INDICATOR SIGNIFICANCE OF NATIVE VEGETATION 269 



vestita) and shadscale (Atriplex confertifolia) associations, due 

 to the shallowness of the alkali-free soil. Land occupied by the 

 grease wood shad-scale (Sarcobatus vermiculatus and Atriplex 

 confertifolia) association is unsuitable for dry farming, but will 

 produce good crops under irrigation. 



The work on the correlation of the native vegetation with 

 the crop-producing capabilities of the land has frequently sug- 

 gested to the writer the possibility of utilizing the native vegeta- 

 tion in the determination of forest sites. In forestry, site is 

 defined as an area considered as to its physical factors with 

 reference to forest producing power; the combination of the 

 climatic and edaphic conditions of an area or the forest habitat. 

 For purposes of comparison the various sites are commonly 

 segregated into site classes. Site class is a designation of the 

 relative productive capacity or quality of different sites with 

 reference to the species employed; the volume or the height 

 produced at a given age being commonly used as the standard 

 for classification. In the United States frequently only three 

 classes are differentiated, designated by Roman numerals, 

 quality I representing the most productive site class. 



In a perusal of forestry literature one is impressed with the 

 apparent fact that until only recently has much attention been 

 given to the native vegetation, aside from the forest trees them- 

 selves, in the classification and segregation of forest sites. The 

 majority of the references to the variation in the native her- 

 baceous vegetation on different forest sites have been made 

 incident to the describing of different sites or in characterizing 

 their ground cover instead of from the indicator point of view. 



The rather radical work of Cajander 3 must be cited as an 

 exception to this statement. As a result of investigations of 

 herbaceous and forest associations conducted in Finland, Ger- 

 many, Austria-Hungary, Switzerland, Northern Russia and 

 Siberia, Cajander concludes that, since no forester is in a posi- 

 tion to determine definitely the limits of a dry or a moist soil, 

 the difference in forest types must be based upon the character 



3 Cajander, A. K. Uber Waldtypen, Helsingfors, 1909, Fennia 28, No. 2, 175 

 pp. Reviewed by Raphael Zon in Proc. Soc. Amer. Foresters 9: 119-125. 1914. 



