commercial types commonly occur at the higher 
elevations, where they are exposed to lightning, the 
principal cause of fires on the national forests. 
The annual loss by fire of saw-timber volume on 
national forests is 0.047 percent of the total na- 
tional-forest saw timber. Very little of the fire- 
killed timber on national forests is salvaged, be- 
cause of inaccessibility to logging operations or 
because the quantity killed on any one area is too 
small to justify salvage logging. 
Outside the national forests the 229,000 acres 
burned over annually during 1926-30 averaged 
1.2 percent of the total. The average annual 
volume loss, not including material salvaged, was 
179 million board feet, or 0.051 percent of the total 
saw-timber stand outside the national forests. 
Acreage burned over is considerably greater than 
on the national forests, largely because causative 
agents are more numerous, climate at the lower 
altitudes is more unfavorable, and the highly in- 
flammable cut-over land types are more prevalent. 
Volume losses would be proportionately much 
greater than on the national forests if salvaged 
timber had been included. Considerable fire- 
killed timber was salvaged on other lands. On 
national forests practically none was salvaged. 
More than one-third of the annual burned 
acreage is recently cut-over land (type 36). During 
1920-32 approximatly 165,000 acres was cut over 
annually, and each year more than half as much 
cut-over land was burned over accidentally, even 
after the slash-disposal broadcast 
burning customarily practiced in western Oregon 
and Washington. Nearly a fourth of the total 
burned acreage was of stands of Douglas-fir seed- 
lings and saplings (type 10). Areas of this type 
were burned over at the rate of 3.2 percent an- 
intentional 
nually. These two types usually occur in the 
vicinity of active logging operations and are ex- 
posed to fire from slash burning of adjacent areas 
and from many other causes. Moreover, they are 
highly inflammable. Undoubtedly, also, they are 
given less effective protection than timber of 
sawlog size. 
Depletion From Other Causes 
Depletion from catastrophic or abnormal causes 
other than cutting and fire is not of great con- 
Tasie 19.—Estimated annual averages | of gross forest-land area 
covered by fire in the Douglas-fir region 
Se 
- 7 Na- Other A 
Type group and type No. penal Tana Sn 
Conifer saw timer (6, 7, 8, 11, 14, 17, 18, 20, | Acres | Acres | Acres 
2OAT 23; 2i ANG oe) = see) ee oe ee ae 7,356 | 35, 631 42, 987 
Conifer second growth, small (9, 12,15,and 21)_| 1,120 | 20,157 | 21,277 
Conifer seedlings and saplings (10, 13, 16, and 
22) ee eee ene ee ane ee ae eee ee 5, 886 | 53, 725 59, 611 
Conifer second growth, small (19, 24, and 28)__ 968 231 1, 199 
Noncommercial (4, 514, 26, 33, and 38)________ 3,135 | 7,808 | 10,943 
Recent cut-over areas (36)_...__________._-__.| 1,039 | 83,797 | 84,836 
Old-cut-over areas, nonrestocked, and _pre- 
viously deforested burns (35 and 37)________| 4,172 | 25,894 | 30,066 
Ward wood timber (31) 225-5..222--_ 2522-2222. 34 | 2,203 2, 237 
INonforestland?(2iand:3) #224 ss- 2 see SEEM see 
Totals ead sen ey they 23,710 |229, 446 | 253, 156 
! For national-forest lands, fire-loss data were averaged for the period 
1924-33, for other land, data are for 1926-30. 
sequence in this region. Losses caused by natural 
phenomena such as landslides, avalanches, floods, 
or sand-dune movement do not form a total merit- 
ing separate consideration and are moreover 
exceedingly difficult to appraise on a region-wide 
and annual basis. Although at present there are 
no disease epidemics in the Douglas-fir region of 
such a scale as to cause extraordinary losses, the 
presence of white pine blister rust in sugar-pine 
stands of southern Oregon threatens serious future 
losses. It has been explained already that the 
current small losses inevitably occurring from 
endemic diseases and normal insect activity, from 
surface fires, from scattered wind throw, and from 
overcrowding in growing stands are allowed for 
in the preparation of growth and yield tables. 
The only such factors requiring separate mention 
are insects and wind throw. 
The only forest-insect species causing material 
losses in the region are the hemlock looper (Ellopia 
fiscellaria var. lugubrosa Hulst.) and Sitka spruce 
aphis (Aphis abietina Walk.) in the spruce-hemlock 
stands near the coast, and the Douglas-fir beetle 
(Dendroctonus pseudotsugae Hopk.) in the Douglas-fir 
forests. ‘Timber are not 
serious in the Douglas-fir region as compared with 
losses due to insects 
the ponderosa pine region of eastern Oregon, for 
example. The most destructive of the insects in 
this region is the hemlock looper, which becomes 
In 1889-91 a severe out- 
in southwestern 
epidemic periodically. 
break of this 
insect occurred 
