FOREST, FISH AND GAME COMMISSION. 73 



but as they are not at present applicable to our woods, a description of them is 

 scarcely necessary. Those who wish to read a description are referred to Adam 

 Schwappach's excellent little book entitled " Leitfaden der Holzmesskunde." 



I\zif}od^ of Aeagartn^. 



If all the trees of a forest had the same diameter, height, and form, the deter- 

 mination of the quantity of timber would present no difficulty. One would need 

 only to count the trees, ascertain the volume of one tree, and multiply its contents 

 by the total number of trees. Such stands, to be sure, one does not find in nature, 

 but the trees of a timber forest are, after all, not so different from each other that 

 a very exact measurement of each tree is necessary. 



In very irregularly grown stands, the conditions are, of course, somewhat unfa- 

 vorable, but even here special ascertainment of volume can be limited to only a 

 few trees. In the greater number of cases it may be taken for granted that, in the 

 same stand, trees of similar basal size do not differ very much in height and form, 

 and, therefore, also in their volume. It is necessary then in such stands only to 

 form classes of the same or nearly the same diameter in order to obtain trees of 

 similar height and form. For every such class, representative trees can then be 

 chosen and the cubic contents found, and from their contents the volume of the 

 whole class can be calculated. In stands in which height and form cannot be 

 considered a function of the basal size, it may be necessary to divide each diameter 

 class into height classes. 



DETERMINING THE NUMBER OF TREES AND THEIR BASAL AREAS. 



All methods of ascertaining the volume of a stand by measuring depend upon 

 a knowledge of the basal area. The determination of this is, therefore, the first 

 and most important part of a volume survey. The basal area of a stand is the 

 sum of the basal areas of the trees. To determine this, the diameters are measured 

 by means of calipers applied to the trees. 



The trees are measured at breast height, generalLy four feet three inches. 

 Measurement at the ground could only be made with difficulty, and, besides, the 

 cross area there is very irregular on account of the manner in which the roots 

 spread. 



In measuring the trees, diameter classes are made, and sometimes height classes, 

 especially where the trees of the same diameter differ much in height. In mixed 

 stands, the species are recorded separately. 



