Al Schneider @ www.swcoloradowildflowers.com
Narrowleaf willow and sandbar willow (S. interior) are closely related, varying mainly by leaf margin and relative hairiness, and their ranges overlap . They are sometimes treated as a single species [94,182,191]; however, this review follows the taxonomy of several systematists [24,64,97,102,119,169] who treat the 2 taxa as distinct species. The Utah Division of Wildlife Resources describes narrowleaf willow as having "taxonomic problems" due to difficulty of recognizing infraspecific taxa .
Narrowleaf willow hybridizes with northwest sandbar willow (S. sessilifolia) .LIFE FORM:
Plants Database provides a distributional map of
FRES21 Ponderosa pine
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES40 Desert grasslands
STATES/PROVINCES: (key to state/province abbreviations)
Common associates throughout the range of narrowleaf willow are other willows (Geyer willow (Salix geyeriana), yellow willow (S. lutea), Booth willow (S. boothii)), red-osier dogwood (Cornus sericea), northern gooseberry (Ribes oxyacanthoides), black cottonwood (Populus balsamifera ssp. trichocarpa), water birch (Betula occidentalis) [31,79], Wood's rose (Rosa woodsii), and prickly rose (R. acicularis) . In the Great Basin, common associates include sagebrush (Artemisia spp.), Fremont cottonwood (P. fremontii), saltbush (Atriplex spp.), and pinyon-juniper (Pinus- Juniperus spp.) . Floodplain associates include saltgrass (Distichlis spicata), sand dropseed (Sporobolus cryptandrus), sedges (Carex spp.), western wheatgrass (Pascopyrum smithii), and little bluestem (Schizachyrium scoparium). Narrowleaf willow frequently occurs with the invasive shrub saltcedar (Tamarix ramosissima, T. chinensis) .
Vegetation classifications describing plant communities where narrowleaf willow is a dominant species follow:
narrowleaf willow community type [173,174]
streamside riparian zones 
narrowleaf willow/sedge community type 
narrowleaf cottonwood (Populus angustifolia)/narrowleaf willow community type 
narrowleaf willow riparian type 
narrowleaf willow/field horsetail (Equisetum arvense) community type 
narrowleaf willow/Kentucky bluegrass (Poa pratensis) community type [145,197]
black cottonwood/narrowleaf willow plant association
narrowleaf willow/prairie sage (Artemisia ludoviciana) plant association
narrowleaf willow/sedge plant association
narrowleaf willow/field horsetail plant association
narrowleaf willow/mesic graminoid plant association
narrowleaf willow/Wood's rose plant association 
narrowleaf willow community type 
narrowleaf willow/mesic forb community type
narrowleaf willow/barren community type [100,145]
eastern cottonwood-peachleaf willow (Populus deltoides-Salix amygdaloides)/narrowleaf willow woodland
narrowleaf willow/mesic graminoid shrubland 
narrowleaf willow community type [21,79,81,82,83,150]
narrowleaf willow dominance type 
narrowleaf willow/Wood's rose community type [122,123]
narrowleaf willow/mesic forb community type [122,123,140]
narrowleaf willow/bench (sparse undergrowth) community type 
narrowleaf willow-narrowleaf willow community type 
narrowleaf willow-vine-mesquite (Panicum obtusum) community type
narrowleaf willow-deergrass (Muhlenbergia rigens) community type
narrowleaf willow-gravel bar community type 
narrowleaf willow-false quackgrass (Elymus x pseudorepens) community type
narrowleaf willow-common threesquare (Schoenoplectus pungens) community type
narrowleaf willow-water sedge (C. aquatilis) community type
narrowleaf willow-common spikerush (Eleocharis palustris) community type
narrowleaf willow-Baltic rush (Juncus balticus) community type
narrowleaf willow-smooth horsetail (Equisetum laevigatum) community type
narrowleaf willow-mule's fat (Baccharis salicifolia) community type
narrowleaf willow-yerba mansa (Anemopsis californica) community type
narrowleaf willow-redtop (Agrostis gigantea) community type [58,138]
narrowleaf willow community type [173,174]
lanceleaf cottonwood (Populus x acuminata)-narrowleaf willow community type
Arizona walnut (Juglans major)-narrowleaf willow community type 
narrowleaf cottonwood/narrowleaf willow community type
saltcedar/narrowleaf willow community type
narrowleaf willow-rubber rabbitbrush (Chrysothamnus nauseosus) community type
narrowleaf willow/woolly sedge (Carex pellita) community type
narrowleaf willow/saltgrass community type
narrowleaf willow/sparse community type 
eastern cottonwood-narrowleaf willow woodland association
narrowleaf willow/switchgrass (Panicum virgatum) shrubland association 
narrowleaf willow seasonally flooded woodland alliance 
narrowleaf willow/mesic forb community type
narrowleaf willow/barren community type
narrowleaf willow/Kentucky bluegrass community type 
narrowleaf willow/field horsetail community type 
narrowleaf willow/Kentucky bluegrass community type [40,184,197]
narrowleaf willow-willow (Salix spp.) community type 
willow-dominated deciduous shrub 
Thayne Tuason @ CWNP.org
GENERAL BOTANICAL CHARACTERISTICS:
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [85,89,113,125,188]).
