The Research Paper by Bowles and others 2007 provides information on postfire responses of several plant species, including eastern cottonwood, that was not available when this species review was written.
Eastern cottonwoods provide a nesting place for white-throated sparrows and myrtle warblers [187]. They provide roost sites for Rio Grande turkeys [14] and nursery colonies for the Indiana bat [24]. In North Dakota, eastern cottonwoods provide important night roosting cover in winter for the greater prairie-chicken and sharp-tailed grouse [146]. Eastern screech-owls are found in plains cottonwood dominated riparian woodlands east of the Continental Divide [69]. Plains cottonwoods are a very important nesting substrate for nesting raptors. Plains cottonwoods are used for nesting by golden and bald eagles, several hawk species, Lewis' and red-headed woodpeckers, and other cavity nesters [17,167,179,180].
The only natural habitat for fox squirrels is plains cottonwood bottomlands. Plains cottonwood stands in Colorado are used by fox squirrels for nesting and feeding [232]. Plains cottonwood forests provide nesting sites for eagles, hawks, and other birds [17,69,167]. The cover value of plains cottonwood for some wildlife species has been rated as follows [49]:
CO MT ND WY Elk ---- Fair ---- Good Mule deer ---- Fair Fair Good White-tailed deer Fair Good Good Good Pronghorn ---- ---- Poor Poor Upland game birds Poor Fair Poor Good Waterfowl ---- ---- ---- Poor Small non-game birds Good Fair Good Good Small mammals Good Poor ---- GoodEastern cottonwood is a native, deciduous bottomland hardwood [68,121,132,212,225]. Height ranges from 36 to 190 feet (11-57.9 m) [37,47,56,67,120,132,150,151,224]. At maturity (approximately 35 years) [132], diameter at breast height ranges from 10.7 inches to more than 6 feet (27.2-182.9 cm) [7,47,67,132,150,224]. In open areas, eastern cottonwood typically has a large trunk that divides into branches near its base and ascends to form a wide, spreading crown [47,100]. In closed stands, it tends to have a tall, straight, and relatively branch-free bole with a small rounded crown [9]. Life expectancy is approximately 100 to 200 years [9,120,142]. It is dioecious. Female catkins range from 2 to 5.1 inches (5-13 cm) long, and fruit capsules are 0.3 to 0.6 inch (.8-1.5 cm) long [56]. The bark is thick and deeply furrowed with wide, flat ridges [56,199]. The rooting depth averages 100 inches (254 cm) [97], and mature stands can reach 117.6 to 196.8 inches (298.7-499.9 cm) rooting depth [22].
Eastern cottonwood is drought tolerant [47,77]. It has been classed as moderately tolerant to water-logged soils [106,110] and is tolerant of short-term inundation [145]. Eastern cottonwood tolerates periodic flooding from January through April, but mortality and growth due to flooding depend on how many events per year, season of year, age class, duration, and depth [89,106,149]. A study using cuttings found that eastern cottonwood survived less than 16 days of complete submergence [109]. Roots die when soaked for more than 1 month and adventitious roots form from dormant buds in the main trunk [110,220].
Plains cottonwood is a quick growing, short-lived deciduous tree [4]. It is smaller than P. d. ssp. deltoides [173] and grows from 10 to 98.4 feet (3-30 m) [4,36,58,124,130,139,173,195,207,223]. It has a diameter at breast height of 5 to 78.7 inches (12.7-200 cm) [4,58,107,124,130,139,173,207]. It is considered the fastest-growing tree in the Great Plains. The life expectancy is about 90 years [173].
Staminate catkins of plains cottonwood range in size from 2 to 3.5 inches (5-9 cm), pistillate catkins are 5.9 to 7.9 inches (15-20 cm) long, and fruits are 0.4 inch (1 cm) in length [173]. Plains cottonwood is susceptible to drought except where water tables are high [4] and drought induced mortality can be high [173]. The average rooting depth is 10 feet (3.1 m), and the longest roots can reach 75 feet (22.9 m) [231].
Rio Grande cottonwood ranges in height from 26.2 to 65.6 feet (8-20 m) [56,59]. It has catkins with pedicels 0.2 to 0.6 inch (.5-1.5 cm) long [56].
Fire adaptations: Eastern cottonwood is a weak sprouter, and fire generally kills it [3,22,86,87,132,145,158]. It may sprout from the roots, root crown, or bole after fire [47,95,152,183], but sprouts are few and usually die. In a survey of postfire response of cottonwoods (Populus spp.) in Alberta, Gom and Rood [86] reported a "very poor" sprouting response for eastern cottonwood: few sprouts were produced, and most of those sprouts died. In their own study, conducted 5 months after "high-intensity" April wildfires on 2 Oldman River sites near Lethbridge, Alberta, 20% of damaged eastern cottonwood trunks produced sprouts, while 80% of damaged cottonwoods in the taxonomic section Tacamahaca produced sprouts. Five years after fire, only 10% of eastern cottonwood trunks damaged by fire still supported live sprouts.
