JOURNAL OF AGHOILT1AL RESEARCH 
Vol. XXVIII Washington, D. C., Mat 24, 1924 No. 8 
INDICATOR SIGNIFICANCE OF THE NATURAL VEGETA¬ 
TION OF THE SOUTHWESTERN DESERT REGION 1 
By H. L. Shantz, Senior Physiologist in Charge, and It. L. Piemeisel, Assistant 
Physiologist, Office of Plant Physiological Investigations, Bureau of Plant Indus- 
try , United States Department of Agriculture 
The natural plant cover, if properly interpreted, indicates the crop-producing 
capabilities of land as well, if not better, than any series of meteorological obser¬ 
vations or soil analyses. The value of the soil and climatic studies is not mini¬ 
mized by this statement, since it is only through a study of soil and meteorological 
conditions that the significance of the vegetation can be interpreted, especially 
where agriculture is not already well established. 
Slight differences in either soil or climate may produce profound changes in 
the vegetation type, and, conversely, changes in the vegetation type may indi¬ 
cate only slight differences in soil or climatic conditions. 
A description of the types of vegetation forms an important and necessary 
part of any adequate study of an agricultural region. In this paper the writers 
are not concerned with a descriptive or geographic study of any particular 
region, but with a determination of the soil and climatic conditions which are 
indicated by different types of natural vegetation. In other words, what are 
the conditions which have led to the development of the principal types of vege¬ 
tation in the region or regions considered, and what do these types of vegetation 
signify in terms of the crop-producing capabilities of the land on which they grow? 
Similar studies have been made on the Great Plains (Shantz, 1911)* and in the 
Great Basin (Kearney, Briggs, Shantz, McLane, and Piemeisel, 1914)* and 
these studies have shown that the character and types of the natural plant cover 
indicate the potentialities for crop production of the soil and climate which pro¬ 
duce them. 
METHODS 
The methods combine those usually employed by the systematist, the plant 
geographer, and the ecologist. 
1 Received for publication Feb. 28,1924. The studies herein recorded have been carried on under the. 
general direction of Dr. T. H. Kearney, Physiologist in Charge of Alkali and Drought Resistant Plant 
Investigations, Bureau of Plant Industry, U. S. Dept, of Agriculture. To him the authors are indebted 
for many suggestions in the preparation of the manuscript and for actual assistance in the field, especially 
in Coachella Valley, Calif., and Casa Grande, Ariz. Acknowledgment should also be made for the 
assistance of Homer Martin, Gardener, Alkali and Drought Resistant Plant Investigations, in the field 
work, and of Paul C. Standley of the United States National Herbarium, and Ivar Tidestrom, of the 
Bureau of Plant Industry, for the identification of the native plants listed in this paper. 
3 Shantz, H. L. natural vegetation as an indicator of the capabilities of land for crop pro¬ 
duction in the great plains area. U. S. Dept. Agr., Bur. Plant Indus. Bui. 201,100 p., illus. 1911. 
* Kearney, T. H., and others, indicator significance of vegetation in tooele valley, utah. 
Jour. Agr. Research. 1: 365-417, illus. 1914. 
Journal of Agricultural Research, Vol. XXVIII, No. 8 
Washington, D. C. May 24,1924 
Key No. G-416 
96038—24f-1 
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