GRASSLAND VEGETATION, 
Classification of forests of the United States into forest regions, 
subregions, and sites —Continued. 
THE WESTERN FORESTS—Continued. 
Forest region. 
Pifion-juniper. 
Chaparral. 
Subregion. 
Association. 
Pifion-juniper_ 
Juniper. 
Oak. 
Digger pine. 
Sites. 
In central Rocky Mountains, 
Rocky Mountain juniper 
( Jumperus scopulorum ) and 
one-seed juniper (J. mono- 
sperma) are the chief species, 
often with some Gambol oak 
(Quercus gambelii ) and west¬ 
ern yellow pine. In Arizona 
and New Mexico pifion, Mex¬ 
ican pifion (P. cembroides), 
single-leaf pifion (P. mono- 
phylla), alligator juniper (Ju- 
niperus pachypnloea), one- 
seed juniper, Rocky Moun¬ 
tain juniper, and Utah ju¬ 
niper (J. utahensis) are the 
chief species, often with some 
Gambol oak and western yel¬ 
low .pine. In Utah, single¬ 
leafjpifi op. Utah juniper, one- 
seed? jumper, and Rocky 
Mountain juniper, often witn 
some Gambel oak and west¬ 
ern yellow pine. In Cali¬ 
fornia, single-leaf pifion and 
Utah juniper, often with 
some western juniper (J. 
occ}dentalis ) and Jeffrey pine. 
In the northern Rocky Moun¬ 
tains juniper is the chief 
species, usually with some 
limber pine, western yellow 
pine, or Douglas fir; in Cali¬ 
fornia, juniper, often with 
some Jeffrey pine and west¬ 
ern yellow pine; in Wash¬ 
ington and Oregon, western 
juniper, often with mountain 
mahogany, and sometimes 
with a little western yellow 
pine. 
In Arizona and New Mexico 
Emory oak (Q. emoryi), 
Arizona white oak (Q. ari- 
zonica), blue oak (Q. oblongi- 
folia ), and whiteleaf oak (Q. 
hypoleuca) are the chief 
species, often with some alli¬ 
gator juniper, Mexican pifion, 
and other species. In Utah, 
pretty scrubby Gambel oak. 
In California, black oak (Q. 
californica), California blue 
oak (Q. douglasii), canyon 
live oak (Q. ehrysolepis) 
California live oak (Q. agri¬ 
folia), highland live oak 
(Q. wislizeni), valley oak 
(Q. lobata), and Garry oak 
(Q. garryana), often with 
some digger pine, madrofie, 
and occasionally knobcone 
pine, Coulter, Jeffrey, and 
western -yellow pines, and 
other species. 
A low foothill belt made up 
approximately of 40 per, cent 
or more of digger pine,- often 
mixed with various oaks, 
Coulter pine, western yellow 
pine, and other species. 
Occurs on any sites below 
the western yellow pine type. 
THE EASTERN FORESTS. 
Spruce-fir. 
Spruce-fir. 
Birch-beech- 
maple-hem¬ 
lock (north¬ 
ern hard- 
wo6d forest). 
White pine- 
Norway 
pine-jack 
pine. 
Oak. 
Chestnut- 
chestnut 
o a k-yellow 
poplar. 
Oak-hickory. 
Oak—shortleaf 
pine. 
Spruce swamps... 
Spruce flats. 
In mixture with 
hardwoods. 
With mixture of 
spruce, balsam 
and hemlock 
(transition for¬ 
est); with mix¬ 
ture of white 
pine or tama- 
rack; with 
mixture of ash, 
elm, basswood, 
or red oak; with 
mixture of pa¬ 
per birch or as¬ 
pen; with beech 
predominating; 
with yellow or 
black birch 
predominating; 
with sugar 
maple predomi¬ 
nating. 
Jack pine plains... 
Pure Norway pine 
Norway-white 
pine in mixture 
with hardwoods. 
Low lying, poorly drained 
areas, whose soil is a muck or 
peat, spongy in texture, and 
acid. The characteristic spe¬ 
cies are red spruce, black 
spruce, balsam, tamarack, 
cedar, soft maples. 
Spruce 1 flats occupy the level 
and rolling flats bordering the 
swamps, lakes, and water 
courses. It is in large meas¬ 
ure a transition between the 
swamp type and the type of 
the mixed hardwood lands, 
and in many respects exhib¬ 
its the characteristics of each. 
Spruce, birch, soft maples, 
white pine, hemlock, and bal¬ 
sam are the characteristic 
trees in mixture. 
These occupy the best soil sites 
of the region, usually the 
benches and the lowermoun- 
tain slopes. The soil is here 
best adapted- to hardwood 
growth, is deep, of more or 
less even texture, fresh, and 
well-drained. Besides spruce, 
hard maple, beech, anil birch 
predominate and there is a 
scattering of hemlock, white 
pine, soft maple, cherry, and 
a variety of other species. 
The proportion of spruce in 
mixture depends on topo¬ 
graphic conditions. Transi¬ 
tion to birch-beech-maple- 
hemlock forest. 
