MORTAUTY PREDICTION FOR 

 NORTH IDAHO SPECIES 



Mortality prediction models were developed for five tree species in north Idaho. 

 Models for western white pine, western larch {Larix occidentat'ts) , Douglas-fir 

 (Pseudotsuga menziesii) , grand fir, and western redcedar (Thuja pl-ieata) are reported 

 in table 2. For each species, table 2 reports the prediction equation, the number of 

 observations used in the analysis, and the means and standard deviations for diameter 

 at breast height and for variables used in the prediction equations. The means and 

 standard deviations of the variables are reported so users are aware of the limita- 

 tions of the models and to enable users to select populations to which the models may 

 be applied with confidence. 



In table 3, annual mortality rates are reported for western hemlock (Tsvtga 

 heterophylla) , lodgepole pine {Pinus contorta) , Engelmann spruce [Picea engelmannii) , 

 subalpine fir {Ahies lasi-ocarpa) , and ponderosa pine {Pinus ponderosa) in north Idaho. 

 Because of limited data and low mortality rates no significant predictors of mortality 

 were found for these species; therefore, only annual mortality rates are reported for 

 these five species. The number of observations, and the mean and standard deviation 

 of the diameter distribution are reported for each species to indicate limitations of 

 the data. 



The "optimal" models for grand fir and western redcedar use the variables, crown 

 class and percent defect. The variables are not available in the growth prognosis 

 model (Stage 1973) in which these models are to be used. Further, percent defect fre- 

 quently is not measured in forest surveys. Thus, the alternative models in table 4 

 were developed using more available independent variables. 



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