He O MRE Swe Roe ha Sa OmOm etwas Ombre he tehe DAO GE A'S = FoTeR REG I © N 
Depletion 
O ONE now knows, or will ever know, what 
the volume of timber in the Douglas-fir re- 
gion was before the coming of the white 
man. It is therefore quite impossible to compare 
the volume of the present stand with that of pre- 
histeric times and thus compute the depletion that 
has resulted from the activities of civilization. It 
is certain that the primeval forest was far from 
carrying, on every acre, the maximum volume of a 
fully stocked, mature forest. Fires, windstorms, 
insects, and diseases had always taken their toll 
and kept certain areas understocked or temporarily 
stripped of large living timber. But it must be as- 
sumed that before the interference of man the for- 
ests of the region maintained from decade to decade 
and century to century a generally constant vol- 
ume; that the natural agencies of depletion were 
constantly at work but were substantially in equil- 
ibrium with growth. — 
Since the region has been settled and industrial 
activity begun there has been great acceleration of 
depletion, particularly by cutting and fire, and the 
natural equilibrium has been upset. Though for- 
ests are a renewable resource, so active has been 
the harvesting of mature timber that the regrowth 
has not been able to keep pace, and depletion of 
the forest capital has resulted. It appears now 
that the saw-timber volume of the Douglas-fir re- 
gion is being depleted about four times as fast as 
it is being replaced by growth. 
The current annual depletion of saw timber from 
all causes is estimated to approximate 8.3 billion 
board feet. It should be remembered that the de- 
pletion considered here includes only that caused 
by man and by epidemics and catastrophes, not 
the normal losses that take place in any forest in 
eee 
a virgin state; normal losses due to causes such as 
scattered wind throw, decay, incidental insect kill- 
ing, surface fires, and suppression in crowded 
stands had been allowed for in the preparation of 
the growth and yield tables used in the survey. 
Nor does it include material unutilized in logging, 
as is explained later. 
The principal agent in this 8.3 billion board foot 
annual gross reduction in the forest inventory is 
cutting, which has been active at an accelerating 
rate in recent decades. Fire, also, is an important 
cause of forest destruction, particularly in second- 
growth stands; it is far more destructive than can 
be measured in terms of volume of timber killed. 
Forest-destructive agents of secondary significance 
in this particular region are insects and wind throw. 
Cutting Depletion 
The statistics of depletion from cutting herein 
given include only material actually removed from 
the woods as a result of harvesting operations; they 
do not include sound material left in the woods, 
because the inventory statistics and the growth cal- 
culations included only the usable part of the tree 
wherever the board-foot unit of measure was em- 
ployed. A study of logging waste in the Doug- 
las-fir region made by the Forest Service in 1926-27 
(6), along with information obtained by the survey, 
formed the basis for adjusting gross volume and 
growth figures to volume actually removed in log- 
ging. The results of this study indicate that nearly 
144 billion board feet of sawlogs were left in the 
woods after logging in 1926 when the total sawlog 
production amounted to about 10 billion board 
feet. 
