CLIMAX COMMUNITIES : PRESENT DISTRIBUTION 



279 



To the north of the Puget Sound region, Sitka spruce (Ficea 

 sitchensis) becomes increasingly important as the forest becomes 

 more closely associated with coastal conditions. Although it has 

 subclimax characteristics near its southern limits, Sitka spruce be- 

 comes, with Tsuga heterophylla and T. mertensiana, an important 

 climax dominant in the northern extension of the forest. 75 At its 

 extreme limit in Alaska, the coastal and boreal forests merge and 

 both P. sitchensis and P. glanca are found at timber line advancing 

 into the tundra. 110 



Southward, the important species of the Puget Sound center 



&«s? 



FIG. 146. Successional community of western white pine (Pinus monti- 

 cola) and western larch (Larix occidentalis) in Idaho. Understory of Thuja 

 plicata and Tsuga heterophylla —U . S. Forest Service. 



extend down the low coastal mountains into Oregon with Port 

 Orford cedar (Chamaecy parts laivsoniana) as an added climax 

 species and Douglas fir of relatively greater importance. 195 Along 

 the coast, however, Sitka spruce is replaced by redwood (Sequoia 



