cent) on lands of other ownerships; (3) virtual clear 

 cutting (95 percent of virgin stand per acre) on 

 private lands and heavy selection cutting (75 per- 

 cent) on lands of other ownerships. The third 

 class of cutting practice approximates that which 

 has prevailed prior to the date of the survey; the 

 current trend is toward lighter cutting. In each 

 instance it was assumed that the portion of the 

 stand removed would be the slowest growing of the 

 total. These percentages of cut are employed to 

 illustrate the effect on growth of leaving various 

 densities of reserve stand ; none is necessarily recom- 

 mended as most suitable for any specific forest. 



Relatively little logging is anticipated in the non- 

 pine types during the next 30 years; hence, only one 

 class of practice, clear cutting, was assumed for 

 them. This does not imply, however, that there 

 may not be advantages in selective cutting in these 

 types. 



Owing to the expected conversion of additional 

 areas to growing condition as cutting continues, the 

 estimated net annual increment increases substan- 

 tially in the three decades following 1936 (table 23, 

 fig. 23). If the cutting practice that has prevailed 

 in the past continues, it is estimated that the annual 

 net growth for the region will increase from about 

 220 million board feet in 1936 to about 615 million 

 board feet in 1966. Under a relatively light selec- 



tion cutting of the same total volume in the pine 

 stands, the estimated net growth for the region as of 

 1966 would reach 900 million board feet, an in- 

 crease in growth 72 percent greater than that 

 anticipated under continuation of past practice. 

 Under heavy selection on private lands and light 

 selection on all other, a net annual growth of 815 

 million board feet could be attained by the year 

 1966. 



Light selection cutting not only converts the 

 static or decadent virgin stands more rapidly to a 

 condition of net growth, but also improves the 

 quality of the growth. Also, owing to the greater 

 reserve stand left and the greater volume and qual- 

 ity of growth obtained, a second cut may be 

 taken after a much shorter interval following light 

 selection. 



At present ponderosa pine types contribute only 

 one-half of the net growth, but suffer nearly 90 

 percent of regional depletion. By 1966, however, 

 they will be making from 71 to 80 percent (de- 

 pending on cutting practice) of the net growth 

 and a relatively high percent of it will be occurring 

 in accessible stands of the most desirable species. 



The effect of cutting practice on future growth 

 is obscured somewhat because the growth shown 

 above includes that of existing immature stands, 

 the increment of which could of course be affected 



Table 23. — Periodic saw-timber growth 1 in the ponderosa pine region, 1936-65, by decade and class of cutting practice 



[La million board feet— i. e., 000,000 omitted] 



State and unit 



193&-45 



1946-55 





1956-65 





50-50 



75-50 



95-75 



50-50 



75-50 



95-75 



50-50 



75-50 



95-75 



Eastern Washington: 



Chelan-Colville . ._ .. 



769 



552 



77 



730 



523 



74 



665 



486 



69 



1,284 

 888 

 156 



1,178 

 812 

 146 



962 

 701 

 132 



1,694 

 1,131 



223 



1,567 

 1,046 



208 



1,240 





883 



North Ttlne Mountain 



188 







Total _ - - - 



1,398 



1,327 



1,220 



2,328 



2,136 



1,795 



3,048 



2,821 



2,311 







Eastern Oregon: 



400 

 355 

 271 

 652 



380 

 306 

 246 

 560 



355 

 235 

 200 

 397 



815 



769 



657 



1,377 



736 



657 



570 



1,167 



649 

 446 

 410 

 722 



1,109 

 1,105 

 1,003 

 1,799 



992 



968 



874 



1,590 



858 





676 





629 



Klamath Plateau.. . . 



1,015 







Total .. ... 



1,678 



1,492 



1,187 



3,618 



3,130 



2,227 



5,016 



4,424 



3,178 









3,076 



2,819 



2,407 



5,946 



5,266 



4,022 



8,064 



7,245 



5,489 







i Growth is shown for all trees 11.1 inches d. b. h., or more, estimated in 16-foot logs to an 8-ineh top, Scribner rule. Under each decade is shown 

 results from three cutting methods: (50-50) light selection, removal averaging 50 percent of virgin stand volume per acre on both private and other areas 

 where cutting occurs; (75-50) heavy selection, averaging 75 percent of virgin stand volume per acre on private lands and light selection, averaging 50 per- 

 cent, on other lands; (95-75) virtual clear cutting on private lands and heavy selection on other. 



46 



