254 CLARENCE F. KORSTIAN 



Various criteria of site determination have been proposed at 

 different times, among which may be mentioned: 



1. Height of dominant trees at a given age. 



2. Volume per acre of even-aged stands. 



3. A formula site factor based on the basal area per acre, the 

 average age of the stand and the height of the average tree. 



4. Classification of the physical and chemical properties of 

 the soil. 



5. Fiber length of the wood. 



6. Empirical personal judgment with no scientific or technical 

 basis whatever. 



The use of the height of the dominant trees at a given age 

 appears to be the most commonly accepted criterion. However, 

 some foresters maintain that height is an unsatisfactory cri- 

 terion of site quality because the height frequently varies to a 

 considerable extent with the density of the stand. Those who 

 support this contention favor the increment of the arborescent 

 species concerned, when judged by the measurement of an ap- 

 proximately fully stocked stand, as the best ultimate criterion 

 of site quality. 



It has been pointed out by Spring 3 that the true quality of a 

 given site cannot be indicated by the height or yield of a stand 

 composed of a species which cannot fully utilize the physical 

 factors of that site. A satisfactory expression of the relative 

 productivity of different sites must fully recognize a proper cor- 

 relation of the climatic and edaphic factors of the habitat with 

 the silvicultural characteristics of the species. If an arbores- 

 cent species is not well adapted to a given site it should not be 

 used in comparing site productivity. 



Zon 4 has shown that, for the purposes of future silvicultural 

 management, the natural classification of forest stands should 

 be based on the potentiality of the site instead of on the average 

 height of the stand. The character of the tree growth is held to 

 be the only reliable expression of the productive capacity of forest 



3 Op. cit. 



4 Zon, Raphael. Quality classes and forest types. Proceedings Society of 

 American Foresters, 8: 100-104, 1913. 



