FOREST VEGETATION. 
Figure 21.—A mixed forest of shortleaf pi,ne and oak (Oak-pine), most characteristic of the Great 
Pied.mont Plateau. In a sense it is a transition zone between the oak forest to the north and the 
southern pineries to the south. In some respects it is similar to the mixed forest of northern hardwoods 
with northern pines to the north of the oak region. The type varies considerably in composition according 
to the altitude and proximity to the coast; loblolly pine and other southern pines enter into the composition. 
Garland County, Ark. Photographed by A. G. Varela. 
Figure 22,—A mixed forest of longleaf pine, loblolly pine, and shortleaf pine (Longleaf-loblolly-slash 
pines), typical of the Coastal Plain, and varying in composition from ppre stands of longleaf to a mixed pine 
forest in which several species of southern pines occur. The typical longleaf pine forest is not unlike the 
yellow pine forests of Arizona (see fig. 8). This forest is at present the only source of commercial naval 
stores in the country. It is also at present the chief timber-producing region in the United States. Georgia. 
Photographed by E. Block. 
birch, and it centers about the region in which the 
white pine lumbering industry developed. 
This northern hardwood forest is distinctly humid , 
and the composition of the forest is therefore influ¬ 
enced chiefly by temperature, except in its western ex¬ 
tension, where moisture may be considered one of its 
limiting factors. The growing season within this for¬ 
est is approximately five months, from May to Septem¬ 
ber, inclusive. The average temperature for the grow¬ 
ing season is about 61° F., while for the oak forest or 
so-called southern hardwoods it varies from 64° to 67°. 
During the growing season the total, average precipita¬ 
tion in the northern hardwood forest is from 18 to 23 
inches. 
The bircli-beech-maple-hemlock forest is of widely 
varying composition. It is found in a great variety of 
mixtures with spruce, fir, beech, sugar and red maples, 
white pine, and hemlock, and with scattered individ¬ 
uals or groups of other species, notably paper birch and 
aspen. Elm and basswood are also frequent compo¬ 
nents of this forest. In the Upper Peninsula of Michi¬ 
gan and in the northeastern part of Wisconsin the hard¬ 
woods are typical northern hardwoods, maple, yellow 
birch, and beech, with their characteristic associate, 
hemlock. In Minnesota this character of forest' peters 
out, and what is known as the hardwood forest is almost 
exclusively popple, white birch, and occasionally bass¬ 
wood and maple of inferior development. The north¬ 
ern hardwoods occupy some of the best agricultural 
land of the northeastern United States. The principal 
crops in this region are timothy, clover, oats, barley, 
corn, especially for silage, potatoes and beans. Fruit, 
especially apples, strawberries, and bush fruits, are suc¬ 
cessfully grown, and where markets are available truck 
gardening has proven profitable. 
The birch—beech—maple—hemlock forest in its bio¬ 
logical characteristics is not unlike the western white- 
pine forests of northern Idaho and western Montana. 
Here the eastern white pine (Firms strobus) takes the 
place of the western white pine (Firms monticola ). 
Hemlock also plays the same part as there, being the 
last stage in the development of the stand and coming 
in as an understory. The place of the western red 
cedar, however, is taken in the East by such hardwood 
species as sugar maple, beech, yellow birch, and the 
lowland white fir is represented by balsam fir. Were 
it not for the difference in the distribution of rainfall 
during the year, the composition of the forests of the 
two regions would possibly be even more closely similar. 
Pacific coast Douglas fir. There is a similar heavy 
precipitation, density of stand, and development of 
the individual trees. If to this is added that hemlock 
and white pine are not lacking in the typical cove 
stands, the comparison becomes particularly strong. 
If the southern hardwoods, especially the southern 
Appalachian hardwoods, have the tendency at maturity 
to develop an understory of hemlock just as the northern 
hardwoods do, the two divisions of our hardwood belt 
may be considered as belonging to one forest unit just 
as do the western white pine-larch region and the 
Pacific coast Douglas fir. The life history, however, 
of most of the southern Appalachian stands is still 
imperfectly known. Therefore the present birch- 
beech-maple-hemlock forests and the oak region must 
be classed as two separate forest units. 
This hardwood forest belt was originally continuous 
and of great luxuriance, but the greater part of it has 
now been cleared for agriculture or turned into brush 
land. There are still large areas, however, of virgin 
hardwood forest, particularly in the Appalachians, 
Tennessee, Kentucky, Missouri, and Arkansas. 
Although greatly modified by repeated surface burn¬ 
ing and heavy destructive culling, this region can still 
be clearly divided into three distinct areas: 
The chestnut-chestnut oak-yellow poplar forest. 
The oak-hickory forest. 
The oak-pine forest. ; 
Ohestnut-chestnut oak-yellow poplar forest (fig. 
19).—This forest is found throughout the greater por¬ 
tion of the highland extending from Pennsylvania into 
northern Mississippi and Alabama. It is best devel¬ 
oped in the southern Appalachians, between and includ¬ 
ing the great Blue Ridge and Unaka Mountain sys¬ 
tems. The region is generally mountainous, but not 
craggy, with steep slopes, narrow coves, ridges, and 
some high and broken or gently sloping land, which 
approaches table-land. The annual precipitation is 
from 50 to 70 inches, the heaviest' coming in July and 
August. With much sunlight, evaporation is relatively 
rapid. The growing season is from five to six months 
long. Although chestnut, chestnut oak, and yellow 
poplar are the characteristic species of this forest belt 
and distinguish it from the hardwood belt west of it, 
many other kinds of trees are found in this forest; in 
fact, it contains probably a larger number of species 
than any other forest area in North America. 
The oak-hickory forest (fig. 20).—In the western 
part of the oak region, embracing western Ohio, In- 
The Oak Forest (Southern Hardwood Forest). 
The lower slopes in the Appalachian region and the 
central Mississippi Valley support a hardwood forest 
in which the oaks make up the great body of the forest. 
It may therefore be characterized as the oak region. 
This hardwood forest is probably the largest hardwood 
Figure 23.—A mixed forest of cypress and tupelo gum on low land. 
(Cypress-tupelo-red gum.) Few other forests present such a variety 
in composition as the bottom-land forest of the South. Where water 
stands for the larger part of the growing season, it Is made up largely 
of cypress and tupelo gum. On the bottom lands where it is over¬ 
flowed for only a few months or weeks there is, besides cypress and 
tupelo, ash, cottonwood, and white and red bays. On the dryer 
ridges within the bottom lands it resembles the hardwood forests of 
the vicinity, made up of red gum, black gum, ash, red maple, water 
oak, and hickory. New Dexter, Stoddard Courrty, Mo. Photo¬ 
graphed by Z. L. Bliss. 
forest in the Temperate Zones of the world. Close to 
markets and surrounded by densely populated country 
it is recognized as the great center of the Nation’s 
hardwood resources. 
There is a certain parallelism between the oak region, 
particularly the eastern part of it, composed of chest¬ 
nut, chestnut oak, and fellow poplar forests, and the 
