SITK DF.Tl-RM I NATION AM) VlKI.n FoKKCAST 3 



as capable of producing different composition types, and two "sites" 

 might contain the same composition type, differing primarily in the 

 rate of ijrnwth. The "silc" classification cuts acrcjss type lines. As 

 between the old Ac(iuisiti(»n '■t\pes" of cove, slope, and ridge, there 

 are general dilYerences not only in merchantable length but also in 

 composition ; but the differences in composition are not such as to 

 designate true types. Cove, for example, may contain poplar type, 

 hemlock type, or any of a variety of mixtures, while the limits set by 

 merchantable length in defining the Acquisition "types" may seMom 

 coincide with the limits of composition types. In the "site" classifica- 

 tion scheme here presented, if the southern upland hardwootls as a 

 whole (the oak-chestnut-poplar association) were regarded as a single 

 type, the "sites" would become sites in the generally accepted sense. 



It was the original plan to identify and classify in a single numerical 

 series all sites within the range of chestnut in terms of the height of 

 this species when mature or at the age of 100 years, as prescribed by 

 Professor Roth. It was hojied that chestnut would furnish a single, 

 generally applicable standard, to which the height growth of other 

 species could be referenced and made a means of identifying the site 

 even when chestnut was absent. It was soon evident that the limita- 

 tions thus imposed were too severe ; a classification based upon chestnut 

 alone would be useless in the absence of chestnut from the stand, while 

 one based upon old trees alone could hardly be applied in terms of 

 young trees. So while chestnut, because of its abundance and wide 

 distribution, was made tiie principal index, other species were also used, 

 notably yellow poplar and scarlet, red. and black oaks. The character- 

 istics which especially fit a species for the purpose are rapid growth 

 and intolerance, wdiich limit the irregularities in height growth po>;sible 

 as a result of suppression. Normally developed "mature" trees ' of 

 practically all species were also measured as indicators, the age being 

 usually roughly estimated from the tliameter. 



^ In the case of large tree.s of slow-growing species a rough estini.iii. , .>-^.. 

 on diameter was considered sufficient in judging "maturity" (as to height 

 growth). "Maturity" as used in this paper relates only to the cessation of rapid 

 growth in hciglit, and applies safely to trees of l')0 years or older in the coves 

 and lower slopes and 100 years or older on the ridges and upper slopes. As 

 a matter of fact tiiese age limits are probahly greater than necessary; subsequent 

 studies of height growth will quite likely lower them for practical purposes. 

 They vary, of course, with the species. As a check upon the estimates of height 

 growth maturity intensive height growth analyses at the top of "mature" and 

 "doubtful" trees were frequently made in the course of the study, the top 

 5 or () feet of the stem being sectioned in 1-foot or 6-inch lengths and the ring 

 counts recorded for curving. 



