Zerihun WolduZemede AsfawErmias LulekalMesfin Belete2025-08-182025-08-182024-06https://etd.aau.edu.et/handle/123456789/7021A study on the vegetation ecology and ethnobotany as well the predition of Piliostigma thonnigii was carried out in Sida forest in South Omo Zone, southern Ethiopia. The aim was to evaluate the status of the forest with variables governing species distribution pattern and further document the ethnobotanical uses and distribution of P. thonningii. Vegetation and environmental data were collected from 82 sample plots (each 20 m × 20 m) placed along twelve transect lines, which is 1km apart and 300m distance between plots. Height and DBH were measured for each woody species that had a height ≥ 2 m and DBH ≥ 2.5 cm. From ech plot a kilogram of composite soil samples were brought to the Wolkite soil testing laboratory for physicochemical analysis. Using stratified random sampling methods, 84 informants were sampled for ethnobotanical data collection focusing on P. thonningii. Structured and semi-structured interviews, guided field walks, and focus group discussions (six individuals in each Kebele) were used for ethnobotanical data collection. Thirty-six occurrence points and nine environmental predictor variables were used to predict the distribution of P. thonningii, which was modeled using MaxEnt (MaxEnt v. 3.4.1). Density, frequency, basal area, importance value index, and size class distribution were used to analyze the vegetation structure of Sida Forest. Hierarchical cluster analysis was used to compute and identify plant community types and CCA was used to analyze the relationship between plant communities and environmental variables. The Shannon-Wiener diversity index was used to compute species richness, diversity, and evenness. Sorensen’s similarity coefficient was used to measure species similarities among the plant community types. Ethnobotanical knowledge held by informants was analysed using relevant descriptive statistical methods, Pearson’s chi-square test, direct matrix and pair-wise ranking. The results of the study revealed that the study area harboured 254 plant species belonging to 180 genera and 82 families. Nine (3.5%) of the species are endemic. Fabaceae (26), Asteraceae (15), and Lamiaceaae (15) were the dominant families in terms of the number of species. Shrubs occupied the highest (35%) percentage followed by herbs (30%). The overall density of woody species was 682.32/ha. The highest density (324.39/ha) was found in the lower DBH class (2.5-10 cm), while the lowest (13.72/ha) was in the higher DBH class (> 60cm). DBH and height class distribution showed an inverted J-shape distribution. The frequency of woody species ranged from 1.2% to 42.7%. The basal area of woody species is 24.15 m2/ha. The IVI value ranges from 0.13 to 14.62. Five plant community types were identified and the environmental factors such as elevation, slope, aspect, sand, pH, and disturbance were the major environmental factors determining plant species distribution and community formation. The Shannon-Wiener diversity indicates species diversity ranging from 3.25 to 4.44. Soresen’s index of similarity showed the presence of the highest similarity between communities two and three (58.9%), while the least similarity was found between community one and community five (18.3%). The physicochemical properties of the soil such as OC, OM, TN, CEC, and exchangeable Mg2+ showed a positive correlation with elevation, while BD, pH, EC, Av. P, exchangeable Ca2+, and exchangeable K+ had a negative correlation with elevation. The results also showed that P. thonningii provides different functions to people’s livelihoods. The results indicated that out of 862,247.05 ha of the total study area, 152,398.39ha (17.67%) was suitable for P. thonningii, of which 2,329.50 ha (0.27%) were highly suitable, 33,809.59 ha (3.92%) moderately suitable and 116,259.31ha (13.84%) was less suitable. Seasonality and annual range of temperature, solar radiation, and elevation had the highest contribution (69.4 %) in predicting P. thonningii distribution. Agricultural expansion, firewood collection and harvesting for fencing were the most threatening factors to Sida Forest in general and P. thonningii in particular. Field survey also confirmed that settlement, forest fire, and human encroachment were threatening factors to Sida Forest. Thus, Sida Forest requires urgent interventions that reduce the threat levels for the conservation of the forest in general and useful plants in particular.en-USPiliostigma ThonningiiPlant CommunitiesSida ForestSoil Physicochemical PropertiesSpecies Distribution ModelingThesis