P/C A/P A/V 



HABITAT TYPE 



Figure 2. --The percent of stands showing active infestation within habitat types. 



By far the most intense beetle activity was found in the Abies lasiocarpa/ 

 Pachistima myrsinites habitat type which exists largely in the middle elevational 

 zone. The high intensity index of 3.4 (figure 2) indicates that the bulk of the 

 stands examined were classed in the medium to heavy categories of susceptible tree 

 killing. The Dell Creek stand, which is described later in this report, exempli- 

 fies the state of advanced stand depletion, succeeded by subalpine fir growth commonly 

 found in a large but undetermined portion of the Abies 1 as iocai'pa/ Pachistima myrsinites 

 habitat type. The incidence of dwarfmistletoe infection ranked relatively low in this 

 habitat type (see figure 2) with an intensity index of 1.9. There is no way of know- 

 ing how much past mortality was caused by dwarfmistletoe in these stands. 



A large proportion of the stands examined in the Pseudotsuga menziesii/ 

 Calamagrostis rubescens habitat type were in the light damage category resulting in a 

 moderate intensity index of 2.2 (figure 2). This index places the type in an 

 intermediate position among the three habitat types with respect to beetle activity. 

 The lowest occurrence of dwarfmistletoe infection was found in the Pseudotsuga 

 menziesii/Calamagrostis rubescens habitat type. The distribution of the disease was 

 spotty with patches of heavy infection interspersed with extensive areas showing little 

 or no infection. 



A high proportion of the 42 stands examined sustained currently active mountain 

 pine beetle infestations. The least activity, 44 percent of stands with active infes- 

 tations, was found in the highest habitat type, Abies lasiocarpa/Vaccinium scoparium 

 (figure 3) . On the other hand, the Abies lasiocarpa/Pachistima myrsinites habitat type 

 ranked first with active infestations in 92 percent of the stands examined. The pine 

 grass type, Pseudotsuga menziesii/Calamagrostis rubescens , was midway with 64 percent 

 of the stands sustaining active infestations. 



7 



