50 College of Forestry 
of vegetative propagation; capacity to yield new variations, 
ete., are qualities that must be considered in this day of 
intensive cultivation. ; 
But to return to the question of zonal relations; North 
America as a whole les in a position with respect to latitude 
such that it presents a succession of hfe zones from tropical 
to arctic, the uniformity of which is of course much modified 
by elevation and other factors. These zones as defined by 
Merriam * are as follows: 
I. Tuer Borat Recron. 
1. The Arctic-Alpine Zone.— The far north beyond 
the limit of tree growth and in the United States, high 
mountains above timber line. Zone of the polar bear, 
musk ox, reindeer and of arctic poppy, dwarf willow, 
ete., in north polar regions. 
2. The Hudsonian Zone.—Includes the northern 
part of the boreal conifer forest stretching from Labra- 
dor to Alaska. In eastern United States it is limited 
to the eold summits of the highest mountains from 
northern New England to western North Carolina. 
3. The Canadian Zone.— Includes the southern and 
most valuable part of the transcontinental boreal conifer 
forest in Canada and parts of Maine, New Hampshire 
and Michigan, extending southward along the Appa- 
lachian highlands to western North Carolina and Ten- 
nessee. Zone of red spruce, balsam fir, paper birch and 
mountain ash. 
II. Tur Austrat Reeron. 
4. The Transition Zone.— The eastern humid area 
called Alleghanian area. Includes the northeastern 
states and part of the Canadian provinces and the 
Alleghanies from Pennsylvania to Georgia. Zone of 
overlap of oaks, chestnut, hickories, ete., with more 
northerly birches, beech, hemlock and sugar maple, ete. 
1 Life zones and crop zones. Bull. U. S. Biol. Surv., 10:1898. Map 
revised to 1910. This bulletin could be profitably read in this con- 
nection. 
