and, therefore, their potential to sponsor biodiversity conservation.