PIPER FLORA OF THE STATE OF WASHINGTON. 41 



the red fir {Pseudotsuga mucronata) which in the Puget Sound region 

 often makes up over 90 per cent of the forest over large areas (PI. 

 VII), and up to an altitude of 1,000 meters seldom forms a smaller 

 element of the total forest than 60 per cent. Nearly all of western 

 AVashington below the altitude mentioned possesses this character- 

 istic red fir type of vegetation, except a narrow strip along the 

 Pacific Ocean. Here the Sitka spruce {Picea sitcheTisis) becomes 

 the dominant tree, making up from 25 to 75 per cent of the forest, 

 while the red fir falls to 10 per cent or less. This narrow strip has 

 been considered as belonging to the next higher zone, the Canadian, 

 but for reasons hereafter expressed we would include it in the Humid 

 Transition. 



The principal features of the vegetation of western Washington 

 may be discussed under the three heads of the principal types of soils, 

 namely, the Uplands, the Bottom Lands, and the Gravelly Prairies. 

 Plant associations of lesser importance, but of marked character, are 

 those of the seashores and of sphagnum bogs. 



UPLANDS. 



The vegetation of the uplands throughout the Pacific area in 

 AVashington is a plant association in which the red fir predominates. 

 The size of this tree and the luxuriance of the associated plants 

 varies with the character of the soil, but otherwise the formation is 

 remarkably uniform. In forests in dry or sterile soils the commonest 

 undershrubs are salal {Gaultheria shallon) and Oregon grape {Ber- 

 heris nervosa)^ while the bracken fern {Pteridium)\ii the most con- 

 spicuous herb. Shrubs or trees of Scouler willow {Salix scouleriana) 

 are also constantly associated. 



In better soils the same shrubs remain, but the salal especially 

 becomes much more luxuriant, often forming almost impenetrable 

 thickets. When, however, the red fir is at its best, forming dense 

 forests into which the sun scarcely penetrates (PI. VIII) the salal 

 and Oregon grape are usually much less conspicuous. Under such 

 circumstances the ground is covered with a thick layer of mosses and. 

 scattered crowns of Chamisso's shield fern {Polystichnm munitum). 

 Among the few shrubs which thrive in such dense shade is the red 

 huckleberry {Vaccinium parvifoUum) . Following the destruction 

 of a red fir forest by logging and subsequent burning, as has been too 

 commonly tjie case, there is a marked sequence in the plants that 

 appear, usually as follows: The first are nearly always the fireweed 

 {Epilohium spicatum,) and the bracken {PteHdinm). These are 

 closely followed by the dewberry {Ruhus macropetalus) which the 

 folloAving year fruits heavily and then gradually disappears. The 

 thimbleberry {Rubus parvifiorus) is often abundant also, as is red- 



