Taste 23.—Species distribution of current annual growth in 
conifer stands 1 of the Douglas-fir region 
CUBIC-FOOT GROWTH 
SSeS rrr 
Balsam firs, |‘‘C edars”’ 
Unit Douglas, hemlocks, 4 and other 
and spruces} species 
Puget Sound units: Percent Percent Percent 
North Puget Sound ---_----------- 66 27 7 
Central Puget Sound__----------- 74 22 4 
South Puget Sound_-------------- 88 9 3 
Total’ Ss eee 77 19 4 
Grays: Harbor==2--- == 31 63 6 
Columbia River units: 
Columbia River, Wash____-_---_- 78 21 1 
Columbia River, Oreg__-_-_------- 73 26 1 
Totals Ss a ee ee 75 24 1 
WillamettenRivers=---eossos = oes 82 17 1 
Oregon coast units: 
North Oregon coast--------------- 77 22 1 
South Oregon coast_-------------- 82 11 7 
Total. oo Poe eee | 80 16 4 
| 
South Oregon units: | | 
Umpqua River | 88 | 6 6 
Rogue River=se-- sesso aan | 57 6 37 
Total Bat Se eee ee | 76 6 18 
Revionaveragesss-= 2 - ae eee ae eee 75 21 4 
| 
BOARD-FOOT GROWTH 
Puget Sound units: 
Worth! Puget Sound ===:-222_-=2=- 62 30 8 
Central Puget Sound__- 69 | 25 | 6 
South Puget Sound 88 9 | 3 
Tota] Ms See ae eae | 77 18 5 
ee 
GraysiHarbors == ee | 32 62 | 6 
Columbia River units: 
Columbia River, Wash___-_--__-- 78 21 1 
Columbia River, Oreg____-__---__ 73 25 2 
To tale se eee ee: | 76 23 1 
Willamette River_........------------ | 85 14 | 1 
Oregon coast units: 
North Oregon coast_--_____-_--__- 82 17 1 
South Oregon coast_____---------- | 82 7 
Totalewwet- <1 severe Ue | 82 | 14 | 4 
| 
South Oregon units: 
Umpqua: Rivers) 2222 ese 88 6 6 
mopne River’ = =e sce use acse se 58 5 37 
Tio tal ais ene ae Se 86 | 6 8 
Regioniaverage:~--- 2222 22-2 77 19 4 
1 On commercial conifer forest land. 
58 
producing most of the board-foot growth. As the 
old-growth timber is harvested and replaced by 
young stands, growth will increase. More signifi- 
cant are the comparisons between depletion and 
realizable mean annual growth and between deple- 
tion and potential annual growth. 
It is particularly significant, however, that the 
timber depletion of the region is principally in the 
high-quality material and that the volume being 
added by growth is of relatively poor quality. 
Hence the spread between current growth and de- 
pletion is much greater on a value than on a volume 
basis. In this connection it should be borne in 
mind that the successful application of selective 
timber management might greatly increase the 
average quality of the net volume increment. 
Hardwood stands occupy 1.1 million acres and 
are making an annual growth of 31 million cubic 
feet or 72 million board feet. These totals each 
represent 3 percent of the region’s total current 
growth. 
Realizable Mean Annual Growth 
The computation of realizable growth assumes a 
uniform rate of growth to assumed age at depletion. 
It prorates and credits the estimated growth of 
every stand, whether present or prospective, to the 
whole of its estimated life. 
Although the concept of realizable mean annual 
growth is not entirely new, the present technique 
for computing such growth, which is explained in 
detail in the Appendix, is original and the term 
“realizable mean annual growth” is believed to 
have been used for the first time in connection with 
the growth phase of the forest survey of this region. 
Results of Computation 
If the present trends of depletion by cutting, fire, 
and other factors continue and if cutting and other 
depletion factors affect forest conditions in the 
future in the same manner as they have in the past, 
the realizable mean annual growth in the region 
for the decade that began with 1933 amounts to 
733 million cubic feet or 3.3 billion board feet. The 
expected conversion of additional areas to second- 
growth conditions increases the realizable mean 
annual growth for the decade 1943-52 to 953 mil- 
lion cubic feet or 3.9 billion board feet. Further 
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