Fresh, well-drained fertile soils 
within the drainage system 
of the St. Lawrence, the 
Great Lakes, and the upper 
Mississippi; throughout 
northern New England and 
southward along the north¬ 
ern and southern Appalach¬ 
ian Mountain ranges to ex¬ 
treme northern Georgia. It 
coincides, with the range of 
yellow birch and centers 
about the region of best de¬ 
velopment of white pine. 
In Minnesota 1 the beech and 
hemlock disappear and the 
forest is made up of aspen, 
white birch, basswood, and 
maple of inferior develop¬ 
ment. 
On the driest, sandiest soils. 
On dry, sandy soils, slightly 
better than those character¬ 
istic of the jack pine plains. 
Usually on moderately moist, 
well-drained soil underlain 
with a clay subsoil. 
Cove. —Poplar, hemlock, bass¬ 
wood, black birch, cucum¬ 
ber, ash, buckeye. Most 
abundant, probably chestnut. 
Very abundant, chestnut, oak, 
hickory, red oak, white oak, 
black gum, dogwood, sour- 
wood, silver bell, white pme. 
There may be distinguished 
poplar cove, hemlock cove, 
white oak cove, etc. 
Ridge— Pitch table-mountain, 
and short-leaf pines; chest¬ 
nut, scarlet, and black jack 
oaks; chestnut; black gum. 
There may be recognized 
pine ridge, chestnut oak 
ridge, oak ridge. 
Slope. —A blending of above 
species, with heaviest pro¬ 
portion of chestnut and oaks. 
Upper slope resembles ridge, 
lower slope resembles cove. 
The most eastern extension of 
the oak region. The oaks 
and the hickories, together 
with some ash and black wal¬ 
nut, are the farthest avant 
post in the prairie region. 
Characteristic species are 
chiefly shortleaf pine as the 
predominating species, with 
varying amounts of black, 
chestnut, post, and -Spanish 
oaks, pignut and mocker-nut 
hickories, and black jack 
oak, approximately in the 
sequence given above: 
Classification of forests of the United States into forest regions, 
subregions, and sites —Continued. 
THE EASTERN FORESTS—Continued. 
Forest region. 
Oak—(Con.). 
Cypress-tu- 
pelo-r ed 
gum. 
Longleaf- 
loblolly- 
slash pine. 
Mangrove. 
Subregion. 
Oak—shortleaf 
pine. 
Association. 
River swamps. 
Sour swamps 
and cypress 
“ponds.” 
Ttiver bottom 
forest. 
Longleaf, slash, 
‘and loblolly 
pines. 
Pure longleaf pine. 
Longleaf pine in 
mixture with 
shortleaf and 
loblolly pines 
and hardwoods. 
Sites. 
On dry ridges (north)— 
shortleaf pine, chestnut 
oak, scrub and some 
pitch pine. 
On dry ridges (south)— 
shortleaf pine, post oak, 
blackjack oak. 
On average rolling lands— 
shortleaf pine, black oak, 
pignut hickory, Spanish 
oak, mockernut hickory 
flower), chestnut oak 
(drier and warmer), scar¬ 
let oak, black gum (gen¬ 
erally scattering), dog¬ 
wood and persimmon 
(understory). 
On low southern situa¬ 
tions—shortleafpine, lob¬ 
lolly pine, red gum, black 
gum, white oak. 
“ Sloughs:” Cypress and tupelo. 
“Glade:” Cypress, tupelo, 
water ash, willow, cotton¬ 
wood, white and red bays. 
“Ridge:” Red gum, slash pine, 
overcup oak, water oak, 
hickory, black gum, ash, red 
maple, honey loeust. 
Poorly drained, highly acid 
soils. Cypress (imbrtcata or 
“pond” form), black gum, 
>ond pine, slash 
Along the larger streams and 
deeper narrow valleys in the 
upper Piedmont sections, the 
forest consists chiefly of hard¬ 
woods, red gum, willow 
and water oak, ash, shell- 
bark, and other hickories, 
black and red gums, some 
yellow poplar and cucumber, 
persimmon, and dogwood. 
Shortleaf pine is prominent on 
the warm, south-facing and 
drier slopes mixed with black; 
oak and post oaks, pignut 
and mockernut hickories. 
Toward the lower or southern 
margin-of this forest forma¬ 
tion loblolly pine occurs in 
increasing importance in 
mixture with shortleaf and 
the species belonging to the 
lower and more moist soils; 
most important in southeast 
Arkansas. South of Vir¬ 
ginia longleaf pine enters and 
m- central ^Alabama, north¬ 
ern and western Louisiana, 
and eastern Texas becomes 
an important member of the 
composition. 
On low marshy lands in the 
vicinity of the Gulf and 
Atlantic coast. Generally 
flat, with deep sandy soil 
lacking in humus, alternately 
very wet and dry. Under¬ 
growth of wire grass and 
palmetto. 
High pine land. This is a belt 
adjoining low marshy lands 
in the vicinity of the Gulf 
and Atlantic coast. Here 
moist depressions bordering 
the creeks and streams are 
occupied by hardwoods, lob¬ 
lolly pine, and cypress. 
