More info for the terms: fern, forbs, shrub, shrubs, vine
Sitka alder is generally found at middle to high elevations in the
mountains of northwestern North America. It is moderately shade
tolerant [20,31], which allows it to survive under stands of lodgepole
pine (Pinus contorta), Engelmann spruce (Picea engelmannii), subalpine
fir, grand fir (Abies grandis), western hemlock, mountain hemlock (Tsuga
mertensiana), Douglas-fir, and Pacific silver fir [1,7,40,46]; however,
it cannot tolerate a dense overstory. Scattered thickets of Sitka alder
are normally located on cool moist sites, on north-facing slopes, or
other shady aspects [3,37,40,46]. It is a vigorous invader of talus
slopes, avalanche chutes, seepage areas, and high elevation mountain
swales, which often have an abundance of surface moisture [29,43].
These sites are often subject to deep winter snow accumulations and
recurrent avalanches. Although typically mentioned as a seral shrub of
cool, moist, shady upland sites, it also occurs along cool mountain
streams in Oregon and Washington [23,29].
Soils: Sitka alder is found on a wide variety of parent materials and
soil textures [20]. Surface soil textures vary from silts to coarse
sands, and are consistently more acidic than those in adjacent conifer
communities [7,40]. Soils under Sitka alder are normally higher in
available nitrogen than soils in adjacent communities, since this
species can fix between 18 to 55 pounds per acre (20-62 kg/ha) of
nitrogen annually [20]. Its ability to fix nitrogen allows it to invade
sterile mineral soil recently exposed by glaciers or avalanches [20].
Associated species: Sitka alder is commonly found with shrubs such as
Rocky Mountain maple (Acer glabrum), vine maple (A. circinatum),
elderberries (Sambucus spp.), willows (Salix spp.), prickly currant
(Ribes lacustre), mountain ash (Sorbus spp.), rusty leaf menziesia
(Menziesia ferruginea). Commonly associated herbs and forbs (usually
shade tolerant) include heartleaf miners lettuce (Montia cordifolia),
Siberian miners lettuce (M. sibirica), arrowleaf groundsel (Senecio
triangularis), wild ginger (Asarum caudatum), lady fern (Athyrium
filix-femina), queencup beadlily (Clintonia uniflora), broadleaf arnica
(Arnica latifolia), sidebells shinleaf (Pyrola secunda), pioneer violet
(Viola glabella), nettles (Urtica dioica), northern bluebells (Mertensia
paniculata), and bracken fern (Pteridium aquilinum) [2,6,7,9,40].
Elevation: Sitka alder is mostly distributed above 3,000 feet (914 m)
[3]. Sitka alder does not grow below 1,640 feet (500 m) in Washington
[22]. Elevational ranges for the following western states are presented
below [6,12]:
from 3,500 to 8,000 feet (1,067-2,438 m) in MT
5,700 to 7,000 feet (1,737-2,134 m) in Eagle Cap Wilderness, OR