B. SCIENTIFIC AND PRACTICAL USES AND VALUES 



1. THE VALUE TO SILVICULTURE OF 



RESERVED AREAS OF NATURAL 



FOREST TYPES 



By W. W. Ashe 



The setting aside of vestigial units 

 of the various forest types has three 

 important objects in view: First, to 

 supply the means for studying the 

 laws which control the distribution 

 of different species of trees. Second, 

 to ascertain the factors which deter- 

 mine forest types. Third, to note the 

 changes in such types induced by the 

 artificial conditions which result from 

 exploitation and silvicultural practice. 



The practical silviculturist is princi- 

 pally concerned with the last named 

 of these objects. It is his function to 

 modify natural conditions, often to a 

 profound degree, in the interest of 

 increased yields of commercially de- 

 sirable species. In this, however, he 

 is constantly taking a chance, since his 

 crop is a slow growing one and he is 

 unable to wait for the results of the pains- 

 taking research, extended through the 

 life of a stand of timber, needed to sup- 

 ply the accurate results under which he 

 could proceed with complete confidence. 

 By determining these factors of dis- 

 tribution and using these vestigial 

 units as check plots, however, it may be 

 possible for him to prevent mistakes or 

 to rectify errors which may be made 

 through deviating too far from the 

 normal. 



It is reasonable to suppose that each 

 site, the biotic corollary^ of which is 

 the forest type, bears in its natural 

 condition (unless modified by fires) 

 the heaviest stand which the native 

 species are capable of producing on 



'Ashe, W. VV. "Forest Types of the Appala- 

 chians and White Mountains." Journal of the 

 Elisha Mitchell Scientific Society, ZT: 1S3-1QS. 1922. 2 Op. cit. 



10 



that site. That is, nature has already 

 established that species or association 

 of species which is best suited for grow- 

 ing under the limiting edaphic and 

 meteorological conditions which are 

 termed site, among the most important 

 of such conditions being soil acidity, 

 rate of nitrification, maximum mois- 

 ture content, number and length of 

 critically dry periods, depth of soil, 

 and available heat units and their 

 distribution. The species forming the 

 type reproduce themselves, not invaria- 

 bly in a definite proportion, but definite 

 within a certain latitude, the oscilla- 

 tion of the type,2 and utilize the full 

 resources of the site, which is capable 

 of producing annually (or on an average) 

 a fixed amount of wood material (cel- 

 lulose). Silviculture seeks to modify 

 or increase this natural yield by cul- 

 tural methods. There may be an at- 

 tempt to concentrate increment in a 

 few select individuals or to simplify 

 the composition of the natural stand 

 by eliminating from it certain of the 

 components which are economically 

 or silviculturally less desirable; or to 

 replace the native species in whole or 

 in part with other species or by a single 

 species which is regarded as more desir- 

 able economically or silviculturally. 



The problems which arise in connec- 

 tion with such changes can be met in 

 two ways. They can be solved empir- 

 ically for each site, as in connection 

 with the introduction of foreign species, 

 by experimental planting with a view 

 to determining what species or combina- 

 tion of species is more advantageous 

 than those in the original type. The 

 establishment of final conclusions by 

 this method may require many dec- 

 ades, during which time a portion of 

 the land might not be producing to 



