Salix nigra, black willow
Tesky, Julie L. 1992. Salix nigra, black willow. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/salnig
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Plants | ||||
| SALNIG | black willow | Salix nigra | Life Form: Plants/Shrub, Plants/Tree Kingdom: Plantae Class: Dicot Order: Salicales Family: Salicaceae Genus: Salix | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The currently accepted scientific name of black willow is Salix nigra Marsh. [11,12,22,26,31]. Recognized varieties are S. nigra var. nigra Marsh., S. nigra var. altissima Sarg., S. nigra var. falcata (Pursh.) Torr., and S. nigra var. lindheimeri [20,22,26].
Salix nigra, S. gooddingii Ball, and S. amygdaloides Anderss. are closely related taxa commonly referred to as the black willows [26]. The three species are not easily distinguished morphologically, and in fact, some authorities consider S. gooddingii to be S. nigra var. vallicola Dudley or S. n. var. venulosa (Anderss.) Bebb. [5,8,36]. S. amygdaloides is sometimes considered to be S. nigra var. amygdaloides Anderss. [13]. For the purposes of this review, however, these varieties will be considered as separate species. S. nigra hybridizes with S. amygdaloides (S. X glatfelteri Schneider); S. alba (S. X hankensonii Dode); and S. lucida (S. X schneider Boivin) [5,20,38].
Synonyms
- None
Other Common Names
swamp willow, southwestern black willow, Gulf black willow, scythe-leaved willow
General Distribution
Black willow is found throughout the eastern United States, adjacent parts of Canada, and Mexico. Its range extends west from southern New Brunswick and central Maine to Quebec, southern Ontario, central Michigan, southeastern Minnesota, and eastern North Dakota. It occurs south and west to the Rio Grande just below its confluence with the Pecos River; and east along the Gulf Coast through the Florida Panhandle and southern Georgia [5,8,11]. Black willow has been introduced in Utah where it is now common along many streambottoms [17].
States and Provinces
- United States: AL AR CT DE FL GA IL IN IA KS KY LA ME MD MA MI MN MS MO NE NH NJ NY NC ND OH OK PA RI SC TN TX UT VT VA WV WI
- Canada: MB NB ON PQ
- Mexico
Site Characteristics
Black willow, Mitchell County, North Carolina. (CC BY-NC 4.0)
Black willow is most common on river margins where it occupies the lower, wetter, and often less sandy sites. It is also common in swamps, sloughs, swales, gullies, and drainage ditches, growing anywhere light and moisture conditions are favorable [5]. It flourishes at or slightly below water level and is not appreciably damaged by flooding and silting [5,16]. On a flooded site in southern Illinois, black willow survived 32 or more days of complete inundation [16]. Black willow, however, is not drought tolerant. Whole stands may die out when water tables lower and soil dries up [39].
Soils: Black willow grows on a variety of soils but develops best in fine silt or clay in relatively stagnant water. It thrives in saturated or poorly drained soil from which other hardwoods are excluded [6,24]. Black willow is commonly found in moderately acidic (lower pH limit is 4.5) to near neutral soils [5].
Climate: Black willow grows best in climates characterized by an average annual rainfall of 51 inches (130 cm), with approximately 20 inches (51 cm) falling from April through August. The average maximum temperature across its range is 93 degrees Fahrenheit (34 deg C) in the summer and 59 degrees Fahrenheit (15 deg C) in the winter [5].
Plant Communities
Black willow occurs as a codominant in some early seral floodplain communities [24,30]. It codominates with sandbar willow (Salix exigua) on floodplains having the greatest water depths and the longest hydroperiods of any of the shallow freshwater swamps of the southern United States [24]. Black willow also codominates with eastern cottonwood (Populus deltoides) in the lower Mississippi Valley [30]. Published classifications listing black willow as a codominant in community types (cts) are listed below:
| Area | Classification | Authority |
|---|---|---|
| Southern U.S. | Southern swamp & marsh cts | Penfound 1952 |
| Arkansas, Mississippi: Lower Mississippi Valley | cts | Shelford 1954 |
Plant associates: Black willow is commonly associated with the following species: eastern cottonwood, red maple (Acer rubrum), black spruce (Picea mariana), river birch (Betula nigra), American sycamore (Platanus occidentalis), boxelder (Acer negundo), red mulberry (Morus rubra), swamp privet (Forestiera acuminata), buttonbush (Cephalanthus occidentalis), water elm (Planera aquatica), and American elm (Ulmus americana) [5,39].
