region alone. It is alleged that in the 3 years 
1934-36 there has been a greater shift to the use 
of tractors in Douglas-fir logging than there was 
in the 14 years 1920-33. There will still be con- 
siderable railroad and donkey-engine logging, but 
trucks and tractors will continue to be substituted 
The use of tractors and 
trucks for logging, regardless of intensity of cut, 
will have marked effects upon the problems of 
slash-hazard abatement and forest protection, some 
(1) 
Since logging with tractors does not knock down 
where they are superior. 
beneficial, some otherwise. For example: 
so much nonmerchantable material as donkey- 
engine logging, it leaves less combustible debris 
on the ground and leaves this debris rather well 
shaded by residual trees. 
by broadcast burning is more dangerous and less 
effective after tractor logging than after absolute 
clear cutting, because the residual trees are likely 
(3) The tractor 
trails and truck roads will be of some value as 
(2) Disposal of slashings 
to be killed and become snags. 
firebreaks and as means of ingress in case of acci- 
dental fire. 
road engines removes one flagrant cause of fires. 
(5) Tractor and truck logging distributes the slash 
hazard over a wider area than do railroad and 
(6) If accidental fires are 
tractor-logged areas have a_ better 
(4) Absence of steam logging and rail- 
donkey-engine logging. 
prevented, 
chance than clear-cut areas to be quickly reclothed 
69 
and shaded with woody vegetation and the fire 
hazard diminished. 
Use of trucks and tractors has expanded the op- 
erable timber area in the region, owing largely to 
the fact that it makes possible the opening up of 
timber tracts with a far smaller capital investment 
than would be necessary for railroad and donkey- 
engine equipment. Past procedure resulted for the 
most part in large, continuous expanses of cut-over 
land, the fronts of which were extended by each 
year’s cutting. 
If protective measures are not adapted to the 
changing situation, the shift to truck and tractor 
logging may increase fire hazard. If areas logged 
selectively are broadcast burned, then hazard will 
be greater than that of clear-cut and broadcast- 
burned areas, because of the killing of reserve trees. 
Where the slash hazard would not be materially 
reduced by burning and a useful reserve stand 
would be killed thereby, very intensive protec- 
tion must be substituted. This will be facilitated 
in the case of very lightly logged areas by the re- 
latively small quantity of debris and by the shade 
resulting from the reservation of large numbers of 
trees. 
In view of the wide range in cutting methods and 
types of machinery, it would be unwise to adopt 
any inflexible method of slash disposal but rather 
to vary the method to fit local conditions. 
