BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Salix hastata | Halberd Willow 



GENERAL BOTANICAL CHARACTERISTICS : 
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].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
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].
  


SITE CHARACTERISTICS : 
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].


SUCCESSIONAL STATUS : 
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].


SEASONAL DEVELOPMENT : 
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].

Related categories for Species: Salix hastata | Halberd Willow