LAND CLASSIFICATION. 239 



only proposals which need to be considered here are those which deal with in- 

 dicator vegetation. The latter necessarily takes account of both soil and cli- 

 mate and furnishes the only basis for an adequate system. The first serious 

 proposals of such a system were made by Hilgard, as already shown in the first 

 chapter. As a student of soils, he was concerned primarily with the indicators 

 of soils (1906: 487), and especially those which were regarded as significant of 

 lime or alkali. He paid almost no attention to indicators of climate, and was 

 concerned only with those which denoted agricultural land. Because of his 

 primary interest in the distribution of animals, Merriam (1898) emphasized 

 the importance of climate in agriculture, and ignored that of soil. His central 

 idea was to enable the farmer "to tell in advance whether the climatic con- 

 ditions on his own farm are fit or unfit for the particular crop he has in view, 

 and what crops he can raise with reasonable certainty." Hence, he was 

 concerned with a use survey rather than with land classification, though his 

 "life zones and crop zones" possess certain values in connection with the 

 latter. 



Clements (1910:52) pointed out the difference between a classification 

 survey and a use survey of occupied lands, and emphasized the necessity of 

 employing soil and climate, native vegetation, and practical experience 

 to constitute a complete system for classifying the lands of a region as agri- 

 cultural, grazing, and forest. Several unoccupied townships of northern 

 Minnesota were classified on this basis and several farming townships of the 

 southern half were mapped in accordance with a use survey. The investi- 

 gations of Shantz (1911) in eastern Colorado dealt chiefly with the indicator 

 value of the different associations with reference to crop production and 

 furnished a new basis for the classification of agricultural land with respect to 

 probable yield. A similarly detailed and accurate study of the saline vegeta- 

 tion of Tooele Valley was made by Kearney and his associates (1914), in which 

 the primary object was to provide a definite method of distinguishing agri- 

 cultural from non-agricultural lands and of determining the relative values of 

 the former. 



The rapid establishment of national forests from 1902 to 1908 necessitated 

 the use of a ready method of distinguishing between forest and agricultural 

 land. The indicator method had not yet been definitized to a point where it 

 was available, and studies of soil and climate were barely begun. In spite of 

 this, forest and woodland constitute such obvious indicators that their use 

 afforded fairly satisfactory results, particularly when water regulation was 

 taken into account. The limits of the forests thus drawn necessarily included 

 some agricultural land as well as great areas of grazing land. Much of the 

 former has later been eliminated by reclassification, while the latter has been 

 classified into various types (Jardine, 1911, 1913). Within the forests proper, 

 the problem of classification has naturally revolved about the question of 

 forest types. This has given rise to an extensive literature (Graves, 1899 ; 

 Zon, 1906; Clements, 1909; cf. Proc. Soc. Am. For., 1913: 73) and is discussed 

 in some detail in Chapter VII. Pearson (1913: 79; 1919) has emphasized the 

 importance of ascertaining the agricultural possibilities of forested land in 

 order to determine with certainty whether it should be classified as one or the 

 other. He proposes a definite program of investigation to make the principles 

 and methods of land classification more accurate. This is based upon actual 



