Plant Diversity and Ethnobotanical Study of Medicinal Plants in Ankober District, North Shewa Zone of Amhara Region, Ethiopia
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2014-06
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Addis Ababa University
Abstract
This research aimed at providing documentation and analysis of plant diversity in Dense Forest along with the ethnobotanical knowledge associated with the medicinal plants used by the people in Ankober District, Ethiopia. Vegetation data were collected from 51, 30 m x 30 m quadrats laid for trees at every 50 m altitudinal drop along transects and 5 m x 5 m and 2 m x 2 m subplots for shrubs and herbs, respectively. Woody species with a diameter at breast height (DBH) > 2 cm were counted and cover abundance values estimated. A hierarchical cluster analysis, with PC-ORD for Windows version 5.0 software, was used to identify plant communities and synoptic values for identification of the dominant species for naming plant communities. Frequency, density, DBH, basal area and importance value indices (IVI) of woody species were also computed. Shannon-Wiener diversity index was used to assess species richness and evenness. Sorensen's similarity coefficient was used to measure similarities among communities in Dense Forest, and between Dense and other montane forests. Ethnobotanical data were collected by interviewing 352 informants (235 males and 117 females). Quantitative approaches were used to determine informant consensus factor (ICF), fidelity level (FL), use value (UV), use diversity (UD) and use equitability (UE) values. Ethnomedicinal knowledge held by different informant categories was compared using One-way ANOVA and t-tests. A total of 23 ethanol extracts of various parts of 19 most-preferred medicinal plants were also studied for potential antimicrobial activity against 12 microbial strains using broth microdilution method. The Dense Forest yielded 158 vascular plant species belonging to 143 genera and 75 families. The vegetation of the Forest was classified into five, namely Erica arborea, Maesa lanceolata-Discopodium penninervium, Podocarpus falcatus-Allophylus abyssinicus, Olea europaea-Galiniera saxifraga and Maytenus arbutifolia-Bersama abyssinica community types, based on the PC-ORD hierarchical cluster analysis. The percentage distribution of individual tree species across different DBH classes indicated relatively high proportion (27.26%) of individuals in DBH class 10-20 cm. The highest IVI values were recorded for Olea europaea subsp. cuspidata (57.63) and the next for Podocarpus falcatus (45.61). The overall Shannon-Wiener diversity and evenness values of Dense Forest were 4.07 and 0.80, respectively. Five representative woody plant population structures were identified. Results of the ethnobotanical study revealed a total of 151 medicinal plant species belonging to 141 genera and 75 families in the whole of Ankober District. The Asteraceae with 13 (9%) species and the Fabaceae with 11 (7.3%) species were families represented by more species in the District. Plants in which roots are used as medicine were more frequent than other parts in the District’s ethnomedicinal lore. Significant difference (P < 0.05) was observed in the mean number of medicinal plants reported by respondents in different age classes, literacy levels and experiences. About 123 (81%) species of medicinal plants were cited for one or more non-medicinal uses. The highest ICF value (0.71) was recorded for livestock gastro-intestinal disease category. The highest fidelity level values were recorded for Zehneria scabra (95%) and Hagenia abyssinica (93.75%). About 17 (74%) of the ethanol extracts showed antimicrobial activity against one or more of the microbial strains tested. Extracts from Embelia schimperi showed the strongest antibacterial activity with minimum inhibitory concentration (MIC) value of 64 μg/ml against Bacillus cereus, Listeria monocytogenes and Streptococcus pyogenes. The Dense Forest and the medicinal plants in Ankober District are under pressure due mainly to ever-increasing anthropogenic influences. Thus, the declining vegetation and wild medicinal plants of the area are in need of application of complementary in-situ and ex-situ conservation. Joint management of the Dense Forest with the local people and increased participation of the local people in overall medicinal plant conservation are actions that would save and rehabilitate the fast-declining plant resources with the rich ethnomedicinal wealth in the District.
Key words:Ankober, antimicrobial activity, ethnobotany, floristic composition, medicinal plants
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Ankober, antimicrobial activity, ethnobotany, floristic composition, medicinal plants