Full-Tree and Complete-Tree Utilization for Pulp and Paper

By the year 2000, world demand for paper and paperboard will be more than 400 million metric tons per year. Demand for wood will be in the order of 4.0 billion cubic meters, while the supply of economically exploitable wood will be in the order of 3.8 billion cubic meters. Some parts of the wood fiber shortfall can be made up from tree components not presently used. Full-tree utilization is use of all above-ground wood components, complete-tree utilization is use of all above- and below-ground wood components, and full-forest utilization is use of all above-ground forest biomass, including tops, branches, and boles of mature and small diameter trees, weed species, dead standing timber, and cull trees. Based on an analysis of biomass and pulping studies of western hemlock, Douglas-fire, white spruce, black spruce, Sitka spruce, and Japanese red pine, additional fiber recoverable from softwoods and hardwoods, respectively, is estimated to be 5 and 10 percent for tops; 10 and 20 percent for branches; and 20 and 30 percent for tum-root systems. For mature softwoods, yield of kraft pulp from mature bole, top, branches, and stump-root system is in the ratio 100:95:75:95. The strength of kraft pulps from the merchantable bole, the full tree, and the complete tree is in the ratio 100:97:95. In general, data is sparse on the yield and quality of kraft pulp from the components of mature hardwoods; detailed studies, on the quality of kraft pulp from the bole, tops, and branches of mature beech, birch, maple, and aspen are underway at the Western Forest Products Laboratory in Vancouver. Little is known of the effect of tree components other than the bole on mechanical pulp processes. For both softwoods and hardwoods, the effect of bark and foliage on the yield and quality of both bleached and unbleached pulps requires extensive study.

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