20 



BULLETIN 418, U. S. DEPARTMENT OF AGEICULTUEE. 



striking. In forests of Douglas fir in western Oregon there are coin- 

 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.^ 



In pure, fuUy stocked stands in the Blue Mountain region there are 

 commonly from 20 to 30 yeUow 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 yeUow pines of merchantable size is naturally 

 less, though the total number of trees of ah species is as a rule larger, 

 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 mixtm'e 

 of species in the several regions, but merely shows by samples the 

 variability of Oregon's normally stocked virgin forests. 



Table 7. — Nuviber of trees per acre by diameter classes of yellow pine and of other species 

 in several representative standi in central and eastern Oregon. 



Diameter at breastheight. 



Near Austin and 



Whitney, Grant and 



Baker Counties. 



Basis: 258J acres. 



Near Lookiagglass 



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 

 2.21 

 2.54 

 2.65 

 2.50 

 2.45 

 2.26 



4.30 



3.44 



2.58 



1.41 



1.04 



.94 



.86 



.59 



.69 



.53 



.53 



.41 



..■?2 



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 



3.43 i .59 

 3. 34 . 45 



1.70 



18 



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 



1.99 1 .22 



.95 



30 



1.41 

 1.15 

 .80 

 .52 

 .37 

 .16 

 .08 

 .09 



.20 

 .14 

 .06 

 .08 

 .07 

 .01 

 .02 

 .03 



.55 



32 



.25 



34 



.30 



36 



.10 



38 





40 





42 



















Total 



38.00 

 25.42 



18.47 

 5.70 



54.81 

 34.57 



18.75 

 5.40 



46.60 



Total over 12 laches 



16.65 







1 Forest Service Circular 175, " Growth and Management of Douglas Fir in the Pacific Northwest," by 

 Thornton T. Munger. 



