. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. mesic sites. Abies magnifica var. shastensis is increasingly common toward the upper limits of the Abies concolor Zone. Pinus contorta is encountered as a pioneer species in the Cas- cade Range. Characteristic understory species in Abies concolor forests are (Whittaker 1960; Waring 1969; Dennis 1959): Shrubs — Holodiscus discolor, Rosa gymno- carpa, Berberis nervosa, Corylus cornuta var. californica, Acerglabrum var. douglasii, Rubus ursinus, R. nivalis, Amelanchier al- nifolia, and Castanopsis chr
. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. mesic sites. Abies magnifica var. shastensis is increasingly common toward the upper limits of the Abies concolor Zone. Pinus contorta is encountered as a pioneer species in the Cas- cade Range. Characteristic understory species in Abies concolor forests are (Whittaker 1960; Waring 1969; Dennis 1959): Shrubs — Holodiscus discolor, Rosa gymno- carpa, Berberis nervosa, Corylus cornuta var. californica, Acerglabrum var. douglasii, Rubus ursinus, R. nivalis, Amelanchier al- nifolia, and Castanopsis chrysophylla. Herbs — Campanula scouleri, Lathyrus poly- phyllus, Anemone deltoidea, Achlys triphyl- la, Trientalis latifolia, Tiarella unifoliata, Galium triflorum, Adenocaulon bicolor, Vancouveria hexandra, Clintonia uniflora, Trillium ovatum, Hieracium albiflorum, Arenaria macrophyllum, Phacelia hetero- phylla, and Fragaria vesca var. bracteata. Successional Patterns Abies concolor appears to be the sole cli- max species on modal habitats (fig. 89). Libo- cedrus decurrens may be a climax associate on more mesic habitats and Pseudotsuga menzie- sii or Libocedrus decurrens or both on xeric habitats. Special Types A variety of nonforested communities is found in the Abies concolor Zone. Brushfields similar to those found in the Mixed-Conifer Zone are encountered. Ceanothus velutinus remains a typical dominant, and Ribes spp. appear increasingly in the Cascade Range. Arctostaphylos patula is a major shrubby as- sociate in the eastern Siskiyou Mountains (Den- nis 1959). Many different kinds of mountain mead- ows and barren openings are also found with- in the Abies concolor and adjacent Abies mag- nifica shastensis Zones. The compositions of these various meadow communities are not known. There is extensive evidence of inva- sion of many of these meadows by tree spe- cies. Libocedrus decurrens is conspicuous as a pioneer tree in many areas (fig. 90); ,. Figure 89. — Abies
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