Narrowleaf willow is a native , winter-deciduous [23,49] shrub that grows up to 33 feet (10 m) tall [49,54,65,71,85,96,109,125,188]. More commonly, narrowleaf willow is 6.5 to 20 feet (2-6 m) tall [24,53,67,80] with many erect shoots . Individual stems arise singly or a few together and form large colonies from spreading roots [71,113]. Lateral roots of narrowleaf willow produce root sprouts in profusion, often in long rows. These shoots elongate rapidly in spring . Narrowleaf willow also resprouts from the root crown .
Individual stems often only live 10 years, though some may reach 20 years. Shoot length, leaf length, number of leaves per shoot, and mean internode length all decrease with age .
Narrowleaf willow is alternately described as "deep rooted"  and shallow rooted . Roots are woody and spreading , forming an extensive root system, especially with the development of large clones .
Narrowleaf willow leaves are linear to linear-elliptic and acute at both ends [6,53,85,96,109,125]. Leaf size ranges from 0.8 to 6 inches (2-15 cm) long and 0.1 to 0.8 inch (3-20 mm) wide [6,6,24,53,65,67,85,113,155].
Narrowleaf willow produces flowers in catkins 0.6 to 4 inches (1.5-10 cm) long [49,54,65,67,109]. Catkins are first produced with or just after leaves, though flowering may occur in succession throughout the summer [24,113].
Narrowleaf willow is both drought resistant  and very tolerant of flooding; it can withstand flooding for periods of 2 or more growing seasons. "Very tolerant" species usually exhibit good adventitious or secondary root growth during periods of flooding [27,155,162,185]. The ability to generate new roots on the original root or submerged stem is important to willows. Elevated soil-water tables result in severely restricted root development and eventual death of the root system. However, adventitious rooting above the flooded soil is abundant in many species of willow and a new root system develops above the soil-water table , which likely contributes to narrowleaf willow's flood tolerance. A greenhouse study of rooted cuttings found that narrowleaf willow cuttings inundated with water for 152 days displayed 72% and 43% increases in shoot and root elongation, respectively . Another greenhouse study found gradual declines in the water table (0.4 to 0.8 inch (1-2 cm)/day) promote root elongation and shoot growth of narrowleaf willow compared to a constant water table, while abrupt declines in water table (>0.8 inch/day) reduce growth and survival . In Texas, narrowleaf willow forms a woodland alliance that is flooded throughout most of the growing season. When flooding subsides, soils often remain relatively saturated .
Willows are very frost tolerant. Mature leaves and winter-dormant stems are
capable of surviving temperatures of -4 oF (-20 oC) and -94
oF (-70 oC) respectively. However, frosts during the early
growing season can cause severe damage to the fast-growing shoots. Temperatures <28
oF (-2 oC) will kill the elongation zone soon after exposure.
Lateral buds below the damaged shoot rapidly form new shoots .
RAUNKIAER  LIFE FORM:
Narrowleaf willow regenerates by seed and asexually by root sprouts .
Pollination: Narrowleaf willow is primarily insect pollinated [132,137,139,194].
Breeding system: Narrowleaf willow is generally dioecious [26,80,137,139]. However, monoecious individuals have also been described. These individuals have both staminate and pistillate aments as well as mixed aments. In mixed aments, staminate flowers are massed at the base with the division between the 2 types of flowers distinct and abrupt .
