Distribution analysis of wild medicinal plants in Ada'a District, Ethiopia: A means to identify most prior species for conservation

In Ethiopia, traditional medicinal plants have been in use since time immemorial and they were the only existing means for health care of the people before the introduction of allopathic medicine. The majority of these plants are originated from wild habitats. By now these medicinal species are highly degraded due to environmental degradation, agricultural expansion, deforestation, and over-harvesting of species. There is a need to practice conservation activities on target species at the local and/or district level to ensure the continuity of medicinal plants. One possible way for achieving this is through distribution analysis of species, which is a central concept in conservation management. Distribution analysis addresses identifying species in a community; how abundant and frequent is each species? And how do the species interact? The present study aimed to assess the degree of occurrences and spatial distribution of the medicinal plants in Ada'a District. A total of 59 study plots with the size of 20 x 20 m were laid randomly on the different land-use types of the District for collecting tree medicinal species. A sub-plot of 5 x 5 m was located in the center of each plot for recording shrubby medicinal plants whereas five 1 x 1 m subplots, four of which were on the corners and one in the center of the main plots were used for recording herbaceous medicinal plant species. The density of each plant species was recorded by counting the number of individuals. Frequency was calculated as the percentage of sub-plots that included the target species. Frequency, abundance, density, and abundance-frequency (AB/F) ratio were estimated. Sorensen similarity index was applied to quantify the floristic similarity of the study area with the other areas in Ethiopia. Results showed that most of the medicinal plants (82%) are locally rare; therefore they need to be domesticated. Moreover, some of these locally species are found only in Ethiopia (i.e. endemic species), thus they registered in the IUCN Red List of Ethiopia. They are highly endangered species that must be among the top priority for conservation urgency in this district.