Soil-vegetation relationship in fresh water swamp forest

Abstract

Soil and vegetation relationships were studied in freshwater swamp forest in Ikot Umiang Ede in Etinan Local Government Area, Akwa Ibom State. The systematic sampling method was used to sample the vegetation in 10 x 10m quadrats. Plants were identified to species level. Frequency, density, height, basal area and crown cover were determined for each species. In each quadrat two soil samples were taken and then bulked into a composite sample. A total of 40 soil samples were collected. Soil physiochemical properties were analysed in the Soil Science Laboratory of University of Uyo, Uyo. The results showed that Elaeis guineensis was the dominant species with 40% frequency of occurrence, while 11 plant species had the least occurrence of 5% frequency. They are Baphia nitida, Cyrtosperma senegalensis, Homalium letestui, Marantochloa cuspidata, Nauclea diderrichii, Poga oleosa, Palisota hirsuta, Smilax anceps and Smilax kranssiana. Bambusa vulgaris, had the highest density of 760 ± 62.8 stem /ha while Palisota hirsuta had the least density of 2.15 ± 0.00 stems/ha. Zanthoxylum zanthoxyloides was the tallest plant with a height of 21.00±0.00m while Poga oleosa and Palisota hirsuta were the shortest species with a height of 0.01 ± 0.00m each. The soil was acidic (5.25 ± 0.11). Organic carbon, total nitrogen and potassium were low with mean values of 4.57 ± 0.25cmol/kg, 0.39 ± 0.02cmol/kg and 0.29 +0.00cmol/kg respectively. Exchangeable cations were low. Among the heavy metals, Fe had the highest mean value of 184.0 ± 52.54mg/kg. The soil had a high sand content (65.45 ±00.93%) and low silt and clay contents 23.25 ± 0.49 and 11.77±0.92%, respectively. Linear regression shows that, the relationship between soil parameters and plants density, height, crown cover and basal area were positive; indicating that soil parameters forms part of constellation of factors determining the existence of plants in the freshwater swamp.