Figure 14. — In an opening resulting from a group selection cutting in central Idaho, 

 ground was scarified just before seedfall from a heavy cone crop. 



reserve stands did not greatly influence levels of reproduction or stocking 35 years 

 after cutting. In contrast, later cuttings in central Idaho showed a decrease in 

 density of reproduction over a 15-year period following cutting, although stocking 

 remained dense (Wilson 1951) . A 1932 study of cuttings made between 1906 and 1924 on 

 the Boise National Forest showed a striking deficiency in establishment of postlogging 

 reproduction except where 26 years had elapsed since cutting (Curtis 1950) . 



As more information became available from research, the kinds or types of trees 

 removed in these stemwise selection cuttings changed (Keen 1943) . The Dendroctonus 

 bark beetles were found over great areas of the West to be the most important cause of 

 mortality in mature and overmature stands, and marking systems were devised so that 

 those stems considered to be the highest risk were removed in the first cutting (Keen 

 1943; Salman and Bongberg 1942). Silviculturally speaking these were actually sanita- 

 tion cuttings, but the effect of their removal was similar to that of single-tree 

 selection cuttings. 



The group-selection method is adaptable to a wide variety of ponderosa pine stand 

 conditions. Mature trees are removed in groups or patches instead of singly, and the 

 openings thus created provide conditions satisfactory for regeneration in an even-aged 

 structure. In addition to being satisfactory for timber growth, group selection may 

 improve other forest values such as wildlife habitat, water production, and esthetic 

 quality. The openings vary in size but are usually small enough to become stocked 

 naturally. 



In central Idaho the rate and amount of reproduction was studied on scarified 

 areas within openings created by group-selection cutting (Foiles and Curtis 1965b) 

 (fig. 14). Seedfall from a heavy cone crop averaged 245,240 ponderosa pine seeds per 

 acre and ranged from 123,320 to 345,080 per acre. In addition to the pine, an average 



2" 



