the amount of space necessary for optimum yield, measured as a percentage. 

 The amount of space needed for optimum yield depends on tree size and site 

 quality. Consequently, the desired amount of space will vary from one 

 sampled acre to the next (Farrenkopf 1967). 



There are three stocking percent classes: less than 60 percent stocked 

 (understocked), 60 to 132 percent stocked, and greater than 132 percent 

 stocked (overstocked). Each field plot can be up to 167 percent stocked, 

 since each individual sample point of the ten point cluster can be up to 16.7 

 percent stocked (10 points x 16.7 percent stocking per point = 167 percent 

 stocking per field plot), depending on the size and number of trees present. 

 Some of the individual sample points tally more trees than required to be 16.7 

 percent stocked. In those instances the stocking percent remains 16.7 and 

 will go no higher. A stocking percent class rating of 100 percent is equiva- 

 lent to 60 percent of the basal area listed by a normal yield table. A normal 

 yield table shows the maximum volume, number of trees, and basal area that a 

 given site can support at a given age (Davis 1966). A stocking percent class 

 rating of 132 percent is equivalent to 80 percent of the basal area listed by a 

 normal yield table. Volume predictions made by normal yield tables are for 

 fully stocked stands grown under "natural" conditions without competition and 

 do not predict the yield that could be captured from a given site if managed. 

 It is believed that a range of stocking between 60 and 100 percent of the 

 normal yield table basal area is the range within which the full board-foot 

 growth potential of a forest acre can be realized. Theoretically, trees in this 

 stocking range are beginning to fully use the site and growth per acre is not 

 reduced by overcrowding. 



Table 27 shows that at the time of sampling about 35 percent of the 

 commercial timberland in Working Circle 3 was improperly stocked for realizing 

 its full board foot growth potential. Approximately 250,500 acres were under- 

 stocked and 165,700 acres were overstocked. Many of the overstocked pole- 

 timber and seedling-sapling stands, jointly covering about 103,500 acres, 

 represent potential thinning opportunities. In the future, some of the medium 

 stocked and understocked stands may also require thinning before they 

 become sawtimber stands. 



-50- 



