CORRECTION OF YIELD TABLES FOR LOCAL USE. 



As earlier stated, the yield tables are based upon a study of 

 well-stocked stands of the four species throughout the greater 

 part of the range of southern pines. The results of this study 

 indicated that geographical location had no consistent effect 

 upon the yields of stands of equal site quality. It, therefore, 

 follows that the productive capacity of any pine tract whose 

 site is correctly identified may be determined from the tables, 

 regardless of its geographical location. 



It is believed that local yield tables will not be appreciably 

 more correct than the regional yield tables, particularly if based 

 on any fewer data than the regional tables. The construction of 

 local tables will involve a very considerable expenditure of time 

 and money. However, if a check of the volume tables shows 

 the need for correction on account of local peculiarities in the 

 form of individual trees, the yield tables should be correspond- 

 ingly corrected. The general method recommended for cor- 

 recting for different limits of utilization, described below, should 

 be equally satisfactory in correcting for locality. 



A further check of the applicability of the yield tables to any 

 given locality may be made through a comparison of the actual 

 measured yields of 20 or 25 local plots with corresponding yields 

 in the tables. The comparison would follow the same lines as in 

 checking the volume tables for local use. It will be seen from 

 the footnotes to Tables 64, 96, 128, and 160 that the plots 

 entering into the yield tables deviated much more widely from 

 the tabular values than did the tree volumes. 



CORRECTION OF YIELD TABLES FOR DIFFERENT LIMITS OF UTI- 

 LIZATION. 



If the yield tables are desired for conditions of utilization 

 other than those assumed in their preparation, correction must 

 be made for the actual limit of use. Probably as accurate a 

 method of doing this as is ordinarily necessitated is based on the 

 average breast-high diameter of the stand 2 inches diameter 

 breast high and over, and the number of merchantable trees per 

 acre. There are two distinct steps, which are described in the 

 following example: 



Assume that the loblolly yield table for board feet by the 

 international rule is to be corrected, like the volume table in an 

 earlier illustration, for an actual utilization to 8 inches in the 

 top, rather than to the 5 inches assumed in the tables. The 

 yield for a 50-year stand on a 90-foot site is wanted. An under- 

 standing of the stand tables, presented under a later heading, is 

 assumed. 



From the loblolly tables it appears that this stand contains 

 220 trees 1.6 inches in diameter and up, and that the average 

 breast-high diameter is 12 inches. The percentage stand table 



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