TRANSPORTATION 125 
profitably on a daily output which is h^ss than 30,000 board feet 
per unit and some have an average dail}^ capacity of 100,000 board 
feet or more. Hence, the daily output far exceeds the require- 
ments of small mills, and during idle periods the carrying charges 
on the machinery are excessive. 
(G) The forestry policy to be pursued. Power logging has 
been extensively introduced on large operations in many parts 
of the country, especially in the southern yellow pine, the Ap- 
palachian mountain, the Central Hardwood (chiefly in the Missis- 
sippi Valley section), the Inland Empire, California, and the Pacif- 
ic Northwest regions. It has not gained any appreciable foot- 
hold in the Northeast and in the Lake States where there is a 
long winter season with a relatively heavy snowfall. The ten- 
dency in power logging in recent years has been to increase the 
amount of power in individual machines and the speed of the skid- 
ding lines in order to increase the output per unit and thus keep 
down the costs of logging which have a more or less constant 
tendency to rise with the advance in the cost of labor and supplies. 
All forms of power logging are more destructive to reproduction 
and seed trees than animal logging, and the ratio of destruction 
increases rapidly with the increase in the speed of the skidding 
lines. It is doubtful if skidding-line speeds in excess of 600 feet 
per minute are compatible with any form of forest management 
other than clear cutting. The so-called high-lead system used 
chiefly in the West has proved to be the most destructive because 
of the damage not only to the base but also to the tops of trees 
which may be left in the forest. The extent of damage by any 
system of power logging is directly proportional to the area covered 
by the runs since, on such areas, all volunteer growth and seed 
trees are destroyed. 
All forms of animal logging have proved to be less destructive 
than power logging because the chief damage results only to those 
trees which are cut to make roads or trails over which to move 
the logs, and to the seedling growth which is on the right of wa3^ 
Since swamping must be done by manual labor, the amount of 
timber cut is reduced to a minimum. Although an occasional 
seed tree may be scarred by contact with the wheels of skidding 
or hauling equipment, this damage usually is slight and the tree 
readily recovers. The damage to seedlings and saplings along 
the trails and roads often is more or less complete but such areas 
