More info for the terms: association, codominant, cover, density, fern, forbs, shrub, shrubs, tree
Alaska: In the Tanana, Yukon, and Susitna valleys, black cottonwood and
balsam poplar stands are some of the most productive in Alaska. American green alder
(Alnus viridus var. crispa) and thinleaf alder (A. incana subsp.
tenuifolia) are usually present throughout stand development; willows (Salix
spp.) are less
common when cottonwood and balsam poplar are mature. Common
associates include prickly rose (Rosa acicularis), viburnum (Viburnum spp.),
red-osier dogwood (Cornus sericea), devil's club (Oplopanax horridus),
horsetails (Equisetum spp.), and bluejoint (Calamagrostis canadensis) [101].
On Sheep Creek, near Juneau, Alaska, black cottonwood grows with salmonberry (Rubus
spectabilis), elderberry (Sambucus spp.), cranberry, and Sitka alder (Alnus
viridis subsp. sinuata) [12]. On the Kenai Peninsula black cottonwood is common on wet
sites; co-dominants include balsam poplar, black spruce (Picea mariana),
Scouler's willow (Salix scouleriana), Barclay's willow (S. barclayi), and
American green alder [135,155].
Yukon: Stanek and others [137] describes "Populus balsamifera"
(likely including black cottonwood, balsam poplar, and their hybrids) in
the mountain alder (Alnus incana)-balsam poplar-field horsetail (Equisetum arvense)
vegetation type as well as the balsam poplar-arctic lupine (Lupinus arcticus)-bog birch (Betula nana) vegetation type. The
former is confined to permafrost-free terraces and floodplains,
and the latter is present on southwest aspects on lower slopes on alluvium.
British Columbia: On floodplains, black cottonwood is
dominant, commonly with red-osier dogwood. Western redcedar (Thuja
plicata) and hybrid white spruce (Picea glauca) Ã Engelmann
spruce (P. engelmannii), though present,
typically do not become dominant because of frequent flooding and sediment
deposition [57]. Other codominants in these black cottonwood communities include
Pacific willow (Salix lucida subsp. lasiandra), red alder (Alnus rubra),
Sitka alder, Himalayan blackberry (Rubus discolor), devil's club, stink
currant (Ribes bracteosum), and
occasionally Sitka spruce (Picea sitchensis) [81]. Forbs in
black cottonwood dominated floodplains include fragrant bedstraw (Galium triflorum), horsetails,
liverleaf wintergreen (Pyrola asarifolia), small enchanter's nightshade (Circaea
alpina), common lady
fern (Athyrium filix-femina), starry false Solomon's-seal (Maianthemum
stellatum), sweetcicely (Osmorhiza berteroi), dwarf red blackberry (Rubus
pubescens), bride's feathers (Aruncus dioicus), common cowparsnip (Heracleum
maximum), stinging nettle (Urtica dioica), slough sedge (Carex obnupta), and
arctic sweet coltsfoot (Petasites frigidus var. palmatus) [57].
Along the Blaeberry River near Golden, British Columbia, black cottonwood and
white spruce are codominant on "stable" islands; dwarf fireweed (Epilobium latifolium)
is dominant in the understory
and Hervey's aster (Aster hesperius), Lindley's aster (A. ciliolatus),
scarlet Indian paintbrush (Castilleja
miniata), northern green orchid (Platanthera hyperborea), and
Aleutian selfheal (Prunella vulgaris) are also present [46].
Other woody species in these floodplain communities include quaking aspen (Populus
tremuloides), Farr's willow (Salix farriae), and Wolf's willow (S. wolfii).
