every unit, but the discrepancy in cubic-foot growth 

 is relatively small. Cubic-foot increment is pro- 

 gressing at a comparatively satisfactory rate in 

 the existing immature stands, particularly in the 

 Deschutes River and in the three Blue Mountain 

 units. The deficiency of board-measure growth so 

 pronounced in every unit is additional evidence of 

 the low quality of current increment. The situa- 

 tion is due largely to the dearth of saw-timber-size 

 growing stock in the immature stands. 



As cutting continues to convert virgin to growing 

 stands, and as the existing immature stands increase 

 in age, board measure growth will increase sub- 

 stantially without change in forestry practice, but 

 the quality of such growth will be low for many 

 decades. Growth can be further increased in vol- 

 ume, and also materially in value, only by improved 

 cutting practices. 



Comparison of Growth and Drain 



The Current Situation 



Normal regional mortality depletion 7 — princi- 

 pally from insect, windfall, and disease loss — added 

 to the average depletion from cutting and fire dur- 

 ing the recent past (table 27) — 1,259 million board 

 feet for cutting and 87 million board feet for fire — 

 gives a total depletion figure of 2,272 million board 

 feet, or twice the gross annual growth. The re- 

 gion's saw-timber stand is thus being reduced by 

 1,127 million board feet annually. If, however, 

 comparison is made directly between that portion 

 of the total growth which is currently effective, i. e., 

 between net growth and cutting depletion plus fire 

 loss, the ratio of saw-timber drain to growth is 

 about 6 to 1. 



On the same basis but in terms of cubic feet, 

 current gross growth is 73 percent of gross deple- 

 tion. Current net cubic-foot growth is 52 percent 

 of net cubic-foot depletion, and (table 27) the 

 regional cubic-foot volume of wood is being cur- 

 rently reduced by approximately 126 million 

 cubic feet annually. 



The annual net reduction in timber volume in 

 the region amounts to 0.9 percent of the saw-timber 



i Estimated normal mortality for immature stands plus 

 loss allowance for virgin stands equal to total gross growth 

 therein. 



stand, but to only 0.4 percent of total cubic volume. 

 The disparity between these percentages is further 

 evidence that net growth is occurring principally 

 on small trees of low quality while larger, more 

 valuable trees are being harvested in logging 

 and killed by insects. Net saw-timber growth is 

 exceeded by depletion from cutting and fire in 

 every unit in the region and net cubic-volume 

 growth in all but the North Blue Mountain units. 

 Growth in these units also is substantially exceeded 

 by depletion on a value basis. 



Fortunately, as already implied, the region's 

 timber budget is not out of balance to the extent 

 indicated by these direct comparisons of growth 

 and depletion. The large excess of depletion over 

 growth is partly explained by the fact that three- 

 quarters of the region's commercial forest land is 

 still covered with virgin stands that are considered 

 as making no net growth, although they contain 

 a large saw-timber supply and the land they occupy 

 possesses a substantial growth capacity. Because 

 of this, the regional cut may exceed growth for 

 several decades without damage; in fact, if such 

 cut is confined to the most mature or decadent 

 trees, the eventuality of greatly increasing net 

 growth can be highly favorable; the extent and rate 

 of increase and the quality are all directly depend- 

 ent upon the character of forestry practice that 

 will prevail. In the region's principal sawmill 

 centers, however, even the best of forestry measures 

 cannot increase net growth to equal the current 

 overcutting. 



Comparison of Potential Growth and Depletion 



Total potential saw-timber growth exceeds 

 recent regional depletion from cutting and fire 

 by about 51 percent. The productive capacity 

 of the ponderosa pine sites alone is about 5 percent 

 greater than recent saw-timber depletion. In 

 terms of cubic volume, however, the growth 

 capacity of the ponderosa pine sites is only 83 

 percent of total drain from cutting and fire. 

 Potential cubic-volume growth of all sites exceeds 

 depletion by 25 percent. As shown in the last 

 two columns of table 27, physical opportunity for 

 net saw-timber growth eventually exceeding cur- 

 rent drain exists in all but Deschutes River and 



50 



