inevitable. Even so, this obtainable growth could 

 be achieved on the whole of the region's commer- 

 cial forest land only after years of careful and 

 effective forest-land management. 



It was anticipated that, under reasonably inten- 

 sive management, timberland sites rated accord- 

 ing to the ponderosa pine classification would 

 produce 60 percent of normal yield-table incre- 

 ment and woodland sites 20 percent. For sites 

 rated by the Douglas-fir classification, an average 

 increment of 75 percent of the full yield-table 

 value was assumed. Growth equal to or in excess 

 of these adjusted standards is now found in many 

 parts of the region's natural forests, uniformly over 

 areas of several thousand acres. The adjusted 

 mean annual growth rate for each site-quality 

 class was multiplied by the corresponding acreage, 

 and the sum of the resulting products is the esti- 

 mated potential growth (table 24 and fig. 20; 

 also, for rates used in making these calculations, 

 . table 42 in the appendix). 



Of the 658 million cubic feet of wood, or 2 billion 

 board feet of trees 11.1 inches d. b. h. or more 

 that sustained-yield forest management can pro- 

 duce annually on the 16.2 million acres of com- 

 mercial conifer land, the four Oregon units, com- 

 prising 63 percent of this area, have about 61 

 percent. 



Approximately three-quarters of the commer- 

 cial forest land, including about 69 percent of the 

 potential growth, is in ponderosa pine sites, and 

 these represent 81 percent of the growth capacity 

 of eastern Oregon, but only 51 percent of that for 

 the Washington units of the region. Seven per- 

 cent of the ponderosa pine lands is in woodland 

 sites, but these include less than 2 percent of the 

 pine-site growth capacity. 



One-half of the region's commercial forest land 

 and of its productive capacity is in the national 

 forests, one-third is privately owned, and the 

 remainder is principally in Indian ownership. 

 Forest lands legally reserved from cutting have 

 about 2 percent of the timber-growth capacity. 



The extent to which yield can be increased when 

 opportunity is afforded for marketing thinnings 

 varies with utilization standard or type of prod- 

 uct, as well as with site quality, age, and density 



Table 24. — Potential annual growth i on commercial forest 

 sites in the ponderosa pine region 





Area 



Growth 

 on all 

 trees 



Growth on saw- 

 timber trees 



State and unit 



Total 



Pon- 

 derosa 











pme 





Thou- 



Million 



Million 







sand 



cubic 



board 





Eastern Washington: 



acres 



feet 



feet 



Percent 



Chelan-Colville . .. 



3,525 



2,177 



140 

 104 



408 

 342 





Yakima River _ . 



45 



North Blue Mountain. . . 



2?8 



12 



36 



49 



Total 



5.990 



256 



786 



51 







Eastern Oregon: 











North Blue Mountain. . 



2,244 



90 



260 



64 



Deschutes River _ .. 



2,016 



79 



252 



84 



South Blue Mountain ... 



2,925 



110 



337 



86 



Klamath Plateau.. .. _. 



2,993 



123 



402 



86 



Total 1 



10, 178 



402 



1,251 



81 







Region total . . ... 



16, 168 



658 



2,037 



69 







1 Growth in cubic feet is shown for that portion of the stem of all trees 

 5.1 inches or more in d. b. h. between stump and a top 4 inches in diam- 

 eter inside bark, exclusive of bark and limbwood. Growth in board feet 

 is shown for all trees 11.1 inches d. b. h. or more estimated in 16-foot logs 

 to an 8-inch top, Scribner rule. 



of stands. No allowance was made for this factor 

 in computing potential growth, but analysis of the 

 normal yield-table mortality rates reveals that the 

 maximum increase in yield derivable from this 

 source may approximate one-third of the cubic 

 measure yields shown in the published tables 

 (70, 12). 



Comparison of Current, Probable Future, 

 and Potential Growth 



Growth status as of 1936, summarized in table 

 25 in comparison with probable future and 

 potential growth, shows that stands that are mak- 

 ing net growth are contributing cubic-foot growth 

 nearly proportionate to the area they occupy, but 

 less than half the board-measure increment of 

 which the sites are capable. This is due chiefly to 

 the fact that the clear cutting and heavy selection 

 cutting prevailing in the past have so depleted the 

 residual stands of sawlog-size growing stock that 

 many of the stands are below saw-timber size. 

 Board-foot growth rates on these areas may be 



48 