Western Washington: Black cottonwood is an early
seral species in western hemlock (Tsuga heterophylla) communities including
western hemlock/skunk cabbage (Lysichiton americanus), western hemlock/common lady fern, and western
hemlock/devil's club habitat types. It is also present in wet and/or cool
grand fir (Abies grandis), Douglas-fir, and western redcedar habitat
types [147]. On the Hoh River on the Olympic Peninsula, a Sitka spruce-bigleaf maple-black cottonwood association occurs
on first terraces. Subdominant trees include red alder and Douglas-fir and
western hemlock if the site is not disturbed. The understory of these communities includes
the grasses redtop (Agrostis gigantea) and fowl bluegrass (Poa palustris) and the forbs
Oregon oxalis (Oxalis oregana), western sword fern (Polystichum munitum), and
small enchanter's nightshade [44].
Eastern Washington and northern Idaho: Black
cottonwood frequently occurs (though never in great abundance) in the seral
stages of the development of western hemlock and western redcedar habitat types,
and is sometimes a minor component of old-growth stands of these types [99].
Black cottonwood is prevalent at lower elevations on floodplains and
terraces where frequently it is mixed with ponderosa pine and Douglas-fir
[33,88]. In drier
areas, like the Palouse River, black cottonwood is dominant with western water
hemlock (Cicuta douglasii) dominant in the understory. Many of these communities have been
disturbed by human activities [32]. In mountainous areas of
eastern Washington, Idaho, and northwestern Montana, black cottonwood sometimes
grows in avalanche chutes with mountain alder, Saskatoon serviceberry, Rocky Mountain maple (Acer glabrum), and quaking aspen
[56].
Oregon: In bottomland forests of the Willamette
Valley of western Oregon, black cottonwood, Douglas-fir (Pseudotsuga
menziesii), big-leaf maple (Acer macrophyllum), and
white ash (Fraxinus americana) are common, all occurring with about the same density.
Subdominant trees in these communities include
Oregon white oak (Quercus garryana), California laurel (Umbellularia californica),
alder (Alnus spp.), bitter cherry (Prunus emarginata), and willows, and the understory usually includes Oregon- grape (Mahonia
repens), salmonberry, rose (Rosa spp.), Douglas' spiraea (Spiraea
douglasii), Pacific ninebark (Physocarpus capitatus), and Pursh's
buckthorn (Frangula purshiana).
Many of
these community types have declined due to cultivation and hydrologic
alterations [54,136]. In the Catherine Creek watershed of eastern
Oregon, black cottonwood is dominant with ponderosa pine (Pinus
ponderosa) in structurally diverse riparian communities.
Subdominants include mountain alder, black hawthorn (Crataegeus
douglasii), Woods' rose, Kentucky bluegrass (Poa pratensis), and common snowberry
(Symphoricarpos albus). Black
cottonwood is commonly the only tree present on recently formed gravel bars
[79].
California: In the North Coast Ranges and Klamath Mountains,
black
cottonwood grows with red alder; older stands with less disturbance also
support grand fir, Sitka spruce, Douglas-fir, western redcedar, or western
hemlock. Black cottonwood is dominant in montane riparian forests of the Sierra Nevada
where Jeffrey pine (Pinus jeffreyi) is a common associate; shrub cover
(red-osier
dogwood, western juniper (Juniperus occidentalis), willows, and common
chokecherry) is commonly about 25% [70]. In southern California, Fremont cottonwood is dominant along
washes and streams in lower elevations and black cottonwood is dominant in
similar habitats at higher elevations [108,146]. Common associates
in the black cottonwood communities include bigleaf maple, white alder (Alnus rhombifolia),
willows, and California laurel [146]. In the South Coast Ranges, Fremont cottonwood and
California sycamore (Platanus
racemosa) are dominant, but black cottonwood and coast live oak (Quercus agrifolia) are also
present [70]. Off the coast near Santa Barbara, on Santa Rosa,
Santa Cruz, and Santa Catalina islands, riparian woodlands are dominated by
black cottonwood with Fremont cottonwood; Tracy willow (Salix lasiolepis var.
lasiolepis) and blue elder (Sambucus mexicana) are also present. Herbaceous vegetation
consists of saltgrass (Distichlis spicata), annual rabbitsfoot
grass (Polypogon monspeliensis), redtop, and tropical medicineplant (Adenostoma
verbesina) [27,110]. Near drainageways in the San Dimas Forest near Los Angeles, black
cottonwood is a dominant with coast live oak, California sycamore, bigleaf
maple, white alder, and willows in open stands [40].
