JOURNAL OF AGlim RESEARCH 
Vol. XXVIII Washington, D. C., April 12, 1924 No. 2 
TYPES OF VEGETATION IN THE SEMIARID PORTION 
OF THE UNITED STATES AND THEIR ECONOMIC 
SIGNIFICANCE 1 
By A. E. Aldous, Classifier in Charge of Homestead Classification , Geological 
Survey , United States Department of the Interior , and H. L. Shantz, Physiologist 
in Charge, Plant Geography in Its Relation to Plant Industry, Bureau of Plant 
Industry, United States Department of Agriculture 
The natural or normal plant cover is a result of all growing conditions of the 
area where it is produced. It is therefore an index or measure of the factors 
influencing its growth and it serves as an indicator of the possibilities of pro¬ 
ducing other plants on the land. The differences in growing conditions have 
resulted in various plants and groups of plants. A number of these have been 
recognized as having indicator value in determining the use that can be made 
of the land for growing farm crops. Some plants can thrive in a wide range of 
growing conditions; others, however, are affected by comparatively small 
changes. In the various plant communities or types some species naay drop 
out and others come in as a result of changes in growing conditions. Better 
or less favorable growing conditions in a region are also indicated by differences 
in the density of the vegetation within the same type. 
In the following paper the principal types of vegetation occurring on the 
unreserved public lands and the patented homestead lands west of tbe one 
hundredth meridian are briefly discussed with special reference to their economic 
significance to crop production and grazing and some of the more important 
ones are illustrated. These types have been recognized and used in connection 
with data on topography, soil, climatic conditions, accessibility, and past agri¬ 
cultural history to determine the value of the lands for the production of culti¬ 
vated crops and for grazing. At the time the land classification work was 
started there were numerous areas that had not been settled or where settle¬ 
ment had been so recent that no agricultural history was available. In most 
of these areas definite climatic data were also lacking. The vegetation there¬ 
fore served as the principal means of determining the relative value of these lands 
for farming. 
The expression “vegetation type” is here used in the sense employed by 
foresters to indicate a plant community of any size, rank, or stage of develop¬ 
ment. It is synonymous with the technical phytogeographic term “plant 
community.” 
In the consideration of the suitability of land for grain farming, forage, or 
grazing, the following 102 vegetation types have been used, which it is believed 
represent the most important ones to be found in the region covered by the 
paper. The key (pp. 117-119) summarizes the types under headings indicating 
their value for the production of grain or cultivated forage crops or for graz¬ 
ing. Owing to the fact that all the types of vegetation are used for grazing, 
1 Received for publication March 10,1924. 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXVIII, No. 2 
Apr. 12,1924 
K>.y No. G-397 
