Key to Utilization of Hardwoods Growing on Southern Pine Sites

For every cubic foot of pine on southern pine sites, there is about 0.8 cubic foot of hardwood. The shaping-lathe headrig, now in the final stages of commercialization, is a key to utilizing these small mixed hardwoods for paYets and industrial lumber. Lathe residues in the form of flakes can be the raw material for a new major industry manufacturing exterior structural flakeboard competitive in price andfunction with sheathing grades of plywood. Other likely uses for lathe residues include manufacture of pulp, medium-density particleboard, and molded composi!es of foamed resin and match-size wood particles. to 8 inches in d.b.h. predominating. Figure I illustrates a stand on easy terrain in central Louisiana. Mountain sites and more scattered stands present harder tasks to the converter. Over the years, countless attempts to use pine-site hardwoods have been thwarted by the diversity of species, scattered occurrence of trees, smallness and shortness of boles, branchiness of crowns, and prevalence of knots. Further, most species have a wood specific gravity about 15 percent greater than that of southern pine, and hence it is difficult to make reconstituted panel products whose weight does not exceed that presently acceptable to the trade. Recent demand for paper, however, has given great impetus to whole-tree chipping of mixed hardwoods to yield barky chips for southern pulpmills. This development will substantially increase drain on the hardwood resource. Simultaneously demand has increased for hardwood pallets and for roof sheathing panels to be used under shingles on houses. On a weight basis, lumber and structural panel products are worth several times more than pulp chips. It therefore seems logical that tree portions that can be converted to lumber and panel products should be so converted, with the remainder chipped for pulping. This has been the course of development in the southern pine industry (2, 4, 5) and will likely be the course for hardwoods if a newly developed shaping-lathe headrig (6, 7) proves as workable ,as it appears. Shaping Lathe Headrig Chipping headrigs used in the conversion of southern pine cut in the 90-0 and 90-90 modes (fig. 2), are best applied to logs 8 feet or more in length without butt swell, crook, or sweep. Products are cants to be resawn into structural lumber, and the peripheral wood is removed as pulp chips. The cants characteristically display some torn grain around knots. A prototype headrig cutting in the 0-90 mode was flTst demonstrated more than 10 years ago (1, 3) and now nears commercial application (6). Operating on the principle of a shaping lathe, it is particularly adapted to short logs of irregular contour, since it relies for workpiece position on end chucks rather than on through-fe~d chains or rolls. Smoothness of the machined surfaces approaches that of millwork. In contrast to other headrigs, this version can readily produce rounds, hexagons, octagons, and trapezoids as well as square or rectangular cants. Thus it lends itself to the manufacture of pallet parts and other industriallumber, together with posts and rails for fencO ff-site hardwoods, growing on land better suited for southern pines, have posed a problem to foresters for decades. Such trees have generally been uneconomic to harvest. If left undisturbed, they occupy space better used by pines, but to destroy them during site preparation for pine plantations is an expensive operation, whether attempted by bulldozing, chaining, or chemical applications. This paper describes a utilization system that has promise of converting these hardwoods from liability.to asset, and at the same time easing site preparation for succeeding plantations.