FIRE REGIMES: In the Northern Great Plains, historic fire frequency was influenced by topography. Where plains cottonwoods occur along rivers, the fire frequency is estimated between 20 to 30 years [189]. These riparian areas burned less frequently than the surrounding uplands; fires skip over or only burn a portion [184]. Fires most likely occurred late in the growing season when the understory vegetation was cured enough to support a fire. In the mesic portions of the Northern Great Plains where eastern cottonwood occurs, the average fire return interval is 1 to 5 years [189].
In the southern United States, "serious" fire seasons occur every 5 to 8 years. The fire season is usually in the fall, except in years with a dry, early spring [171].
Fire return intervals for plant communities and ecosystems in which eastern, plains, and Rio Grande cottonwood occur are summarized below. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) silver maple-American elm Acer saccharinum-Ulmus americana 218] bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium 135,164] Nebraska sandhills prairie Andropogon gerardii var. paucipilus-Schizachyrium scoparium sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [164] Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [215,233] plains grasslands Bouteloua spp. blue grama-buffalo grass Bouteloua gracilis-Buchloe dactyloides cheatgrass Bromus tectorum 164] sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica 218] northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [164] beech-sugar maple Fagus spp.-Acer saccharum > 1000 black ash Fraxinus nigra 218] Rocky Mountain juniper Juniperus scopulorum wheatgrass plains grasslands Pascopyrum smithii pinyon-juniper Pinus-Juniperus spp. 164] longleaf-slash pine Pinus palustris-P. elliottii 1-4 [159,218] loblolly-shortleaf pine Pinus taeda-P. echinata 10 to sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana 218] eastern cottonwood Populus deltoides 5 to 200 [164,171,189] mesquite Prosopis glandulosa mesquite-buffalo grass Prosopis glandulosa-Buchloe dactyloides Texas savanna Prosopis glandulosa var. glandulosa 164] mountain grasslands Pseudoroegneria spicata 3-40 (10**) [5,6] oak-hickory Quercus-Carya spp. 218] oak-juniper woodland (Southwest) Quercus-Juniperus spp. 164] white oak-black oak-northern red oak Quercus alba-Q. velutina-Q. rubra bur oak Quercus macrocarpa oak savanna Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [164,218] chestnut oak Q. prinus 3-8 northern red oak Quercus rubra 10 to black oak Quercus velutina 218] elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. < 35 to 200 [52,218] *fire return interval varies widely; trends in variation are noted in the species summaryPrescribed fire is not recommended on bottomland forest sites in the north-central states where wood production is a primary management objective. Seedlings and young trees are easily killed by surface fires, while mature trees are often wounded. Wounded trees often contract heartrot, leading to substantial cull and volume loss [28]. Prescribed burning may stimulate sprouting and improve food supplies for wildlife species [183]. For optimum timber production, plantations must be completely protected from fire and grazing [28]. Fire prevention measures suggested for eastern cottonwood plantations include natural firebreaks (roads, trails, and sloughs) dividing stands into 40-acre (16 ha) blocks and plowed lines, at least 15 feet (4.6 m) wide [145]. To promote eastern cottonwood recovery, livestock should be excluded from burned areas for 5 years following fire and wildlife browsing should be monitored [95].
FIRE REGIMES: Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Eastern cottonwood primarily grows on the moist alluvial soil of floodplains and bottomlands [132,145,158,171,229]. It is also found in ravines [16,107,229], along disturbed streams [117], and in low spots of sandy uplands with a high water table [229]. It also found on batture lands, the unprotected areas between the Mississippi River and its levees [145].
Plains cottonwood is found on floodplains and small sandbars in the river beds or large bends where stream flow is dramatically retarded during high water. It is found next to springs that flow long enough to form ponds [4,130,173].
