Biological Productivity of Renewable Resources Used as Industrial Materials (1976) / Chapter Skim
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UNITED STATES TIMBER SUPPLY
UNITED STATES TIMBER SUPPLY
Pages 9-18
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From page 9... ...
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)
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From page 10... ...
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.
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From page 11... ...
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.
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From page 12... ...
. 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.
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From page 13... ...
Higher growth rates can be attained in intensively managed stands. Source: The Outlook for Timber in the United States, U.S.
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From page 14... ...
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.
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From page 15... ...
In the United States, shallowness of soils and dry climatic 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)
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From page 16... ...
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.
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From page 17... ...
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.
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