60 BULLETIN 1294, U. S. DEPARTMENT OF AGRICULTURE 
When it comes to carrying out light burning in country of broken 
topography the difficulties are tremendous, due to the variable mois- 
ture content of the litter. While it is fairly easy to burn in stands 
where reproduction and brush is scanty and hazard low, it is extremely 
difficult to secure a burn where brush and reproduction, which it is 
desired to remove, are abundant and hazard is relatively high. 
RESULTANT HAZARD REDUCTION 
A single surface fire reduces hazard only temporarily. In one or 
two years the amount of inflammable material on the burned area is 
generally greater than before the fire. Light fires consume but a 
small portion of the inflammable material, and this material is soon 
replaced or even increased by the fall of needles and twigs from trees 
and brush killed but not consumed by the fire. 
It has, indeed, been shown, in the Lassen County fire, that five 
years after the fire the amount of inflammable material was decidedly 
ereater than before the fire. The value of banking trees with earth, 
which had so carefully been undertaken, had been lost, for the rain 
had meanwhile leveled these mounds and litter again reached the 
base of the trees. 
What is unavailing in virgin forest is even less advantageous in 
second-growth stands where even repeated surface fires at frequent 
intervals do not immunize the stand from devastating crown fires. 
Light burning has been carried out successfully only where the 
inflammable material consisted mainly of litter, with only scattered 
brush and reproduction. It has not been successful where large 
amounts of brush and reproduction are present and where the haz- 
ard is consequently high. The practice, therefore, has temporarily 
reduced the hazard only where it is already low. 
INDIRECT COST IN DAMAGE INCURRED 
A light-burning operation may be regarded, at best, as negatively 
successful when no dain ato resuits to mature timber and only moder- 
ate damage to small timber. Unless damage to merchantable timber 
can be prevented by special protection of the individual trees, the 
minimum damage to mature timber is of the same nature and magni- 
tude as that from summer fires, namely, the burning down of some 
fire-scarred trees, usually the largest and most valuable in the stand. 
In addition, an occasional flare-up on even the lightest fire may be 
expected to result in a small amount of heat killing of merchantable 
timber. The enlargement of old fire scars and the creation of new 
ones inevitably occur where fire reaches the trees. Each fire over a 
given area must thus be counted on to take its toll of large trees. 
Light surface fires, like any other, may induce sudden and inten- 
sive epidemics of tree-destroying insects, during which a rate of loss 
from 8 to 12 times as much as the normal rate may be incurred for a 
period of at least two years. 
Surface fires during any season of the year, under any method of 
control, destroy practically all seedling reproduction up to 6 feet high 
on areas actually paid Since these fires are normally patchy, 
however, a single or even a series of light fires does not necessarily 
~ * 
_—~ ——' 
A * = D\e eA aes cae 
Ye eee et ek ek Lee | tke oe 
