Application of Canonical Correlation for Soil -Vegetation Interrelationship in the Cocoa Belt of South Western Nigeria

Abstract

This paper investigates the multivariate relationships between the soil and vegetation characteristics of plant communities of forest, fallow and cocoa for two reasons. The first is to bringing out the interactions among a set of inde- pendent variables and pinpoint the relative importance of each of these variables on a dependent variable be it a soil or a vegetation element. The second is to illustrate the changes that occur to the soil-vegetation properties as the tropical rainforest is cultivated to cocoa and field crops. The processes of choosing the study sites followed a random selection of sample points under three land use types: forest, fallow and cocoa (Theobroma cacao). A total of 300 sample points were selected under each of fallow and cocoa and 260 were selected under the forest. From each sample point soil samples were collected to a depth of 45 cm (i.e. 0-15 cm; 15-45 cm) placed into well-labelled polythene bags and taken to the laboratory for analysis. The results for the forest shows that the canonical variate of the vegetation variables account for 31% of the variance extracted by the soil factors, while the soil variables also account for 31% of the variance extracted by the vegetation variables while the result of the canonical correlation for fallow soil and vegetation extracted for the first and second canonical variates are 0.91 and 0.61 respectively. The result for the canonical correlation coefficients for cocoa for the first and second canonical variates is 0.68 and 0.51 respectively. The study concluded that while simple relationships were observed among soil and vegetation properties in the forest and fallow, complex relationships were recognised in the cocoa plant community.