The Pacific Northwest refers to northwestern North America which is bounded by the Pacific Ocean to the west and Rocky Mountains to the east.

Redwood Forest

These magnificent forests are characterized by the giant, endemic conifer Sequoia sempervirens (coastal redwood) (Cupressaceae). These are the world’s tallest trees reaching heights of 112 m and have growth rates close to the world’s maximum. This together with the fact that they have extremely long life spans, sometimes reaching over 2000 years, also results in the greatest biomass accumulation of any know ecosystem. These forests have been in existence for many millions of years, with fossils of Sequoia, dating back as far as the Jurassic Period. They were also much more extensive than they are today, and its generally believed that the last Ice Age limited Coastal Redwoods to their present narrow strip stretching from southern Oregon to Central California. Prior to this, the fossil record shows that they occurred throughout what is now the western United States and Canada, and along the coasts of Europe and Asia. Other endemic or near endemic conifers found in these forest include Chamaecyparis lawsoniana (Cupressaceae), Libocedrus decurrens (Cupressaceae), Torreya californica (Cephalotaxaceae), while other commonly associated conifers include Abies grandis, Picea sitchensis, Pinus contorta, Pinus jeffreyi, Pinus lambertiana, Pinus monticola, Pseudotsuga menziesii, Thuja plicata, Tsuga heterophyllum. Typical hardwood species include various endemic or near endemic species such as Arbutus menziesii (Ericaceae), Lithocarpus densiflora (Fagaceae), Quercus agrifoliai (Fagaceae), Umbellularia californica (Lauraceae)together with Alnus oregona, Acer macrophylla, Fraxinus latifolia, Quercus chrysolepis, Q. garryana and Q. kelloggii. Forests of the alluvial flats and moist lower slopes have the lushest under stories with many herbaceous species such as Anemone deltoides, Asarum caudatum, Disporum smithii, Hierochloe occidentalis, Oxalis oregana, Tiarella unifoliata, Trillium ovatum, Viola glabella and ferns such as Polystichum munitum. Stands in the middle and upper slopes differ somewhat in having understories characterised by evergreen shrubs such as Gaultheria shallon, Rhododendron macrophyllum and Vacccinium ovatum.

Klamath-Siskiyou Mixed Evergreen Montane Forest

These typically include Pseudotsuga menziesii with one or more evergreen hardwoods such as Arbutus menziesii, Castanopsis chrysophylla, Lithocarpus densiflorus and Quercus chrysolepis. Stands are usually two-storied with Pseudotsuga forming a canopy up to 65 m and emerging above the hardwood canopy by up to 35 m. The shrub layer typically includes Arctostaphylos nevadensis, Berberis nervosa, Holodiscus discolor, Lonicera hispidula, Rhus diversiloba, Rosa gymnocarpa and Symphoricarpos mollis, while among the common herbs are Achlys triphylla, Chimaphila umbellata, Goodyera oblongata, Linnaea borealis, Smilacine stellata, Trientalis latifolia, Xerophyllum tenax, and the endemic Whipplea modesta (Hydrangeaceae). At higher elevations Abies concolor may dominate in virtually pure conifer stands and it is within this zone that the near endemic Pinus breweriana (Pinaceae) predominantly occurs. Common shrubs within this zone include Amelanchier pallida, Arctostaphylos nevadensis, Berberis dictyota, Cornus stolonifera, Corylus cornuta var. californuca, Paxistema myrsinites, Quercus sadleriana, Ribes lobbii, Rubus parviflorus and Symphoricarpos hesperis, while the many herbs include Achlys triphylla, Clintonia uniflora, Frageria californica, Stellaria jamesiana and endemics such as Adenocaulon bicolor (Asteraceae), Vancouveria hexandra (Berberidaceae) and Vicia americana var. oregona (Fabaceae).

Sierra Nevada Mixed Conifer Montane Forest

These predominantly mid-montane forests are the most extensive forest type in California, and typically include conifers such as Calocedrus decurrens, Pinus contorta, P. jeffreyi, P. lambertiana, P. ponderosa, Pseudotsuga menziesii, and hardwood species like Acer macrophyllum and Quercus chrysolepis. However, the tallest trees found here are the famous, endemic giant redwoods Sequoiadendron giganteum. These are the most massive living things on the planet with some specimens reaching heights of up to 85 m and have diameters of over 10 m at their bases. Some of the larger trees are over 3200 years old.

Abies amabilis-Tsuga heterophylla Sub-Alpine Forest

These forests characterize the mountain regions from the central Oregon Cascades north through the mountains of southern British Columbia and the Olympic Mountains. They contain a mixture of temperate and sub-alpine species. Abies amabilis, Abies procera, Pinus monticola, Pseudotsuga menziesii and Tsuga heterophylla are the typical trees. The shrub layer usually includes Acer circinatum, Berberis nervosa, Oplopanax horridum, Rhododendron albiflorum, Ribes lacustre, Rubus spectabilis and several species of Vaccinium including V. alaskaense.


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