FOREST TYPES. 339 



a system of types and subtypes is now in use. A forest type is understood to 

 be an area in which the climatic and soil factors are uniform and which may 

 therefore produce stands of like composition. A subtype is a subdivision of 

 a type in which the struggle for existence is not yet completed and whose 

 composition is therefore changing. Generally this temporary condition is 

 caused by fire, lumbering, windfall, etc. The most common species in sub- 

 types are light-needing ones which occupy the ground quickly, but which will 

 ultimately give place to more tolerant species. " 



Moore (1913: 75) summarizes his views of forest types as follows: 



"A forest type is a tree society having such differences of composition from 

 other tree societies as to make necessary a separate study of yield. Physical 

 factors are the cause of forest types, but not forest types themselves. They 

 cause confusion when used in classifying forest types. Yield studies are at 

 the foundation of forest management, and must be based on forest types 

 distinguished by composition. Reconnaissance must furnish material to 

 which yield studies can be applied. For this purpose it must distinguish 

 forest types by composition, whatever other method may be used in addition. 

 Fortunately, this is, for most regions, the easiest way of distinguishing forest 

 types." 



Greeley (1913: 76) points out: 



"There have been three general stages in the work of the Forest Service, 

 each involving a somewhat different point of view in the classification of 

 forest types. During the first stage the 'cover type' in its simplest terms was 

 adequate. In the second stage, the 'cover type' in itself is inadequate. We 

 need rather the 'management type.' In the third phase of the work to which 

 I have alluded, we need possibly an additional type — the 'physical type' or 

 'land type.' The type needed for the classification and description of National 

 Forest lands is the 'management type.' The classification of forested areas 

 should be attacked from the standpoint of what those areas will grow best 

 under scientific administration. Let us have, then, a classification of forest 

 types based upon present cover interpreted where necessary by the uses which 

 we will make of it in management. Let us leave the intensive study of 

 physical factors to the working-plan expert or the silvicist. The 'manage- 

 ment type,' in my judgment, is the key to the classification of complex stands 

 arising from changes in composition at different periods in the life-history of 

 the forest. I would apply this principle to any complex situation where a 

 temporary type is followed by a permanent type, selecting for the purposes of 

 our classification the stage in the natural rotation of species which, as far as 

 we can now see, will be the basis of the forest management. In a word, the 

 existing cover interpreted by our knowledge of the life-history of the type 

 and of what the land should produce under management will, I believe, furnish 

 the best basis for classification." 



Pearson (1913:84) emphasizes the value of communities as indicators and 

 summarizes the bases for the classification of forest land into types, as follows : 



"The only scientific basis for such a classification is that of potential pro- 

 ductiveness, considering both agricultural and forest crops. The productive 

 value may be ascertained in two ways: The first measures directly, as far as 

 possible, all physical factors on the site and gauges the productive capacity 

 by the measure in which the sum of these factors meets the requirements of 

 various crops. The second method uses characteristic forms of vegetation 