Across its range, eastern cottonwood is found from 255 to 6,500 feet (78-1,981 m) [10,12,37,165,169,187], usually 15 to 40 feet (5-12 m) above stream level [90,151,187]. Elevation ranges for plains and Rio Grande cottonwood are given in the following table:
The average annual precipitation across the eastern cottonwood range is 13.78 to 55 inches (350-1,397 mm) [125,169]. Average annual precipitation ranges for some states where eastern cottonwood occurs is listed below:
IN 35 to 47 inches (889-1,193.8 mm) [141] MI 33.86 inches (860 mm) [71] OH 34 inches (863.6 mm) [18] TX 14.96 to 33.07 inches (380-840 mm) [213,214] ON 37 inches (939.8 mm) [234] Eastern cottonwood occurs in a wide range of temperature regimes with extremes ranging from -49 degrees Fahrenheit (-45 oC) in winter to 114.8 degrees Fahrenheit (46 oC) in summer [125]. The mean annual temperature or annual temperature range for some states is as follows:
The annual precipitation varies between 12 and 30 inches (305-762 mm), averaging less than 20 inches (508 mm) across most of the plains cottonwood range. The temperature can range between -50 degrees Fahrenheit (-45.56 oC) in January and 115 degrees Fahrenheit in July (46.11 oC) [173]. The average annual precipitation and temperature for some states in the plains cottonwood range are given in the table below [4,11,15,20,36,73,82,104,105,124,127,130,146,162,175,182,186,198,208,221,231]:
Eastern cottonwood tolerates a wide range of soils ranging from coarse sands to clays but grows best on moist, well-drained fine sandy loams or silt [47,90,129,145,151,154,158].
Plains cottonwood is found on sandy soils [124,130] or well-drained soils with a high water table to supply year-round moisture [4]. Availability of moisture is reportedly more significant to plains cottonwood than soil texture or fertility [173].
In the northern Great Plains, eastern cottonwoods are a component of riparian forests and moist woodlands that provide critical habitat for many wildlife species [9,15,107,119,187,200]. These woodland areas may constitute up to 50% of the habitat for deer and 70% of the habitat for sharp-tailed grouse throughout much of the Great Plains. Domestic livestock use these communities for shade, forage, and water in the summer, and for thermal cover in the winter [15]. Eastern cottonwood has been classified as having fair value for all wildlife, songbirds, upland game birds, fur and game mammals [32].
The bark and leaves of eastern cottonwood seedlings and saplings are eaten by field mice, rabbits, deer, and domestic livestock [9,28,122,145]. Wesley and others [226] observed the use of eastern cottonwood plantations in Arkansas and Mississippi by wild turkeys for courtship, prenesting, nesting, and poultry rearing. Eastern cottonwood plantations were used by white-tailed does, rabbits, and northern bobwhite more than surrounding natural stands.
Plains cottonwood stands provide habitat for 82% of all bird species breeding in northeastern Colorado [181]. These forests provide roosting and nesting sites [21,80,91,107,153,167], feeding sites [63,107,116,205], and nest material for several bird species [80]. Beavers use the wood of plains cottonwood for food and for buildings dams and lodges [92]. The plains cottonwood/red-osier dogwood community provides thermal cover, debris recruitment, and streamside stability for fishes [92,173]. Plains cottonwood is eaten by prairie porcupines [98] and is the most important browse species for mule deer in the fall [148].
Eastern cottonwood often occurs as a dominant or codominant component of
floodplain and bottomland hardwood forests [28,42,70,112,158]. It is a principal species in riverfront forests in
the eastern United States [150]. The maintenance
of eastern cottonwood-dominated stands depends on periodic flooding [96,155,229]. Most of these riparian areas tend to
be in early successional stages and are composed chiefly of scrub willows (Salix
spp.) interspersed with occasional eastern cottonwood stands [155].
Trees: Throughout its range, eastern cottonwood can
grow in pure stands [145], but more often grows in mixed stands [10,28]. Common tree
associates include hackberry (Celtis
occidentalis) [26,30,90,111,141], sugarberry (C. laevigata) [111,141,150,161], boxelder (Acer negundo)
[10,30,111,114,131,141,161,166], silver maple (A. saccharinum)
[2,8,10,51,102,111,141,202,221], sycamore (Platanus occidentalis)
[2,26,114,131,141,150,161,196],
American elm (Ulmus americana) [8,26,62,99,111,114,141,150,161,166,202], green ash
(Fraxinus pennsylvanica) [2,3,8,62,70,99,111,141,150], sandbar willow (Salix exigua) [8,166,234], and bur oak (Quercus
macrocarpa) [118,141].
