TIMBER GROWING IN DOUGLAS FIR REGION 31 
ductive. In such stands the number of trees per acre and the yields 
under minimum measures will not be up to those of so-called 
normal, fully stocked stands. 
The tables which follow * are based on measurements of completely 
stocked forests, and in using them for a forest which is not fully 
stocked a discount must be made proportional to the blanks and 
understocked patches. Also if there is delay in securing the restock- 
ing of the area that delay must be allowed for, as the tables are based 
upon the age of the trees composing the new crop and not upon the 
number of years since the former crop was cut. 
In the yield studies referred to five classes of land were recognized, 
according to their ability to grow timber—excellent, good, fair, poor, 
and very poor. The last two classes are uncommon and are of im- 
portance in only a few restricted portions of the Douglas fir region. 
Accordingly, in the following tables data are presented for only the 
three best qualities of land. i 
In Table 1 is indicated the approximate number of trees of all sizes 
to be found at various ages on 1 acre in a fully stocked stand of 
Douglas fir. Satisfactory but not ideal stocking may be had during 
the first decades with somewhat fewer trees to the acre than are 
indicated in.this table. To get full use of the ground space and to 
produce a second crop of fair quality it is desirable that by five years 
after the slash burn there .be at least 500 established seedlings to the 
acre. If by five years after burning cut-over land has less than 250 
‘established and well-distributed seedlings per acre, it can not be con- 
sidered to be reforesting in accordance with the standards set in this 
bulletin. 
TaBLE 1.—Total number of trees per acre 2 inches in diameter and larger in fully 
stocked stands 
Quality of land 
Age of 
stand 
Excelient| Good Fair 
Years | Number | Number | Number ! 
20 571 880 1, 460 
40 240 385 585 
60 138 288 337 
80 97 159 232 
100 75 123 184 
120 63 101 152 
In attempting to answer the common question, “‘How long does it 
take to grow a crop of timber?” it may be observed that there are 
many tie mills in this territory operating in timber less than 75 years 
old; one mill is known to be operating exclusively in 43-year-old 
timber and getting a satisfactory cut. On poor sites it would take 
very much longer to produce the same size and grade of logs. Table 
2 shows the yield in board feet of fully stocked stands considering 
only those trees of the final crop (not thinnings) which are 12 inches 
and larger in diameter. Close utilization to an 8-inch top is assumed, 
and no allowance has been made for defect or breakage. 
4Tables 1, 2, and 3 are from a manuscript report by Richard &. McArdle, summarizing the results of 
an exhaustive study of the growth and yield of Douglas fir conducted by the Pacific Northwest Forest 
Experiment Station. 
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