ATLAS OF AMERICAN AGRICULTURE* 
Figure 8.—Pure western yellow pine forest. (Yellow pine-Douglas fir.) An open stand, usually with 
grass underneath, affording good grazing; the most extensive and commercially the most important type ot 
the yellow pine-Douglas fir forests. Compare this forest with Figure 22, the southeastern pine forest. 
Coconino National Forest, Ariz. Photographed by A. G. Varela. 
Figure 9.—Typical lodgepole pine forest. (Yellow pine-Douglas fir.) Characteristic dense stand. 
It comes in, as a rule, as a result of fires in Douglas fir and Engelmann spruce forests. Big Horn County, 
Wyo. Photographed by E. M. Griffith. 
Figure 10.—Mixed forest of sugar pine, yellow pine, incense cedar, and white fir. (Yellow pine- 
Douglas fir.) A sequoia in the background; typical of the west slope of the Sierras, best developed yellow 
pine found in this type; also sugar pine and incense cedar. Most favorable climatic conditions for the 
growth of yellow pine. Sequoia National Park, Calif. Photographed by Alfred Gaski 11. 
ception of the cedar-hemlock division, which is con¬ 
fined to a distinct geographic region, namely, the Pa¬ 
cific Northwest. 
WOODLAND. 
The woodland, as has been noted, has tw,o divisions, 
the chaparral and the pinon-juniper. 
Chaparral. (Figs. 5 and 6.) 
Chaparral is a mixed forest of stunted hardwood 
trees and shrubs. It occupies a belt below the yellow 
pine and above the desert shrub. Although this type 
of forest vegetation occurs throughout most of the 
foothills of the central and southern Rockies and the 
mountains of Arizona, Nevada, Utah, and California, 
it is most typical of southern Arizona and southern 
California. The chaparral belt sometimes alternates 
in the Rockies with the pinon-juniper belt, and often 
it forms a distinct fringe along the upper edge of the 
sagebrush belt. In southern California the chaparral 
belt occupies an area of about 5{~ million acres. In 
some places in southern California chaparral extends 
to sea level and in others it reaches an altitude of 8,000 
feet. There are about 116 different species which make 
up the chaparral belt, the bulk of which are found at 
elevations from sea level to about 5,000 feet. 
The species composing the chaparral vary in the 
different regions. Thus, in the Rockies chaparral is 
mainly of scrub oak (Quercus gambelii ) or mountain 
mahogany (Oercocarpus parvifolius) or juneberry 
(A me lane Kiev ). 
In southern California the following are the most 
important species: 
Highland live oak ( Quercus wislizeni ), scrub oak 
(i Quercus dumosa ), holly-leaf cherry (Prunus ilici- 
folia .), sumac ( Rhus lawrma), wild lilac ( Ceanothus 
hirsutus), and manzanita ( Arctostaphylos glauca). 
The chaparral areas of southern Arizona are open 
groves of oak scattered over the desert grassland. In 
the lower belt of the interior valley of California a 
similar open oak type of savanna occurs on the foot¬ 
hills above the weed grass. Above the oak zone the 
dense shrub cover of manzanita, wild lilac, and oak 
brush form a broad belt below the coniferous forest. 
Nearer the ocean immense tracts are covered by a pure 
stand of Adenostoma fasciculata , which is the most im¬ 
portant plant of the lower shrub types of chaparral 
along the Pacific coast of southern California. It 
occurs for the most part just above the southern desert 
shrub and below the oak-brush type of chaparral. It 
occurs most abundantly near the ocean, where, although 
subjected to extended periods of drought, it is never 
subjected to the extreme heat or dry air which is char¬ 
acteristic of the southern desert shrub. 
The chief economic importance of chaparral lies in 
its Watershed protection. The climatic conditions are 
similar to those of the pinon-juniper belt. 
The chaparral, especially in southern California and 
Arizona, occurs on dry mountains which are ill-adapted 
to agricultural development. Citrus fruits are grown 
in so far as possible only in the relatively frost-free 
zone which occupies the low bench lands. The hilly 
land, because of its steeply rolling surface and its in¬ 
accessibility to irrigation water, has not been developed. 
Pinon-Juniper. (Fig. 7.) 
