Site Treatment 



The cover species and seedbeds that remain on the site 

 after timber harvesting are influenced by the type of site 

 preparation used to dispose of slash or prepare for artifi- 

 cial regeneration. For most species in most habitat types, 

 scarification resulted in the largest proportion of seedlings 

 (table 5). Moss mats, which were moderately efficient or 

 very efficient seedbeds for most species, usually occurred 

 on sites that had been scarified and occasionally on sites 

 that had been broadcast burned. Broadcast burning 

 resulted in the largest proportion of Douglas-fir seedlings 

 in both the Douglas-fir/white spirea and grand fir/blue 

 huckleberry h.t. 



Table 5— Occurrence of tree seedlings (percentage) by site 



preparation methods for Douglas-fir/white spirea, grand 

 fir/mountain maple, and grand fir/blue huckleberry 

 habitat types 



Scarification 



No Broadcast 



Species preparation burn Light Heavy 



Douglas-fir/White Spirea Habitat Type 





Percentage of 











microplots 



6 



15 



50 



29 



Lodgepole pine 





41 



59 





Ponderosa pine 



19 



22 



44 



15 



Douglas-fir 



8 



58 



27 



7 



Grand Fir/Mountain Maple Habitat Type 





Number of microplots 



15 



7 



55 



23 



Lodgepole pine 







100 





Western larch 







87 



13 



Ponderosa pine 



29 



14 



12 



45 



Douglas-fir 



24 



4 



35 



37 



Engelmann spruce 







80 



20 



Grand fir 



17 



27 



33 



23 



Grand Fir/Blue Huckleberry Habitat 



Type 





Number of microplots 



4 



11 



64 



21 



Lodgepole pine 





29 



42 



29 



Ponderosa pine 







80 



20 



Douglas-fir 





39 



36 



25 



Engelmann spruce 







67 



33 



Grand fir 





38 



24 



38 



Silvicultural Methods 



Silvicultural activities influence the safe site both by 

 altering the availability of site protection and by influenc- 

 ing the dispersal of seed to the safe site. In the Douglas- 

 fir/white spirea h.t., the largest proportion of lodgepole 

 pine and ponderosa pine seedlings was found under 

 shelterwood cuts (table 6). As would be expected, seed- 

 lings occurred predominately in cutting units with a seed 

 source for the particular species present within or close to 

 the cutting unit. In the grand fir/mountain maple h.t., only 

 Engelmann spruce and grand fir were most common in 

 shelterwoods. Western larch and Douglas-fir occurred 



predominately in seed-tree cutting units. In the grand 

 fir/blue huckleberry h.t., lodgepole pine and Engelmann 

 spruce were most common in shelterwood cuts, while 

 ponderosa pine, Douglas-fir, and grand fir were 

 predominate in clearcuts. 



Species 



Lodgepole Pine— Lodgepole pine regenerated best 

 under shelterwood cuts in the Douglas-fir/white spirea and 

 grand fir/blue huckleberry h.t. and best under seed-tree 

 cuts in the grand fir/mountain maple h.t. Lodgepole pine 

 is mostly nonserotinous in central Idaho (Steele and others 

 1981), and the high incidence of lodgepole pine seedlings 

 under the shelterwood was probably because of an ade- 

 quate seed source rather than the environmental condi- 

 tions provided by the residual overstory. In south-central 

 Oregon, Dahms (1963) found that 85 percent of the seed 

 dispersed into clearcuts fell within 66 ft (20 m) of the seed 

 source. Boe (1956) reported that in central Montana, 84 

 percent of the seed fell within 198 ft (60 m) of the seed 

 source. Dahms (1963) recommends that clearcutting units 

 should not be larger than 400 ft (122 m) across. Trappe 

 (1959) suggests using long, narrow clearcuts or seed-tree 

 cuts with seed-trees placed not more than 198 ft (60 m) 

 apart. 



For all three habitat types, most seedlings occurred on 

 sites with light scarification. Trappe (1959), Boe (1956), 

 Day and Duffy (1963), and Roe (1952) also found that 

 lodgepole pine occurred most often on scarified sites on 

 mineral soil. In central Idaho, mineral soil or moss mats 

 were efficient, moderately efficient, or very efficient seed- 

 beds. Most seedlings occurred in moderate shade in all 

 three habitat types. Several covers were moderately effi- 

 cient or very efficient for lodgepole pine including Utah 

 honeysuckle (Lonicera utahensis), thimbleberry, blue 

 huckleberry, and white spirea. 



Western Larch— Western larch seedlings occurred ex- 

 clusively in the grand fir/mountain maple h.t. Most seed- 

 lings were found under seed-tree cuts with a western larch 

 overstory, particularly on sites with scarification. Boe 

 (1953) found that western larch in northwestern Montana 

 dispersed seed up to 396 ft (121 m). Shearer (1959), also 

 working in northwestern Montana, reported that virtually 

 all seed that disseminated farther than 264 ft (80 m) were 

 released during good seed years and that the smaller the 

 seed crop, the shorter the average dispersal distance. 

 Shearer also indicated that most of the seed was dissemi- 

 nated by thermal slope winds generated by warm, dry 

 weather rather than by prevailing winds. Boyd (1969) 

 found in northern Idaho that clearcuts ranging from 264 

 to 462 ft wide (80 to 141 m) produced more seedlings than 

 seed-tree cuts or shelterwood cuts. Mineral soils were 

 the most common seedbeds in other areas (Boyd and 

 Deitschman 1969; Roe 1952). However, in central Idaho, 

 moss mats and rotten wood were very efficient seedbeds. 

 Even though Roe (1952) found more western larch seed- 

 lings in light shade, most seedlings in central Idaho were 

 found in moderate shade, particularly under blue huckle- 

 berry, currant (Ribes spp.), and Utah honeysuckle. 



7 



