Ethnobotany, diversity and bioactivity of medicinal plants in lake victoria basin: A case Study of the Catchments of Rivers Mara and Mori in Tarime District, Tanzania.

Ethnobotanical practices by local communities in Tarime District were linked to the current plant diversity and to the effectiveness of some local healing practices. Ethnobotany and plant resource data were collected by using standard social and field sampling procedures from 122 respondents and from 125 quadrats size, each measuring 50 x 20m. Agar Disc Diffusion and Tube Dilution Assays were employed for screening tests. The programmes TWINSPAN, CCA and descriptive statistics were used to analyze the socio-economic and species data. Fifty nine ethnobotanical uses were recorded of which 85% were for subsistence and 15% for marketing. A total of 519 plant species were sampled, of which 47 were trees, 195 shrubs, 220 herbs, 49 grasses, 4 ferns and 4 mushrooms comprising of 79 families. Mean tree density was 212stems ha'1. The Shannon and Wiener diversity index was 1.12. Though ethnobotanical uses for subsistence per unit household had relatively less effect to plant diversity, improved infrastructure and acculturation subjected plant resources to over-exploitation through commercialization. As a result, five plant species were over-exploited, seven species were threatened and one plant species was locally extinct. Meanwhile, indigenous conservation has lost grounds in the light of socio-cultural changes. Screening of 37 medicinal plants confirmed that 91% of these were effective against the test microbes. Other active practices included multi-extract therapy and use of mineral supplement. Basing on the above, medicinal plants namely Melhania velutina, Peponia vogelii and Kedrostis sp are recommended for further pharmaceutical research on the merit of their high bioactivity against wide array of bacteria and fungi.