Name:
Alaskan Maritime Western Hemlock - Sitka Spruce Rainforest Group
Reference:
NatureServe Biotics 2019
Description:
This group is composed of tall evergreen needle-leaved tree-dominated, closed- to open-canopy forests of coastal Alaska from Cook Inlet and Kenai Peninsula south through the mainland and coastal islands of southeastern Alaska, ending at approximately Prince Rupert, British Columbia, along the Alaska-Canadian border. These forests are dominated by <i>Tsuga heterophylla</i> or <i>Picea sitchensis</i> but are also often mixed stands with other conifers often present to codominant, such as <i>Callitropsis nootkatensis</i> and <i>Tsuga mertensiana</i>. Stands of <i>Picea sitchensis</i> are often codominant with <i>Tsuga heterophylla</i>. At the southern end of the range, <i>Thuja plicata</i> may also occur, as well as <i>Pinus contorta</i>. The understory is rich with shade-tolerant shrubs and ferns, including <i>Gaultheria shallon, Vaccinium ovatum, Polystichum munitum, Dryopteris</i> spp., and <i>Blechnum spicant</i>, as well as a high diversity of mosses. Stands are mostly restricted to areas within 25 km of saltwater. They occur within the hypermaritime coastal boreal climatic zones of high precipitation in winter and summer along the coast. The northern limit is the northern extent of <i>Picea sitchensis</i>, where the dominant tree shifts to <i>Picea glauca</i> and climate becomes colder, with a true boreal climate at the coast. The southern limit is based on a transition to a more temperate climate, where minimum temperatures remain above 0°C and summer precipitation begins to decrease, and additional species appear such as <i>Thuja plicata</i> and <i>Pinus contorta</i>. These forests occupy the outermost coastal fringe where salt spray is prominent, riparian terraces and valley bottoms near the coast where there is major fog accumulation and the maritime "interior" part of northern forests, often on steep, well-drained productive slopes. Annual precipitation ranges from 623 to 3235 mm (24-127 inches) with an average of 1464 mm (58 inches), that falls year-round, with the majority falling as rain on the immediate coast, but at higher elevations the climate is wet with heavy snow and rainfall, and coastal winter rains can be heavy. Coldest monthly temperature range from -15° to -1°C (5-30°F). Stands ranges from sea level to about 1000 m (3000 feet) in elevation. These forests occur along a coastal belt on deep, acidic soils derived from marine sediments, but can also occur at higher elevations along stream channels, snow avalanche paths, mass-wasting slopes or loess deposits. In British Columbia, much of the hypermaritime band is shallow soils derived from acidic bedrock with deep organic accumulations due to hypermaritime climate. Glaciation resulted in a scouring of the landscape with little till accumulation. There are also pockets of richer bedrock that is reflected in the productivity of the stands. Disturbance is mostly small-scale windthrow or other gap-mortality processes with occasional widespread intense windstorms.
Accession Code:
urn:lsid:vegbank.org:commConcept:40333-{526A28FD-59DE-424F-A862-81F6D8091DE1}
Plot-observations of this Community Concept:
0
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