20 
BULLETIN" 418, U. S. DEPARTMENT OF AGRICULTURE. 
striking. In forests of Douglas fir in western Oregon there are com- 
monly as many as 167 trees per acre, when the diameter of the average 
tree is 16 inches, and 88 trees when the average is 26 inches. 1 
In pure, fully stocked stands in the Blue Mountain region there are 
commonly from 20 to 30 yellow pines per acre over 12 inches in 
diameter, of which but few are over 30 inches. Over large areas the 
average number per acre is ordinarily less than 20. On the slopes of 
the Cascades the number of trees per acre averages somewhat less 
than in the Blue Mountains, but the trees are larger. In mixed 
stands the number of yellow pines of merchantable size is naturally 
less, though the total number of trees of all species is as a rule larger 7 
the moist soil on which the mixed forest grows being able to carry a 
denser stand. 
Table 7 gives an indication of the average number of trees per acre 
and the distribution of their diameter classes in representative 
stands in various parts of the State; it is based on the measurement 
of several large sample plots in each locality. It does not attempt 
to show the comparative density or size of the timber or the mixture 
of species in the several regions, but merely shows by samples the 
variability of Oregon's normally stocked virgin forests. 
Table 7. — Number of trees per acre by diameter classes of yellow pine and of other species 
in several representative stands in central and eastern Oregon. 
Diameter at breastheight. 
Near Austin and 
Whitney, Grant and 
Baker Counties. 
Basis: 258^ acres. 
Near Lookingglass 
Creek, 
Union County. 
Basis: 44 acres. 
Near 
Winlock's 
Mill, 
Wheeler 
County. 
Basis: 
20 acres. 
Yellow 
pine. 
Others. 
Yellow 
pine. 
Others. 
Yellow 
pine. 
Inches. 
2 
3.70 
2.46 
2.22 
2.29 
1.90 
2.01 
2.23 
4.30 
3.44 
2.58 
1.41 
1.04 
.94 
.86 
4.00 
3.00 
3.11 
5.02 
5.11 
5.27 
4.53 
4.00 
3.00 
3.55 
1.41 
1.39 
1.09 
1.07 
4 
11.45 
6 
11.45 
8 
4.50 
10 
2.55 
12 
2.85 
14 
2.80 
16 
2. 21 . 59 
3.43 ; .59 
3. 34 . 45 
1.70 
18 
2.54 
2.65 
2.50 
2.45 
2.26 
1.99 
1.41 
1.15 
.80 
.52 
.37 
.16 
.08 
.69 
.53 
.53 
.41 
.32 
.22 
.20 
.14 
.06 
.08 
.07 
.01 
.09, 
1.35 
20 
2.52 
2.86 
2.75 
2.68 
2.07 
1.41 
1.21 
.68 
.80 
.25 
.36 
.14 
.27 
.57 
.48 
.29 
.32 
.09 
.09 
.07 
.09 
.11 
.09 
1.40 
22 
1.50 
24 
1.65 
26 . 
1.25 
28 
.95 
30 
.55 
32 
.25 
34 
.30 
36 
.10 
38 
40 
42 
Over 43 
.09 .03 
Total 
38.00 ( 18.47 
25. 42 B- 70 
54.81 
34.57 
18.75 
5.40 
46.60 
16.65 
1 Forest Service Circular 175, " Growth and Management of Douglas Fir in the Pacific Northwest, 
Thornton T. Munger. 
by 
