Soil-Woody Plant Relationship in Oban Forest Reserve, Akamkpa, Cross River State, Nigeria

Aims: Relationship between soil and woody species were assessed in the forest reserve in view of highlighting plant diversity status, population density and nutrient-relations in the forest.

Study Design: Systematic sampling method was used in sampling soil and vegetation parameters.

Place and Duration of Study: The study was conducted in the Oban Division of Cross River National Park, Nigeria, between November 2015 and July 2016.

Methodology: Systematic sampling method was used in studying the vegetation and soil. A total of thirty plots were sampled in each season. Total area of vegetation sampled was 1500 m2. Soil samples were analyzed following the standard procedures outlined by the Association of Official Analytical Chemist.

Results: The result revealed a total of 24 species from 16 families and 23 plant species from 21 families in the wet and dry seasons respectively. Coula edulis was the most frequent plant species (100%) while Baphia nitida, recorded low frequency (20%) values. Barteria nigitiana (120±5.26) and Diospyros mespiliformis (120±6.20) dominated in density. Berlinia confusa was the tallest species (47.33±0.67 m) while Anthocleista vogelli was the smallest plant species (4.73±0.96 m). Brachystegia nigerica and Berlinia confusa had the widest crown coverage of 15.27±4.61 m2/ha and 15.27±4.73 m2/ha, respectively. Brachystegia nigerica had the largest basal area (0.42±0.07 m2/ha). Shannon and Simpson diversity indices were high in both wet (2.684 and 0.9029) and dry (2.968 and 0.9373) seasons respectively. Correlation analysis indicated significant relationship between woody species and soil edaphic factors. Stepwise multiple regression technique showed that soil variables predicted for the variations observed in vegetation parameters in both seasons.

Conclusion: The pedological indices and nutrient status of soil play critical roles in plant species distribution and vegetation morphology in Oban Forest Reserve.