Relationships between Soil and Vegetation Structural Properties of Secondary Forest Regenerating in Degraded Rubber Plantation in the Niger Delta Area of Nigeria

Abstract

The effects of soil on vegetation structural attributes (tree density, tree height, tree diameter, basal area and estimated aboveground biomass) of a secondary forest following the abandonment of a degraded rubber plantation in Orogun area of Delta state Nigeria was studied using the multiple linear regression model. Four secondary forests of different age categories (1-year, 5-year, 10-year old secondary forests and a mature secondary forest of about 80 years old) were studied. Vegetation parameters were measured by quadrat method. Forty quadrats (30m x 30m), ten in each secondary forest categories were delineated for soil sampling and for the measurement of vegetation structural properties. Twenty composite soil samples were collected in each secondary forest category and analyzed for organic matter, pH, available phosphorus, total porosity, ECEC (effective cation exchange capacity) and water holding capacity. Vegetation structural properties for each of the quadrats were measured using appropriate field measurement techniques. Multiple linear regression was used to investigate the relationship between the vegetation structural properties and soil properties. The result of multiple linear regression showed that soil organic matter, total porosity, water holding capacity, available phosphorus and ECEC were the most outstanding soil factors influencing the regenerative capacity of the vegetation structural properties in secondary forests. Relationship between Soil and vegetation Structural Properties of Secondary Forest regenerating...

Key words: Tree height, Tree density, Basal area, multiple regression, ECEC, Water holding capacity.