Seed production: Narrowleaf willow produces many small seeds with morphological adaptations to enhance dispersal [42,135,144]. Flowering and seed production may begin as early as age 2 to 3 years .
Seed dispersal: In general, willow seeds are dispersed primarily via wind and water [49,135,144,162]. Narrowleaf willow seeds are small, fragile, light, and sufficiently aerodynamic to be wind-dispersed .
Seed banking: Narrowleaf willow seeds are nondormant  and quickly become desiccated if not on a moist substrate [44,139]. Seed viability beyond 1 week is rare [135,138,187], and viability lasts no longer than 3 weeks [44,49].
Germination: Narrowleaf willow seeds usually germinate with 24 hours of landing on a suitable substrate (freshly deposited, wet alluvium in full sunlight) [44,49,135,138,139]. Because narrowleaf willow requires moist exposed surfaces for germination, there may be a period of only a few days where suitable substrate is available due to the rapid recession of water in riparian zones .
Seedling establishment/growth: Seedling recruitment of narrowleaf willow may be limited by site availability - establishment requires areas that are both close enough to streams for adequate water and yet protected from intense scouring during floods [55,127]. Seedling mortality also results from herbivory, pathogens, and competition with other seedlings for available resources . Narrowleaf willow seedlings have been characterized as "fast growing" . Annual height increases are 12 inches (30 cm), and stem diameter increases at 0.1 inch (2.6 mm) . Shoot growth in willow species varies from year to year in response to resource accumulation from the previous year. Snow cover, early season temperatures, and drought may have little visible effect on current year's growth but may reduce shoot growth and rooting success the following year. Willow height growth is most rapid during late afternoon and early evening .
Asexual regeneration: Narrowleaf willow typically develops dense clonal thickets from root sprouts [24,49,67,77,99,135,139,144,162]. Stems develop from shoot buds on lateral roots  and form extensive spreading colonies [65,96]. This colonial habit allows narrowleaf willow to dominate riparian sites . A field study in the Sacramento Valley of California found that clonal growth is an important component of narrowleaf willow's life history. Clones up to 1,065 square feet (325 m2) were found . Individual narrowleaf willow plants are generally shrub-like, though older individuals may resemble small trees. Clones expand vegetatively along moisture gradients resulting in dispersed and linear clones, with new clones developing progressively closer to moisture sources . Due to potentially high seedling mortality (see Seedling establishment/growth), asexual clones may be largely responsible for narrowleaf willow's success . Because narrowleaf willow reproduces primarily through asexual sprouting, lack of a resident population can limit establishment of narrowleaf willow, even on favorable sites .
Narrowleaf willow branches are flexible and resprout if buried in sediment; plants may also
regenerate vegetatively from broken stems and roots transported during high stream flow and
deposited on exposed, wet soils [135,138]. Narrowleaf willow also readily resprouts from the
root crown after fire or cutting [49,99].
Narrowleaf willow has a wide elevational range, occurring from low elevations in the Great Basin  up to 9,500 feet (2,900 m) in western mountains [85,105,139]. The following table presents the elevational distribution of narrowleaf willow in several areas:
|Arizona||up to 9,500 feet (2,900 m)|||
|California||up to 8,860 feet (2,700 m)|||
|Colorado||5,000 to 9,500 feet (1,525-2,900 m)|||
|Idaho||<7,000 feet (<2,135 m)|||
|Montana||2,460 to 5,775 feet (750 - 1,760 m)|||
|Nevada||1,400 to 8,000 feet (425-2,440 m)|||
|New Mexico||3,500 to 7,500 feet (1,070-2,290 m)||[125,138]|
|Utah||2,707 to 8,497 feet (825-2,590 m)|||
|Wyoming||5,000 to 9,200 feet (1,525-2,800 m)|||
|Rocky Mountain region||1,500 to 9,200 feet (457-2,800 m)|||
|Southwest region||7,000 feet (2,135 m)|||
Narrowleaf willow grows on moist or wet sites from the plains, desert shrub, and sagebrush zones to lower montane habitats in western North America [31,65,71,101,109,117,135,139,139,151]. It is the only willow to grow in the lowest and hottest portions of the North American deserts, provided the roots are in moist soil [137,139].
