20 BULLETIX 149 9, U. S. DEPARTMENT OF AGRICULTURE 
Forest in Colorado, where cutting took place about 1918. On the 
former area slash was close to the ground after about three years 
and was no longer a serious fire menace. On the latter area, where 
the timber was utilized to a 4-inch top diameter, it was hardly evi- 
dent 10 years later that any slash had been left. Fire hazard on 
such areas will probably be greater than in the uncut stands for a 
number of years, but whether the expenditure, which averages $10 
an acre for piling and burning all slash, is warranted, depends on the 
degree of fire danger, and this is light in much of the lodgepole 
region. 
Piling and burning slash in all places of special fire hazard, such 
as around sawmills and camps and along main roads (not exceeding 
5 to 10 per cent of the entire cutting area), and lopping elsewhere 
has since 1922 been the plan followed on practically all national- 
forest cuttings in Colorado and east of the Continental Divide in 
Wyoming, including the large operation in Wyoming mentioned 
above. No increase in the acreage burned annually has resulted in 
these forests, even in dry summer seasons — 1924 being the driest 
since 1888. So far no additional fire-protective force has been em- 
ployed, though this may be warranted during seasons of extreme 
hazard. Should a special patrol become necessary, the maximum ex- 
penditure on this account would not anywhere nearly equal the cost 
of piling and burning all slash. It is essential, though, that areas 
of special hazard, such as those mentioned, be cleaned up by piling 
and burning if adequate protection is to be assured. (PL 7, A.) 
In most cutting operations on national-forest lands in the lodge- 
pole type in the northern and western portions of the region, all 
slash was piled and burned prior to 1928. However, beginning with 
that year, the policy outlined above was adopted in those localities, 
except that in the northern and western portions of the region, as a 
modification of this practice, tops not piled and burned are left 
nnlopped. 
In the Engelmann spruce type more slash and debris are usually 
left after logging than are left in lodgepole pine. This is because 
the spruce has more and larger limbs and utilization is generally not 
so complete. However, spruce needles drop off during the first year 
after cutting, unlike the lodgepole needles, which may persist for 
two years or longer. This characteristic is an important reason why 
spruce slash does not ordinarily need to be piled and burned, except 
on specially hazardous areas. The moist sites and short clanger sea- 
son are also important in this respect. Accordingly, on the national 
forests throughout the greater portion of the region (pi. 7, B) the 
spruce limbs are lopped and left, except on areas of special hazard, 
where they are piled and burned as in the lodgepole pine type. How- 
ever, in the national forests of the northern and western portions of 
the region, where conditions are more dangerous, all slash is piled 
and burned. 
Results from lopping slash are different from those obtained by 
merely leaving the tops where they fall, the practice followed on 
private lands. Snow soon crowds the lopped slash close to the 
ground in contact with moisture, instead of leaving it up off the 
ground subject to rapid drying out, Unlopped tops not only make 
hotter fires but seriously interfere with travel and so may retard 
suppression. 
