RF.VIRWS ^>'''9 



There are two features of silvics which appear to have been over- 

 looked by the authors, and a regard for which would have greatly 

 increased the value of the bulletin. 



First is the rather common fault of presenting conclusions drawn 

 from one or a few stands as though these conclusions were valid and 

 applicable to all stands throughout the type. There is a marked dis- 

 tinction, which is not clearly brought out in the text, between the 

 silvical information which is applicable to a single stand, to a site, to 

 a type, to a region, and finally to tree growth in general. Laws gen- 

 erally applicable to tree growth must, of course, be considered in the 

 treatment of a region, type, site, or stand. The management of the 

 stand, again, involves the application of the silvics of the region, the 

 type, and the site where the stand is, inasmuch as the stand is within 

 those forest divisions. The converse, however, is not true. The 

 silvical information pccuUar to an individual stand is not to be taken 

 as characteristic of the entire type in which the stand is. A stand is 

 on ascertain quality of site; and the type which embraces the stand 

 embraces a number of different sites, besides the one bearing the stand 

 in question. Studies of a few small tracts cannot be expected, on 

 account of the number of variants, to apply with validity to others; 

 certainly not unless these stands are found by some suitable stand- 

 ards to be essentially identical in character. How to determine whether 

 or not stands are essentially identical in character leads the thought 

 to the second principal criticism. 



This second criticism is the absence of any standard of site or 

 "cjuality" or any stated criterion of site quality by which data can be 

 compared and the application of the conclusions to other stands ren- 

 dered possible. Not one set of data, not one simple statement of 

 fact, in the publication, is definitely tied to a good criterion of site 

 quality and, indeed, while the gross characteristics of the types are:, 

 perhaps, quite clearly described and determined, the data are onlv 

 hazily referenced to them. 



Silvical data should be of reliable assistance in the practice of silvi- 

 culture ; they should be dependable guides if they are to be of value. 

 It may be said that the greater part of the information given in this 

 study, as it stands, is not reliable as a guide simply because it is not 

 referenced to site qualities. 



For example: Figure 2, page 24, gives rate of growth of spruce 

 under a stand of yellow birch, and the rate of growth given doubtless 

 is correct for this plot. But it can be used nowhere else inasmuch 



