THE ABSOLUTE FORM QUOTIENT ^ 



By H. Claughton-Wallin 

 Dominion Forestry Branch, Ottawa, Canada 



The stem forms of Norway spruce and Scotch pine have been very 

 thoroughly studied by Mr. Tor Jonson, forest engineer and professor 

 in mensuration and forest mathematics at the Royal Forestry College. 

 Stockholm. Some very interesting conclusions have been reached and 

 volume taper and growth per cent tables, based on the results of the 

 investigations, have been constructed and adopted for use by the 

 Swedish Forest Service. 



These conclusions are : 



(i) The taper of the stem follows a law which, broadly speaking, 

 is independent of age, d. b. h., height, and also of site. 



(2) As an expression for taper a mathematical equation, giving the 

 relation to each other of the diameters in different portions of the stem, 

 may be used to great advantage. 



(3) The degree of taper differs considerably, however, and a char- 

 acteristic expression thereof can be obtained by comparing the diameter 

 at breast height with the diameter at a point situated half way between 

 breast height and the top of the tree. This "upper diameter" is divided 

 into the diameter at breast height, and the quotient, called the "absolute 

 form quotient," expresses the "form class" of the tree. 



(4) With the knowledge of form class, total length, and diameter at 

 breast height, all other dimensions may be accurately determined. 



(5) There is no essential dift'erence in form between the Scotch pine 

 and spruce inside bark. The bark, if added, however, gives the pine a 

 poorer form and lower form quotient. In spite of this dift'erence in 

 form, however, the cubic contents (bark included ) of si)ruce and Scotch 

 ])ine with the same d. b. h., total height, and form quotients are found 

 to b(j practically the same. 



'This article is based upon the following: Taxatoriska undersokningar ofz'er 

 skogslriidcns form, by Tor Jonson; I. Granens stam-form, Skogsvardsforen- 

 ingens Tidskrift, 1910, No. 11; II. Tallens stam-form, Skogsvardsforcningens 

 Tidskrift, 191 1, No. 9-10; and III. Formbcstiimiiing a stacnde triid, Skogs- 

 vardsforeningens Tidskrift, 1912, No. 4. 



Most of tlie information contained in the article and cognate matter having 

 reference to form quotients has been briefed in Forestry Quarterly (see Vol. I, 

 56; V, 29; XI, 3f)9) and in the Journal (Vol. XV, p. 665), but it was deemed 

 desirable to give a fuller and more connected account of the later development 

 of the important subject. 



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