Assessment of Plant Diversity and Soil Properties Along Awba Dam Watershed Ecosystem, University of Ibadan, Ibadan, Nigeria

Abstract

This study examined the impact of land use on soil physicochemical properties and floristic composition within the Awba dam watershed ecosystem. A systematic random sampling technique was used to lay out plots (25m x 25m) in alternate positions on identified land use
types (secondary regrowth, grassland, wetland, and farmland). Plant species were enumerated, and composite soil samples (0-25 cm depth) were collected from four quadrants in each sample plot. Descriptive statistics and diversity indices were computed, and principal component analyses were used to assess the association among the variables. Land use has a significant influence on soil chemical properties. Soil from the wetland had the highest pH (6.46), grassland had the highest organic carbon content (1.95%), while the wetland had the highest available phosphorus (40.90 %). There was a significant relationship between species diversity and soil physicochemical properties. A positive relationship was observed between the species dominance, evenness indices, with sodium, potassium, and calcium. The analysis also revealed that manganese, acidity, and sodium content in soil were more associated with farmland, availability of phosphorus in soil, soil PH, and high species diversity are more associated with riparian forest, while the number of species occurrence are associated with secondary regrowth in the area. This study revealed that the land use system influenced tree species diversity and
soil properties in the watershed ecosystem. Therefore, appropriate measures are needed to ensure the survival of key tree species in the watershed to help maximize the structural and functional role of the ecosystem.