Botanical Description
Black willow foliage and catkins, Hamilton County, Ohio. (CC0 1.0)
Black willow is a small (sometimes shrublike) to large, short-lived, deciduous tree [3,5,8,27,29]. It is fast growing and may reach maturity within 30 years [8,17]. This tree usually obtains a height of 66 feet (20 m) but can grow up to 138 feet (42 m) on some sites [8]. The massive trunks are usually leaning and are often divided. The bark is thick and deeply divided into furrows separating thick, scaly ridges. The crown is broad and open with stout branches [27]. Twigs are slender and easily detached [8]. Leaf blades are variable in size, the larger to 4.7 inches (12 cm) long. Black willow roots are shallow and laterally extensive [5,39].
Raunkiaer Life Form (Raunkiaer 1934)
- Phanerophyte
Seasonal Development
Black willow flowering begins in February in the southern portion of its range and extends through late June at the northern limits. The catkins usually appear at the time of or immediately preceding leaf emergence [5,39]. Seeds ripen and fall in April to July [39].
Regeneration Processes
Sexual reproduction: Black willows start producing seed when they are about 10 years old [4,5]. Optimum seed-bearing age is from 25 to 75 years. The trees have good seed crops almost every year. producing an average of 2.3 million seeds per pound (5 million/kg). Seeds ripen 45 to 60 days after catkins are pollinated by insects or wind. As the seeds fall, the long silky hairs act as wings to carry the seeds long distances. The seeds are also disseminated by water [5].
Seeds are not dormant. Viability is greatly reduced by only a few days of dry conditions. Germination is epigeal, and germination capacity is usually high. Very moist bare mineral soil is best for germination and early development [5,14,28]. Once seedlings are established, full light promotes vigorous growth. Seedlings grow rapidly in a favorable environment, often exceeding 4 feet (1.2 m) in the first year. Low ground cover competition and shade, however, greatly hampers growth [28].
Vegetative reproduction: Root stocks of very young black willow trees sprout prolifically. Propagation by cutting is the usual method of artificial regeneration [5,39].
Successional Status
Black willow is a pioneer or early seral species commonly found along the edges of rivers and streams, mud flats, and floodplains. This tree is very shade intolerant and usually grows in dense, even-aged stands. Black willow stands periodically stagnate and are eventually replaced by more shade-tolerant trees such as American elm, sycamore (Platanus spp.), ash (Fraxinus spp.), boxelder, and sweet gum (Liquidambar styraciflua) [5,14,32,34,41].
Immediate Fire Effects
Although black willow does exhibit some fire adaptations, it is very susceptible to fire damage and will typically decrease following fire [1]. High-severity fires can kill entire stands of black willow. Low-severity fires can scorch the bark and seriously wound trees, leaving them more susceptible to insects and disease [5,37]. Surface fires will also destroy young seedlings and saplings [5,24,37].
Postfire Regeneration Strategy (Stickney 1989)
- Survivor species; on-site surviving root crown or caudex
- Off-site colonizer; seed carried by wind; postfire years 1 and 2
- Off-site colonizer; seed carried by animals or water; postfire years 1 and 2
Fire Adaptations
Black willow has the ability to sprout from the base following fire [37]. Its wind- and water-dispersed seeds are also important in revegetating areas following fire. Fires are rare in the bottomland areas where black willow typically occurs [1].
Plant Response to Fire
Black willow will sprout from the base following fire [5,37]. Fires that expose bare mineral soil may create a favorable seedbed for black willow establishment. However, because seed viability is greatly reduced by dry conditions [5], seedling establishment on burned sites depends on the season of the burn, amount of moisture available, and amount of exposed mineral soil.
Following a spring fast-moving head fire in a palm (Sabal spp.) grove in south Texas, all black willow trees up to 13 feet (4 m) tall were scorched badly and had few green leaves. Three months after the fire all aboveground portions of black willow trees had died, but almost all sprouted from the base. Following a low to moderate-severity Oklahoma grassland summer fire, black willow density decreased. Preburn density was 169 stems per acre (417 stems/ha); a year following the burn density was only 51 stems per acre (125 stems/ha) [1].
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name on the Advanced Search page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
Burning has been shown to be beneficial in maintaining tallgrass prairies by inhibiting the invasion of black willow and other woody species [1].
Federal Status
No special status.
Other Status
No entry.
Importance to Wildlife and Livestock
Birds eat the buds and flowering catkins of black willow; deer eat the twigs and leaves; and rodents eat the bark and buds [8,35]. The yellow-bellied sapsucker feeds on the sap [5,39]. Black willow is somewhat tolerant of grazing and browsing [39]. Black willow/cottonwood stands are also commonly used as nesting habitat by some small nongame bird species [30].
