EFFECTS OF UNEVEN-AGED SILVICULTURE ON THE STAND STRUCTURE, SPECIES COMPOSITION, AND ECONOMIC RETURNS OF LOBLOLLY-PINE STANDS

Uneven-aged silviculture in loblolly pine (Pinus taeda L.) stands has many economic and ecological benefits. Here, the consequences of vario us uneven-aged management regimes are predicted with the SouthPro simu lator. Results indicate that target distributions for pines with resid ual merchantable basal areas of approximate to 12.5 m(2) ha(-1), maxim um diameters of ca. 40 cm, and q-ratios of 1.2-1.25 for 2.5 cm DBH cla sses are Likely to provide high economic returns on good sites when co mbined with hardwood control. Increasing this maximum diameter would e nhance tree-size diversity, but reduce sawtimber production and profit s. Retaining a hardwood component with 1.15-2.3 m(2) ha(-1) of basal a rea could enhance tree-species diversity, but this too would result in moderate reductions in income. Insisting on maximizing tree-size dive rsity or tree-species diversity among softwoods, soft hardwood, and ha rd hardwoods would be quite costly in terms of lost income and product ion. Results also illustrate how short-term economic incentives can le ad to high-grading practices, despite substantial reductions in stand productivity and net returns in the long term. (C) 1998 Elsevier Scien ce B.V.