12 



age of chestnut is low. As will appear later, even if species 

 other than red oak take the place of chestnut the difference in 

 volume production will not be greatly changed. By careful 

 selection of plots error due to the presence of chestnut was 

 reduced to a small percentage. By reducing the diameters of 

 the few chestnuts on the plots by two diameter classes it was 

 practically eliminated. 



The red maple, which is a considerable element in all 

 stands, produces good cordwood, but many trees are too 

 poor in quality to yield saw timber. Species such as horn- 

 beam, shad bush, dogwood, etc., were limited to the lower 

 diameter and suppressed crown classes and were insignificant 

 in volume production. 



Table II gives the normal yield per acre in cords and cubic 

 feet of fully stocked natural stands of second growth better 

 hardwoods. All trees two inches and over in diameter breast 

 high are included. But 'two site classes exist. The thin- 

 soiled, bouldery ridge-tops of third quality, because of their 

 low yield per acre and inaccessibility have never been clear 

 cut, and on sandy soils, deficient in organic content and 

 moisture, the competition of white pine and inferior hard- 

 woods is such as to exclude the better hardwoods. 



In discussing the construction of the tables the various 

 columns will be taken up separately giving the methods 

 used in obtaining yield table values and their application. 



Basal Area. Omitted in the majority of American yield 

 tables, basal area is always desirable and is essential unless 

 both the number of trees per acre and the average diameter 

 are given, in which case it may be computed. Basal area, not 

 trees per acre, is the criterion of density of stocking on 

 similar sites and is therefore indispensable. The percentage 

 density of stocking of a given stand results from dividing the 

 basal area of a representative acre of that stand by the nor- 

 mal basal area for the site as given in the yield table, site 

 being determined by the average height of the dominant 

 trees. 



