76 BULLETIN 12M, U. S, DEPARTMENT OF AGRICULTURE 
useless expenditure of money. The present degree of protection 
results in an average fire rotation of 160 years for timberlands, even 
including the open and understocked stands, and an average of less 
than 30 years for brush fields. It may, therefore, fairly be said that 
the objects of protection are being measurably accomplished in one 
case and are not in the other. 
The minimum-cost theory is particularly difficult to use in con- 
sidering brush fields and cut-over lands. It may well be impossible 
to justify statistically*the necessary expenditures for complete exclu- 
sion of fires, the fundamental requirement once an area of brush land 
is dedicated to the production of timber. But no halfway measures 
can apply. This study has shown clearly that the primary need of 
this class of land is complete protection. Any theory which fails to 
recognize this must ultimately fail in its application and can at best 
result in merely maintaining the status quo. The brush fields, as 
now, will continually be just coming into a state of productiveness, 
after a period of decades devoted to the establishment of reproduc- 
tion, only to be again swept by fire. 
Thus the principal difficulties in a plying the minimum-cost theory 
of protection to restocking brush fields are: 
1. The factor of damage in the equation can not be readily deter- 
mined because it depends on an assumed interest rate, on assumed 
stumpage values, and on a knowledge of yields which we do not pos- 
sess. : 
2. The expenditure for protection during the first timber rotation 
is partly a capital investment and can not be charged entirely to the 
initial crop, for adequate protection not only assures the maturity 
and harvest of the advanced growth already on the ground, but per- 
petuates the forest without the expense of artificial regeneration. 
THE MINIMUM DAMAGE THEORY. 
The most simple and direct statement of our objectives as applied 
bo forest lands is contained in what is termed the minimum-damage 
theory. 
To Hike extent that present expenditures make it easier and more 
certain to establish future forest crops after the first is harvested; 
to the extent that systematic fire exclusion produces a type of cover 
which makes fire protection itself more easy; to the extent that site 
quality improves as a result of fire protection—to this extent it is 
evident that a great part of the money that must be spent in grow- 
ing the first timber crop can not be properly charged against that 
crop. It is a capital investment in the land itself which will benefit 
successive timber crops. 
Kven the most ardent advocate of forest production will recognize 
that on very poor sites and where logging is physically impossible the 
deliberate production of timber for a wood crop can not be justified, 
but the danger of confusing current and capital expenditure is that, 
through mathematical computation and by charging all expenditures 
to the initial crop, it is easily possible to make timber production even 
on favorable sites appear financially unwarrantable. 
Systematic fire protection in the virgin forest has as its object not 
merely preventing losses, but building up the forest and the quality 
of the land itself, both of which are, in part, capital investments. 
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