8. Net board- foot volume . The board- foot volume of the sawlog portion 

 of merchantable sawtimber trees, as measured by International 1/4- 

 inch rule, 



9. Net cubic volume . The total cubic-foot volume discounted for un- 

 merchantable material. Includes the merchantable portion only of 

 sound,, sound cull, and rotten cull sawtimber and poletimber trees 

 and hardwood limbs larger than 4»Q-inch top diameter. 



10 o Net annual growth . The average annual change during a specified 



period In volume of growing stock on commercial forest land result- 

 ing from natural causes. Gross growth is the increment before al- 

 lowance for mortality. 



11^, Net annual mortality . The average annual volume removed from grow- 

 ing stock on commercial forest land during a specified period through 

 death from natural causes. 



12. Commodity production . The total output of timber products during a 

 specified period „ 



13 o Commodity drain . The timber volume removed from growing stock as 

 timber products and logging waste during a specified period. 



14. Logging waste . The net volume of growing stock cut or killed by 



logging on commercial forest land and not converted to timber prod- 

 ucts* 



15 o Timber products from miscellaneous sources . The volume of timber 

 products cut from cull trees, limbs, dead trees, timber from non- 

 commercial and nonforest land, and overutilization of growing stock. 



16. D,b »h, (diameter breast high) . Tree diameter in inches, outside 

 bark, measured 4g feet above average ground level. 



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