. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. Figure 155. — Ultramafic rock outcrops in Washington typically consist of open woodlands and barren slopes; left, landscape mosaic on ultramafic slopes and, right, local outcrop of serpentine showing the extremely barren openings (Teanaway River drainage, Wenatchee National Forest; photos cour- tesy A. R. Kruckeberg). pentine sites from 300- to 2,000-meter eleva- tion (Whittaker 1960; Waring 1969). Pinus jeffreyi is typically the only tree species pres- ent in these open woodlands (fig. 154) along
. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. Figure 155. — Ultramafic rock outcrops in Washington typically consist of open woodlands and barren slopes; left, landscape mosaic on ultramafic slopes and, right, local outcrop of serpentine showing the extremely barren openings (Teanaway River drainage, Wenatchee National Forest; photos cour- tesy A. R. Kruckeberg). pentine sites from 300- to 2,000-meter eleva- tion (Whittaker 1960; Waring 1969). Pinus jeffreyi is typically the only tree species pres- ent in these open woodlands (fig. 154) along with a rather sparse growth of grasses (, Stipa lemmoni, Sitanion jubatum, Melica gey- eri, Elymus glaucus, and Festuca ovina) and occasional Arctostaphylos viscida. Forests, in- termediate in elevation and moisture regime, are typified by a sparse and xerophytic ap- pearance and dominated by a mixture of sev- eral conifers — Pseudotsuga menziesii, Libo- cedrus decurrens, Pinus jeffreyi, P. monticola, P. lambertiana, and P. attenuata (Whittaker 1960). Associated with them is a dense layer of sclerophyllous shrubs such as Quercus vac- cinifolia, Lithocarpus densiflora, Vaccinium parvifolium, Garrya buxifolia, and Umbellu- laria californica. Herb coverage is generally low but rich in species. Whittaker (1954b, 1960) has commented at length on the "two- phase" or patchwise distribution of the shrub cover in these forests with essentially closed shrub patches alternating with herbaceous openings. On more mesic sites the shrubs form the matrix, but on more xeric sites the herbaceous openings are dominant. Other community types described on Siski- you serpentines include: Chamaecyparis lawsoniana-Pinus monticola-Pseudotsuga men- ziesii stands, with a dense shrubby understory in ravines and draws, and higher elevation for- ests dominated by Abies concolor and Pseu- dotsuga menziesii and Pinus monticola, singly or collectively, over a Xerophyllum tenax and Arctostaphy
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