Abstract

This study examined the growth yield and the nutrient status of two prominent tree species in Ogun State Forestry Plantation Project Area, Pinus carribaea stands established in 1991, 1992 and 1996 and Nauclea diderrichii in 1974, 1975, and 1976. Growth data and composite soil samples from 2 depths (0-15 and 15-30cm) were collected from five plots (20m x 20m²) randomly located in the plantation of the two species and the adjacent natural forest for comparison. Growth tree variables measured includes number stem, diameter at breast height, basal area, tree height and volume and were subjected to two-way analysis of variance (ANOVA), Pearson Correlation Coefficient, Duncan Multiple Range Test (DMRT) statistical tools. The results show there was significant difference in number of tree per hectare, dominant diameter, volume/ha and mean diameter at dbh for the Pinus stands. A total of 4032 trees/ha, 752 trees/ha, 1744 trees/ha for the 1996, 1992 and 1991 years’ Pinus stand respectively, with highest in years 1996 (4032/ha) while 816 tree/ha, 928 trees/ha, 704 trees/ha for the 1976, 1975, 1974 years’ Nauclea stand respectively, Year 1996 (3210.26 m³) has the highest in terms of volume and the least recorded in year 1992(1078.45 m³) in Pinus, and highest in 1974(2362.89 m³) and lowest in 1976 (1761.69m³/ha) in Nauclea. There was high correlation between percentage sand and most of the tree growth variables for both species. Comparison of soil nutrients in the plantations with the nutrients in the natural forest revealed ability of the plantation establishment to replenish soil nutrient status.

Key Words: Soil Depth, Plantations, Stand Age, Growth Variables, Correlation