YIELD TABLES FOR STANDS GROWN UNDER MANAGEMENT 407 



313. Yield Tables for Stands Grown under Management. Normal 



yield tables for stands grown under management may be constructed 

 by the above methods, whenever plots are available which have been 

 under proper management, but may in the course of time be checked 

 and finally supplemented entirely if desirable by the yields of plots 

 which have been measured at intervals of from five to ten years. 



10 20 30 40 50 GO 70 80 



Age, Years 



Fig. 86. — Curves of yield based directly on cubic volume plotted on age. Jack 

 Pine, Minnesota. 



WTiere a series of plots, differing in age by ten years, is available, 

 the measurement a decade later on these plots will give fragments of 

 a curve of growth which may be pieced together. The greater the 

 period over which these re-measurements extend, the more nearly do 

 these fragmentary curves form a complete series. 



It may be expected that yields on areas under treatment will exceed 

 the so-called normal yields used as a standard for natural growth. 