Narrowleaf willow generally grows in open to densely-vegetated riparian communities along streams, gravel bars, lakeshores, and ditches [4,6,53,67,109,117,118,138,151]. At high elevations it is confined to streamside communities [31,170] though at low to mid-elevations, narrowleaf willow may be found on moist, well-drained benches, floodplains, and bottomlands [23,31,117,151]. Common sites include fluvial canyons, braided stream channels, and low elevation alluvial valleys . Narrowleaf willow frequently establishes on favorable sites below the high-water line (depositional gravel bars, other sites subject to frequent flooding) [4,31,138,162]. However, a study on the Owens River in California found narrowleaf willow was much more common above channel banks and was rarely found inside the river channel, perhaps due to channel scouring . Occurrence of narrowleaf willow on Gallatin River sites in Wyoming actually increased with distance from the river (up to 66 feet (20 m)), where soil moisture decreased .
Narrowleaf willow is often more abundant where river bank angles are moderately steep or where canyons narrow . Sites have a generally high water table, and most stands are adjacent to flowing water [80,118]. Frequent flooding in these areas commonly causes scouring and deposition of alluvium, resulting in surface horizons with up to 85% bare soil or rock. Available water capacity varies from low to high depending on textures and amount of coarse fragments . Soils are generally rocky, gravelly, or sandy [31,80,146,155] and sand content has been positively correlated with willow growth and willow cover . Less frequently, narrowleaf willow is also found on clay soils . Akashi , however, suggests narrowleaf willow may occasionally favor fine, impermeable soils. A study on the Bighorn River in Wyoming found narrowleaf willow especially prevalent on fine clay sediments .
Though neutral pH (7.2 to 7.6) is optimal, narrowleaf willow also grows outside that narrow range .
It is more often found on alkaline soils, though it may also be found on slightly acid soils . Narrowleaf
willow is tolerant of low nutrient levels . In general, willows have poor height growth on sites with
low pH and low nutrient availability. However, they will tolerate low nitrogen levels and sustain healthy,
if dwarfed, shoots .
Narrowleaf willow is a pioneer species [77,78,84,144,146] that rapidly colonizes fresh alluvial deposits . Narrowleaf willow's proliferation of seeds, ability to resprout, tolerance of low nutrient levels, and tolerance of disturbance are all characteristic of pioneering species. A study of the Swan River in northwest Montana found that narrowleaf willow is consistently among the first plants to colonize newly exposed gravel bars . It typically forms narrow bands along streams, rivers, lakes, and ponds. Narrowleaf willow colonizes rocky, gravelly, and sandy stream and lake edges, moist, well-drained alluvial terraces and bottomlands, and recently deposited sand and gravel bars that are below the high-water mark, where it is subject to annual flooding, ice jams, and associated scouring and deposition [78,80,135,156,192].
Narrowleaf willow is shade intolerant [2,77,135,138]. Seedlings of narrowleaf willow and cottonwoods
(Populus spp.) are often established at the same time on newly-deposited alluvium. Initially,
narrowleaf willow may grow faster than cottonwood; however, in a few years cottonwoods overtop the
willows and begin to dominate the overstory. As a dense canopy develops, narrowleaf willow is shaded
out [2,79]. In a seral riparian cottonwood community, Boggs and Weaver  found that narrowleaf
willow decreased as cottonwood saplings reached pole and mature stages of growth. Where cottonwoods are
not present, other willows (Geyer willow, yellow willow, Drummond willow (Salix drummondiana))
may become the climax vegetation as narrowleaf willow communities promote bank building and soil development,
preparing hospitable sites for other species [78,81]. The narrowleaf willow community type in Montana
is a seral stage that may persist under a regime of repeated fluvial disturbance [78,79]. Where narrowleaf
willow dominates riparian vegetation, it may reach 10 to 16 feet (3-5 m) tall and 95% cover .
Narrowleaf willow flowers appear with or just after the leaves in mid- to late spring [53,113,125,132,135,139,190]. Flower buds in willows are formed during the season prior to flowering and are likely activated by specific temperature thresholds or accumulated heat units; however, narrowleaf willow also initiates flowers at the tips of current shoots throughout the growing season . Narrowleaf willow may continue to flower sporadically through the growing season following a peak flowering period in May [24,132,139,146]. Willows demonstrate a strong thermal control over flowering, which occurs in response to heat pulses and may be delayed by cold spells .
