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CHAPTER 2 UNITED STATES TIMBER SUPPLY INTRODUCTION The forests of the United States are biologically diverse. More than 40 major forest types include some 120 commercially important tree species. Each has its distinctive range, its particular site requirements, its unique physical and chemical properties, and its own set of commercial uses. The conifers or softwoods are the most fully usedâfor structural lumber, plywood and veneer, and paper pulp. Resinous pines produce naval stores as important extractives. Broad-leaved trees or hardwoods are used for specialty products as solid wood or as plywoods and veneers for furniture, pallets, floorinq, and many other uses, including paper and paper board. Hardwoods vary more than softwoods in their physical properties and have more specific uses. In short, wood comes from many different trees, has a wide ranqe of characteristics, and finds many different uses. Although we deal with it in the generic sense in this report, the resulting simplicity is apt to be misleading unless the actual complexities are kept in mind. A total of 7 54 million acres, one-third of all land in the United States, is classified as forest land. This land ranges in elevation from sea level to 12,000 feet and includes extremely diverse soils, climates, and topography. Forest management must be geared to maintain diverse plant communities in all regions of the country to permit future options for changing forest products and to provide a broad range of environments for varying levels of recreation, wildlife, water, and other forest-related uses. The status of the forests of the United States with regard to acreage of commercial forest land, forest yield, growth and harvest is under continual study by the Forest Service, United States Department of Agriculture, and is summarized by this agency at intervals of approximately 10 years. The most recent updating of forest statistics is contained in "The Outlook for Timber in the United States" (USDA 1974) which we will refer to throughout this report as the "Outlook Study". The study summarizes recent trends in forest land and timber resources in the United States. It also projects future trends in timber supplies through intensified management and use at home, and through greater reliance upon world timber resources abroad. Finally, both the Outlook Study, and the Report of the President's Advisory Panel on Timber and the Environment (PAPTE 1973) - 9 -
project future demand for timber products as well, and deal with timber demand-supply relationships. The Outlook Study thus provides a base for a critical evaluation of the biological potential of the commercial forest lands of the United States. Such an evaluation is possible, however, only so long as we use the same parameters defined in the same way as in the Outlook Study. For this reason, we have adopted the same definitions in our evaluation. Thus, we have considered the area devoted to the production of forest products in terms of commercial forest land as defined in the Outlook Study and have dealt with forest products in terms of the cubic-foot volume of the boles (i.e., trunks) of standing trees above a one-foot stump to a four-inch top diameter outside bark. Total bole value, including stump and tip will range slightly higher. For a 12-inch spruce tree 60 feet high, the stump volume is 6 percent of that of the merchantable bole while the top adds another 2 percent. For a larger spruce 24 inches in diameter and 90 feet high, the stump adds only 4 percent to the merchantable volume while the top adds less than 1 percent (Spurr 1952). At the same time, we are aware of the potential import- ance of the total biomass production of the forest, both in the complete tree and in other biota. Although insufficient data are currently available to permit accurate projections of total productive capacity of the forests of the United States, it is nonetheless useful to summarize the work on this subject. CONSUMPTION OF TIMBER IN 1970 The Outlook Study provides data on United States timber as of 1970. The apparent consumption is derived by taking the annual removals from United States forests, adding timber imports and subtracting timber exports. The overall estimates are summarized in Table 2. The cubic-foot estimates are derived from the Outlook Study. The weight estimates are obtained by multiplying the volumes by a conversion factor of 27.4 pounds per cubic foot for softwoods and 32.8 pounds per cubic foot for hardwoods. These conversion factors were obtained by weighting the average oven-dry weight per green cubic-foot for a given species, as given in the Wood Handbook, by the total volume of that species in the United States removed in 1970, as given in the Outlook Study. Whereas volume data are for wood content of the merchantable bole only, weight data include a 10 percent increase to estimate combined wood and bark mass of the bole. - 10 -