Palatability and Nutritional Value
Palatability of black willow has been rated as fair for livestock and deer [7,39].
Black willow has been rated as fair in energy value and poor in protein value [7].
Cover Value
Black willow cover values in Utah are rated as follows [7]:
| Wildlife Type | Rating |
|---|---|
| Pronghorn | Poor |
| Elk | Poor |
| Moose | Fair |
| Small mammals | Fair |
| Small nongame birds | Good |
| Upland game birds | Good |
| Waterfowl | Fair |
Value for Rehabilitation or Restoration of Disturbed Sites
Black willow was commonly used in soil stabilization projects in early efforts at erosion control. Its flood tolerance and the ease with which it establishes from cuttings continue to make it an excellent species for reducing erosion of streambanks, bars, and islands [5,8,18,39]. Post-sized willow cuttings have been rooted for use in flood projects to prevent gullies from forming [5].
Seeds lose viability rapidly if stored at room temperature. Refrigerated storage of moistened seeds for no longer than 1 month is recommended. Commercial seed is not usually available [39]. Planted seedlings or cuttings should be protected from livestock, beavers, small rodents, and rabbits. Hardware cloth placed around individual plants will protect them from rodents and rabbits. Livestock should be excluded by fencing the entire area, and firebreaks should surround the revegetated area. Additionally, the area around each tree should be kept free of weeds [18]. To reduce competition densities greater than 494 to 556 trees per acre (200-225 trees/ha) should be avoided [18].
Other Uses
Ancient pharmacopoeia recognized the bark and leaves of willow as useful in the treatment of rheumatism [5]. Pioneering settlers boiled the bark of black willow for its purgative and vermin-destroying powers [40]. In 1829, the natural glucoside, salicin, which is closely related chemically to aspirin, was isolated from willow [5]. Black willow was once used as a source of charcoal for gunpowder [8].
Black willow is the largest and only commercially important willow in North America. The wood is light, usually straight grained, and moderately high in shock resistance. It stains and finishes well but is relatively unendurable [5]. The wood was once used extensively for artificial limbs because it is lightweight, does not splinter easily, and holds its shape well [5,8]. It is still used for making boxes and crates, furniture core stock, turned pieces, table tops, wooden novelties, doors, cabinets, polo balls, and toys [5,8,15]. Black willow is also used for pulp [5,8].
Other Management Considerations
Thinning: To increase yields and reduce mortality of black willow, stands should be thinned as soon as economically feasible; thinning should continue at 5-year intervals [5,28]. Spacing between trees after thinning should average about 21 times the mean stem diameter of 10 inches (25.4 cm). This results in a 17.5 feet (5.3 m) spacing [5].
Insects and Disease: The forest tent caterpillar (Malacosoma disstria), the gypsy moth (Lymantria dispar), the cottonwood leaf beetle (Chrysomila scripta), the willow sawfly (Nematus ventralis), and the willow leaf beetle (Plagiodera versicolora) partially or occasionally completely defoliate willow trees, reducing growth but seldom causing death. The cottonwood borer (Plectrodera scalator) attacks black willow and may kill by girdling the base. Top and branch rot account for 86 percent of the cull in willow. Leaf rust, fungus scab, and black canker can cause leaf and shoot destruction of black willow seedlings [5,39].
Because of its weak wood and shallow roots, black willow is susceptible to breakage and windthrow [39].
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES16 Oak - gum - cypress
- FRES17 Elm - ash - cottonwood
- FRES36 Mountain grasslands
- FRES41 Wet grasslands
BLM Physiographic Regions (Bernard and Brown 1977)
- 6 Upper Basin and Range
- 12 Colorado Plateau
- 14 Great Plains
- 16 Upper Missouri Basin and Broken Lands
Kuchler Plant Associations (Kuchler 1964)
- K091 Cypress savanna
- K092 Everglades
- K098 Northern floodplain forest
- K101 Elm - ash forest
- K113 Southern floodplain forest
SAF Cover Types (Eyre 1980)
- 61 River birch - sycamore
- 63 Cottonwood
- 94 Sycamore - sweetgum - American elm
- 95 Black willow
- 101 Baldcypress
- 102 Baldcypress - tupelo
- 103 Water tupelo - swamp tupelo
- 235 Cottonwood - willow
SRM Rangeland Cover Types (Shiflet 1994)
- No entry
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