Plants Diversity along Watershed Environment: A Case Study at Ikot Uso Akpan Wildlife Sanctuary in Itu L.G.A. of Akwa Ibom State, Nigeria

Plant diversity and soil characteristics were studied along watershed environment in Ikot Uso Akpan Wildlife Sanctuary of Itu Local Government Area, Akwa Ibom state. The systematic sampling method was used to sample the vegetation in 10m x10m quadrats. Plants were identified to species level. Vegetation attributes such as frequency, density, height, basal area and crown cover, were measured for each species. In each quadrat, two soil samples were collected and bulked into one composite sample. A total of twenty soil samples were collected. Soil physicochemical properties were analyzed in the Soil Science Laboratory of University of Uyo, Uyo. 42 plant species belonging to 33 families and 38 genera were identified in all the sampling area. The results showed that Elaeis guineensis was the most abundant species with 70% frequency of occurrence while Rauvolfia vomitoria was the least with 10% frequency of occurence. Carpolobia lutea had the highest mean density of 250±0.00stems/ha while 6 plant species had the least mean density of 25±0.00stems/ha. Brachystegia eurycoma had the highest mean height while Aframomum sceptrum was the shortest plant. Brachystegia eurycoma had the highest mean basal area of 1.10±0.001m2/ha, while Costus afer had the smallest mean basal area of 0.00002±0.000008m2/ha. Brachystegia eurycoma had the highest mean crown cover of 213.71±0.00m2/ha, while Aframomum sceptrum had the smallest mean crown cover of 0.077±0.009m2/ha. The soil was slightly acidic with pH mean value of 5.41±0.15. Organic Carbon, Total Nitrogen, Sodium and Potassium were low with mean values of 1.53±0.33%, 0.07±0.01%, 0.06±0.004 Cmol/kg and 0.10±0.01 Cmol/kg, respectively. Among the heavy metals, Iron (Fe) had the highest mean value of 36.16±8.94mg/kg, followed by Manganese (Mn) with mean value of 6.48±0.46mg/kg. The soil had high sand content of 89.20±0.80%, and low silt and clay contents of 5.40±0.20% and 5.40±0.60%, respectively. Linear regression of soil parameters and vegetation components showed that soil characteristics affected the abundance and distribution of vegetation components. This indicates that they play a vital role in plants diversity and distribution along watershed environments.