Author: Okoro Ogochukwu Grace
Affiliation: Nnamdi Azikiwe University Awka
This study examined the ecological characterization and human impact assessment on a watershed in Awka, Anambra State. The study site was situated along a perennial stream which was 1490 m long with an average width of 3 m.The study site was divided into three segments (head, middle and tail), these segments were further sub divided into two aspects, that is, left (WEST) and right (EAST) hand side of the stream. At each segment and aspect, sampling of plant species was conducted using quadrat method to determine species abundance and species diversity. Soil samples at three depths (10 cm, 30 cm and 50 cm) were also collected in each segment and aspect to determine the soil pH and microorganisms. The various land use practices on the watershed were also noted by segment and aspect. In data computation, the importance value index was used to determine the species abundance while Shannon Weiner index of diversity was used to determine the species diversity of the watershed. In statistical analysis, the Analysis of Variance (one-way, two-ways and three-ways) and regression analysis were utilized. The findings of the study show that nearly all parts of the watershed were disturbed through human activities ranging from wood lumbering, farming and construction although the intensity varied across segments. The study showed also that with respect to segment, the species diversity of the watershed is higher at the head segment (0.81) and lower at the tail segment (0.72). Also with respect with aspect, the study revealed that the species diversity is higher towards the left aspect (0.68) than the right aspect (0.66). With respect to soil analysis, there was significant difference in the number of microorganisms and pH between soil depth aspect and segment (in three way interaction model). The study shows a negative significant relationship between land use pattern in the watershed and soil pH, microorganisms and species diversity. The study further showed a positive relationship between species diversity, soil pH and microorganisms.
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