38 



YELLOW POPLAR IN TENNESSEE. 



TABLE 13. Time required for trees of yelloiv poplar to grow one inch 

 in diameter, under average conditions, and annual rate per cent, of 

 increase in value by growth. 



Operating costs $12 

 a 1,000 board feet 



Rate of 



Stumpage increase 

 value in value 

 per tree a year 



Operating costs $16 

 a 1,000 board feet 



Determination of the future yield in mixed selection stands. In con- 

 nection with the management of selection stands of mixed forest, it is 

 frequently desirable to know what yield of yellow poplar can be expected 

 from a tract at different future periods, or what number of poplar trees 

 of different diameter classes it would be necessary to have growing, to 

 provide for a sustained yield (normal distribution of age classes). The 

 following table enables this to be determined, if the poplar in the stand is 

 in^uplliwwied groups. It shows for average conditions of soil what should 

 lie the relative number of trees of different diameter classes to an acre, to 

 provide for a sustained annual yield of 430 board feet on average quality 

 sites, which would be the yield from fully stocked acres of pure stands if 

 each diameter class occupies the same proportional crown area. 