Alberta: In southern Alberta, most riparian
communities in the semi-arid portion of the province are dominated by cottonwoods, including black
cottonwood, eastern cottonwood (Populus deltoides), narrowleaf
cottonwood (P. angustifolia), and balsam poplar. Shrubs include common chokecherry (Prunus virginiana), Saskatoon serviceberry (Amelanchier
alnifolia), Wood's rose, and
western snowberry (Symphoricarpos occidentalis) [49].
North Dakota: Black cottonwood occurs with green ash
(Fraxinus pennsylvanica) and American elm (Ulmus americana) in riparian areas in western North Dakota
[71].
Montana: In
western Montana, the most common codominant tree with black cottonwood is ponderosa
pine. Others include Douglas-fir, Engelmann spruce, western redcedar, Rocky Mountain juniper
(Juniperus scopulorum), and
quaking aspen. The shrub component includes Wood's rose, mountain alder, Bebb willow (Salix
bebbiana), common chokecherry, red-osier dogwood,
western snowberry, and common snowberry
[60]. Herbaceous
species commonly dominant include quackgrass (Elytrigia repens),
Kentucky bluegrass, creeping bentgrass (Agrostis
stolonifera), starry false Solomon's seal, Virginia strawberry (Fragaria virginiana), and
fragrant bedstraw [60,62]. In central and eastern Montana black cottonwood grows with narrowleaf and
eastern cottonwoods in transitional zones (narrowleaf and eastern cottonwoods
are dominant at lower elevations) [60]. Along the North Fork of the
Flathead River, near Glacier National Park, 3 black cottonwood community
types were studied by Jenkins and Wright [75]. In early successional
communities the black cottonwood overstory is approximately 50%. Coniferous
canopy cover is low (<5%), and shrubs are not prominent. Other species
present on these sites include common yarrow (Achillea millefolium),
mountain alder, asters (Aster spp.), fireweed (Epilobium spp.),
prairie Junegrass (Koeleria macrantha), timothy (Phleum pratense),
bluegrass (Poa spp.), and Canada goldenrod (Solidago canadensis).
In later-successional community types the canopy cover of hybrid spruce (white
spruce à Engelmann spruce) increases to approximately 50% and gradually
replaces black cottonwood. Shrubs include red-osier dogwood, roses (Rosa
spp.), and common snowberry; these species become less prominent with increasing
hybrid spruce canopy cover.
Eastern and southern Idaho: Black cottonwood/red-osier dogwood is a common community type; it develops best along large rivers but
is also present in narrow bands along small streams in the subalpine zone [58]. Subdominant members of the
overstory include narrowleaf cottonwood, lanceleaf cottonwood (P. acuminata),
and peachleaf willow (Salix amygdaloides var. wrightii). Common shrub associates include
sandbar willow (Salix exigua), water birch (Betula occidentalis), yellow willow
(Salix lutea), and Wood's rose [58,74].
Nevada: Confined to riparian areas, black cottonwood commonly grows with
lanceleaf and narrowleaf cottonwoods, with these 3 species having
approximately 85% canopy cover. Wood's rose is prominent in
these habitats (25-90% canopy cover); currants (Ribes spp.) and
red-osier
dogwood are also common [90]. In central Nevada, black cottonwood
is sometimes associated with big sagebrush (Artemisia tridentata) [15].
Classifications describing plant communities in which black cottonwood is a
dominant species are as follows:
Alaska [17,153]
California [27,70,108,147]
Idaho [58,74,149]
Nevada [90]
Montana [60,61,62,111]
Oregon [54,79,82]
Washington [32]
Wyoming [105]
British Columbia [81]
Yukon [137]