Table 2 Consumption of Timber in the U.S., 1970 (roundwood equivalent) Softwood Hardwood Total Removals, U.S. Import Export Consumption Removals, U.S. Import Export Consumption 9.623 2.090 1.150 10.563 145,018 31,496 17,330 159,184 billion cubic feet (wood only) 4.409 0.335 0.205 4.539 14.032 2.425 1.355 15.102 thousand tons (including bark) 79,538 6,043 3,698 81,883 224,556 37,539 21,028 241,067 Source: The Outlook for Timber in the United States, U.S. Department of Agriculture Forest Service (1974) - 11 -
The projections of the Outlook Study are presented in terms of two different concepts: removals and supplies. Both include the total cubic-foot volume of trees that are harvested from the qrowinq stock and used. The removals value includes also the volume of logging residues left in the woods and the volume of timber on land cleared for non- timber uses or on land withdrawn for parks, wilderness areas, or other purposes. The supplies value consists primarily of trees harvested from the growing stock and includes logging residues and trees on non-commercial forest land only to the extent they are used. The data summarized in this report are based on removals, which characteristically run higher than comparable supply statistics. It will be seen that the United States is a net importer of timber products both for hardwoods and for softwoods. The total consumption of timber in the United States in 1970 was over 15 billion cubic feet or more than a billion cubic feet higher than actual removals from American forests in that year. The annual growth in 1970 exceeded annual harvest. While the growth of sawtimber expressed in board feet was only 95 percent of removals in 1970, the growth of total growing stock expressed in cubic feet was 133 percent of re- movals in the same year. For softwoods as a group, sawtimber growth was 84 percent of removals, while growing stock growth was 111 percent. Hardwoods, on the other hand, were being cut at a much lower rate than growth. Sawtimber growth was 131 percent of removals of hardwoods, while growing stock growth was 179 percent of removals. In 1970, the current annual growth of the commercial forest lands of the United States was estimated at 38 cubic feet per acre per year. The mean growth varied from 65 cubic feet per acre on forest industry lands on the Pacific Coast to 23 cubic feet on public lands in the Rocky Mountains (Table 3). Had all the commercial forest areas been fully stocked in 1970 and had a normal distribution of age classes existed at that time, the potential annual growth of the commercial forests of the United States estimated from normal yield tables would have been 74 cubic feet per acre per year, or almost twice the estimated net annual growth. considerable gain would be achieved through harvesting old-growth stands on the Pacific Coast and in the Rocky Mountains, stands where current growth is negligible, and replacing them with faster growing second-growth forests. - 12 -
Table 3 Average Net Annual and Potential Growth per Acre by Owner, Class and Section 1970 (Cubic feet) All National Other Forest Farm and Section Owners Forest Public Industry mi see 1 laneous North: private Current 31 38 33 40 29 Potential 68 66 59 72 69 South : Current 45 55 45 53 42 Potential 76 70 71 81 75 Rocky Mountains: Current 24 23 23 47 25 Potential 60 65 54 70 50 Pacific Coast: Current 45 27 60 65 58 Potential 95 88 100 107 96 Total : Current 38 30 39 52 36 Potential 74 73 68 83 72 Potential growth is defined as the average net growth attainable in fully stocked natural stands. Higher growth rates can be attained in in- tensively managed stands. Source: The Outlook for Timber in the United States, U.S. Department of Agriculture Forest Service (1974) - 13 -
PROJECTED SUPPLY IN 1985 AND 2000 In the Outlook Study, the Forest Service projected future timber supplies of the United States from 1970 through 2020 at 10-year intervals. These projections are stratified by geographic section of the country, species group (softwoods and hardwoods), and ownership class (national forest, other public, forest industry, other private). The projected supplies are given both in terms of cubic feet (roundwood products) and board feet (sawtimber products). The base-line projection in the Outlook Study is based on the assumption of a continuation of the 1970 level of management. This level is defined as the average amount of forest management activities prevailing throughout the 1960s. Specifically, it was assumed that current levels would be maintained in such matters as expenditures for fire control and area burned, expenditures for pest control and level of damage, expenditures for reforestation and area planted, expenditures for forest fertilization and area treated, assistance to private forest landowners, support of forestry research, expenditures for forest roads and mileage developed, and the like. The average investment in constant 1967 dollars during the 1960s was $148 million for forest fire protection (an- nual burn 3.9 million acres), and $13 million for forest pest control. During the decade, an average of 1,477,000 acres was planted annually at an estimated cost of roughly $85 million. For the period 1968-70, an estimated 1,413,000 acres were treated annually to improve the timber stand at an estimated cost of $25 million per year. By 1971, forest industries were reported to be applying