Other tree species found with
eastern cottonwood include swamp
white oak (Quercus bicolor), pin oak (Q. palustris) [90,141], white mulberry (Morus alba), black cherry (Prunus serotina),
chestnut oak (Quercus prinus), black oak (Q.
velutina), sassafras (Sassafras albidum), tree-of-heaven
(Ailanthus altissima), bigtooth aspen (Populus grandidentata), red
elderberry (Sambucus racemosa ssp. pubens) [90], American hornbeam (Carpinus caroliniana), bitternut hickory (C.
cordiformis) [114,141], white ash (Fraxinus americana) [114,131],
basswood (Tilia americana) [99,114], balsam poplar
(Populus balsamifera), pussy willow (Salix discolor),
speckled alder (Alnus rugosa) [8], black willow (Salix nigra) [10,62,161,166], Shumard oak (Quercus shumardii)
[141,219], post oak (Q. stellata), cherrybark oak
(Q. pagoda), northern red oak (Q. rubra), Kentucky coffeetree (Gymnocladus
dioicus), shagbark hickory (Carya ovata), mockernut hickory
(C. tomentosa), shellbark hickory (C.
lacinios), pignut hickory (C. glabra), river birch (Betula
nigra), red maple (Acer rubrum), sweetgum (Liquidambar styraciflua), eastern
redbud (Cercis canadensis), pawpaw (Asimina triloba), honey-locust
(Gleditsia triacanthos) [141], hawthorns (Crataegus spp.),
common persimmon (Diospyros virginiana) [141,161], black walnut (Juglans nigra)
[3,123,141], chinkapin oak (Q. muehlenbergii), white oak (Q. alba),
[118], peachleaf willow (Salix amygdaloides) [99,221], pecan
(Carya illinoensis) [26,150,161,166], French tamarisk
(Tamarix gallica) [166], eastern swampprivet (Forestiera acuminata), red mulberry (Morus
rubra), Chinaberrytree (Melia azedarach), water hickory (Carya
aquatica), buttonbush (Cephalanthus occidentalis) [161], gum
bully (Sideroxylon lanuginosum) [30], and cedar elm (Ulmus
crassifolia) [30,161].
Shrubs: Some common shrubs associated with eastern cottonwood are winged burning bush (Euonymus
alata), northern spicebush (Lindera
benzoin), black tupelo (Nyssa
sylvatica), multiflora rose
(Rosa multiflora), southern arrowwood (Viburnum
dentatum), blackhaw (V. prunifolium) [90], sand shinnery oak
(Quercus havardii), sand sagebrush (Artemisia
filifolia) [206], and common ninebark (Physocarpus
opulifolius) [8].
Graminoids: Graminoid species found in the understory of eastern cottonwood
stands include streambank wheatgrass (Elymus
lanceolatus ssp. psammophilus), sanddune sandbur (Cenchrus
tribuloides) [234], Canada wildrye (Elymus canadensis) [166,234], switchgrass (Panicum virgatum) [206], Japanese brome
(Bromus japonicus),
Bermuda grass (Cynodon dactylon), johnsongrass (Sorghum halepense)
[166], big bluestem (Andropogon gerardii var. gerardii), Indiangrass
(Sorghastrum nutans),
alkali sacaton (Sporobolus airoides), and eastern gamagrass (Tripsacum
dactyloides) [206].
Forbs and vines: Several forbs and vines are found in eastern cottonwood stands.
Some common species are common moonseed (Menispermum canadense), Asian bittersweet
(Celastrus orbiculatus), privet (Ligustrum spp.) [90],
poison-ivy (Toxicodendron radicans), [90,111,166,234], trumpet creeper (Campsis radicans), oneseed bur cucumber (Sicyos
angulatus) [111],
peppervine (Ampelopsis
arborea), grape (Vitis spp.), Rubus species [111,166], Smilax species, Helianthus species, American pokeweed
(Phytolacca
americana) [26], Virginia creeper (Parthenocissus
quinquefolia) [111,166], goldenrod (Solidago spp.), saw greenbrier
(Smilax
bona-nox), great ragweed (Ambrosia trifida), Canadian horseweed (Conyza
canadensis) [166], white sweetclover (Melilotus alba), roughleaf dogwood (Cornus
drummondii), coltsfoot (Tussilago farfara), and American searocket (Cakile
edentula) [234].
Classifications systems listing eastern cottonwood is an indicator species
or as a dominant component of community types, habitat types, plant
associations, or riparian site types are as follows:
Plains cottonwood:
Trees: Common tree associates of
plains cottonwood include boxelder [4,9,12,25,39,61,74,92,105,124,130,143], green ash
[4,9,12,19,25,39,54,61,74,83,84,92,104,124,130], American elm
[9,12,19,25,39,61,104,105,124,130,143], chokecherry (Prunus
virginiana) [19,54,92,130,143,163,208], peachleaf
willow [12,20,25,36,61,95,124,130,143],
red-osier dogwood (Cornus sericea) [92,95,130,143,208], Russian-olive (Elaeagnus angustifolia) [36,95], willows (Salix spp.)
