Historical maps are useful in areas that have suffered 

 repeated severe outbreaks where remaining stands can 

 be haz£ird rated. Through forest inventory and survey 

 data, forest cover types can be delineated showing 

 mature, overmature, pole, and reproduction-size stands. 

 When location and stand composition are known, maps 

 can be composed depicting susceptible stands. These 

 maps provide a rough hazard rating over large areas, 

 which managers can use to initiate strategies to prevent 

 future infestations or to salvage logs and reduce fuel 

 loads in stands devastated by the mountain pine beetle. 

 Usually managers can expect that another epidemic will 

 begin within 20 to 40 years, when remaining trees reach 

 size classes with phloem thickness conducive to a 

 population buildup (Amman 1975). However, this 

 depends on characteristics of stands and how soon 

 residual trees become susceptible; and it is likely that in- 

 festation recurrence will be prolonged in managed 

 stands. Historical maps, timber type maps, and timber in- 

 ventory surveys C£in provide the basis for hazard rating 

 stands. The ratings can be in very broad, but also ex- 

 tremely accurate, categories (McGregor 1982). However, 

 significant differences occur within areas rated high 



hazard as to the amount and rate at which mortality 

 develops, peaks, and subsides in various stands. 

 Relating mortality with habitat type on a stand basis 

 has helped refine hazard rating of lodgepole pine stands 

 in the Forest Service Northern Region. 



The Insect and Disease Damage Survey Model 

 (INDIDS) (Bousfield 1981) and our Rate of Loss Model 

 were tested using approximately 1,200 stands with 

 mountain pine beetle infestations ranging from 1 year to 

 the end of the epidemic (McGregor £ind others 1982.) The 

 INDIDS Model is used to analyze forest insect and 

 disease data collected from variable or fixed plots. It 

 uses summaries of detailed mensurational data of in- 

 fested and residual green stands— a tree species, size 

 class, and damage class for each designated survey type. 

 Use of INDIDS Model results in computations of tree 

 and volume loss and bascil area killed per acre (Dilworth 

 and Bell 1968). 



The Rate of Loss Model was integrated with the 

 INDIDS Model to estimate mortality trends for infested 

 stands or to obtain loss estimates (tree, cubic, and board 

 foot volume) by diameter class over infestation time for 

 green stands, should they become infested (table-«6). 



.11 



