18 



Number of Trees per Acre. It will be noted that there are 

 more trees per acre on site quality one than on two. This is 

 due to the high diameter limit. While there are actually more 

 trees per acre on quality two sites at a given age, as will be 

 seen by reference to Table II, not so many grow into the 

 limits of Table III in a given period of years, so that the 

 number of trees included is greater on the better sites. 



Board Foot Volumes. In obtaining board foot volumes the 

 present milling practice throughout the region was carefully 

 taken into account. Volumes are, therefore, actual not 

 theoretical, and as they are based wholly on natural stands, 

 represent a conservative minimum for fully stocked stands 

 under forest management. Practically all hardwood is 

 sawed through and through into round-edged lumber. Any 

 tree which will given an eight foot log out of which a board 

 with a minimum face of five inches can be sawed is con- 

 sidered merchantable. At the time of measuring the plots the 

 top diameter and length of each log contained in the individ- 

 ual trees was calculated and recorded with due allowance for 

 crook and defect. Board foot volumes of logs were computed 

 by the use of Clark's International Log Rule which is shown 

 by the sawmill practice of the region to be conservative. 

 Mill tally studies on the Harvard Forest show slightly higher 

 values than those in Clark's rule. In calculating the addi- 

 tional cords six board feet to the cubic foot and sixty-five 

 cubic feet to the cord were assumed. This figure is admittedly 

 but a rough estimate. Under favorable market conditions 

 the cordwood in the trees two to seven inches in diameter, 

 which is omitted in the table, could be utilized. The volume 

 of this product may be found by subtracting the cord volumes 

 given in Table III from those given in Table II for the same 

 age and site class. 



Table IV gives the normal yield in cubic feet and cords of 

 inferior second growth hardwood stands. All trees two inches 

 and over in diameter breast high are included. But one site 

 quality, an average between quality one and quality two for 



