Floristic Composition of Forest Patches, Ethnobotanical and Nutraceutical Studies in Soro District, Central Ethiopia
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2024-06
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Addis Ababa University
Abstract
This PhD dissertation was conducted to document the floristic composition of the forest patches and the ethnobotany of the medicinal and wild edible plants in Soro District, central Ethiopia. The investigation targeted the vegetation of the remnant forest patches and the indigenous and local knowledge on plant use and management of the Hadiya ethnolinguistic community of Soro District. The floristic composition, the traditional medicinal plants used for the treatment of
human and livestock ailments and the wild edible plants, the latter including the determination and analysis of the nutritional values of selected species constitute the main focus areas.
Vegetation data were collected in different months in 2021, 2022 and 2023 from 98 systematically laid plots of 20 m x 20 m (400 m2) for trees at every 50 m altitudinal drop, 250 m far apart along transects, 5 m x 5m (25 m2) small sub-quadrats for shrubs, and 1 m x 1 m (1 m2)
for herbs. Woody plant species with a diameter at breast height (DBH) > 2 cm were counted, whereas basal area (BA), important value index (IVI) and height classes were computed and used to determine the regeneration status of the dominant species and the R software was used for the analysis. Ethnobotanical data about the human and livestock traditional medicinal plants were collected by interviewing systematic randomly sampled 387 informants consisting of 255
male and 132 female research participants in addition to key informants and focus group discussions. Descriptive and quantitative approaches, and different ethnobotanical analytical tools were applied to analyze the data. The t-test statistic was used to compare indigenous knowledge based on the mean values reported in the cases of the medicinal and wild edible plants considering different parameters. A total of 280 plant species distributed in 214 genera and
88 families were documented from the four forest patches sampled and studied that yielded 34.64% trees, 27.86% shrubs, 24.64% herbs and 6.79% climbers including hemiparasites, grasses, lians, ferns, and orchids. Families with highest number of species included the Asteraceae that accounted for 11.07% and the Fabaceae constituting 8.93% of the species. The analysis produced five clusters corresponding to five plant community types. The vegetation of the forest patches of Soro District is of the Dry Afromontane type has been classified as Erica arborea-Olea europaea subsp. cuspidata-Olinia rochetiana-Spiniluma oxyacantha, Afrocarpus gracilior-Apodytes dimidiata-Olinia rochetiana, Croton macrostachyus-Ficus vasta, Combretum molle-Combretum aculeatum, and Dodonaea viscosa subsp. angustifolia-Balanites aegyptiaca community types. The total basal area of forest patches is 61.85% m2/ha. The species Olinia
rochetiana, Juniperus procera, and Afrocarpus gracilior were the dominant species at the sites of mountainous forest patches, with a high density of 47%, 42%, and 38%, respectively, and the most common and frequently-recorded IVI values of the woody species were also for Afrocarpus gracilior (14%), Erica arborea (13.84%), Juniperus procera (13%), Olinia rochetiana (12.10%), and Gymnosporia arbutifolia (11.45%). Overall, the highest Shannon Wiener diversity index,
Shannon Evenness, and Simpson Diversity values of Soro forest patches were 4.299, 0.91, and 0.51, respectively, and the least were 3.767, 0.86, and 0.36. The most common woody species, and unique species in each four forest sites were identified, and these are importance for conservation priory setting, sustainable management and utilization. The ethnobotanical study recorded a total of 246 human and 132 livestock traditional medicinal plants, and 64 wild edible
plant species. The nutritional values of the three most-preferred wild edible (non-cultivated) nutraceutical plant species revealed food values of high potential as indicated by the bioactive compounds, antioxidant levels and vitamin C contents with some anti-nutritional factors. The family Asteraceae is represented by 24 (9.76%), Lamiaceae by 18 (7.32%), Fabaceae 16 (6.50%), and Solanaceae 13 (5.28%) species of the human medicinal plant species. In the LsMPs, Asteraceae 10 (7.58%) species, Fabaceae nine (6.82%), Lamiaceae seven (6.82%) species and Solanaceae seven (5.30%) species. In the case of wild edible plants, the highest value of 4 (6.25%) species was recorded for families Salicaceae, Solanaceae and Moraceae. In human and livestock medicinal plants, leaves and roots were the most frequently used as herbal medicine, as were concoctions and decoctions. The fruits were the most palatable contributing to 53.13% of the wild edible species, while the leaves accounted for 29.69%. Significant differences (using a t-test) in ethnobotanical knowledge (P <0.05) was shown in the mean
