CLASSIFYING FOREST SITES 3T9 



sifr must be known. The limits of all its sites then correspond to 

 all or a part of those of the standard to which it belongs. 



IVhy not a single standard^ 



It will be noticed that in Roth's table of "standards of site classi- 

 fication"' the site intervals under a given standard are of equal width, 

 but that the standards differ in this respect, standard "a" having 20- 

 foot site intervals, "b'' 15. and *'c" 10. Each is a multiple of '>. The 

 question arises why a single standard could not be used for all species, 

 all sites having equal amplitude of, say, 10 feet. With a range of from 

 110 to 40 feet there would thus be eight sites in the single standard. 

 A dominant tree of any species wdiich is TO feet high in 100 years 

 would belong to "site 5" and no question about it — whether or not 

 it were on its best site. The best site for the species included in Roth's 

 standard "c" would become "site 5" and the poorest "site S." This 

 .would certainly greatly simplify matters. Roth's objection to it is 

 that site is always a matter of species and must bear the species mark, 

 as "jack pine, site 1" ("standard c, site 1,'' being only another way of 

 saving "jack pine, site 1." or "tamarack, site 1." or "white oak, site 1,'' 

 as the case may be). To say that the best height growth of jack pine 

 indicates only site 5 is not only an offense to the species but is in oppo- 

 sition to our generally accepted way of looking at things: "1" means 

 best for whatever particular commodity— wheat, mortgages, or trees — 

 we are talking about. Roth would sacrifice the simplicity of a single 

 standard to what he considers the demands of our psychology. The 

 single standard would be too great an innovation and might cause 

 much confusion. 



THE HEIGHT-GROWTH BASIS IN USE 



Watson ( op. cit. ) has told how the identification of sites by the 

 height-growth method may be applied in timber reconnaissance. It is 

 simnlv a matter of recording the height, age, and species of dominant 

 trees measured in the areas traversed, and their comparison with 

 standard height growth curves indicating site limits for the various 

 species concerned. Each of the areas may then be assigned to the 

 site (or sites) designated in the standard classification for any of the 

 species which may have been measured. 



The choice of trees for measurement is an important matter. The 

 trees selected must be normal, dominant, and (unless certain conditions 

 can be shown under which this is unnecessary) there must be sufficient 