[4,17,61,92,139,163,208], bur oak [19,25,61,104,105,124,130,143,173], silver
maple [4,61], hackberry [12,25,61], black willow [42,143], and sandbar willow
[4,12,25,143,175].
Other trees found with plains cottonwood include silver buffaloberry (Shepherdia argentea)
[54,139], river willow (Salix fluviatilis) [20],
black cottonwood (Populus balsamifera ssp. trichocarpa) [96], narrowleaf
cottonwood [95,96], Rocky Mountain juniper (Juniperus scopulorum) [83,84,163], Cornus species [61], black willow
[42,143], red elderberry [143], fivestamen tamarisk
(Tamarix chinensis) [17], red mulberry [12,105], basswood [25,105], northern red oak,
chinkapin oak, bitternut hickory,
slippery elm (Ulmus
rubra), black oak (Quercus velutina), white ash,
eastern redbud, black cherry [105], American plum (Prunus
americana), eastern redcedar (Juniperus virginiana) [19],
eastern hophornbeam (Ostrya virginiana) [25,105], eastern
redcedar, black walnut, Kentucky coffeetree, slippery elm, and rock elm (Ulmus thomasii)
[25].
Shrubs: Shrubs associated with plains cottonwood are western snowberry (Symphoricarpos occidentalis)
[4,20,54,83,84,92,130,143,163,175], Wood's rose (Rosa woodsii) [20,83,84,92,95], plains
silver sagebrush (Artemisia cana ssp. cana), [20,50], golden currant (Ribes
aureum) [92], Rocky Mountain maple (Acer glabrum) [208],
Saskatoon serviceberry (Amelanchier alnifolia) [130,208],
Douglas hawthorn (Crataegus douglasii) [208], American hazel (Corylus americana)
[105,143], American black currant (Ribes americanum),
alderleaf buckthorn (Rhamnus alnifolia), smooth rose (Rosa blanda)
[143], common reed (Phragmites australis) [175],
desert false indigo (Amorpha fruticosa) [4], toughleaf dogwood (Cornus asperifolia), red raspberry (Rubus idaeus), common cocklebur (Xanthium
strumarium), eastern wahoo (Euonymus atrourpureua), smooth sumac (Rhus glabra) [105], and skunkbush sumac (R. trilobata) [107].
Graminoids: Graminoid species found in the understory of plains cottonwood
stands include blue grama (Bouteloua gracilis) [4,50], cheatgrass (Bromus tectorum) [50], Canada wildrye
[20,36,83,92,95,175], prairie cordgrass (Spartina pectinata) [175],
sand dropseed (Sporobolus cryptandrus), buffalo grass (Buchloe
dactyloides) [4], barnyard grass (Echinochloa crus-galli) [20,143], western wheatgrass (Pascopyrum smithii)
[20,36], prairie sandreed (Calamovilfa
longifolia) [20,107], smooth brome (Bromus
inermis) [20,36,92,95], quackgrass (Elytrigia repens), green
muhly (Muhlenbergia racemosa) [20,92,95], hairy wildrye (Elymus villosusi), creeping bentgrass (Agrostis
stolonifera), timothy (Phleum
pratense) [92,95], Kentucky bluegrass (Poa pratensis) [36,92,95,107,143], sedges (Carex spp.), Bromus species, Scirpus species [39], Virginia wildrye (Elymus virginicus)
[36], Assiniboia sedge (Carex assiniboinensis),
and slender
wheatgrass (Elymus trachycaulus) [143].
Forbs and vines: Forbs and vines found in plains
cottonwood stands are Virginia creeper [20,92,95,105,124],
western poison-ivy (Toxicodendron rydbergii) [20,92,95],
peppervine [92], longroot smartweed (Polygonum amphibium),
golden dock (Rumex maritimus), riverbank grape (Vitis riparia),
Louisiana sagewort (Artemisia ludoviciana) [20], white sweetclover [20,83,84,95,107,175], wild licorice (Glycrrhiza
lepidota) [20,95], yellow sweetclover (Melilotus officinalis) [95], American
bittersweet (Celastrus scandens), frost grape (Vitis vulpina)
[105,124,175], western white clematis (Clematis
ligusticifolia) [124], poison-ivy [36,143,175], woodbine, American
vetch (Vicia americana), Canada thistle (Cirsium arvense), common
milkweed (Asclepias syriaca) [36], starry Solomon's seal (Maianthemum stellatum)
[83,84,143],
veiny meadowrue (Thalictrum venulosum), purple meadowrue (T.
