COVER TYPE AND FIRE CONTROL 11 
WHAT CONSTITUTES SUCCESSFUL PROTECTION? 
There is no general agreement as to what average annual burned 
area can be accepted and still make timber management on the 
national forests a successful venture. Neither the extent nor the 
value of damage in the different types is known with even approxi- 
mate accuracy. 
A reasonable maximum of acceptable loss might well be based on 
the acreage that can be burned annually without seriously reducing 
the ultimate forest crop, although what the protective organization 
may be expected to attain in the future can not be disregarded entirely. 
Figures to be given later (Table 12) indicate that, at least in the tim- 
ber types, 0.2 per cent loss annually is not too low a mark to be 
reached. Even this low figure would mean a loss of 20 per cent of 
the possible yield of a 100-year ‘“‘crop.”’ A loss of 0.2 per cent a 
year of the area protected can not be completely justified by any 
of the available data, but neither can it be successfully challenged 
merely by proving that present efforts have not attained it. For 
the purposes of discussion, this rate is therefore used as a rough 
criterion to compare with actual accomplishments. In the future it 
may even prove to be too high, as timber acquires a higher value 
and as more forest lands are placed under sustained yield manage- 
ment. 
During the decade 1911 to 1920 the degree of protection in effect, 
averaging good years and bad, resulted in an average annual burned 
acreage of 0.89 per cent of the total area in the timber-producing 
types (grassland, chaparral, and woodland excluded) for the national- 
forest group as a whole. Obviously, this rate of fire loss, which is 
equivalent to burning over the entire forest area in 110 years, is 
altogether too great as compared with the timber-growing rotation 
of 80 to 120 years, even if only part of the destructible value is lost 
after each fire. This is particularly true since only a relatively small 
area was reburned. In this study each fire over 40 acres was blocked 
im on one map, but not over 2 per cent of the areas overlapped as 
reburned tracts. 
Neither has the 0.2 per cent maximum been reached in the chaparral, 
grass, and woodland types. Radical reduction of burned area im 
these types is important, however, since fires originating within them 
will, unless promptly controlled, sweep into adjacent merchantable 
stands of timber or young er owth and destroy in part what has been 
accomplished in the other types. Although the values at stake here 
are not represented primarily by the timber and young growth but 
by the cover as an influence equalizing run-off and minimizing erosion, 
and by the forage, an annual crop, the preservation of these values 
requires a far lower percentage of land burned over annually than 
has thus far been attained. 
WHAT CONSTITUTES NEED FOR SPECIAL PROTECTION? 
Each spring forest protection organizations face the problem of 
determining when the protection afforded by the year-round staff 
becomes inadequate and when special protection measures, such as 
placing of lookouts, fire guards, and road and trail crews are justified 
and needed. A similar problem arises each fall in determining when 
the need is past. A major consideration in the decision, though by 
no means the only one, is how many fires may be expected. 
