By the ecological classification developed 

 by Daubenmire, 1 the majority of plots fell 

 into the Thuja-Tsuga/ Pachistima habitat 

 type. The only other types represented were 

 Abies grandis/ Pachistima and Thuja/ Pach- 

 istima, each with about 10 percent of the plots. 



From the 108 plots, we had a total of 483 

 recorded observations of height of western 

 white pine and trees of associated species. 

 These records include some remeasurements 

 of several trees at different ages. Adequate 



data for analysis were found for five of white 

 pine's common associates — western larch, 

 lodgepole pine, Douglas-fir, grand fir, and 

 western hemlock. Western hemlock and lodge- 

 pole pine had fewer than half as many mea- 

 sured height comparisons as the others, but 

 the important age-class range between 20 and 

 80 years was quite well represented (table 1). 



1 Daubenmire, R. Forest vegetation of northern 

 Idaho and adjacent Washington, and its bearing on 

 concepts of vegetation classification. EcoL Monog. 

 22:301-330. 1952. 



Table 1 . — Number of observations of comparative height between 

 western white pine and other species,, by age class 



Age class 



Western 



Lodgepoie 



Douglas- 



Grand 



Western 



(years) 



larch 



pine 



fir 



fir 



hemlock 



21-40 



28 



14 



34 



38 



26 



41-60 



82 



61 



80 



79 



30 



61-30 



116 



41 



106 



77 



29 



81-100 



39 



2 



27 



35 



23 



101-120 



2 







12 



16 



8 



121-140 



3 







9 



11 







Total 



270 



118 



268 



256 



116 



STATISTICAL METHODS 



Multiple linear regression analysis was 

 used to develop equations for (1) estimating 

 the height . of five alternative species from 

 site data that included western white pine 

 height or site index, and (2) estimating west- 

 em white pine site index from known heights 

 of the alternate species. The variables enter- 

 ing into the analyses are noted below. 



Estimating Height of Alternative Species 



The dependent variable was the average 

 height of dominant and codominant trees at 

 given 3tand age for any single species other 

 than white pine. Thirteen independent vari- 

 ables were included in the gross analyses for 

 each species: 



L Western white pine site index (WPSI 2 ) : 



Determined from stand measurements and 

 reference to published site index curves. 3 

 Watt* had already verified validity of these 

 curves for general application. 



2. Stand age (A): As defined by Haig, 5 

 the age of the oldest tree, providing it does not 

 differ by more than 3 years from the age of 

 the next oldest tree. 



^Abbreviated variable designation as used in subse- 

 quent equations. 



1 Haig, Irvine T. Second- growth yield, stand, and 

 volume tables for the western white pine type. US. 

 Dept. Agr. Tech. BuL 323, 67 pp. 1932. 



*Watt, Richard F. Second-growth western white 

 pine stands: site index and species changes; nor- 

 mality percentage trends; mortality. UJ5. Dept. 

 Agr. Tech. BuL 1226, 60 pp. 1960. 



i Haig, op. cit. 



2 