Broom sedge, turkey oak 
(Q. catesbaei), and bluejack 
oak (Q. cinerea ) form the 
undergrowth. 
A broken and hilly country 
lying still farther ‘inland 
from- the coast. Here the 
longleaf pine mingles with 
shortleaf pine forests and 
mixed hardwoods of the 
uplands. 
Southern shores of Florida, 
overflowed generally by salt 
tidewater. Representative 
of the tropical forest vegeta¬ 
tion. 
Figure 26.—Diagram showing points of similarity between the 
forests of the western and eastern parts of the country and the rela¬ 
tionships of the different forests. 
GRASSLAND VEGETATION, 
The central grassland area may be divided into the 
tall grass (prairie grassland), lying.for the most part 
east of the one hundredth meridian, the short grass 
(plains grassland) which lies to the west of this line, 
the mesquite grass (desert grassland), which lies 
south of the short grass and occupies much of the 
higher land of west Texas and the lower southern 
part’s of New Mexico and Arizona, and the mesquite 
and desert grass savanna, which extends across Texas 
from the Red River southward to the Gulf of Mexico. 
Bunch grass (Pacific grassland), occurs on the higher 
plateaus and foothills of eastern Washington, Oregon, 
and western Idaho, also on the foothills and in the 
mountain valleys of California and Utah. The short 
grass extends on the south into the highlands of New 
Mexico and Arizona, while isolated areas of tall grass 
occur in east central Texas, the coast regions of Texas 
and Louisiana, and in portions of Mississippi, Ala¬ 
bama, and Florida. (Fig. 2.) 
In addition to these types of grassland, the areas 
above timber-line on the high mountains of the Cas¬ 
cade-Sierra and Rocky Mountain ranges are occupied 
by alpine meadows, characterized by low grasses and 
sedges and a rich admixture of showy-flowered herbace¬ 
ous plants. 
On low, undrained land over which water stands to 
a depth of several inches during most of the year, such 
as is found in relatively restricted areas near the Gulf 
and Atlantic coasts and in Oregon and California, an¬ 
other type of grassland occurs which may be called 
marsh grassland. It is characterized by coarse, tall 
grasses, sedges, and rushes, and is often marked in 
Oregon and along the Gulf and Atlantic coasts by 
alkali or salt-water plants. 
Although all of these areas are characterized by 
grassy plants, the species, the biological forms, and the 
conditions of climate and soil are quite distinct. 
The short grass characteristic of the high plains 
develops in a region of early spring and summer rain¬ 
fall. The average annual precipitation ranges from 12 
to 22 inches. The moisture during ordinary years does 
not penetrate more than 2 feet below the surface. This 
enables the grasses to grow only a comparatively short 
time following rains, and they then pass into a 
drought rest period, which is relatively long in the 
south and short’ in the north. Often they do not 
fruit during the whole summer because of drought. 
The tall grass and the short grass are distinct in habit 
of growth, both in height of plant and depth of root 
penetration, although the latter is largely a response to 
the soil-moisture conditions, since even the short 
Figure 27.—A bluestem sod characteristic of the great prairie grass 
region of Illinois, Iowa, and Missouri. (Tall grass.) Bluestem 
predominates. In spring great quantities of flowers are produced, 
especially shooting stars, phloxes, violets, and spiderworts, which 
later are not pronounced features of the grass cover. This vegeta¬ 
tion is characteristic of a rich soil, and the land has proven most valu¬ 
able for agricultural use. Savanna, III. Photographed by H. C. 
Sampson. 
grasses will penetrate to great depths if the soil is 
moist. The tall grasses grow in a region where the soil 
moisture is distributed to a depth of 2 feet or more. 
Their growth, as a rule, is not limited by deficient 
moisture supply, as is usually the case with short 
grass. The line of demarcation between the tall 
grass and the short grass is not distinct, since the 
change in climatic conditions is very gradual, due 
to the absence of a definite topographic division be¬ 
tween the two. A series of wet years will swing the 
apparent division line westward and a series of dry 
years will swing it eastward. Notwithstanding the 
gradual change from one type to the other, these types 
represent widely different climatic, soil, and soil-mois¬ 
ture relations, and the agricultural significance of the 
two is quite distinct. It is chiefly a matter of moisture 
supply; but this is influenced by the conditions favoring 
water loss and by the permeability of the soil. The 
tall grass pushes farther west on sandy soil, while the 
hard lands favor the eastern extension of the short 
grasses. Heavy grazing also favors the eastern exten¬ 
sion of the short grasses. 
The division line between the short grass and tall 
grass corresponds to,rather sharp soil differences. It 
is correlated with the depth below the surface of the 
layer of carbonate accumulation which marks the depth 
of the periodically moist layer of surface soil. Below 
this layer of carbonate accumulation the soil is per¬ 
manently dry except during occasional years of un¬ 
usually heavy rainfall. Where the depth of moist soil 
is less than 2 feet, the short-grass type of vegetation 
predominates. Where greater than about 30 inches, 
or where lacking entirely, the prairie type of grassland 
