26 BULLETIN 1402, U. S. DEPAKTMEK^T OF AGEICULTUEE 
strips were laid out before logging and recounted after logging. Of 
an original 3,060 seedlings to the acre, 2,440, or 80 per cent, remained 
after yarding was completed. The survi^^ng trees, too, were well 
distributed, for on 95 per cent of 40 small plots part of the original 
stand remained. 
Similar strips on private land in the same operation show that 
63 per cent of the advance reproduction survived, and that on 80 
per cent of the one-hundredth acre plots (66 by 6.6 feet) some of the 
original stand remained. 
The big-wheel method of j^arding scars the forested area but 
lightly. Characteristically, reproduction on wheeled ground is 
bunched and the brush is thrown out in windrows paralleling the 
wheel roads, on which practically all advance reproduction is de- 
stroyed (fig. 7). On some areas a high percentage of the ground 
may be covered by the roads, and at times in the heavier stands of 
over 25,000 board feet to the acre fully 60 per cent of the reproduc- 
tion is destroyed. The essential difference between national forest 
and private big-wheel yarding is that on the former fewer main 
roads are constructed and consequently a lower percentage of the 
entire area is covered. 
Wheel yarding has several outstanding virtues. Even under the 
worst conditions it alone is never responsible for complete de- 
struction of advance reproduction; and it does not seriously injure 
seed trees that may remain. If used intelligently and with reason- 
able care, it is the least destructive of any method of yarding 
now in general use. A wide experience with big wheels on national 
forest cuttings and an examination of many private areas provide 
adequate evidence that needless damage is seldom caused. Existing 
damage comes mainly from swamping out roads, and since this 
costs real money, unnecessary road construction is avoided, except 
in so far as inefficient supervision and labor result in a poor layout 
of roads. The area laid bare by landings is usually smaller in wheel 
logging than where donkeys or trucks are used. 
Big-wheel yarding is not a cause of fires, and this ranks as one 
of its principal advantages. Donkey engines, on the other hand, 
are a constant risk, and on donkey operations perpetual care is re- 
quired to avoid damaging and costly fires. 
A serious defect of wheel yarding is that the windrows of slash 
left after yarding are always in the strips between roads, just where 
the surviving reproduction is. The burning of this slash, as it lies, 
either by controlled or accidental fires, is impossible without serious 
loss to seedlings and smaller trees that have survived logging. 
DONKEY YARDING 
GENERAL CHAEACTERISTICS 
There is a wide variety of forms of donkey yarding with power, 
but the general layout is similar in all of them. The essential part 
of the equij^ment is the power plant, which drives the drums on 
which a steel cable runs. One cable or ''main line" is used to drag 
the logs in from the woods to the landing; another lighter cable or 
" back line " returns the main line to the woods. Logs may come in 
a direct line to the donkey or may be shunted around obstacles by 
