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UNITED STATES TIMBER INVENTORY
Pages 19-26

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From page 19...
... These varying dimensions are catalogued in the "American Lumber Standards," an industrially accepted specification originally promulgated some 50 years ago and changed only moderately since. Under these lumber standards a nominal 2" by 8" dry, surfaced board must have a minimum dimension of 1-1/2" by 7-1/2".
From page 20...
... Given the lack of precision in measuring lumber and timbers and the lax manufacturing procedures reflected in lumber standards, the task of attempting to estimate recovery of these materials from round logs of various sizes is a difficult one. Two general types of log rules have been widely adopted by industry and government, and several of them are in current use.
From page 21...
... Here the log rules, based as they are upon estimated lumber recovery, make no technological sense at all. With the advent of large-scale electronic computers, the possibility has been explored of using simulation models to predict product recovery under the manufacturing conditions actually projected for use.
From page 22...
... Most volume tables are developed by making assumptions concerning the choice of a geometric solid configuration that approximates the shape of the tree bole, the probable stump height and minimum usable top diameter, and, sometimes, the mixture of logs that are potentially recoverable. In some cases, the volume estimate by volume tables is the cubic volume of the whole stem, but most volume tables have concentrated upon estimation of the volume of the so-called merchantable bole.
From page 23...
... Adeguate sampling of extensive forest areas through the management of sample plots in the field is time consuming and expensive. Even the best designed forest surveys are of questionable accuracy because of the problems already described with the basic units of measuring, the difficulty of making accurate measurements of basic parameters in the field, and the high cost of adequately sampling highly variable forests.
From page 24...
... The first technique is better, but the number of plots remeasured in practice is seldom enough to permit adequate sampling, and the precision of the repeated measurements is seldom good enough to provide accurate measurements of the differences that constitute growth. The use of increment cores in the stand-table projection method is adeguate to provide data on the gross growth of individual forest stands, but may not provide accurate estimates of net growth because of the difficulty of measuring tree mortality over a specific period of time.
From page 25...
... A CONTINUOUS FOREST INVENTORY The United States forest resource is on the one hand extensive and valuable, and on the other remarkably poorly defined as to extent, content, and current and potential growth. This is not to say that large efforts by competent professional foresters have not been productive.
From page 26...
... It should be based upon sufficient actual measurements in the field that current inventory and growth data can be provided on a unit-area basis for the important (both biologically and economically) forest types, forest site classes, forest age and size classes, major ownership classes, geographical regions, and other stratifications needed to form the basis of public management and policy decisions.


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