Abstract

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There is generally lack of emphasis on effective management of natural forest in Nigeria. These have led to decline in the natural forest areas while some economic trees are gradually becoming extinct. Studies on growth space requirements for the trees are generally lacking and inventory information is scarce in the southern guinea savanna of Nigeria. Growing space was associated with crown size. Therefore, crown and stem diameter relationship models were tested on data recorded from D. oliverii (Rolfe) Hutch and Daviz trees in Makurdi. The study area was divided into nine hectare blocks, i.e. a total of nine blocks as sample plots (sizes 100 x 100 meters each) which was randomly laid down. Simple random sampling technique was used to collect data on tree height, diameter at breast height (dbh), diameter at the base, middle, top (with the use of diameter tape and a portable ladder) and crown diameter (with the use of 30 meter measuring tape) within the study area. The data collected on trees >10 cm dbh were tested on seven models on crown diameter and stem diameter relationship. The linear model provided the best model fitted with R2 values of 0.799%. For optimum planting, fast growth and high production/yield the tree would require a planting spacing of 4 x 4 meters. The results shows, a dominant free-growing tree of diameter 48.7 cm diameter tree would require 0.0060 hectare of growing space with a stocking of 168 trees per hectare. Stand basal area (density) converges around 0.000055 m2, 0.000038 m2 and 0.000013 m2. The baseline information provided by this study could serve as a guide for optimum planting distances and tree density in large scale plantations establishment.

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