6 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 



valuable heartwood. Neither is there any constant accumulation of 

 gain; after some years the sapwood is turned into heartwood and 

 as such becomes liable to decay. In other words, in trees of this group 

 infected with heartwood-destroying fungi, the value of newly formed 

 wood is small; when it becomes valuable by transformation into 

 heartwood it becomes subject to decay — that is, loss. This loss from 

 decay is by its very nature as a heart rot confined to those individ- 

 uals in which heart-rot formation has taken place. All trees below 

 the age of heartwood formation do not enter into consideration. In 

 speaking of a given stand the representation by ages must be of 

 prime importance. In all considerations of regulation it is neces- 

 sary, therefore, to make a clear distinction between forests and 

 stands, between many-aged and even-aged stands, between mixed 

 and pure stands, with particular emphasis on the composition of the 

 stand as to species. All generalization is not only useless but mis- 

 leading. 



But in full realization of the almost complete lack of fundamental 

 knowledge, American forestry is confronted with the urgent neces- 

 sity of adopting, even temporarily, some kind of a system of regula- 

 tion of yield. Whatever this system may be, its tentative, tempo- 

 rary, and local character can not be overemphasized. 



Various attempts at adopting local temporary systems have found 

 an expression in the shape of working plans. Inseparable from the 

 problem of working plans is the choice of a rational rotation and 

 cutting cycle. 



ROTATION. 



The gleanings in American literature treating on the choice of 

 rotation from a general point of view are rather meager, outside of a 

 few well-known handbooks, such as those by Recknagel, 1 by Fernow, 2 

 and by Roth, 3 particularly in so far as the practical application to 

 our virgin forests is concerned. Recknagel 4 excludes financial rota- 

 tion from North American forests with the following words : 



Since this method of calculating the rotation [financial rotation or that of highest 

 soil rent] is suitable only to very intensive conditions, it would serve no useful pur- 

 pose to elaborate it at this point. 



On the other hand, the strong influence of European forestry is 

 clearly felt in the ever-recurring advice to adopt some kind of a 

 financial rotation in the national forests of the United States. Kirk- 

 land 5 is of the opinion that — 



1 Recknagel, A. B. The Theory and Practice of Working Plans (Forest Organization), 235 pp. New 

 York, 1913. 



2 Fernow, B. E. Economics of Forestry, 520 pp. New York, 1902. 



3 Roth, Filibert. Forest Regulation, or the Preparation and Development of Forest Working Plans, 

 218 pp., illus. (maps). Ann Arbor, Mich., 1914. (His Michigan Manual of Forestry, v. 1.) 



* Recknagel, A. B. Op. cit., p. 39. 



5 Kirkland, B. P. Working plans for national forests of the Pacific Northwest. In Proc. Soc. Amer. 

 Forest., v. 6, no. 1, pp. 16-37, 1911. (See p. 21.) 