dasycarpum) [83,84], smooth Solomon's seal (Polygonatum biflorum var. commutatum),
California nettle (Urtica dioica), heartleaf four o' clock (Mirabilis
nyctaginea), wild sarsaparilla (Aralia nudicaulis)], creeping violet (Viola
canadensis var. rugulosa), fireweed (Epilobium angustifolium), moist sowthistle (Sonchus arvensis ssp. ulginosus),
smooth aster (Aster laevis), white panicle aster (Symphotrichum
lanceolatum ssp. lanceolatum), wild mint (Mentha
canadensis), common hop (Humulus americanus), Blue Ridge carrionflower (Smilax
lasioneura), hedge false bindweed (Calystegia sepium) [143], lambsquarters (Chenopodium album), poison hemlock (Conium
maculatum), curly dock (Rumex crispus) [175], common sunflower (Helianthus annuus), Chenopodium species,
and prickly
Russian-thistle (Salsola tragus) [4].
Classifications systems listing plains cottonwood is an indicator species or as
a dominant component of community types, habitat types, plant associations,
riparian site types, or dominance types are as follows:
Montana [92,93,94,95]
North Dakota [83,84,223]
Wyoming [162,207]
Manitoba [143]
Rio grade cottonwood:
Common tree associates of Rio Grande
cottonwood include
peachleaf willow [73,113], hybrid crack willow (Salix x rubens) [73],
Russian-olive, Goodding willow (Salix gooddingii)
[59,113], saltcedar (Tamarix
ramosissima) [59], and sandbar willow (Salix exigua) [113]. Understory species include mule's fat (Baccharis glutinosa), desert false indigo,
stretchberry (Forestiera neomexicana), screwbean mesquite (Prosopis
pubescens), and Torrey wolfberry (Lycium torreyi) [59,113].
Classifications systems listing Rio Grande cottonwood is an indicator species or
as a dominant component of community types, habitat types, plant associations,
or riparian site types are as follows:
Arizona [204]
New Mexico [53,116,204]
Texas [46,206]
Eastern cottonwood seedlings are highly susceptible to grazing and
trampling damage from wildlife and domestic livestock. Control measures
generally must be taken, particularly on plantations, for successful
establishment and growth [9,40,47,145]. These can
include the selection of certain
clones that may be somewhat less palatable, weed control, use of repellent
materials, fencing, and direct control of the animals [47]. Eastern
cottonwood should not be planted next to European
alder (Alnus glutinosa) [168] or Siberian elm (Ulmus pumila) in shelterbelts,
because it will be shaded and mortality occurs within 10 years [191].
Strips or buffer zones of eastern cottonwood stands immediately adjacent to
streams and rivers are effective for erosion control [96].
In the Great Plains region, recruitment and survival of plains cottonwood has
been adversely affected by the construction of dams and reservoirs. Changes in
magnitude and frequency of floods, rates of sedimentation, and rates of meander
migration contribute to the reduction of suitable recruitment sites [23,124].
Periodic large releases of reservoir water to simulate natural flooding are
recommended to ensure vigorous recruitment and growth of cottonwood forests on
prairie river floodplains [23]. Flooding also decreases litter
accumulation and can reduce the threat of fire [59]. In Colorado, moderately high
flows that occur every 5 years are required to create the new point bars where plains cottonwood
establishes [72]. Seedlings will establish close to the edges of river channels,
but will probably not survive future ice jams and high discharges. The long-term
survival of seedlings established during flood-free periods
is greater the higher above stream channel they are established [179]. See black cottonwood
for further information on the effects of watercourse damming and
stream diversion on plains and other cottonwoods.
Disease and insect pests that affect eastern cottonwood have been described by
several authors [28,44,156,173,195].
Russian-olive and saltcedar have invaded many riparian woodlands across the
Great Plains and southwestern United States dominated by cottonwoods (Populus
spp.) and willows. The invaders have displaced the
native vegetation, taken up water, and increased fire frequency [137,185,197].
Russian-olive and saltcedar provide habitat for some wildlife species [137,185].
However, the loss of larger trees, especially eastern cottonwoods, has led to a
decrease in habitat for cavity-nesting birds [185].
Eastern cottonwood is relatively drought resistant [47] and has been used extensively in shelterbelt and windbreak plantings in the Great Plains region of the United States and Canada [35,173,178,209]. Hybrid clones bred for improved winter hardiness and resistance to insects and diseases are commonly used in such plantings [47]. Eastern cottonwood was introduced to Victoria, Australia, and is recommended for use in fire shelterbelts [190].