The pinon-juniper division forms a distinct wood¬ 
land belt which, like the chaparral, is just below the 
yellow-pine zone. This belt is to portions of western 
Texas, to the foothills of the southern Rockies and of 
the mountains of Arizona and Nevada, and to the 
eastern slope of the Sierras, what chaparral is to the 
foothills of southern Arizona and southern California. 
In places it intermixes with the chaparral. Only a few 
areas of pinon-juniper are found north of latitude 44°. 
The principal species of juniper are the Rocky Moun¬ 
tain red cedar (/. scopulorum ), Utah juniper ( J . 
utahensis) , the one-seeded juniper ( J . monosperma ), 
and alligator juniper (Juniperus pachyphloea) , while 
pinon is represented by two species of pihon (Pinus 
edulis and P. monophylla) . At the upper part of 
this belt pinon preponderates, while juniper is a little 
more abundant in the lower portions. It is often 
found mixed with western yellow pine and occasion¬ 
ally with stunted Douglas fir ( Pseudotsuga taxifolia) 
at higher altitudes,' and with so-called scrub oaks 
(Quercus- gambelii and Q. undulata). In the south it 
occurs with a number of other small oaks and hard¬ 
woods, together with Mexican pinon ( Pmus cem- 
broides ), Arizona cypress ( Cupressus arizonica ), and 
junipers. Over thousands of square miles pinon- 
juniper and sagebrush alternate, the former occupying 
rough broken country or shallow stony soil, while sage¬ 
brush occurs on the more level ground, which has a 
deep, uniform soil. 
The area of land occupied by pinon-juniper, espe¬ 
cially in the Great Basin, is very great. Economically 
these trees are important, since they form the chief 
source of timber for mine props, fence posts, and fuel 
for local use. The juniper-pinon belt is characterized 
by rather hot, dry summers, the annual rainfall being 
less than 20 inches. The moisture supply is inadequate 
for any save dry-land agricultural methods. The ac¬ 
tual production of crops within this area is small, due 
largely to the rough, stony character of the land. Under 
irrigation good crops of cereals, alfalfa, fruits, and 
vegetables are produced on the better types of soil. 
TIMBERLAND. 
The timberland has three divisions: (1) Western 
yellow pine-Douglas fir, (2) cedar-hemlock, and (3) 
spruce-fir. 
The Western Yellow Pine-Douglas Fir Forest. 
This division of the timberland includes: 
(a) The pure forest of western yellow pine of Ari¬ 
zona, New Mexico, southern Utah, the Black Hills of 
South Dakota, the eastern slope of the Cascades -and 
the Sierras and the Columbia Basin, as well as the 
yellow pine stands throughout the central and southern 
Rocky Mountains, western Montana, western Idaho, 
and eastern Oregon (Blue Mountains). 
(b) The western yellow pine-sugar pine-incense 
cedar forest of the Sierras in California. 
(c) The Rocky Mountain Douglas fir forest. 
To these may be added two other types of forest of a 
more temporary character which, if left undisturbed for 
a long period, would gradually give way to other types, 
namely, (d) the lodgepole pine (Pinus contorta ) forests 
of Montana, Wyoming, and Colorado; and (e) the 
western larch—Douglas fir forests of northwestern Mon¬ 
tana and northern Idaho. 
It may seem at first too far fetched to include in the 
western yellow pine-Douglas fir division such appar¬ 
ently widely differing stands. Yet if we analyze the 
biological peculiarities of the species which make up 
these stands, their habitats, and trace their life histories 
after severe burns and logging, it becomes clear that a 
large number of the lodgepole pine stands in northern 
Wyoming and throughout the central Rocky Moun¬ 
tains, the western yellow pine—western larch—Douglas 
fir stands of northwestern Montana and northern 
Idaho, the sugar pine-incense cedar-western yellow 
pine forests on the west slope of the Sierras, and the 
Jeffrey pine forest mixed with white fir (Abies con- 
color) on the east slope, the pure forests of western 
yellow pine on the east slope of the Cascades, as well as 
AT ° se Arizona, of the Black Hills and of northern 
Nebraska, all grow under more or less similar climatic 
conditions and occupy, as a rule, southern slopes or 
o eiwise dry situations. At the two extreme ends of 
