Halberd Willow

Halberd willow

More info for the term: shrub

Halberd willow is a native, multibranched, spreading shrub typically
between 3 and 6 feet (1-2 m) tall [12,21]. It has small, simple,
alternate, deciduous leaves. Male and female flowers occur on separate
plants in 0.75- to 2-inch-long (1.5-5 cm), erect catkins [21]. Halberd
willow has a remarkable characteristic of plasticity; its growth form
adapts readily to a wide variety of habitats [10].

In North America, Halberd willow occurs in northern Alaska, the
mountains of central Alaska, including the Alaska range, and extreme
northwestern Canada. It is most common near the Arctic Coast. Halberd
willow also occurs in northern Europe and Asia, southward in the
mountains of both [7,21].

More info for the terms: fire regime, root crown, top-kill

Information on Halberd willow's ability to sprout after fire is lacking.
It is assumed that following top-kill by fire, this willow sprouts from
the root crown like most other species of willow [14]. Halberd willow
produces numerous, minute seeds that are dispersed by wind, and are
important in colonizing recently disturbed areas [10].

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".

More info for the terms: competition, forest, natural

Prescribed fire is widely used as a management tool to rejuvenate
decadent willow stands and stimulate sprouting [10]. Early seral stage
communities created by fire can increase the carrying capacity of winter
range for moose in interior Alaska [25]. Recurring fires within some
parts of the boreal forest have allowed aspen and willow to replace
coniferous forests. The tendency of willows to expand quickly following
fires and other disturbances and to form dense thickets inhibits natural
regeneration of conifers. Prescribed burning can reduce initial
competition from willow in areas to be planted with cultivated species
[10].

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More info for the term: phanerophyte

Phanerophyte

More info for the term: root crown

In Alaska and northern Canada, Halberd willow is found in wet areas such
as heaths, riverbeds, and streams and on floodplains frequently
disturbed by flooding and the resulting erosion and siltation [1]. In
interior Alaska, Halberd willow occurs along streambanks, areas formed
by glacial drift, outwash deposition areas, and old river floodplains
with rocky substrates [3,17].

Soils: Halberd willow grows best in moist, alluvial bottomlands but is
also found in well-drained sandy or gravelly substrates. The general pH
range for willows is 5.5 to 7.5. Halberd willow will tolerate
moderately alkaline soils but does poorly in extremely acidic or
alkaline conditions [10]. Growth of Halberd willow is severely reduced
when water levels are maintained at or above the root crown for extended
periods. Halberd willow is also shade intolerant and grows best in full
sunlight [4,10].

Plant associates: Halberd willow is commonly associated with the
following species: Barclay willow (Salix barclayi), Alaska willow,
tealeaf willow, Richardson willow (S. lanata ssp. richardsonii), black
cottonwood (Populus trichocarpa), alder (Alnus spp.), sedges (Carex
spp.), and mosses (Polytrichum spp.) [17].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

201 White spruce
202 White spruce - paper birch
203 Balsam poplar
204 Black spruce
217 Aspen
251 White spruce - aspen
252 Paper birch
253 Black spruce - white spruce
254 Black spruce - paper birch

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES23 Fir - spruce
FRES44 Alpine

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

K015 Western spruce - fir forest
K052 Alpine meadows and barren

More info for the terms: root crown, top-kill

Information on the fire effects on Halberd willow is lacking. It is
assumed that like most other willow species, Halberd willow is
fire-tolerant and sprouts readily from the root or root crown after
being top-killed by fire [14]. Severe fires can kill willows completely
by removing soil organic layers and charring the roots. Less severe
fires only top-kill plants [10].

In interior Alaska, willows (Salix spp.), are the most important source
of browse for moose. Halberd willow is a lightly browsed species by
moose and is considered an unimportant dietary component [17]. Willow
shoots, catkins, leaves, and buds are eaten by numerous small mammals
and birds [10].

More info for the terms: forest, shrub, tundra

Halberd willow is a common thicket-forming shrub on streambanks and
moist slopes in the Arctic, extending to alpine regions and onto tundra
[2,12]. In the boreal forest of interior Alaska, Halberd willow occurs
primarily in willow thickets along small streams and is a pioneer
species on river sandbars and glacial moraines. It is found
occasionally in alpine sedge bogs [17,21]. Halberd willow also occurs
in floodplain thickets on rivers and grows on newly exposed alluvial
deposits that are periodically flooded [1,21].

More info for the term: shrub

Shrub

Willow establishment along riparian zones is an effective management
tool because of the importance of willows in stabilizing streambanks and
providing erosion control on disturbed sites [10].

AK NT YT

All willows produce salicin, which is closely related chemically to
salicylic acid, the active ingredient in aspirin. Native Americans of
the Yukon Territory used the chewed leave of willows for mosquito bites,
bee stings, and stomach aches. The branches were used for muskrat
traps, fish traps, hare traps, and ribs of birchbark canoes [11].

In interior Alaska, Halberd willow is considered less palatable to moose
than Alaska willow (S. alaxensis), littletree willow (S. arbusculoides),
sandbar willow (S. interior), and tealeaf willow (S. planifolia ssp.
pulchra) [17]. Palatability of willows increases as the season
progresses [16].