fertilizer to nearly 150,000 acres annually, almost entirely on the Pacific Coast and in the South. Road construction for forestry purposes totaled $180 million in 1970 for National Forests alone. The Outlook Study's projection of future timber produc- tion is based upon a continuation of these "1970" levels of management. In actual fact, the intensity of timber management has increased over the years. While it would be entirely appropriate to base estimates of future production on a trend line of increasing intensity of management, the baseline of a continuing of 1970 levels of management adopted by the Forest Service is acceptable for a conservative projection. If we assume the continuance of these expenditures and forest management achievements, the trends in productive potential of the United States forests can be highlighted as in Table 4. The data for 1985 are interpolated from the Outlook Study. Compared with total removals in 1970 of 14 - 14 -
billion cubic feet, those for the year 2000 are estimated to be 20.3 billion or an increase of <*5 percent. In addition, the ultimate productive potential of the United States forests, as estimated from normal yield tables, is appended in the bottom line. As can be seen, the potential productivity of our forests as defined by this measure is over twice as qreat as the 1970 harvest for softwoods and nearly four times as qreat for hardwoods. The productive potential as defined by yield tables is, however, only a rough measure, and it should be taken as such. In the first place, it is totally unrealistic to assume that all the commercial forest land could be brought to a fully stocked condition with a balanced distribution of age classes created within each working circle. Inevitably, average volumes over large areas of forest are less than those measured on selected sample plots. Ostrom and Gibbs (1973) cite a Swedish study by Eriksson (1967) over a 30- year period. Comparing yield data from permanent sample plots averaging 1/U hectare with the yield of surrounding stands averaging eight hectares in area that were periodically thinned, Eriksson found that the yield of entire stands was only 90 percent of the yield measured on the growth plots. He attributed the difference to unproductive spots caused by rocks, blanks resulting from windfall, the occurrence of other species, irregularity in spacing, edge effects, log landings, logging damage, and greater care in management within the plot boundaries. In the United States, shallowness of soils and dry cli- matic conditions often result in stands less than fully stocked in terms of crown closure. Particularly in the ponderosa pine type in the interior of the western United States, actual yields will often be substantially under those indicated by normal yield tables (MacLean and Bolsinger 1973) . While the estimates of future timber supplies based upon yield tables are unrealistic, the estimates in Table 4 of the productive potential of timber based upon the contin- uation of 1970 levels of management for 1985 and 2000 appear to be fully attainable. From the Outlook Study projections of the United States Forest Service, it is clear that harvests from United States forests could be increased by approximately 25 percent over 1970 levels by the year 1985 and by as much as 50 percent by the year 2000, by continuing at 1970 levels of forest management. Much of this increase, however, would come from hardwoods, a category which is currently being underused. The projected increase in softwood timber supplies would be only 1U percent by 1985 and 25 percent by 2000. - 15 -
Table 4 Past Production and Future Productive Potential for U. S. Forests Softwoods Hardwoods Total billion million billion million billion million cu.ft. tons cu.ft. tons cu.ft. tons 1952 7.8 118 4.1 74 11.9 192 1962 7.6 115 4.2 76 11.8 191 1970 9.6 145 4.4 80 14.0 225 1985 11.0 166 6.5 117 17.5 283 2000 12.1 182 8.2 148 20.3 330 Potential (Yield table) 20.5 309 17.5 316 38.0 625 Source: The Outlook for Timber in the United States, U.S. Department of Agriculture Forest Service (1974) - 16 -
PROBLEMS OF ESTIMATING CURRENT AND FUTURE RAW MATERIAL SUPPLY Among the renewable resources, forests differ from agricultural crops, both animal and plant, in ways that make the problem of estimating current and future supplies unique, not well understood, and vastly more difficult. The forest is both the product and the means of production; when we harvest the trees, the capacity of the land to produce more wood in the immediate future is largely dissipated. And when we reforest the land, no products are available for long periods. Even after products are initially available, they must be allowed to accumulate in the forest factory to insure maximum future and average production. Even if we exclude social, political, and environmental factors to which forests are peculiarly subject, the uniqueness of the forest makes economic rationalization of forestry extremely complicated as an enterprise. Data on current and future raw materials supply must be collected in a way that makes the economic analyses possible. It is apparent from the above that the task is a difficult one. - 17 -