Plains cottonwood, the "Pioneer Tree of the Plains," is often the only tree found in the western United States. It is a sure sign of water and welcome shade [31,47,173]. During severe winters saplings were used as horse and cattle feed by Native Americans and early settlers [9,47,81]. Native Americans used the roots to start fires [31] and used smaller trees for lodge poles and travois. The teepee pattern is supposedly patterned after the deltoid leaf shape [173]. The Teton Dakota ate the inner bark and the Omaha used it to make the Sacred Pole. Nebraska tribe children made toys with the leaves and made gum and play jewelry from the fruits [81].
Plains cottonwood grows into an effective windbreak in 15 to 20 years, reaching 40 to 50 feet (12.2-15.2 m). It is recommended for planting in shelterbelts only if irrigated, on wetter sites, or in rows near the center of the shelterbelt [78,79].
The wood of Rio Grande cottonwood was used by the Navajo for firewood, fence posts, cradles, tinderboxes, wooden tubes of bellows, dolls, and images for ceremonies. Chewing gum was made from the sap or the catkins mixed with animal fat [60].
Top-killed eastern cottonwood may sprout from the roots, root crown, and/or bole following fire [183,184,190]. Although studies are few, sprouting response appears to be weak, and the long-term survivability of sprouts is poor [86]. Sprouting ability of eastern cottonwood declines with age [173]. In general, the ability of cottonwoods to sprout depends on (1) species (with those in section Tacamahaca sprouting more vigorously than those in section Aigeiros), (2) age (younger trees are more efficient), and (3) location of the water table (higher water tables increase sprout survivability) [86,95].
Plains cottonwood is a weak sprouter, and is especially susceptible to late summer and fall burns [95]. It does not readily form suckers [87,132]: Root and shoot sprouts are uncommon except for flood-trained shoot suckering [179].
Eastern cottonwood regenerates sexually and vegetatively.
Sexual reproduction: Large seed crops (25 to 28 million seeds/tree/year) [9,22,129] dispersed by wind and water over long distances, are generally produced annually once the trees reach 10 to 15 years of age [9,22,47,132,142,158,173,221,225].
There is no seed dormancy in eastern cottonwood [227,228]. Germination occurs as soon as seeds arrive on a seedbed that is moist, free of vegetation, and in full sunlight [9,23,67,132,173,181]. Seeds are highly viable at dispersal [66,124], but viability decreases rapidly in the absence of a suitable germination environment [66]. Under natural conditions, seeds remain viable for 1 to 2 weeks [22]. Suitable recruitment sites occur naturally as a result of spring flooding [156,173] and scouring by ice [9]. Receding floodwaters leave freshly deposited, exposed alluvium, and seed germination along prairie river floodplains often occurs exclusively on these sites [124,229]. Exposed soil is essential, as young seedlings do not compete well with overtopping vegetation [34,124,171].
Vegetative reproduction: Cottonwood species (Populus spp.) reproduce vegetatively by sprouting from stumps and root crowns, and by the formation of suckers (adventitious shoots on roots ) [47,176,229]. There is asexual reproduction from broken limbs (flood training) and crown breakage [22]. The ability of cottonwoods to sprout declines with age [173]. Cottonwoods in the Aigeiros section of Populus, including eastern cottonwood, do not sprout as readily as cottonwoods in section Tacamahaca. Eastern cottonwood sprouts from the roots and bole after top-kill or damage, but the response is weak [22,86]. Most suckers arise from suppressed buds embedded in the periderm of undisturbed roots after death or injury of aboveground parts. There is disagreement on the ability or eastern cottonwood to sprout from the bole after being cut [47,154].Plains cottonwood does not readily form suckers or stem sprouts [87,132], and sprouting is uncommon except in flood-trained shoots [23,86,179].
Growth: Eastern cottonwood is the fastest growing native tree in North America [28,47,121,132,212]. It commonly increases 0.7 to 1 inch (1.69-2.54 cm) in diameter and 5 feet (1.5 m) in height annually up to 10 to 15 years of age, and grows at only a slightly slower rate up to 30 to 35 years of age [28]. In the Mississippi valley, eastern cottonwood can reach 20 inches (50.8 cm) in diameter at breast height and 120 feet (36.6 m) in height at 35 years [28,145].
Growth of young seedlings is rapid [132]. The first 3 weeks of development of seedlings are slow, after which the growth rate rapidly accelerates [145]. Root growth of seedlings is also rapid. Seedlings have been observed to extend taproots 12 to 16 inches (30.5-40.6 cm) and lateral roots 24 inches (61 cm) by the end of their first growing season [222]. These roots serve as anchorage during floods and help to ensure a supply of water during dry periods.
Once established, seedlings are susceptible to damage from flooding. In one instance, 8 days of complete inundation weakened all seedlings, while 16 days resulted in their mortality [112]. Seedlings can survive if flooded less than 50% of the growing season [158]. Inundation does not necessarily have a detrimental effect upon germination [108].
