112 



lower altitudinal range to drought en- 

 durance. The soil, except locally, rarely 

 acts as a limiting factor. He does not 

 regard light as a limiting factor in the 

 range of trees, but it may affect the 

 composition of stands. 



Marinus Westveld (Type Defini- 

 tions Based on Statistics of Stand Com- 

 position, 1934) gives type definitions 

 of the red spruce-yellow birch (with 

 yellow birch subtype) as well as the red 

 spruce-sugar maple-beech (with sugar 

 maple subtype) types. In the red 

 spruce-yellow birch type, the conifers 

 usually make up more than 40 percent 

 of the stand, with spruce and the bal- 

 sam fir in about equal numbers, the 

 yellow birch composing between 25 and 

 50 percent, and sugar maple seldom 

 more than 5 percent of the total stand. 

 In the red spruce-sugar maple-beech 

 type, the conifers make up 25 to 45 per- 

 cent of the stand, spruce usually being 

 more abundant than fir. Sugar maples 

 generally make up more than 10 per- 

 cent of the stand and, combined with 

 beech, usually considerably exceed the 

 yellow birch in number. 



Again, in the field of forest classifi- 

 cation systems and their terminology, 

 there is a large literature and differ- 

 ences in viewpoint. 



The eminent German forester Hein- 

 rich von Cotta in 1804 listed forest 

 lands in 100 quality classes, "0" being 

 absolutely barren land incapable of 

 producing wood of any sort, and "100," 

 the best imaginable land. 



W. Schiitze, who wrote Beziehungen 

 zwischen chemischer Zusammenset- 

 zung und Ertragsfdhigkeit des Wald- 

 bodens in 1871, classified six areas of 

 German forest land on the basis of 

 determining in a surface layer 5^4 feet 

 deep the percentage of mineral matter 

 soluble in hydrochloric acid. This is a 

 refinement in the methodology of forest 

 typification which obviously it has not 

 been practical to utilize in this country 

 on any large scale. 



The late John W. Harshberger, in 

 his Phy to geographic Survey of North 

 America, 1913, divides the part of 

 North America lying within the United 



Yearbook of Agriculture 1949 



States into two zones, temperate and 

 subtropical. These zones, so far as for- 

 ests are concerned, are again divided 

 into 9 regions, 24 districts, and 16 areas. 

 Under these forest areas, forest and 

 other plant formations are recognized. 



Jesse B. Mowry (The Nature and 

 Development of Forest Types, 1920) 

 recognizes two classifications of the 

 term "forest type" : Where type means 

 ( 1 ) locality, and ( 2 ) composition. He 

 believes that, for the present at least, 

 forest types should be designated by 

 terms indicating both concepts. He em- 

 phasizes the importance of moisture in 

 tree growth, their tissues consisting of 

 from 65 to 95 percent of water, and 

 quotes Ebermeyer to the effect that 

 conifers require less potash, lime, and 

 phosphate than do deciduous trees. 



Although published a quarter of a 

 century ago, still the best available map 

 of the vegetation of the United States 

 is that by Homer L. Shantz and 

 Raphael Zon (Natural Vegetation, 

 Section E, Atlas of American Agricul- 

 ture, U. S. Department of Agriculture, 

 Bureau of Agricultural Economics, 

 Part I The Physical Basis of Agricul- 

 ture, 29 pages, Washington. 1924). 

 This map is reproduced on the next 

 page, on a smaller scale and with 

 hatching replacing the original colors. 

 It will be observed that the forested 

 and woodland areas are classified in it 

 under 18 divisions. 



A booklet of the Forest Service, In- 

 structions for Making Timber Surveys 

 in the National Forests, 1925, has a 

 chapter, "Standard Classification of 

 Forest Types," covering 7 treeless land 

 types and 52 woodland and forest-land 

 types. 



The Committee on Forest Types of 

 the Society of American Foresters in 

 1940 recognized and defined 97 forest 

 types in the eastern United States. 

 "Eastern United States" is interpreted 

 to include "the eastern forests which 

 are separated from the western forests 

 by a broad zone of relatively treeless or 

 desert country. The territory covered 

 by the committee extends in some 

 places to the westward of the eastern 



