Factors for Determining 

 Residual Inventory 



Product removal figures are relatively easy to obtain for a particular harvesting 

 operation, but such figures do not adequately represent the total removals and, there- 

 fore, initial inventory less products removed does not equal the residual stand. An 

 adequate calculation of the remaining inventory after logging can be done only by 

 subtracting total removals (including product volume plus residues from felling and 

 skidding) from the prelogging inventory. 



It is important that removal volume consists only of volume included in the 

 inventory and not amounts overutilized according to Forest Survey standards. Over- 

 utilized material can come from (a) harvesting saw logs from growing stock trees of 

 less than sawtimber size (from trees less than 9 inches d.b.h.); (b) utilizing wood 

 below the Survey standard 1-foot stump; (c) wood from treetops above top diameters 

 specified in the timber inventory; or (d) nongrowing stock trees by Survey standards. 



In computing removal factors "(table 1) for applying to product output estimates 



in order to arrive at total removals, net overutilized material (by Forest Survey 



standards) has been excluded from the total net removal volume measured. However, in 



dpvelopin^; these factors, the net overutilized volume must be included in tlie net 



product volume because it is part of the reported product output volume to which 



c ^ -Tiu i-jm.^ ij^^ removal volume . . 



factors will be applied. Therefore, removal factor = — ^ . This is equiv- 



product volume 



alent to product volume (excluding overutilization) + net residue volume 

 net product volume (including overutilization) 



In the four States, the net volume in cubic feet of timber removed from growing 

 stock inventory in harvesting operations is more than the cubic-foot volume of saw 

 logs harvested. In other words, the ratio of cubic feet of inventory removed 

 (including residues) to cubic volume of saw logs harvested is greater than one. On 

 the other hand, factors based on board-foot^ volumes to estimate removals from saw- 

 timber inventory are somewhat less than those for cubic feet used for growing stock 

 estimates because considerable wood measured as net cubic-feet residue is not included 



^Board-foot volumes used in this paper are based on the International 1/4-inch 

 log rule. 



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