The Coastal Western Hemlock (CWH) zone
occurs in valley bottoms and lowlands from Vancouver Island and the
lower mainland up to Taku and Tatshenshini rivers in northwestern
BC. Elevations range from sea level to 1000m in the south and from
sea level to 300 m in the north. The CWH zone is replaced by the subalpine
Mountain Hemlock zone with increasing elevation. Mean annual precipitation
ranges between 1100mm in the submaritime regions to over 4000mm in
the hypermaritime. Less than 15% of the precipitation falls as snow
in the south, which contrasts with the 40-50% snowfall in the northern
end of the range. The mean annual temperature ranges from 5.2C to
10.5C (Meidinger and Pojar 1991).
Podzolic soils characterize the CWH zone.
Soils are derived from coarse textured morainal, colluvial, glaciofluvial
and marine parent materials. Leaching and elluviation in the mineral
horizons is common. Folisol soil development occurs commonly in some
areas (>40cm organic matter or >10cm organic matter over bedrock).
Humus forms tend to be thick, well developed Mors. Organic matter
retention is required for maintaining long-term ecosystem productivity
on nutrient poor sites.
Ecosystems
The following plant species information
is summarized from Green and Klinka (1994) and Meidinger and Pojar
(1991).
Hypermaritime sites commonly have mixtures
of western hemlock, western redcedar and Sitka spruce. Yellow cedar
occurs at the upper end of the CWH elevation range. Understory species
on zonal sites include salal (Gaultheria shallon) and Lanky moss (Rhytidialdelphus
loreus).
Maritime sites are typified with mixed
stands of western hemlock, western redcedar, Sitka spruce, yellow
cedar, Douglas-fir and amabilis fir. Understory species on zonal sites
includes flat moss (Plagiothecium undulatum), Pipecleaner moss (Rhytidiopsis
robusta), oval-leaved blueberry (Vaccinium ovalifolium), and Oregon
beaked moss (Kindbergia oregana).
Submaritime sites are dominated by western
hemlock, western redcedar, Douglas-fir and amabilis fir in the overstory.
Understory species on zonal sites includes Electrified Cat’s
tail moss (Rhytiadelphus triquetrus), Step moss (Hylocomium splendens),
and five-leaved bramble (Rubus pedatus).
Grand fir is also a common tree species
in the drier regions of the CWH. Bigleaf maple (Acer macrophyllum)
and red alder (Alnus rubra) can often form pure stands in seral forests.
Shore pine (Pinus contorta var. contorta) occurs on either dry rocky
outcrops or very wet boggy sites.
Resources
Valley bottom in the CWH are very productive
and many sites have been converted to agriculture in the lower mainland.
Forestry operations are very common, as the forests are both productive
and occupy low elevation sites. Development of the CWH zone from over
the past 100 years has lead to British Columbia becoming a world leader
in forestry.
Commercial salmon fishing and salmon farming
occur in the ocean waters adjacent to the CWH zone. All of the salmon
species use the freshwater rivers and brackish estuaries of the CWH
for migration and spawning.
Recreational activities
include fishing, hiking, cycling, hunting, and wildlife viewing. Marine
sports include kayaking, boating, sailing and surfing.
References
Green, R.N. and Klinka. 1994. A Field Guide
for Site Identification and Interpretation for the Vancouver Forest
Region. Ministry of Forests. 185 pp. http://www.for.gov.bc.ca/hfd/pubs/docs/lmh/lmh28.htm
Meidinger, D. and Pojar, J. 1991. Ecosystems
of British Columbia. British Columbia Ministry of Forests. 330 pp.
http://www.for.gov.bc.ca/hfd/pubs/Docs/Srs/SRseries.htm
Images © Evan MacKenzie and Derek
Marcoux
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