Although there was no significant difference in sur- 

 vival between the three aspects, the causes of mortality 

 differed widely. Gophers were responsible for 48 and 

 35 percent of the total mortality on the northwest and 

 southeast aspects, respectively. The northeast aspect 

 had only 15 percent gopher-kill. Of the mortality on the 

 northeast aspect, 19 percent was caused by sheep graz- 

 ing. From the data collected in this study we cannot 

 explain why we got less gopher damage on the northeast 

 aspect. 



A small amount of frost damage to Douglas-fir did 

 occur during this study, but the data were too limited to 

 determine if any of the site preparations increased the 

 chances of frost damage. 



Because the site preparation treatments tested in this 

 study removed up to 6 inches (15 cm) of topsoil from the 

 immediate vicinity of the planted trees, we suspect that 

 the increased height growth was a response to less com- 

 petition for available soil moisture rather than for 

 nutrients. We need to test a toothed scalping blade that 

 would remove the vegetation but leave most of the top- 

 soil on the scalped area. Another possible method would 

 be use of herbicides to create scalps yet leave topsoil in 

 place. We would expect greater height growth response 

 from both methods, but the more fertile topsoil may 

 allow a quicker invasion of scalps by vegetation. 



As expected, the climax species, Douglas-fir, tended 

 not to perform as well in the large clearcut as the two 

 serai species, ponderosa pine and lodgepole pine. At 

 6,000 ft (1 830 m) ponderosa pine is nearing its upper 

 elevational limit in that part of Idaho. Had the planta- 

 tion been 500 ft (150 m) lower, ponderosa pine may have 

 performed better. In large clearcuts of this nature, 

 unprotected Douglas-fir seedlings are susceptible to frost 

 damage. Where lodgepole pine is an associated species 

 on this habitat type, large clearcuts can be most readily 

 regenerated by planting lodgepole. Douglas-fir and pon- 

 derosa pine can also be established, but perhaps at 

 greater costs. Regeneration of Douglas-fir on this kind of 

 site would be more successful in small clearcuts, group 

 selection cuts, or shelterwood cuts (Steele and others 

 1981; Ryker and Losensky 1983). 



The 2-ft (0.61-m) hand-made scalp is too small on sites 

 with a high coverage of elk sedge. Competition from elk 

 sedge is not greatly reduced because the sedge roots 

 spread well beyond the aboveground plant canopy and 

 still occupy much of the space below a 2-ft scalp. On 2-ft 

 scalps, tree survival was lower and total height was less 

 than on 4-ft (1.2-m) machine-made scalps and 8-ft (2.4-m) 

 dozer strips. This was especially true of the pines. 



In deciding how big the scalps must be to insure seed- 

 ling survival at a minimum cost, many factors must be 

 considered. High temperature and plant water stress are 

 the most common reasons for seedling mortality in the 

 Northern Rocky Mountains (Running 1982). If vegeta- 

 tion is light and moisture is adequate as described by 

 Miller and Breuer (1984), little or no site preparation 

 may be required. It appears that on hot and dry sites a 

 more extensive site preparation is needed. Although not 

 as important here, competition for nutrients and light 

 should also be considered. Scalping removes topsoil and 

 nutrients from the seedling microsite, which may cause a 

 reduction in initial growth on some sites. More study is 

 needed in this area. Competition for light is important to 

 remember on sites supporting taller grasses, forbs, and 

 shrubs. The best we can do is match the species to the 

 site and then give the seedlings as much help as they 

 need at the time of planting. 



Elk sedge seems to create severe competition in many 

 central Idaho plantations. Each year of this study, sur- 

 vival of seedlings in the 2-ft scalps fell further behind 

 the 4-ft scalps and strip treatments. The dramatic 

 decline in seedling survival on 2-ft scalps, as seen espe- 

 cially in the first to third years, is similar to what has 

 been observed in plantations of central Idaho. 



Even though elk sedge and other grasses of central 

 Idaho are tough competitors they can be overcome by 

 doing an adequate job of site preparation. Matching the 

 cutting method to the species as well as stand and site 

 conditions, adequately preparing the site before planting, 

 and following up with adequate control of livestock and 

 gophers will help ensure a successful forest plantation on 

 these sites. 



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