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Parkia biglobosa (Jacq) Benth has great importance to the people of rural and urban communities in the guinea savanna of Nigeria, and this exposes it to high exploitation and is facing regeneration problem. There is lack of information on growth spacing of P. biglobosa for plantation establishment and sustainable management. This have led to the species declining in the natural forest areas and the loss of biological values (genetic hereditary). A total of nine blocks as sample plots sizes 100 x 100 meters each was randomly laid. Simple random sampling design was used to collect data on tree heights, diameter at breast height (dbh), diameter at the base, middle, top (using diameter tape) and crown diameter. The data collected were tested on seven equations on crown and stem diameter relationship. The linear equation (equation 3) was the best model fitted with R² value of 0.854 species. Based on the results, a dominant free-growing tree species with diameter 50.5cm would require 0.009 hectare of growing space with a limiting stocking of the stand in terms of total occupancy by tree crowns of 110 trees per hectare. Stand basal area (density) converges around 0.000038 m². For optimum planting spacing in term of fast growth and high production/yield, P. biglobosa would require a planting spacing of 4 x 4 meters for non-wood forest products while for timber purpose, thinning can be applies to create more spacing until merchantable size of timber is achieved. The species requires a definite amount of growth space and this study could serve as a guide for optimum planting distance and tree density when establishing plantations of the economic species.

Crown- diameter, Stem-diameter, Growth space, Sustainable forest, Parkia biglobosa