BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Salix bebbiana | Bebb Willow 



GENERAL BOTANICAL CHARACTERISTICS : 
Bebb willow is a large shrub 10 feet (3 m) tall or a small multistemmed
tree with a bushy top 15 to 25 feet (4.6-7.6 m) tall [6,23,25,41,43].
The twigs are slender and branch at wide angles, and are thinly to
densely hairy [5,41].  Largest mature leaves are 2.6 to 6 inches (7.2
cm) long [1].  The bark is smooth when young but becomes rough and
furrowed with age [41].  Roots of Bebb willow are shallow and dense
[45].


RAUNKIAER LIFE FORM : 
   Phanerophyte (Microphanerophyte)
   Phanerophyte (Nanophanerophyte)


REGENERATION PROCESSES : 
Sexual reproduction:  Male and female flowers of Bebb willow are borne
on separate individuals.  Bebb willow starts flowering from 2 to 10
years of age, with optimum seed-producing years from 10 to 30
[17,18,45].  Bees are the chief pollinating agents [15].  Large
quanities of lightweight seed (approximately 2 to 3 million per pound
[4.4-6.6 million/kg]) [15] are produced and dispersed in the spring, but
seeds remain viable for only a few days [8,17,18,45].  Seeds do not
require a period of dormancy prior to germination, but successful
establishment requires a moist, exposed mineral substrate that receives
full sunlight.  These conditions are best on recent deposits of alluvial
silts and gravels along waterways or in silted-in, abandoned beaver
ponds [8,17,18,45].  Bebb willow seed germination in Alaska was 90 to
100 percent at temperatures between 41 and 77 degrees Fahrenheit (5-25
deg C).  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 [46].

Vegetative reproduction:  Bebb willow will establish by root shoots and
basal stem sprouting [17,45].  Stem and root fragments root naturally if
buried in moist soil.  Damaged and cut stems produce prolific sprouts
from the stem base or root collar.  Layering also occurs readily if
branches become buried [17].


SITE CHARACTERISTICS : 
In northern Alberta, Bebb willow is common around sloughs in prairies,
and in foothills, upland forests, wet lowlands, thickets, and muskegs.
It is often found in thickets adjacent to streams, swamps, and lakes in
Alaska [45].  In Idaho and Montana, Bebb willow is best represented in
riparian communities within the Douglas-fir (Pseudotsuga menziesii) zone
and sagebrush/grass habitats.  It is apparently absent in the subalpine
zone but does sometimes occur in cool Engelmann spruce (Picea
engelmannii) dominated streambottoms in the upper Douglas-fir zone
[6,18].

Soils:  Bebb willow is usually found on moist sandy or gravelly soils
but is adapted to a wide variety of soil textures [45].  It will
tolerate moderately alkaline soils but does poorly in extremely acidic
or alkaline conditions [21,45].  The general pH range for willows is 5.5
to 7.5 [17].  Bebb willow can survive short periods of standing water,
but growth rates decline sharply if water persists above the root collar
[18,30].  This willow is not drought tolerant, however, and prefers
sites with adequate moisture.  It is also shade intolerant and grows best
in full sunlight [45].

Elevational range:  The elevational range of Bebb willow in several
states is as follows [6,9,22]:

        Utah: 4,400 to 8,600 feet (1,341-2,621 m)
        Colorado: 5,000 to 9,600 feet (1,524-2,926 m)
        Wyoming: 4,500 to 8,300 feet (1,372-2,530 m)
        Montana: 2,800 to 8,500 feet (853-2,591 m)
        Arizona: 8,000 to 11,000 feet (2,438-3,353 m)               
        Idaho: 3,300 to 7,900 feet (1,010-2,410 m)

Plant associates:  Bebb willow is commmonly associated with the
following species:  Pacific willow (Salix lasiandra), thinleaf alder
(Alnus tenuifolia), redosier dogwood (Cornus stolonifera), dwarfed
blackberry (Rubus pubescens), black cottonwood (Populus trichocarpa),
quaking aspen (P. tremuloides), water birch (Betula occidentalis),
bluejoint reedgrass (Calamagrostis canadensis), beaked sedge (Carex
rostrata), water sedge (C. aquatilis), false-Solomons-seal (Smilacina
stellata), sweet scented bedstraw (Gallium triflorum), rush (Juncus
spp.), and bluegrass (Poa spp.) [18,19,37,45].


SUCCESSIONAL STATUS : 
Bebb willow is a pioneer species and once established may persist in
areas with moist site conditions or frequent disturbance such as fire or
flooding.  Channel changes that reduce the availability of water may
prevent successful germination and establishment of Bebb willow within
established stands.  Bebb willow has low shade tolerance and therefore
loses dominance on sites as the more shade-tolerant species such as
black cottonwood, quaking aspen, and Engelmann spruce become established
[11,18,19,27].


SEASONAL DEVELOPMENT : 
In general, Bebb willow flowers from April through July or August
[9,15,41].  The fruit ripens soon after flowering, followed by seed
dispersal [15,41].  Blooming dates for several western states are as
follows [9]:

                Utah: April-July
                Colorado: May-August
                Wyoming: June-August
                Montana: April-June
                North Dakota: April-May

Related categories for Species: Salix bebbiana | Bebb Willow