Narrowleaf willow seeds are generally released during a 1- to 2-month period from mid-May to mid-July [44,127,139]; however, seed release may continue through October . Seed dispersal may correspond to low water levels , which may be important for reducing the number of seeds washed away and allowing seeds to germinate when soils are moist but not inundated .
Narrowleaf willow is winter deciduous [23,49].
Fire regimes: Specific information regarding the fire regime of narrowleaf willow is not available in current literature. The following section summarizes available information on riparian fire regimes, where narrowleaf willow almost exclusively occurs.
Fire is a common disturbance in both riparian ecosystems and the surrounding hillslopes. Fires in areas containing riparian ecosystems may burn only the upland parts of the watershed, or they may burn both the riparian ecosystem and the upland areas. Fire rarely occurs only in a riparian ecosystem, however, unless it is prescribed . The role riparian forests play in the propagation or suppression of fire disturbance on the landscape is poorly understood [62,165]. Riparian areas with heavy, continuous fuels may serve as corridors for rapid spread of fire  or reservoirs of smoldering fuels. Conversely, less dense or more mesic riparian areas may serve as firebreaks for surface fires . Riparian microclimates are generally characterized by cooler air temperature, lower daily maximum air temperature, and higher relative humidity than the adjacent uplands, contributing to higher fuel moisture content and presumably lowering the intensity, severity, and frequency of fire in riparian areas [3,59]. During fire events, the lower wind speeds generally associated with riparian zones may result in less severe fire behavior, with decreased rate of spread, decreased flame lengths, and lower fireline intensities. However, steep canyons may serve as wind tunnels, increasing fire intensity in narrow valleys with riparian habitat. During droughts, weather and fuel conditions may become the primary determinants of fire behavior, and differences between fire behavior in riparian areas and uplands are likely to disappear . When only upland areas burn, adjacent riparian areas may buffer the effects of fire on the watercourse. Recovery of riparian vegetation depends on the severity of the fire and any postfire flooding .
Deciduous riparian plant communities often exhibit low fire incidence due to high moisture in potential fuels and rapid decomposition of litter . However, some riparian areas are surrounded by greater and more continuous fuel accumulations than in the past .The fuel buildups may increase fire severity in these surrounding forests, substantially impacting water flow and sediment transport in riparian areas [1,62]. In southwest riparian areas, the extent of fires that do occur is likely associated with areas of saltcedar . In native riparian plant communities dominated by cottonwood, willows, or mesquite (Prosopsis spp.), wildfires are infrequent; however, fire return intervals may be considerably shorter in areas infested with saltcedar [34,128]. The invasion of saltcedar with its propensity for periodic burning has changed the disturbance regime in low-elevation southwestern floodplain ecosystems . The drought-deciduous nature of saltcedar contributes to a heavy fuel load, increasing both fire severity and frequency . In addition, the tendency of fire to volatilize nutrients, increase soil concentrations of mineral elements, and reduce available moisture may favor saltcedar invasion at the expense of native woody riparian species . For more information, see the fire ecology section of the salt cedar species summary.
The limited research available on fire regimes in riparian areas relative to adjacent uplands indicates that fire frequency and severity vary by region and forest type. In the northwest United States, fire return intervals tend to be longer and and fires less severe in riparian areas, though in drier forest types riparian fire regimes more closely approximate those in surrounding upland forest . A study of 3 areas in the Blue Mountains and southern Cascades of Oregon found that fires occurred frequently in riparian forests, with fire intervals ranging from 13 to 14 years at one site, 12 to 26 years at the 2nd site. Fires were characteristic of a low-severity and high-frequency fire regime. The 3rd site was representative of a moderate-severity fire regime, with fire return intervals averaging 23 to 56 years. The overall range in this study area was 3 to 167 years. In all 3 study areas, the fire return interval for riparian zones was similar to that of upslope forests, indicating that fire return intervals may be influenced more by forest composition and overall climate than by whether they occur in riparian or upslope areas. When forest compositions are similar between riparian and upslope communities, they will experience similar fire return intervals. However, where sufficient moisture gradient exists to allow a mesic riparian forest next to a dry upslope forest, the resulting dissimilar vegetation will likely result in more variation in fire return intervals .
