The Engelmann Spruce Subalpine fir zone
(ESSF) occupies high elevation subalpine habitat throughout the province.
In the south, it occurs above the Interior Cedar Hemlock zone and
the Montane Spruce zone. In central BC, the ESSF occurs above the
Subboreal Spruce. In northern B.C., the ESSF is gradually replaced
by the Spruce-Willow-Birch zone. The Mountain Hemlock zone is the
equivalent subalpine zone on the coast. The elevational ranges for
the ESSF are between 1200-2100m in the southwest, 1500-2300m in the
southeast and 900-1700m in the north (Meidinger and Pojar 1991).
The ESSF is typified by long cold winters
and deep snowpacks. In the wetter regions of the interior, snowfall
accumulation can be as much as several meters. The drier ESSF zones
have annual precipitation between 400-500mm and the wetter regions
have as much as 2200mm of which 50-70% falls as snow (Meidinger and
Pojar 1991). Mean annual temperatures range between –1C - +2C.
Meidinger and Pojar (1991) recognize 15
subzones in the ESSF zone. This zone occurs over a widely different
climate belts ranging from the very wet southern interior to the dry,
cold regions of the central interior. Four dry subzones (ESSFxc, ESSFdc,
ESSFdk, ESSFdv) are found to occur above the Montane Spruce. Three
moist subzones (ESSFmv, ESSFmc, ESSFmm) occur along the leeward side
of the Coast Mountains in the same elevational band as the Mountain
Hemlock zone. Six wet subzones (ESSFwm, ESSFwk, ESSFwc, ESSFvc, ESSFvv)
are found in southeastern and northwestern regions of the province
above the Interior Cedar Hemlock zone. With increasing elevation,
the ESSF gradually opens into the ESSF parkland zone. The parkland
is transitional to the true Alpine Tundra.
Podzolic soil development is common in
the ESSF zone along with thick Mor humus forms. Brunisols occur in
areas with less annual rainfall.
Ecosystems
In the drier subzone regions, Grouseberry
(Vaccinium scoparium) can be the dominant understory shrub and can
often form pure cover under a mixed canopy of Subalpine fir, Engelmann
Spruce and Lodgepole pine. Additional understory species may include
Cladonia spp. Lichen, black huckleberry (Vaccinium membranaceum) and
Soopollalie (Sheperdia canadensis) are also common species. In these
areas, pure stands of lodgepole pine are common due to a widespread
fire history. Many of these stands have existed for over 200 years
(Steen and Coupe 1997).
In the moist and wet regions, grouseberry
is restricted to dry sites and zonal vegetation includes dense covers
of black huckleberry, white-flowered rhododendron, false azalea (Menziesia
ferruginnea), Oak fern (Gymnocarpium dryopteris) and Sitka Valerian
(Valeriana sitchensis). Moss cover can include knight’s plume
moss and leafy liverworts.
Avalanche chutes are common in the steep
regions of the ESSF. In the dry subzones such as along the Rocky Mountains,
avalanche chutes can consist of mostly low-growing herbaceous vegetation.
In the wetter regions, the chutes are often a very dense combinations
of alder (Alnus spp.), Indian hellebore (Viratrum viride), cow-parsnip
(Heracleum maximum) and ladyfern (Athyrium filix-femina).
Lloyd et. al. (1990) recognizes two high
elevation grasslands in the ESSFxc subzone. Vegetation is dominated
by bluebunch wheatgrass (Pseudoroegneria spicata), western pasqueflower
(Anenome occidentalis), Junegrass (Koeleria macrantha), and Pinegrass
(Calamagrostis rubescens).
Resources
Although forestry is common in the ESSF,
accessibility is the main limitation in some of the steep, mountainous
terrain. Regeneration in the upper elevations of the ESSF is often
hindered by a short growing season. In areas where harvesting occurs,
Engelmann Spruce and Lodgepole pine are the most common tree species
for regeneration.
The forested and parkland zones are common
hiking destinations during the summer months for people to access
the high elevation lakes or alpine meadows. During the winter, the
ESSF is widely used for alpine skiing, cross-country skiing and snowmobiling.
The ESSF is an important area for water
production in the province. Together with the Alpine Tundra zone,
the area provides late season snowmelt to refill watersheds. Clearcutting
within this zone can shorten the length of time it takes for this
water to melt. The shorter period can lead to a greater risk of flooding
water during spring runoff and also water deficit later in the growing
season. However, clearcuts also accumulate more snow on the ground,
which can lead to less loss of the snowpack through evaporation from
the forest canopy and greater amount available for recharge to the
water supply
References
Lloyd, D., K. Angove, G. Hope, and C. Thompson.
1990. A guide to site identification and interpretation for the Kamloops
Forest Region. B.C. Min. For., Res. Br., Victoria, B.C., Land Management.
Handbook. No. 23. http://www.for.gov.bc.ca/hfd/pubs/docs/lmh/lmh23.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
Steen, O.A., and R.A. Coupé. 1997.
A field guide to forest site identification and interpretation for
the Cariboo Forest Region. B.C. Min. For., Res. Br., Victoria, B.C.,
Land Management. Handbook. No. 39. http://www.for.gov.bc.ca/hfd/pubs/docs/lmh/lmh39.htm
Images © Derek Marcoux
{Back to Top}
