Highlight Direct-seeded slash pines (Pinus elliottii Engelm. var elliottii) were thinned at age 3 years to densities ranging from 500 to 5,300 trees/acre. At stand age 12 years, herbage yields were inversely related to tree basal area, varying from 560 lb./acre under tree basal areas of 125 fta to 2,230 lb. under 54 fta. Where timber stand densities were equal, yield did not vary between plots that had been thinned selectively and those on which continuous opening had been created by removing trees in strips.
At age 16 years, average diameters and merchantable volumes were inversely related to density in a stand that was precommercially thinned at age 3. Heights of dominants and codominants were related to site factors and not to treatment effects. At residual stocking levels of 1,450 and 2,900 trees per acre, strip thinning was as effective as selective thinning.
Longleaf pine (Pinus palustris Mill.) trees growing in thinned plantation studies in Louisiana and Texas and unthinned stands from the Louisiana sites were sampled for establishing taper, volume, and specific gravity. Stem analysis data were collected on 147 stems ranging in age from 30 to 50 yr. Analyses of covariance (ANCOVAs) were employed to determine coefficients and to detect differences among treatments, for tree taper and specific gravity. Taper and volume equation coefficients and statistics at specified ages were developed for intermediate plantation ages by examining and aging internal growth rings from the stem sections. Biomass was computed by combining the taper and specific gravity equations. Seemingly unrelated regression (SUR) was used to simultaneously fit the system of four equations composed of specific gravity, taper, volume, and biomass, because of the correlated error structure of these equations. Biomass equations, however, could not be developed for the intermediate ages because specific gravity could not be determined or related to earlier tree ages. South. J. Appl. For. 19(1):29-35.
Site index equations were developed for direct-seeded loblolly pine (Pinus taeda L.) and longleaf pine (Pinus palustris Mill.) based on data from 148 and 75 permanent plots, respectively. These plots varied from 0.053 to 0.119 ac in size, and were established in broadcast, row, and spot seeded stands throughout Louisiana. The Bailey and Clutter (1974) model was selected for stand height prediction. Site index curves are presented for both species based on these equations. These site index models should provide satisfactory short-term height projection for direct-seeded loblolly and longleaf pine stands in Louisiana. South. J. Appl. For. 21(3):134-138.
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