There is evidence from studies in the mixed conifer region of California that fires affect riparian areas of perennial streams less frequently than in the adjacent uplands; however, in the upper reaches of watersheds where riparian reserves are associated with intermittent streams, fires appear to have burned with frequency similar to the surrounding uplands [165,166]. In a study of the Sierra Nevada mixed conifer forest, proximity to streams was more important in determining forest composition (conifer/hardwood balance) than was the occurrence of fire. Riparian zones appear to alter community dynamics in such a way as to reduce the likelihood and impact of fire. Stream proximity has direct impacts on soil moisture, generally favoring hardwood species. Proximity also dictates flood occurrence, which increases soil moisture and can suffocate the roots of flood intolerant species, resulting in more open canopy cover and reduction in the forest duff layer .
Studies of grasslands and shrublands indicate long fire return intervals and low-severity burns in riparian areas relative to upland vegetation, though very little research has been conducted addressing this comparison . Determining fire return intervals in riparian areas is complicated by the presence of tree wounds from other disturbance (i.e. ice flows) and the short life spans of most riparian hardwood species .
Fire Effects: Fire affects riparian zones both directly (when burned) and indirectly via changes in transport of sediment, biomass, and water through the riparian area. In general, riparian areas do not burn or burn at reduced intensity because they are wetter sites with more deciduous vegetation and higher fuel moistures. However, headwater riparian areas sometimes burn with greater intensity than surrounding slopes because of a channeling effect of wind in an area of generally higher biomass than elsewhere. If a small fire creeps through a riparian area it often top-kills most shrubs and deciduous trees, such as willows and cottonwoods, but because most of these species resprout, soil stability is not impaired. In higher severity fires, even riparian stringers are killed .
As described above, there is little consensus regarding fire regimes and fire return intervals in riparian areas. However, riparian communities may be influenced by the fire regimes of adjacent and surrounding plant communities. The following table provides fire return intervals for plant communities and ecosystems where riparian vegetation is likely to include narrowleaf willow. 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".
|Community or ecosystem||Dominant species||Fire return interval range (years)|
|grand fir||Abies grandis||35-200 |
|California chaparral||Adenostoma and/or Arctostaphylos spp.||<35 to <100 |
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||<10 [110,148]|
|Nebraska sandhills prairie||Andropogon gerardii var. paucipilus-Schizachyrium scoparium||<10 |
|silver sagebrush steppe||Artemisia cana||5-45 [88,153,193]|
|sagebrush steppe||Artemisia tridentata/Pseudoroegneria spicata||20-70 |
|basin big sagebrush||Artemisia tridentata var. tridentata||12-43 |
|mountain big sagebrush||Artemisia tridentata var. vaseyana||15-40 [11,32,133]|
|Wyoming big sagebrush||Artemisia tridentata var. wyomingensis||10-70 ( x=40) [181,195]|
|saltbush-greasewood||Atriplex confertifolia-Sarcobatus vermiculatus||<35 to >100 [148,196]|
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||10 to <100 [129,148]|
|plains grasslands||Bouteloua spp.||<35 [148,193]|
|blue grama-needle-and-thread grass-western wheatgrass||Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii||<35 [148,157,193]|
|blue grama-buffalo grass||Bouteloua gracilis-Buchloe dactyloides||<35 [148,193]|
|grama-galleta steppe||Bouteloua gracilis-Pleuraphis jamesii||<35 to <100|
|blue grama-tobosa prairie||Bouteloua gracilis-Pleuraphis mutica||<35 to <100 |
|cheatgrass||Bromus tectorum||<10 [149,189]|
|California montane chaparral||Ceanothus and/or Arctostaphylos spp.||50-100|
|paloverde-cactus shrub||Cercidium spp./Opuntia spp.||<35 to <100 |
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1,000 [13,160]|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||<35 to <100|
|blackbrush||Coleogyne ramosissima||<35 to <100|
|Arizona cypress||Cupressus arizonica||<35 to 200 |
|California steppe||Festuca-Danthonia spp.||<35 [148,171]|
|juniper-oak savanna||Juniperus ashei-Quercus virginiana||<35|
|western juniper||Juniperus occidentalis||20-70|
|Rocky Mountain juniper||Juniperus scopulorum||<35 |
|western larch||Larix occidentalis||25-350 [10,17,45]|
