Woldu, Zerihun (Professor)Belachew, Getaneh2018-07-182023-11-092018-07-182023-11-092015-11http://etd.aau.edu.et/handle/123456789/9221Ecological Study of the vegetation in Choke-Koso Ber Mountain range was conducted in Gojjam, Amhara zone, Northwest Ethiopia, to identify and describe floristic composition, diversity, community types, community-environment relation, population structure and regeneration status. A total of 212 sample plots, each with a size of 20 m x 20 m, were systematically laid at 25 m altitudinal intervals along transect lines. In each plot, geographical coordination, altitude, aspect, slope and identity of woody species were recorded; percentage aerial cover of the species was estimated. Height and circumference at breast height (CBH) were measured for each woody species with height 2.5 m and CBH 7.85 cm. In five small sub-plots, herb species were recorded, percentage aerial cover of the species was estimated, seedling and sapling of woody species were counted and composite of soil samples were collected. Soil texture was determined using the Boycouos hydrometric method and USDA Soil Textural Triangle. Soil pH was measured using pH meter, while electrical conductivity and total dissolved salts of the soil samples were measured using Conductivity/TDS/Salinity/ Resistivity Meter. Diversity and multivariate analyses were conducted using appropriate packages in R program (Version 3.1.2). 243 plant species, belonging to 177 genera and 71 families, were recorded. Of these, 17 species (7%) were trees, 3 species (1.23%) shrub/tree, 37 species (15.23%) shrubs, 171 species (70.37%) herbs, 12 species (4.94%) climbers and 3 species (1.23%) mosses. Out of the total identified species, flowering plants were represented by 228 species (93.83%), non-flowering by 15 species (6.17%), dicots by 176 species (77.20%) and monocots by 52 species (22.80%). Asteraceae, Poaceae, Fabaceae and Lamiaceae were the dominant families. Of the total species, 33 species (13.58%) were endemic plants to Ethiopia. Agglomerative Hierarchical Cluster analysis resulted in three plant community types of Afroalpine vegetation and five plant community types of Dry Evergreen Afromontane vegetation. Analysis of Shannon and Weaver diversity index showed that species richness, diversity and evenness varied among the plant communities. Diversity and richness tended to decrease with increasing altitude, while species turnover tended to increase with increasing altitude. In general, community types with largest number of sample plots, diversified environment, highest altitudinal range and moderate disturbance were found to have the highest species diversity, richness and evenness. Soil textural classes of the study area were sandy loam, loamy sand, sandy clay loam, clay loam and loam. The vegetation and the environmental data were subjected to direct gradient analysis. The output of CCA revealed that the most influential environmental variables that had effect on the distribution of species and segregation of some plant community types in both Afroalpine and Dry Evergreen Afromontane vegetation were Sand (%), Disturbances, Aspect and Slope. ANOVA and Turkey’s pair-wise comparison showed significant different (P < 0.05) between the community types with respect to mean of Altitude, Silt (%), Clay (%) and Disturbance in both Afroalpine and Dry Evergreen Afromontane vegetation. In addition, there was significant difference between the community types of Dry Evergreen Afromontane vegetation with regard to mean of Sand (%), pH, EC and Total dissolved Salt (TDS). Pearson’s correlation test for environmental variables of Afroalpine showed significant positive correlation (P < 0.05) occurred between Sand (%) and pH, Silt (%) and Disturbance, and EC and TDS. On the contrary, significant negative correlation occurred between Altitude and Slope, Sand (%) and Slope, Sand (%) and Silt (%), Sand (%) and Clay (%), Silt (%) and Clay (%), and TDS and Disturbance. Similarly, the correlation test for environmental variables of Dry Evergreen Afromontane vegetation showed significant positive correlation between Altitude and Aspect, Slope and pH, Sand (%) and EC, Sand (%) and TDS, and EC and TDS. In contrast, significant negative correlation occurred between Altitude and Disturbance, Sand (%) and silt (%), Sand (%) and Clay (%), Silt (%) and EC, Silt (%) and TDS, Clay (%) and EC, and Clay (%) and TDS. Structure was carried out for the Dry Evergreen Afromontane forest. In general, woody species had high density in the lower DBH and height classes, and the density gradually decreased with increasing DBH and height classes. The dominance of smallsized woody individuals in the lower DBH and height classes indicated the characteristic of a good regeneration status. Four patterns of population structure were identified: Inverted J-shaped, Gaussian-curve, J-shaped and U-shaped. The total basal area of woody species was 28.65 m2/ha. The six most important woody species were Maytenus arbutifolia, Maesa lanceolata, Acacia abyssinica, Schefflera abyssinica, Prunus africana and Pittosporum virdiflorum. These woody species represented 71.96% of the total Important Vale Index. The remaining 28.04% was contributed by eighteen woody species.enEcological AnalysisThesis