APPENDIX — CONVERTING FACTORS 



643 



Mine Timbers and Miscellaneous 



Board-feet International ],i-inch rule 

 per cubic foot 



Round mine timbers: AH species Softwood Hardwood 



North 1. 15 



South 1.22 



West 2.77 



Continental United States. 1. 35 

 Miscellaneous: 



North 3.08 



South 3.05 



West 5.12 



Continental United States. 3. 57 



2. 80 



1. 36 



2. 77 

 2. 43 



74 

 58 

 12 

 70 



1. 01 



1. 15 



1. 04 



3. 11 



3. 72 



3." 48 



UTILIZATION FACTORS 



Utilization factors show the volume of growing 

 stock (live sawtimber and poletimber trees) cut 

 per unit of output of various timber products 

 (table 82). They show, for example, liow much 

 sawtimber is cut per M board-feet of lumber and 

 the volume of growing stock cut per cord of 

 pulpwood, including pulpwood from both round 

 timber and plant residues. 



Utilization factors are computed for 1952 on 

 the basis of inventory standards and utilization 

 practices prevailing in that year. Their principal 

 function is to provide a basis, until significant 

 changes in utilization practices occur, for estima- 

 ting the cut of live sawtimber and growing stock 

 associated with a given volume of output of 

 timber products. 



Average utilization factors for each product were 

 estimated also for 1975 on the basis of 1952 

 inventory standards and future utilization prac- 

 tices indicated by probable future trends in the 

 various regions. They appear in the section 

 "Future Demand for Timber," page 468, as indexes 

 showing deviations from 1952. The indexes were 

 used to translate projected levels of demand for 

 timber products in 1975 to timber cut from 

 domestic forests. 



Part of the growing stock that is cut for timber 

 products is not being used. Varying amounts are 

 left as residues depending on the product. The 

 growing stock inventory consists of the net volume 

 of sound material in live sawtimber and poletimber 

 trees measured in board-feet International 1/4-inch 

 log scale for the saw-log portion of sawtimber trees, 

 and in cubic feet for entire trees to a minimum 

 top of 4 inches d. i. b. The saw-log portion 

 corresponds to top merchantability limits and 

 quality standards consistent with defined utiliza- 

 tion practices in various regions. 



In terms of inventory standards there is under- 

 utilization if any sound merchantable material 

 classed as growing stock is left unused, whether 

 felled purposely or knocked down or killed in 

 logging. There are also instances of overutilization 

 of growing stock, both in board-feet and cubic feet. 

 For example, parts of the stem above the recog- 

 nized saw-log portion may be cut for lumber and 

 thus represent overutilization in board-feet. In 



this instance all the material utilized is charged 

 as timber cut in cubic feet, but only the volume 

 represented by the saw-log portion is charged as 

 timber cut in board-feet. Likewise pidpwood 

 cutting might extend above the minimum 4-inch 

 top in which case overutilization in cubic feet 

 results. The excess in this instance is not levied 

 against growing stock but shows up as being 

 production from other sources. 



In all regions there is both under- and over- 

 utilization because of the varying practices of 

 logging operators. The practice of overutiliza- 

 tion of growing stock is more prevalent in the 

 North and South than in the West since the vol- 

 ume would need to be much more substantial to 

 offset the presently large volumes of residues 

 developed from logging in these areas. 



Tlie fact that less than a thousand feet of saw- 

 timber on the average is required for a thousand 

 feet of lumber simply means, for one tiling, that 

 some production comes from material below mini- 

 mum size and quality, by inventory standards, in 

 sawtimber trees and from sources other than 

 growing stock, such as cull and dead trees, trees 

 from noncommercial forest and nonforest land, 

 and that this additional output in itself may be 

 enough to more than compensate for the volume 

 of growing stock residues left in the woods. 



There are a number of other factors that may 

 also contribute to this favorable growing stock- 

 output relationship. For instance, lumber tally 

 overruns International M-inch log scale an average 

 of about 3 percent. More board-feet of lumber 

 therefore are cut from saw logs on the average 

 than are scaled by the International log rule. 



Differences (overrun) between reported lumber 



tally and 



International 



}4-inch log scale 



are as 



follows: 











Percent 





Percent 



North 



ti. 7 



0. f) 



West 



3. 4 



South . 



.\11 regions . - ^ . 



_ 2. 8 



However, in the case of veneer logs and bolts 

 and cooperage logs and bolts reported volumes 

 according to various local log rules underrun by 

 considerable amounts what they would be by the 

 International }4-inch scale. 



Another reason why timber cut is less than 

 output concerns the practice of cutting pole trees 

 for lumber and other products generally derived 

 from sawtimber trees. While volume cut from 

 poletimber is credited against growing stock in 

 cubic feet no charge is made in board-feet. 



Plant residues constitute part of the output of 

 such items as pulpwood, fuelwood_, and posts. 

 This material, which develops in the primary 

 manufacture of lumber, veneer, and other products 

 from logs and bolts, is counted originally as grow- 

 ing stock cut for these items and is, therefore, not 

 counted again for pulpwood and other products 

 for which it subsequently may be used. In addi- 

 tion, considerable quantities of dead and cull 