|creosotebush||Larrea tridentata||<35 to <100|
|Ceniza shrub||Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa||<35 |
|wheatgrass plains grasslands||Pascopyrum smithii||<5-47+ [148,153,193]|
|Engelmann spruce-subalpine fir||Picea engelmannii-Abies lasiocarpa||35 to >200 |
|black spruce||Picea mariana||35-200 |
|blue spruce*||Picea pungens||35-200 |
|pinyon-juniper||Pinus-Juniperus spp.||<35 |
|Rocky Mountain bristlecone pine||P. aristata||9-55 [51,52]|
|whitebark pine*||Pinus albicaulis||50-200 [1,7]|
|Mexican pinyon||Pinus cembroides||20-70 [134,172]|
|Rocky Mountain lodgepole pine*||Pinus contorta var. latifolia||25-340 [16,17,175]|
|Sierra lodgepole pine*||Pinus contorta var. murrayana||35-200 |
|Colorado pinyon||Pinus edulis||10-400+ [66,72,106,148]|
|Jeffrey pine||Pinus jeffreyi||5-30|
|western white pine*||Pinus monticola||50-200 |
|interior ponderosa pine*||Pinus ponderosa var. scopulorum||2-30 [9,14,116]|
|Arizona pine||Pinus ponderosa var. arizonica||2-15 [14,41,161]|
|Table Mountain pine||Pinus pungens||<35 to 200 |
|galleta-threeawn shrubsteppe||Pleuraphis jamesii-Aristida purpurea||<35 to <100 |
|quaking aspen (west of the Great Plains)||Populus tremuloides||7-120 [9,76,131]|
|mesquite||Prosopis glandulosa||<35 to <100 [129,148]|
|mesquite-buffalo grass||Prosopis glandulosa-Buchloe dactyloides||<35|
|Texas savanna||Prosopis glandulosa var. glandulosa||<10 |
|mountain grasslands||Pseudoroegneria spicata||3-40 ( x=10) [8,9]|
|Rocky Mountain Douglas-fir*||Pseudotsuga menziesii var. glauca||25-100 [9,11,12]|
|California mixed evergreen||Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii||<35|
|California oakwoods||Quercus spp.||<35 |
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||<35 to <200 |
|canyon live oak||Quercus chrysolepis||<35 to 200|
|blue oak-foothills pine||Quercus douglasii-P. sabiniana||<35|
|Oregon white oak||Quercus garryana||<35 |
|California black oak||Quercus kelloggii||5-30 |
|bur oak||Quercus macrocarpa||<10 |
|oak savanna||Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium||2-14 [148,183]|
|little bluestem-grama prairie||Schizachyrium scoparium-Bouteloua spp.||<35 |
|western redcedar-western hemlock||Thuja plicata-Tsuga heterophylla||>200|
|western hemlock-Sitka spruce||Tsuga heterophylla-Picea sitchensis||>200|
|mountain hemlock*||Tsuga mertensiana||35 to >200 |
Prescribed burning of willow-dominated streambanks temporarily removes aboveground biomass, accelerating streambank erosion .
After fire, livestock grazing in the first 2 to 3 years may substantially damage young, palatable willow stems .
Narrowleaf willow is browsed by moose, elk, and to a limited extent, mule deer [79,112,135,137]. Where abundant, it may be important late summer and winter browse for elk [68,124,147]. Narrowleaf willow is important and heavily-used browse for beaver [25,79,135,137].
Palatability/nutritional value: Narrowleaf willow is palatable to domestic livestock, big game, and beavers , though palatability varies with location and season . Dittberner and Olson  rate narrowleaf willow palatability "fair" for domestic sheep, cattle, and horses . Domestic cattle find it more palatable in late summer than earlier in the season. The fallen and brown leaves are eaten by domestic sheep . Narrowleaf willow is moderately palatable for elk . Narrowleaf willow also provides "good food value" for large game animals and small mammals, and "fair food value" for waterfowl and small nongame birds .
Narrowleaf willow communities in the southern Great Plains are used extensively during winter months
by migratory waterfowl , and narrowleaf willow provides important nesting and cover sites for
nongame birds [29,50,73,86,143,194,198]. It may also provide fair cover for elk, fair to good cover
for antelope, waterfowl, and small mammals, and good cover for mule deer, white-tailed deer, and upland
game birds [50,135]. Narrowleaf willow thickets, in particular, offer valuable cover for birds and other
VALUE FOR REHABILITATION OF DISTURBED SITES:
Restoration: Narrowleaf willow is recommended for riparian revegetation projects in Intermountain, northern and southern Rocky Mountain, northern and western Great Plains, desert Southwest, and mediterranean California areas . It is effective in shoreline protection and in stabilization and revegetation of eroded stream channels [91,144] because of its early successional status, rapid growth, ability to root sprout, and quick development of fibrous and adventitious roots [18,135]. Narrowleaf willow is especially suited for planting on stream bottoms to prevent surface erosion .
