Table 6 — Predicted probability of stocking and trees per acre by species for five projections 

 where only habitat type and elevation were changed. Variables held constant were 

 the Idaho Panhandle National Forests, north aspect, 30 percent slope, no planting, 

 no residual overstory basal area, no site preparation, and 10 years since harvest 



Habitat type and elevation 



PSME/PHMA^ ABGR/CLUN TSHBCLUN ABLA/CLUN ABLA/XETE 

 Stocking 3,000 ft 3,500 ft 4,000 ft 5,000 ft 5,500 ft 



Probability 



of stocking 



0.2596 



0.7380 



0.9015 



0.6272 



0.6671 



Trees/acre 



195 



1 li. 



2,<:4o 



/4b 



/DO 



Trees/acre 













by species 













WP2 







49 



129 



16 



22 



L 



18 



30 



5 



18 



82 



DF 



148 



193 



222 



96 



225 



GF 







460 



801 



236 



61 



WH 











682 











C 











268 











LP 



10 



9 



16 



3 



71 



S 







22 



5 



50 



79 



AF 











120 



327 



228 



PP 



19 



9 















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

 ^See table 1 for species abbreviations. 



of 0.7380 and 772 trees per acre. Species composition is more diverse with 

 grand fir having the highest density. 



The Tsuga heterophylla/Clintonia uniflora habitat t/pe has the highest prob- 

 ability of stocking (0.9015) and density (2,248 trees per acre) of the five habi- 

 tat types projected. The Abies lasiocarpa/Clintonia uniflora habitat type regen- 

 erates well to subalpine fir (327 trees per acre). The probability of stocking on 

 this habitat type is 0.6272, and density is 746 trees per acre. 



On the Abies lasiocarpa/Xerophyllum tenax habitat type, the probability of 

 stocking and density are close to the Abies lasiocarpa/Clintonia uniflora habitat 

 type. The probability of stocking is 0.6671, and density is 768 trees per acre. 

 The Abies lasiocarpa/Xerophyllum tenax habitat type has more western larch, 

 Douglas-fir, and lodgepole pine. Grand fir is less frequent. 



These five examples illustrate the diversity of results that can be expected 

 among habitat types. Growth and mortality predictions in the Prognosis 

 Model are also sensitive to habitat type, which helps represent the diversity 

 of ecosystems found in the Northern Rocky Mountains of the Western United 

 States. 



Example of The effects of western spruce budworm on regeneration success have not 



Spruce Budworm dramatic in the separate equations shown thus far. However, the cumula- 



Effects ^^^^ effects of budworm can be quite important, as will be illustrated by exer- 



cising the model with and without budworm. 



Two hypothetical stands were chosen for illustration. The first is a clearcut 

 in the Lolo National Forest in Montana at 4,500 feet elevation, north aspect, 

 30 percent slope, no planting, no site preparation, Pseudotsuga menziesii/ 

 Symphoricarpos albus habitat type, and 10 years since harvest. The second 

 stand is the same except the elevation is 5,500 feet and the habitat type is 



31 



