Table 5 — Number of Vaoo-acre plots sampled by classification variables 



Budworm Habitat Regeneration method and site preparation 



defoliation 

 history 



type 

 series^ 





Clearcut 







Seedtree 







Shelterwood 







Selection 





None Mech 



Burn 



Road 



None 



Mech 



Burn 



Road 



None Mech 



Burn 



Road 



None 



Mech 



Burn 



Road 



No 



PSME 



80 



71 



70 



11 



82 



30 



11 



7 



176 



124 



61 



18 



302 



67 



25 



13 





ABGR 



197 



171 



163 



41 



229 



139 



87 



41 



135 



61 



19 



3 



211 



53 



18 



9 





THPL 



193 



193 



251 



44 



133 



129 



4 



31 



265 



31 



10 



29 



256 



31 



3 



30 





TSHE 



275 



123 



232 



53 



150 



34 



3 



16 



172 



51 



2 



13 



122 



48 



35 



17 





ABLA 



149 



121 





18 



134 



109 



51 



14 



139 



68 



20 



13 



106 



16 



5 



8 



Subtotals 





894 



679 





167 



728 



441 



1 56 



109 



oof 





112 



76 



997 



215 



Off 



86 



77 



Yes 



PSME 



66 



155 



146 



8 



138 



63 



75 



3 



275 



61 



72 



3 



153 



50 



16 









ABGR 



174 



251 



493 



51 



99 



56 



47 



15 



304 



171 



70 



32 



113 



90 



22 



13 





THPL 



122 



24 



101 



16 



29 



16 







2 



99 



35 



14 



18 



53 



10 



2 



6 





TSHE 



2 



1 



7 



1 



















8 



6 



5 



2 



8 



1 













ABLA 



94 



168 



282 



48 



89 



91 



40 



10 



135 



89 



49 



14 



181 



47 



13 



12 



Subtotals 





458 



599 



1,029 



124 



355 



226 



162 



30 



821 



362 



210 



69 



508 



198 



53 



31 



Totals 





1,352 1,278 



1,963 



291 



1,083 



667 



318 



139 



1,708 



697 



322 



145 



1,505 



413 



139 



108 



I = 12,128 



'See table 2, footnote 1, for habitat type abbreviations. 



combinations were difficult to find; for example, selection cuttings that were 

 burned. Also, spruce budworm defoliation was rarely foimd in Tsuga hetero- 

 phylla habitat types. 



Probability of Probability of stocking equations predict the probability of at least one 



Stocking estabUshed seedling on a yaoo-acre plot. Separate equations were developed for 



the Pseudotsuga menziesii, Abies grandis, Thuja plicata/Tsuga heterophylla, 

 and Abies lasiocarpa series (appendix B, table 9). A fifth equation was devel- 

 oped for the 683 plots that were sampled on road cuts, road fills, and unmain- 

 tained roadbeds. 



The equations given in appendix B, table 9, were exercised to show the 

 effect of important independent variables on the probabihty of stocking. In 

 figures 2 to 9, independent variables are held constant except those being 

 displayed. Default conditions are an Abies grandis/Clintonia unifLora habi- 

 tat type on the Idaho Panhandle National Forests, north aspect, 30 percent 

 ' slope, 10 years since last disturbance, 3,500 feet elevation, no residual over- 



story, no site preparation, and no planting. 



Figure 2 illustrates the interaction of slope and aspect on predicted prob- 

 ability of stocking. On southerly slopes, the probability of stocking decreases 

 quite rapidly with increasing slopes. On northerly aspects, the probability 

 of stocking increases only slightly as slope increases. 



Increases in the probability of stocking over time differ by aspect (fig. 3). 

 North aspects increase the most rapidly and attain the highest stocking level. 

 South aspects have the poorest stocking over time. East and west aspects 

 are intermediate between north and south. For equations predicting the 

 probability of stocking, the highest rate of stocking over time occurs at the 

 optimum aspect and the lowest rate of stocking occurs at the poorest aspect. 



Habitat types also differ in the rate of stocking over time. These differences 

 are illustrated in figure 4. Of the four habitat types shown (each representing 

 a different equation), the ThujalTsuga series has the highest rate of stocking 

 and achieves the highest stocking level. The probability of stocking on the 

 Abies grandis series increases nearly as quickly as the ThujalTsuga series, 



12 



