48 



YIELD TABLES. 



Yield tables show the volume in board feet or other units 

 for an acre of fully-stocked woodland at any given age. 

 By the term "fully-stocked" we mean that the crowns of the 

 trees occupy all the available space on the acre and that 

 there are no blanks nor openings. 



A yield table can be used to predict the future yield of 

 young or middle-age stands. The owner finds the age and 

 volume of his present stand in order to determine in which 

 quality site it belongs, and from the table he can predict its 

 yield at any period in the future. In making his calculations 

 allowance must be made for the fact that his immature stand 

 may not be fully stocked. In the same way the yield table 

 is necessary in predicting the returns from an investment in 

 planting. They are of particular value in suits where damage 

 to immature timber is involved, for in such case the loss is 

 the destruction of possible future growth. They are of some 

 use in estimating the present contents of stands if the esti- 

 mator can determine the present age, and, from the height, 

 the quality of the site on which his stand is growing. 



For the data on the pine yield tables 177 sample plots were 

 measured in stands ranging from twenty to seventy years. 

 All the trees on each quarter or eighth acre plot were calipered, 

 and the volumes computed from the volume tables. These 

 sample plots were divided into three site or soil classes (called 

 Quality I, II, III) according to their rate of growth in volume. 

 It has since been generally agreed by foresters that height 

 growth is a better index of quality of site than volume, and 

 the yield tables on hardwoods are divided on this basis. For 

 the latter, two sets of tables are given, one of which includes 

 all trees of 2 inches diameter and over, in which the mer- 



