AN ECOLOGIC STUDY OF THE FLORA OF MOUN- 
TAINOUS NORTH CAROLINA. 
JoHN W. HARSHBERGER. 
(Concluded from p. 258.) 
THE VEGETATION OF THE MOUNTAIN REGION. 
Tne characteristic features of the vegetation of this whole 
region are found in the broad-leaved species, of which it is 
largely composed, associated with deciduous and evergreen 
shrubs, while lianes stretch from tree to tree, and herbaceous 
plants grow beneath the dominant forest species, or clothe the 
natural meadows of the higher mountain summits and the alluvial 
bottoms of the principal mountain streams. The association of 
these plants in the forest is largely due to their relation to light, 
soil, and moisture. 
Relation to light—A\ll trees require a certain intensity of light 
for photosynthesis. Hence weak light is injurious; otherwise 
there is no reason why the foliage in the interior of the crowns 
of the trees should not be as dense as near the periphery. 
Marked differences occur among the various species of trees 
with regard to the measure of light necessary, and though 
affected by soil and situation, these differences are sufficient to 
admit of classification into tolerant and intolerant species; that 
is, into shade-bearing or light-demanding trees, and trees that 
occupy an intermediate position.2> The different trees of the 
forests of North Carolina may be classified accordingly, as to 
their tolerance : 
Sugar maple, flowering dogwood. 
Hornbeam. 
Red maple, yellow oak, beech. 
Butternut, black walnut. 
Witch hazel, chestnut oak, white oak. 
5 NISBET, Studies in forestry 54. 1894. FOLEY, JOHN, Conservative lumbering 
at Sewanee, Tennessee. Bureau of Forestry, Bull. 39. 
368 [NOVEMBER 
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