In the southwest, narrowleaf willow often shares dominance with the invasive saltcedar and may be useful in restoring these areas to native vegetation .The ability of narrowleaf willow to resprout from both root crowns and roots after major disturbance allows it to re-establish and spread, and may increase its competition with saltcedar, which re-establishes from seed and root crowns . Narrowleaf willow has rapid growth potential under low environmental stress and may competitively exclude saltcedar when seedlings are concurrently established after flooding. This ability is compromised under harsher environmental conditions such as high soil salinity and drought .
Propagation: Propagation studies in Ontario have achieved 90% rooting success in bareroot plantings of narrowleaf willow .
Narrowleaf willow propagates well from stem cuttings [43,49,57]. Dormant willow stem cuttings strike root easily in moist sand or soil, and direct planting of cuttings is commonly used for revegetation and restoration of riparian areas. One field study in California found 95% to 99% of willow cuttings rooted, with 1st year survival reaching 75%. Second year survival was 65% to 70%. Larger diameter cuttings were more successful . In a Nevada laboratory study, 86% of cuttings successfully rooted . One field experiment achieved 90% survival after 14 weeks, only slightly exceeded by rooted transplants at 93% survival after 14 weeks . Unrooted cuttings may be used successfully on low-elevation sites where the water table remains high throughout the growing season. Rooted stock should be used on sites with fluctuating water tables, high flooding potential, or short growing seasons [135,186]. Cuttings develop roots along the entire length of the stem; roots and shoots appear in 10 to 15 days [135,151].
Narrowleaf willow seed germination occurs over a wide range of constant or alternating incubation temperatures. In one set of laboratory tests, narrowleaf willow germinated at all 55 temperatures tested. Seeds are also highly viable, with 100% germination achieved under at least 1 temperature regime (34/59 oF (1/15 oC) alternating). However, germination may be substantially reduced by late frost. Optimum germination temperatures ranged widely for different seed sets, from a constant 36 oF to 86 oF (2-30 oC) and including 50/104oF (10/40 oC), 59/104 oF (15/40 oC), and 68/104 oF (20/40 oC) alternating temperature regimes . Baskin and Baskin  found optimum seed germination of narrowleaf willow was reached at 72 oF (22 oC).
The Natural Resources Conservation Society has released the commercial narrowleaf willow cultivar "Silvar"
Native Americans used flexible willow stems for baskets, arrow shafts, scoops, and fish traps [38,109,137]. All willows produce salicin, which is closely related chemically to acetylsalicylic acid, commonly known as aspirin . Medicinal uses of narrowleaf willow by Native Americans include toothache, venereal disease, dandruff, wound healing, indigestion, worms, and other stomach ailments [38,109,137]. .
OTHER MANAGEMENT CONSIDERATIONS:
Livestock browsing in Oregon substantially reduced the height and density of narrowleaf willow stems in riparian areas . Wildlife browsing, too, may substantially reduce development and increase mortality [39,147,163]. In addition, trampling reduces the establishment of narrowleaf willow in riparian areas . Narrowleaf willow density and growth may be enhanced by no or moderate grazing compared to heavy grazing practices . A field study in eastern Oregon found that following seedling establishment, narrowleaf willow density was highest in areas subjected to moderate spring cattle grazing and lowest in areas grazed moderately in fall or heavily all season long. Where growth of narrowleaf willow does not exceed browsing height, site stability and on-site seed sources are slow to develop . Heavily browsed willows may take 3 or more years to recover . Narrowleaf willow is adapted to most forms of disturbance. It is a prolific sprouter and will re-establish following release from heavy grazing pressure, provided it has not been totally removed from the site .
A number of insects attack narrowleaf willow, including leaf mining beetles, lepidopterans, sawflies, and galling insects. A bud galling midge affects both terminal and lateral shoots, arresting growth of the immediate shoot .
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