Download Sandbar Willow - Department of Animal and Rangeland Sciences

Sandbar Willow
Salix exigua Nutt.
It is the smallest native, lowland, short-lived,
dioecious willow. In the Intermountain region
there are three subspecies, ssp. interior, exigua,
melanopsis. Sandbar willow creates dense
thickets from spreading clones. In its natural
habitat, this species has more male than female
counterparts. Many willow species, especially
sandbar willow, are self infertile and freely
hybridize with other willow species. In
Northern America this species is used as a
short wood fiber rotation crop. Willow bark
has aspirin like properties used by Native
Americans to cure many common illnesses.
Plant Characteristics
VEGETATIVE CHARACTERISTICS
Form and Stature: Assuming the form of a grayish soft wooded
tree or shrub, this species can reach up to 8 m (26 ft) tall, but typically
ranges around 1.5-3 m (5-9.8 ft) in height. Twigs are slender with
new leaves.
Leaves: Leaves are densely soft, short, divergent spreading hairs
and often less than 6cm (2.3 in) long. Mature leaves are up to 15
cm (6 in) long, elliptical to slightly lance shaped, smooth to toothed
edges, frequently losing pubescence. (3, 4, 10)
Inflorescence: The first catkins are bore 2 cm (0.78 in ) from the
axillary bud on the twigs. Catkins can appear before or after the
leaves. Tiny, deciduous stipules accompany each catkin. Male
catkins are slender with a very wide hairy base. Female catkins look
similar to its counterparts without as much basal hair. (3)
Roots: Extensive roots spread rapidly through the soil profile. Root
elongation increases with gradual declines in the water table (1).
Lateral roots can extend belowground producing new clones around
waterways (10). Roots prefer more saturated soils, thus more
anaerobic conditions, than cottonwoods.
GENERAL HABITAT CONSIDERATIONS
Soil Types and Conditions: Colonizes disturbed sites with coarse
to fine loamy soil textures of alluvial or fluvial depositions.
Characteristically, sandbar willows occur on open sand or gravel
bars. Often immediately adjacent to riparian edges.
Moisture/temperature requirements: Typically found partially to
fully submerged (3,10) on floodplains, foothills, bar islands and wide
valley bottoms. Sandbar willow occurs between 609-2,743 m (2,0009000 ft) elevations. Subspecies, exigua and melanopsis, reside below
1,828 m (6,000 ft) and 2,133 m (7,000 ft), respectively (2). At lower
elevations, sandbar willow becomes tolerant of many environmental
stressors (1).
Prepared by OSU Rangeland Ecology
and Management, April 2005.
Management Considerations
Sandbar Willow
Salix exigua Nutt.
UTILIZATION
Forage and Palatability: Fair forage for cattle during the summer
when other palatable species have been depleted (8). Grazed often
in the summer when drier conditions are less likely to cause soil
compaction.
Wildlife Use: Sandbar willow is exclusively home to a northern
Arizona leaf beetle, Disonycha plunligata. Gall flies have been
observed attacking youthful stems. Important forage for elk and
moose; often browsed by mule deer. Large thatches provide great
cover for many bird species. Birds, also, feed on catkins buds.
Beavers utilize willow branches for nesting and food.
PLANTING
Growth Season and Seedling Establishment: Active growth occurs
from April to July (10) with catkins developing over several weeks.
Pole establishment can have 80% survival if planted between
November to February. When establishing poles chose a site that
mirrors the donor site and monitor water table fluctuations for a year
prior to planting. Preplanting treatments require trimming of excess
branches and terminal buds and soaking for 5-7 days. Using a electric
hammer with a 1-in diameter, 3-foot bit, drill holes deep enough to
access the lowest seasonal water table levels. Plant poles 30.5 cm
(12 in) deep, leaving at least 20 cm (8 in) exposed, and compact soils
directly around propagule to ensure proper establishment. Protect
poles from grazing for at least a year (10).
Propagation: Produces from seeds or root suckers. Germination
viability is often very short, lasting up to 24 hours (10). In cold
temperatures, 0-5 C (32-41 F), seeds can be kept for 4-6 weeks. This
willow species has the longest dispersal interval of any other species.
Like many willow species, sandbar willow is pollinated by bees and
dispersed by wind or water.
DISTURBANCE
Response to Competition: Sensitive to dense tall grasses during
germination. Hard to establish under Salt cedar, Russian olive and
Giant Reed, unless there is an open canopy. Sandbar willow is
intolerant of shade. Eventually out competed, successionally, by
other trees especially cottonwoods (11).
Response to Grazing: Tolerant of grazing if managed properly.
Grazing pressures will indicate willow structure. Light to moderate
season long grazing can increase canopy cover as long as adequate
moisture and persistent willow crowns are available, providing
favorable environmental conditions. Removal of grazing can initiate
rapid recovery of willows in stem height and canopy cover. It also
leads to swift succession to trees.
Response to Fire: Resprouts after top kill fires. Does not experience
fires frequently due to close proximity of water.
Response to Drought: Less drought tolerant than cottonwoods (1).
Abrupt changes in water table will promote mortality. Drought
stresses can particularly retard shoot cell elongation. Sandbar willow
also does not tolerate frost.
Sources:
1. Amlin, Nadine M. and S. B. Rood.
2002. Comparative tolerances of riparian
willows and cottonwoods to water-table
decline. Wetlands 22(2): 338-346.
2. Brunsfeld, Steven and Fredrich
Johnson. 1985. Field Guide To The Willows
Of East-Central Idaho. Bullentin 39.
Moscow, Idaho: University of Idaho, Forest,
Wildlife, and Range Sciences. 95p.
3. Cook, Sarah. 1997. A Field Guide
to the Common Wetland Plants of Western
Washington and Northwestern Oregon.
Seattle: Seattle Audubon Society. 417p.
4. Davis, Ray J. 1952. Flora of
Idaho. Dubuque, IO: WM.C. Brown
Company. 836p.
5. Dixon, Mark D. 2003. Effects of
flow pattern on riparian seedling recruitment
on sandbars in the Wisconsin River,
Wisconsin, USA. Wetlands 23(1): 125-139.
6. Douhovinkoff, Vladimir, J.R.
McBride, and R.S. Dodd. 2004. Salix exigua
colonal growth and population dynamics in
relation to disturbance regime variation.
Ecology 86(2): 446-452.
7. Hitchcock, C. Leo and Arthur
Cronquist. 1973. Flora of the Pacific
Northwest. Seattle, WA: University of
Washington Press. 730 p.
8. Holland, Kathryn A., W.C.
Leininger, and M.J. Trlica. 2005. Grazing
history affects willow communities in a
montane riparian ecosystem. Rangeland
Ecol. Manage. 58:148-154.
9. Plants for a future-Species
Database. 1997-2000. Salix exigua.
www.ibiblio.org/ [Accessed: April 12, 2005].
10. Uchytil, Ronald J. 1989. Salix
exigua. In: Fire Effects Information System,
[Online]. U.S. Department of Agriculture,
Forest Service, Rocky Mountain Research
Station, Fire Sciences Laboratory (Producer).
Available: http://www.fs.fed.us/database/feis/
[2005, April 13].
11. USDA, NRCS. 2004. The
PLANTS Database, Version 3.5
(http://plants.usda.gov). National Plant Data
Center, Baton Rouge, LA 70874-4490 USA.