Abies lasiocarpa/Carex geyeri. These two stands were projected with and 

 without budworm defoUation for the time period 5 years before harvest 

 through 10 years after harvest. 



Results of these four projections are shown in table 7. Budworm decreases 

 the probability of stocking from 0.4109 to 0.3485 for the Pseudotsuga menziesiil 

 Symphoricarpos albus habitat type and from 0.4391 to 0.3005 for the Abies 

 lasiocarpa/Carex geyeri habitat type. Density also decreases in the defohated 

 stands. The Pseudotsuga menziesiil Symphoricarpos albus habitat ty^e has 

 310 trees per acre without budworm compared to 250 with budworm. The 

 Abies lasiocarpa/Carex geyeri habitat ty^e has 450 trees per acre without 

 budworm compared to 295 with budworm. The effect of budworm defoliation 

 on stocking and density can be to reduce stocking below acceptable levels. 



In addition, budworm defoliation changes species composition. The density 

 of host species is reduced; for example, the density of Douglas-fir is 161 trees 

 per acre without budworm compared to 123 with budworm in the Pseudotsuga 

 menziesii/ Symphoricarpos albus habitat type. In addition to changes in species 

 composition, there can be a shift in the proportion of advance and subsequent 

 regeneration within a species. 



Seedling heights are also affected by budworm. Host species are shorter. 

 This is caused by a longer delay to germination of an established seedling or 



Table 7 — Results of projecting two stands with and without budworm defoliation for the 

 time period 5 years before harvest through 10 years after harvest. Results are 

 shown as of 1 years 



Habitat type and elevation 



PSMBSYAL,^ 4,500 ft ABLA/CAGE, 5.500 ft 



Stocking Budworm No budworm Budworm No budworm 



Probability 

 of stocking 



0.3485 



0.4109 



0.3005 



0.4391 



Trees/acre 



250 



310 



295 



450 



Trees/acre 











by species 

 WP2 



















L 



62 



75 











DF 



123 



161 



39 



63 



GF 











11 



25 



WH 



















C 



















LP 



29 



32 



105 



164 



S 











50 



37 



AF 











90 



161 



PP 



36 



42 











Average heights 

 of best trees (ft) 











L 



4.2 



4.4 







DF 



4.9 



4.2 



4.0 



3.9 



GF 







2.8 



3.0 



LP 



3.7 



3.4 



3.1 



3.0 



S 







2.5 



2.7 



AF 







4.1 



3.8 



PP 



5.7 



5.6 







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

 ^See table 1 for species abbreviations. 



32 



