Pacific Maritime Rainforest

General Description significant disturbance factors in some areas. In The Pacific Maritime Rainforest zone covers an area general, stand-replacing fire plays a relatively minor of almost 88,000 km² at low to mid-elevations of the role in the disturbance regime. However, fire southern and central (BC) coast, as becomes an increasingly important factor in forest well as Vancouver Island and Haida Gwaii. This zone dynamics where climatic conditions are drier, represents the central portion of North American primarily in the more southern and eastern portions Pacific coastal rainforests, extending from Alaska to of the zone. Otherwise, gap replacement of single or northern California. The maritime climate is cool and small groups of trees is the common regeneration wet. Landcover is dominated by evergreen process. coniferous forests. Western hemlock (Tsuga heterophylla ) is the Vegetation characteristic tree species. Western red cedar (Thuja plicata ) is the most common canopy Upland vegetation is dominated by temperate associate, except at the northern edge of the zone rainforests characterized by tall, long-lived where it occurs less frequently. Other common evergreen coniferous trees in stands that may trees include Pacific silver fir ( Abies amabilis ), coast persist for centuries. Stand structure is typically Douglas-fir ( Pseudotsuga menziesii var. menziesii ), multi-storied, but can be single-storied after stand- Sitka spruce ( Picea sitchensis ), yellow-cypress replacing disturbance. Cold-deciduous broad-leaved (Callitropsis nootkatensis ), grand fir ( Abies tree species are sometimes present following grandis ), red alder ( Alnus rubra ) and big-leaved disturbance. Understory structure varies from dense maple ( Acer macrophyllum ). Shore pine (Pinus to sparse, and is usually dominated by cold- contorta var. contorta ) is dominant on some very deciduous and evergreen broad-leaved shrubs, dry sites, as well as in treed coastal bogs. Western conifer regeneration and ferns. The moss layer is typically well developed. white pine ( Pinus monticola ) and mountain hemlock ( Tsuga mertensiana ) occur occasionally. Wildfires, windthrow, slope failures, pathogens and Alluvial forests dominated by western hemlock, insect infestations are the most widespread forms of western red cedar, Sitka spruce, red alder and natural disturbance throughout the zone. Forest black cottonwood ( Populus trichocarpa ) occur on harvesting, roadbuilding, agricultural conversion and stable floodplain terraces. settlement clearance, urban development, and industrial and recreational activities are also

Common upland shrubs include oval-leaved Lyngbye’s sedge ( Carex lyngbyei ), Pacific blueberry ( Vaccinium ovalifolium ), red huckleberry silverweed ( Potentilla anserina ssp. pacifica ), (V. parvifolium ), salal ( Gaultheria shallon ), false Beringian hairgrass ( Deschampsia cespitosa ssp. azalea ( Menziesia ferruginea ) and, in drier beringensis ), seaside plantain ( Plantago maritima ), climates, Cascade barberry ( Berberis nervosa ). Virginia glasswort ( Salicornia depressa ), saltgrass Deer fern ( Blechnum spicant ) is the most (Distichlis spicata ), sea milkwort ( Lysimachia widespread herb, but three-leaved foamflower maritima ) or sea ditchgrass ( Ruppia maritima ). (Tiarella trifoliata ) and western sword fern Sparsely vegetated rocky shorelines and (Polystichum munitum ) are also common. Lanky beaches/dunes occur in coastal areas. moss ( Rhytidiadelphus loreus ), stairstep moss