number of medicinal and wild edible plants among differences in gender, key and general informants, and other parameters. In human and livestock medicinal plants, leaves and roots were the most frequently used as herbal medicine, as were concoctions and decoctions. While differences among different plant species nutritional values, anti-nutritional factors, bioactive compounds, antioxidants, and vitamin C were analysed using a one-way ANOVA test (p<0.05) in mean comparisons using Duncan’s multiple range test. The highest plant use citation, ICF value (0.76) was recorded for human healthcare for gastro-intestinal ailments and 0.72 for livestock dermatological ailments. The highest fidelity level values were recorded for Afrocarpus gracilior (100%) to treat rabies and diarrhoea of humans; and Datura stramonium (100%) to treat rabies and evil eye while Dodonaea viscosa subsp. angustifolia and Asparagus africanus were used for the treatment of livestock pestedes petits ruminants and evil eye respectively, at 100% of the FL value of each.
There was a significant difference (P <0.05) in the mean number of medicinal plants claimed by males and key respondents in human medicinal plants, while males, illiterates, distance > 5km from modern veterinary healthcare center (s), key informants, and their experiences. In the three WEPs, the values of proximate composition were recorded in their respective ranges. The fresh leaves and shoots of Amaranthus tortuosus and fruits of Landolphia buchananii and Oncoba
spinosa had moisture and pH values of (85.36%, 6.80), (81.22%, 4.59), and (61.35%, 5.74), respectively. The total soluble solids (TSS) content of the respective fruit juices of Landolphia buchananii and Oncoba spinosa was 2.4 and 8.4 ⁰Brix. The other dry basis nutrients were: total ash (3.00-20.60 g/100g), crude protein (5.51-33.77g/100g), crude fat (3.00-5.50 g/100g), crude fiber (6.05-9.60 g/100g), utilizable carbohydrate (24.07-66.09 g/100g), gross energy (283.70- 330.23 kcal/100g); the mineral contents: calcium (868.33-10595 mg/kg), iron (20.99-342.24 mg/kg), zinc (12.57-50.08 mg/kg); and vitamin C composition of (26.42-43.15 mg/100g). The highest crude protein content (38 g/100 g) was observed in Amaranthus tortuosus, and total ash (20.60 g/100g) for Landolphia buchananii; and utilizable carbohydrate (66.09 g/100g) for Oncoba spinosa. The highest total phenolic (171.39 mgGAE/100g), flavonoid (132.43 mgQE/100g), and vitamin C (44.15 mg/100g) contents were in Landolphia buchananii fruit. The Landolphia buchananii extract had comparable IC50 value (84 μg/ mL) with ascorbic acid (82 μg/ mL) in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The highest percentage of DPPH inhibition was for ascorbic acid (96.42%), followed by Landolphia buchananii (94.63%) fruits at the concentration of 200 μg/ mL, and it indicated that WEPs had more antioxidant activity than popular crops, and their non-food values were within acceptable limits, suggesting that they can be incorporated to make more nutrient-dense and healthy diets.
Nowadays, the forest patches and ethnomedicinal plants are being affected by anthropogenic factors. Therefore, decreasing access to vegetation in the area leads to the decline and local extinction of medicinal, wild edibles, and multipurpose native plant species from the natural habitats. Taking strong attention to the forest patches with joint management actions for in-situ and ex-situ conservation in the District with the linkage of the local people and nearby higher learning and research institutions is crucial. Such actions can increase the conservation potential of the natural vegetation with the rich floristic composition and ethnobotanical plants that would save and rehabilitate them with the associated indigenous and local knowledge and curb their rapid decline.
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Keywords
Ethnobotany, Forest Patches, Medicinal Plants, Nutrition, Soro District, Wild Edible Plants