BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Salix alaxensis | Alaska Willow 



GENERAL BOTANICAL CHARACTERISTICS : 
Alaska willow is a deciduous shrub or small tree reaching heights of 20
to 30 feet (6-9 m) and stem diameters of 4 to 7 inches (10-18 cm) [44].
In exposed high arctic and alpine sites it may assume a low,
semiprostrate growth form [6].  The bark is gray and smooth but becomes
rough and furrowed into scaly plates with age [44].  Male and female
flowers occur on separate plants in 2- to 4-inch-long (5-10 cm) erect
catkins [3].  The fruit is two-valved capsule.


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (microphanerophyte)
   Undisturbed State:  Phanerophyte (nanophanerophyte)
   Burned or Clipped State:  Hemicryptophyte
   Burned or Clipped State:  Therophyte


REGENERATION PROCESSES : 
Alaska willow's primary mode of reproduction is sexual.  It produces an
abundance of small, light-weight seeds.  Like most willows, it probably
begins seed production at an early age (between 2 and 10 years) [16].
At maturity, the fruit splits open, releasing the seed.  Each seed has a
cottony down that aids in dispersal by wind and water.  The seeds are
dispersed during the growing season.  They remain viable for only about
1 week without moisture.  Viable seeds will germinate within 24 hours of
dispersal on moist seedbeds [11].  In germination tests, 94 to 97
percent of the seeds germinated within 1 to 3 days at temperatures
between 50 and 77 degrees F (10-25 deg C) [52].  Seedlings are common on
freshly deposited river alluvium [5,37,42].  Silty soil tends to be a
good germination medium because it usually remains moist; however, sandy
soils is a poor germination medium because it tend to be dry [22].
Forest litter prevents Alaska willow germination and establishment [46].
Seedlings readily establish on disturbed forested sites where mineral
soil is exposed.

Vegetative reproduction:  Alaska willow sprouts from the rootcrown or
stem base if aboveground stems are broken or destroyed by cutting,
flooding, or fire [22].  Detached stem fragments quickly form
adventitious roots if kept moist.  Thus, Alaska willow stem fragments
transported by floodwaters develop into new plants when deposited on
riverbars [10].


SITE CHARACTERISTICS : 
Alaska willow is shade-intolerant and usually found in open or semi-open
habitats such as stream and riverbanks, lakeshores, alpine slopes and
meadows or less frequently in forest openings [3,6,17].  It is
relatively common in open white spruce (Picea glauca) forests, but is
otherwise restricted to forest openings in more dense forests [36,40].

Associates:  Alaska willow often mixes with other willows, including
Bebb willow (S. bebbiana), grayleaf willow (S. glauca), Sitka willow (S.
sitchensis), Pacific willow (S. lasiandra), barren-ground willow (S.
brachycarpa), halberd willow (S. hastata), littletree willow, and
tealeaf willow [1,3,12,37].  Alders (Alnus spp.) and cottonwoods and
poplars (Populus spp.) are also commonly associated with Alaska willow.
Common herbaceous associates include horsetails (Equisetum spp.) and
bluejoint reedgrass (Calamagrostis canadensis) [1,17,37].


SUCCESSIONAL STATUS : 
Alaska willow is an early seral species.  Abundant wind-dispersed seed
and rapid seed germination allow it to quickly colonize moist disturbed
sites.  It is one of the first species to colonize newly formed silt
bars following flooding, where it quickly forms thickets [42].  It also
pioneers recently deglaciated sites [1].

Alaska willow communities are usually short-lived.  Thinleaf alder
(Alnus incana ssp. tenuifolia) often establishes within 5 years of
initial Alaska willow colonization [42].  Balsam poplar often
establishes with or shortly after the alder, and 20 to 30 years after
Alaska willow first colonized the site, the poplars begin to overtop the
brushy canopy and dominate.  By this stage in succession, overstory shade
has eliminated most Alaska willow plants, but some may persist as
scattered individuals [42].  In riverbank communities of the Tanana
River, near Fairbanks, the oldest Alaska willow was 48 years old and
found in the balsam poplar stage of succession [46].  As the river
terrace builds up, these sites eventually become climax white spruce
forests.

In northern Alaska, pioneer Alaska willow communities on river alluvium
are also short-lived.  They are replaced by low-statured willows and
dwarf shrubs which form dwarf heath meadow communities [5,9].


SEASONAL DEVELOPMENT : 
Alaska willow catkins appear in the spring before the leaves.  In
Alaska, flowering generally occurs in May and June, and seeds generally
mature in June and July [44].  Seeds are dispersed shortly after
ripening.  In general, seeds are dispersed later as latitude and
elevation increase [11].  Dispersal often coincides with receding spring
floodwaters, when newly exposed mineral soil seedbeds are moist [46].

Related categories for Species: Salix alaxensis | Alaska Willow