Results of a Slash Pine Spacing and Thinning Study in the Southeastern Coastal Plain

Results are summarized for a slash pine (Pinus elliottii Engelm.) spacing and thinning study installed 28 yr ago at 28 locations in the southeastern coastal plains in plantations established on cutover land after mechanical site preparation. Stocking densities of 100 to 900 trees/ac are represented in the spacing study with 15 yr thinning response data for thinning intensities ranging from 25 to 65% of the trees removed in selective thinnings from below. Per-acre basal area and volume prediction equations are presented for unthinned plantations and for thinned plantations when a specified number of trees per acre is left. Survival and dominant height projection equations for both unthinned and thinned plantations are presented, and a competition index to account for the thinning response relative to a comparable unthinned plantation is defined. Application of the prediction equations is demonstrated with an example that shows the nature of the implied thinning response relative to a comparable unthinned plantation. South. J. Appl. For. 20(2):94-98.