10 BULLETIN 1496, U. S. DEPARTMENT OF AGRICULTURE — 
with the drainage conditions, and somewhat with the depth and 
character of peat on which the forest grows. Tamarack swamps are 
usually found on the least-drained lowland in which the peat is 3 
or more feet in depth. Where the peat is between 2 and 3 feet deep 
and is better drained there is a greater admixture of spruce and cedar. 
Where it is shallow, from 1 to 2 feet, and the drainage is good, the 
swamp assumes the mixed composition of the transition type—the 
most valuable type of all swamp forests. Occasionally, the peat is 
10 to 20 feet thick and yet the swamp is fairly well drained; under 
such conditions all swamp species grow well. Apparently it is not 
the depth of the peat that affects the growth but the poor drainage 
conditions which usually are found in the heavier peat swamps. 
The present merchantable black-spruce forests are more than 100 
years old and over large areas do not average more than 8 to 12 cords 
to the acre. They are made up of trees of various diameters if not 
of different ages. Trees 3 inches through are often 70 to 80 years 
old, and may be 150 to 200 years old. Many spruce stands in the 
swamps have the appearance of young reproduction but upon exami- 
nation prove to be made up of old trees. Reproduction in the spruce 
swamps is rarely dense. On poor sites it rarely exceeds 1,000 to 1,500 
young trees per acre. 
It takes swamp white cedar from 10 to 20 years to grow 1 inch 
in diameter. Cedar produces 6-inch posts in 60 to 90 years and 
ties in 150 to 175 years; poles are not produced in less than 175 
to 200 years. Tamarack in swamps may produce ties in 100 to 120 
years. 
On the drier and warmer sites, white cedar may grow 10 inches 
in 100 years and tamarack 8 to 10 inches in 40 years. Even black 
spruce can be grown on the better and drier sites in 50 to 60 years 
for pulp, and will average about 6 inches in diameter. Balsam fir 
does even better than spruce on the better sites. White cedar on 
dry or well-drained soils grows almost twice as fast as in the swamps. 
On loamy soils cedar has been found to grow 6 inches in 39 years. 
The poor growth in swamps is, therefore, not inherent in the species 
themselves but is due to the conditions under which they grow. 
WHAT LOGGING AND FIRES DO TO THE FOREST 
Any conclusion as to the measures needed to keep the forests of 
the region productive must be based upon a clear understanding 
of the effects which fires and present methods of logging have upon 
second growth. These effects vary in different kinds of forests. 
An analysis of what’happens to second growth as a result of cutting 
or of cutting and fires must, therefore, be made for each type of 
forest separately. : 
EFFECT OF LOGGING AND FIRES UPON HARDWOOD-HEMLOCK 
FORESTS 
The hardwood forests of birch, beech, and maple are almost entirely 
in private ownership, and at present are cut for all the merchantable 
timber there is in them. Merchantability, however, varies con- 
siderably from place to place. In certain districts, for instance, 
cordwood from the tops and defective logs can be disposed of for 