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More info for the terms: fruit, seed

Halberd willow flowers in late spring or midsummer (May-June). The
fruit ripens soon after flowering, followed by seed dispersal in late
July and early August [21,26].

More info for the terms: density, fire severity, herbaceous, organic soils, severity

Halberd willow's density probably increases shortly after burning.
However, it is shade intolerant, and density will decline as young trees
overtop it [21]. Halberd willow seeds need a nutrient-rich mineral
seedbed to germinate. The chance of Halberd willow establishing after a
fire lessens as available mineral soil seedbeds become occupied by
faster growing herbaceous species and mosses [5]. Fire severity
affects the mode of willow postfire recovery. Following light-severity
fires most willows recover quickly, sending up new shoots from undamaged
root crowns. Few, if any, seedlings establish following this type of
fire because the partially consumed organic soil layers comprise an
unfavorable seedbed. Following severe fire, however, the primary mode
of recovery is seedling establishment. Severe fires that burn into
organic soils kill willows, but expose mineral soils which provide
excellent seedbeds [26].

More info for the terms: ground residual colonizer, root crown, secondary colonizer, shrub

Small shrub, adventitious-bud root crown
Ground residual colonizer (on-site, initial community)
Secondary colonizer - off-site seed

More info for the terms: adventitious, capsule, cover, dehiscent, dioecious, fruit, litter, root crown, seed, tree

Sexual reproduction: Halberd willow is dioecious. The fruit is
contained in a dehiscent capsule that releases many seeds that are
dispersed by wind or water. Optimum seed production occurs between 2
and 10 years. Bees are the chief pollinating agents [10]. The seeds of
Halberd willow are short-lived, germinating immediately on moist
surfaces with high relative humidity, exposed mineral substrates, and in
full sunlight. Germination is inhibited on sites with a continuous
cover of tree litter [5,10]. Seed germination occurs over a broad
temperature range, 41 to 77 degrees Fahrenheit (5-25 deg C). This
appears to be a compensatory mechanism because of the short seed life
[5,26]. This adaptation to a wide range of temperatures is particularly
important in interior Alaska, where surface soil temperatures may vary
over a relatively wide range [26].

Vegetative reproduction: Most willows are prolific sprouters. It is
assumed that Halberd willow also sprouts from the root crown or stembase
if aboveground stems are broken or destroyed by cutting, flooding, or
fire [10]. Detached stem fragments form adventitious roots if kept
moist [1,23].

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More info for the term: succession

Obligate Initial Community Species

Halberd willow is frequently found in early seral plant communities that
occupy from 2.5 to 250 acres (1-100 ha) along river systems of interior
Alaska. Halberd willow is a pioneer species that becomes established
after disturbances such as fire, logging, or recent alluvial deposits
resulting from floodplain processes [24]. Floodplain willow communities
are short-lived; thinleaf alder (Alnus incana ssp. tenuifolia) and
balsam poplar (Populus balsamifera) establish within 5 years of initial
willow colonization. By 20 to 30 years, poplars begin to overtop the
brushy canopy and dominate. By this stage in succession, overstory
shade has eliminated most Halberd willows because of its shade
intolerance [23].

S. walpolei (Cov. and Ball) Ball

The currently accepted scientific name of Halberd willow is Salix
hastata L. [1,2,7,12]. Salix farriae, formerly S. hastata var.
farriae, is now recognized as a distinct species. Although there
remains some confusion regarding the taxonomy of these two entities,
their geographical distributions are distinctly different. Salix
hastata is limited to Alaska, Yukon, and the District of Mackenzie.
Salix farriae occurs from southern British Columbia and Alberta
southward to Oregon, Idaho, Montana and Wyoming [7]. Recognized
varieties of Salix hastata are as follows [12]:

Salix hastata var. hastata L.
Salix hastata var. subintegrifolia Flod.
Salix hastata var. subalpina Anderss.
Salix hastata var. alpestris Anderss.

More info for the terms: natural, restoration, root crown, shrub, succession, taiga

Halberd willow is useful in stabilizing streambanks and providing
erosion control on severely disturbed sites [9]. Willow species are the
most important colonizers of disturbed sites in the Alaskan taiga
because of their ability to produce root and root crown shoots, which
provide for quick recovery [25]. On the North Slope of Alaska, large
areas of riparian shrub river valleys were destroyed when the
Trans-Alaska Pipeline System (TAPS) was constructed. The affected area
had 12,300 acres (492 ha) of primary moose habitat prior to construction
of TAPS, of which 2,825 acres (113 ha) or 23 percent were disturbed.
Habitat restoration was not possible on 60 percent of the disturbed
area, which had been mined below the level of the river. Three to four
years after disturbance, natural regeneration had occurred on all
disturbed sites within the impact area. Salix hastata and other willows
colonized all moist silty areas and dry areas but not moist gravel
areas. Site conditions affecting natural revegetation of disturbed
areas were similar to those affecting riparian succession on areas not
disturbed by construction [6].