Eastern cottonwood is shade intolerant [9,47,151,171,217,225] and a pioneer species that typically establishes on freshly exposed alluvium of sandbars, streambanks, and other floodplain sites [16,23,103,117,124,150,222]. Establishment and dominance may also occur after sandbar willows have stabilized the site [229]. Eastern cottonwood invades unburned prairies in Kansas [1] and old fields and upland sites in the lake states [47,111].
Maintenance of seral, eastern cottonwood-dominated communities depends on either periodic flooding or timber harvest [23,92,155,158]. In the Great Plains, dams and reservoirs which alter the magnitude and frequency of floods, sedimentation rates, and stream meander migration rates have detrimentally affected cottonwood communities by reducing seedling recruitment and survival [23]. In the absence of flooding, succession proceeds, and the shade-intolerant cottonwoods are eventually replaced by more shade-tolerant species [155]. Eastern cottonwood stands are replaced by American elm, sycamore, pecan, sugarberry, boxelder, and sweetgum [103]. The eastern cottonwood/Rocky Mountain juniper community type is an early successional stage in North Dakota. It succeeds to the green ash/western snowberry community if left undisturbed [83].
Plains cottonwood with willow and boxelder represents an early stage on floodplains in Nebraska [4]. The plains cottonwood-willow type progresses to the plains cottonwood-green ash type in North Dakota [124]. It contributes significantly to dune formation on Lake Michigan [38].
The currently accepted name of eastern cottonwood is Populus deltoides Bartr. ex Marsh.
(Salicaceae) [56,128]. It is in the Aigeiros section of Populus
[86]. Recognized infrataxa are as follows:
Populus deltoides ssp. deltoides Bartr. ex Marsh.
eastern cottonwood
Populus deltoides ssp. monilifera (Ait.) Eckenwalder plains cottonwood
[48,126,128]
Populus deltoides ssp. wislizeni (S. Wats.) Eckenwalder Rio Grande cottonwood
[48,56,126,128]
In this species summary eastern cottonwood refers to the species (Populus deltoides) unless otherwise noted as P. d. ssp. deltoides.
Plains cottonwood and Rio Grande cottonwood refer to P. d.
ssp. monilifera and P. d. ssp. wislizeni, respectively.
Eastern cottonwood produces several hybrids:
Carolina poplar (P. × canadensis Moench); from hybridization with Lombardy cottonwood (P. nigra) [56,57,88]
lanceleaf cottonwood (P. × acuminata Rydb.); afrom hybridization with narrowleaf cottonwood (P. angustifolia) [47,88]
balm-of-Gilead (P. × jackii Sarg.); from hybridization with balsam poplar (P. balsamifera)
[47,57,65,88]
Eastern cottonwood is well suited for revegetating disturbed riparian sites and has also been used extensively in the reclamation of strip-mined lands [27,157,217]. Eastern cottonwood (P. d. ssp. deltoides) has been planted successfully on mine spoils in Ohio both in pure stands and in mixture with black locust (Robinia pseudoacacia) [140]. The extensive root system holds streambanks in place [220], is effective in shoreline protection, and revegetating eroded stream channels [101]. Eastern cottonwood can be used as living dams for erosion and flood control work [145].
Eastern cottonwood may establish on suitable sites through natural seedfall [138,177,216], or it may be established by cuttings [47,68,133]. The average length of cuttings in the Pacific Northwest and the southern United States is about 20 inches (50 cm), while 8- to 12-inch (20-30 cm) cuttings are typical in the northern United States and Canada. However, cuttings of 8 feet (2.4 m) or more planted in 3-foot (1 m) deep holes have advantages over standard 20-inch (50 cm) cuttings. These advantages include less intensive site preparation requirements, a reduced need for browsing protection, and less intensive weed control [133]. In general, cuttings should be longer where upper soil moisture is limiting [47]. In Ohio, eastern cottonwood had better growth and survival when planted on loamy and clayey soils of previously coal strip-mined lands [140].
The growth of young cottonwood seedlings on favorable sites is rapid, but the plants must be kept free of competing vegetation to survive [34,132]. Browsing and trampling by wildlife and domestic animals must also be controlled for successful growth [47]. Whether revegetating by seeding or cuttings, native stock should be selected if available, since significant geographic variation exists in growth rate, drought resistance, wood characteristics, and sprouting ability [41,169].
Plains cottonwood was planted on surface-mined lands in Indiana 1928-1975 [27]. Rio Grande cottonwood is recommended for planting in the western Great Plains and desert southwest. Plains cottonwood is recommended for the northern Great Plains and western United States [33].
