20 



Forest Mensuration 



properly, "reducing factors." These form factors alone are nowadays 

 practically used. They are based on diameter measurements, chest high, 

 and have reference not merely to the bole of the tree, but as well to any 

 parts of the bole, to root and branch wood, to saw logs, etc. These form 

 factors depend entirely on the height. If, for instance, a paraboloid is 

 one rod high, the form factor is 0.673; and if it is 8 rods high, the form 

 factor is 0.517. 



PARAGRAPH XXXI. 



KINDS OF COMMON FORM FACTORS IN EUROPEAN PRACTICE. 



The following kinds of form factors may be distinguished: 



1. Tree form factors. The tree is considered as bole plus branches. 



2. Timber form factors. The term timber, in Europe, includes all 

 parts of the tree having over 3 inches diameter at the small end. 



3. Bole form factors. Bole is the central stem from soil to top bud. 

 For America, form factors would be of great value ascertained by exact 

 measurements and arranged according to diameter, height and smallest 

 log diameter used. 



Tables of form factors may be constructed, for instance, for shortleaf 

 pine, on the basis of Olmsted's working plan, pages 17-33. 



PINUS ECHINATA. 



The influence of age, soil, density of stand, height, diameter and 

 species on the various form factors, with cubic measure as a basis, has 

 not been fully ascertained. 



For the tree form factor, the most important influence, in the case of 

 trees less than 150 years old and raised in a close stand, seems to be 

 that of the height of the tree; with increasing height the tree form factor 

 decreases e. g., for Yellow Pine : 



One pole high 93 



Two poles high 65 



Four poles high S3 



Six poles high ,,, 49 



