ae 
/4 
WHITE PINE TYP2 
The forests which are et present most valuable, lie within the asso- 
ciation which has been designated by foresters as the white pine type. 
The conviction is inescapable that in certain restricted situations 
at intermediate elevations, such as broad 2lluvial bottoms end gentle 
slopes with northerly exposure and uvon similar benches, the climax 
of this type is represented by stands of Thuja plicata. The effect 
of repeated burning has seemingly prevented completion of succession 
in all but a few sites, and these vary in composition as one passes 
from the north to the south. In the north, in the Pend Oreille and Kan- 
iksu forests, Tsuga heterophylla reacts as a codominant and indeed would 
appear even tc replace the longer-lived Thuja, inasmuch as Tsuga is the 
principal constituent of the understory in the best developed Thuja 
groves. Whether a Thuja or Tsuga climax would be attained generally 
throughout the white nine type is questionable. The critical nature 
of (a) the climate with respect to the growth of Thuja pliceta and 
Tsuga heterophylla, (tb) the basic difference in underlying rock (in 
contrast with that of the Pacific Coast mountain ranges ) which charac- 
terizes most of ovr region, and (c) the ever-recurrent fires which must 
be reckoned with as a natural factor of environment for long veriods 
yast, react together to limit the actuel attainment of this climax ex- 
cept in very local areas. As a result cf these factors the subclimx 
of the Thuja and Tsuga formation, the "white pine tyve" of the foresters, 
has assumed the sractical role of the climax throughout most o° the “or- 