(Hylocomium splendens ) and Oregon beaked moss Climate (Kindbergia oregana ) predominate in the moss layer. Moderate temperatures and high precipitation Coastal treed swamps usually include red alder, characterize the climate of the Pacific Maritime western red cedar, western hemlock, big-leaved Rainforest zone. In general, the macroclimate is maple and yellow-cypress in the tree stratum, with maritime temperate, with cool summers, mild yellow skunk cabbage ( Lysichiton americanus ), winters and high annual precipitation, the majority of which falls in winter as rain. Local climatic salmonberry ( Rubus spectabilis ) and ferns in the variation influences vegetation patterns. Areas with understory. lower precipitation have an increased frequency of Non-treed or sparsely vegetated communities fire. In the hypermaritime zone along the immediate occur frequently on a variety of site conditions. coast, frequent fog and low clouds during warmer These include wetlands, estuaries, shallow soils, months produce a uniformly wet and mild climate, rocky shorelines and beach/dune systems, with fog drip often contributing significant additional avalanche tracks, talus slopes and cliffs. site moisture. Inland, the climate is still relatively mild but typically with lower overall precipitation Extensive “blanket mire complexes” occur in outer and greater temperature extremes. coastal areas. These complexes typically include both treed and non-treed bogs, dominated by Mean annual precipitation is generally high, shore pine, yellow-cypress, common juniper averaging >3000 mm (varying between (Juniperus communis ), common Labrador tea approximately 1500 and 5300 mm). The majority (Rhododendron groenlandicum ), black crowberry of total precipitation falls as rain; snow is only a (Empetrum nigrum ), tufted clubrush minor proportion, occurring mostly in northern, (Trichophorum cespitosum ), narrow-leaved montane and submaritime areas, and “rain-on- cottongrass (Eriophorum angustifolium ) or peat snow” events are common wherever snowpack mosses ( Sphagnum spp.). accumulates. Rain shadow effects from the Queen Charlotte Ranges, the Vancouver Island Ranges, Shallow marshes and wetter fens usually are the Olympic Mountains and, in some places, the dominated by Sitka sedge (Carex aquatilis var. create the largest variability in dives ), woolly-fruit sedge (C. lasiocarpa ), three-way precipitation patterns across the zone, accounting sedge (Dulichium arundinaceum ), sweet gale for the lower values in the continuum. Mean (Myrica gale ) or white beakrush ( Rhynchospora annual temperatures vary from approximately 3°C alba ). Sitka willow (Salix sitchensis ), shining willow to 10° C, depending mostly on latitude and (Salix lucida ), mountain alder ( Alnus incana ssp. elevation. Growing degree days above 5°C vary tenuifolia ) or Douglas’ meadowsweet ( Spiraea between approximately 1000 and 2200 throughout douglasii ) dominate shrub swamps and annually the zone. Frozen soils are uncommon in winter, active floodplains. which is important for the survival of many of the Coastal estuaries and intertidal zones have coastal plant species. marshes and wet meadows dominated by

Physiography, Geology, Topography and All of the zone has been glaciated numerous times Soils and the most prevalent parent material is glacial till. Colluvium is also common because of steep

This zone occurs in the westernmost Cordillera of mountain slopes, often with bedrock exposures. Canada, occupying the windward portions of the Several large rivers terminate at the Pacific Ocean, creating riparian and estuarine benches, beaches Coast Mountains in BC, including the Pacific and deltas of alluvial materials. Parent material Ranges, the Ranges and some lower valleys textures vary considerably but are mostly coarse to in the . It also occurs in the medium-textured with moderate to high coarse insular mountains of Vancouver Island and Haida fragment content. Although geologically young, Gwaii, as well as their adjoining coastal lowlands. A the soils are generally well developed. Organic minor portion of the zone occurs in the Cascade matter tends to accumulate in the wet, cool Mountains of southwestern BC and the St. Elias Mountains of northwestern BC. The zone occurs at climate. Mineral soils are mostly Podzols, with sea level over most of its area and extends up to some Folisols; Gleysols occur locally on moist, poorly drained sites. Peatlands dominated by about 900 mASL in southern BC and to 450 mASL in Organic soils are extensive in some locations. northern BC on windward slopes. On leeward slopes in the eastern part of the zone, the upper elevation can reach 1000 mASL. Notes

The Coast, Cascade and St. Elias Mountains are At low elevations, the Pacific Maritime Rainforest zone usually extends to sea level, except in the primarily crystalline igneous and metamorphic rocks. Georgia Depression where it adjoins the Pacific Dry The Vancouver Island and Queen Charlotte Ranges, Forest . At higher elevations, it is bounded by the as well as the coastal lowlands, comprise mostly Pacific Montane Forest . To the south and north, it folded and faulted volcanic and sedimentary Tertiary continues into the United States. rocks. The terrain is a complex of high mountains (some >4000 mASL), valleys and rugged coastlines.