stocking for comparable sites and stands. Basal area is used as a basis 

 for measuring stocking. 



"Stocking percentages" express current area occupancy in relation to 

 specified standards for full stocking based on number, size, and spacing 

 of trees considered necessary to fully utilize the forest land. 



Full utilization of the site is assumed to occur over a range of basal 

 area. As an interim guide, 60 percent of the normal yield table values 

 has been used to establish the lower limit of this range which represents 

 full site occupancy. This is called 100-percent stocking. The upper 

 limit of full stocking has been set at 133 percent. Sites with less than 

 100-percent stocking represent under-stocking with less than full site 

 occupancy. Over-stocking is characterized by sites that have over 133 

 percent stocking. 



Tertiary deposits 



Rock and materials deposited in the period of geologic time previous to 

 the current period, which ran from about 65 million to about 2.5 million 

 years ago. 



Tree class 



A classification assigned to each live tree based on such physical charac- 

 teristics as surface and internal defects, crown ratio, crown class, and 

 damage sustained by the tree. (See also desirable tree, acceptable tree, 

 rough tree, and rotten tree). 



Tree size class 



A classification of trees primarily according to diameter at breast 

 height outside bark, including sawtimber trees, pole timber trees, sap- 

 lings, and seedlings. 



Unproductive forest land 



Forest land incapable of producing 20 cubic feet per acre of industrial 

 wood under natural conditions, because of adverse site conditions. 

 (Note: Adverse conditions include sterile soils, dry climate, poor drcdn- 

 age, high elevation, steepness, and rockiness). 



Variable radius plot 



A plot on which a predetermined critical angle is projected from a central 

 point, and swept in a full circle, to determine the basal area, tree 

 count, and volume per unit of area. The radius of this plot is a func- 

 tion of tree basal area and is therefore variable. 



Young-growth sawtimber stands 



Sawtimber stands in which 50 percent or more of the stand is occupied 

 by young-growth sawtimber trees. 



Young-growth sawtimber trees 



Sawtimber trees less than 100 years old. 



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