42 BULLETIN 544, U. S. DEPARTMENT OF AGRICULTURE. 



Having decided whether or not, during the period for which the 

 future yield is to be forecasted, cutting will take place and in what 

 amount, a volume growth table such as that outlined on page 41 

 would be prepared. If a cutting is contemplated, there should be 

 indicated on the stand table, as column 5, the average number of 

 spruce trees of the different diameters which will be left for future 

 growth. The present yield per acre of the stand would then be 

 determined by multiplying the values in column 2 of the stand table 

 by those in column 4 of the volume growth table. The future 

 yield would similarly be determined by multiplying the values in 

 column 5 of the stand table by those in columns 8, 9, 10, etc., of the 

 growth table. 



The yield of second-growth stands may be arrived at in a manner 

 similar to that just outlined. The more direct method, however, 

 is to measure all the trees on sample areas in stands of typical devel- 

 opment and known age. The height, diameter, volume, and all 

 other data for each plot are determined separately; and these various 

 data are finally combined into a table on the basis of the age of the 

 trees and the site quality to which they belong. Such a table appears 

 below for normally stocked second-growth stands measured in Maine, 

 New Hampshire, and Vermont. This table is based on data col- 

 lected in unthinned stands of spruce which have come up on formerly 

 cleared lands. So far as concerns the production of cubic volume 

 and correspondingly, of cord wood volume, ■ these values represent 

 approximately the maximum for their respective ages and site classes. 

 The table is thus suitable for use without modification in predicting 

 the future yields of stands maintained for the production of pulp wood. 



