)) CLATSOP Wee UMBIA 
COLUMBIIA \ 
t 
e t 
- ee 
RIVER), eee of 
= rer 
WASHINGS “Sa \. HOOD 
TON Portland MULTNOMAH‘ RIVER 
( 
Ti/LLAMOOK 
BAY 
6) 
NORTH ete 
UMPQUA 
DOUGLAS 
RIVER 
MILES 
QO 25 50 
——————e 
O 
JACKSON Survey-unit boundary 
JOSEPHINE ! — -— County boundary 
| RIVER 
' 
Figure 4.—Map of western Oregon showing survey units, counties, and 
important drainages 
to economic availability. Class |! 
includes timber that according to 
estimate could profitably be logged 
under the production and marketing 
conditions that prevailed during the 
period 1925-29; class II, timber that 
under those conditions could be 
logged at a loss of not more than $5 
per 1,000 board feet; and class II], 
all other timber. 
In order to calculate growth and 
volume of immature conifer stands. 
most of these stands were classified 
according to age, in 10-year classes, 
and according to density, in three 
degrees of stocking. If an area were 
70- to 100-percent covered, according 
to the stocked-quadrat method of 
measurement (explained in the ap- 
pendix), it was classified as well 
stocked; if 40 to 69 percent, medium 
stocked; if 10 to 39 percent, poorly 
stocked; and if less than 10 percent, 
nonstocked. 
The term “site quality’? denotes 
the forest-productive capacity of an 
area, determined by the composite 
effect of all climatic and soil con- 
ditions. Site-quality classifications 
based on height of dominant and 
codominant trees at a given age 
have been adopted for the Douglas- 
fir type and the ponderosa pine type. 
The classification for Douglas-fir 
consists of five classes and that for 
ponderosa pine of six classes; in each 
case, the highest class is designated 
I. The Douglas-fir classification was 
employed for all forest-cover types 
in the region except ponderosa 
nomic influences and industrial conditions. In pine, lodgepole pine, subalpine, oak-madrone, 
most cases unit boundaries were made to coincide hardwood, and noncommercial rocky. The pon- 
with county lines, so that data could be assembled derosa pine classification was used for all ponder- 
by counties. It was impossible to establish abso- osa pine types except woodland. Land occupied 
lutely self-contained units. by the other types listed was not classified by site 
Saw timber was ranked in three classes according quality. 
