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Wildlife, Animals, and Plants |
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VALUE AND USE
WOOD PRODUCTS VALUE:The light colored wood of Scouler willow offers no striking grain pattern, but its light weight and ability to absorb shocks make it suitable for specialty products like prosthetic devices [182].
IMPORTANCE TO LIVESTOCK AND WILDLIFE:Scouler willow is an important browse species for domestic livestock and wildlife ungulates [6,8,17,36,60,68,124,131,132,150,164,179,204,218,219,226,227], providing critical winter and spring browse [19]. It is often the most preferred browse in ponderosa pine forests for mule deer, white-tailed deer, elk, bighorn sheep, moose, and domestic livestock [23,24]. Upland sites are heavily used by deer and elk; in riparian areas moose particularly prefer Scouler willow [26,146,179,190,192,223,235,256,260,264], especially in winter months [87]. In disturbed areas, Scouler willow may contribute more moose forage than any other species present [194]. Scouler willow, occurring in younger stands, is more important in the moose diet than willows present in older stands [219]. Scouler willow leaves, twigs, and bark are utilized as browse [209]. In British Columbia, it is of moderate to high importance for black-tail deer, is utilized from April through November, and is favored during spring and summer months [45]. Areas of high Scouler willow cover have been associated with high elk use [82]. In Idaho, it is preferred elk forage, important in both summer and winter months [105,108,130]. Elk use tends to be higher in early rather than late summer [60]. In Montana, Scouler willow is a large part of the regular winter diet for elk as well as a reservoir of surplus feed on which elk depend whenever climatic conditions are of unusual severity [73]. It is also heavily utilized by white-tailed deer and mule deer in Montana and Idaho, predominately as winter forage [115,116]. In Utah, it provides important summer browse for mule deer [221]. In California, Scouler willow provides abundant browse of satisfactory quality for domestic livestock and deer. Domestic cattle feed on it in all habitats, while domestic sheep and goats feed on it on drier sites. It has been rated good to fair browse for domestic sheep and goats, fair for deer and domestic cattle, and poor for horses [204]. Small mammals also browse Scouler willow [264], and it provides food for grizzly bears [48]. Upland game birds, ducks, and other birds feed on willow buds, leaves, twigs, and seeds [8,89], and Scouler willow provides nesting and feeding habitat for small birds [226,227]. Scouler willow buds provide an important winter food source for grouse, Clark's nutcracker, and the Rocky Mountain jay [95,179,218]. In the early spring, honey bees use willow pollen and nectar as a source of food for brood rearing [8].
PALATABILITY:Like most willows [8,18], Scouler willow is moderately to highly palatable for white-tailed deer, mule deer, and elk [40,41,73,89,104,121,165,206,209]. The leaves and twigs are highly palatable for black-tail deer in British Columbia [45]. Scouler willow is of intermediate quality and high palatability for moose [44]. It is moderately palatable for beaver and for domestic livestock [121]. The palatability of Scouler willow for livestock and wildlife has been rated as follows [52,73,115,130,204,226]:
NUTRITIONAL VALUE:Fresh willow browse has the following average nutrition content [176]:
Overall, Scouler willow is of intermediate nutritive quality, containing relatively high amounts of carotene and ascorbic acid, important for ungulate nutrition [44]. In an Alaskan study, Scouler willow contained 5.6 to 6.7% protein [146]. The nutritional value may be improved by burning by increasing levels of phosphorus and crude protein and decreasing lignin content [24]. The following table contains the mean nutritional content (in mg/g) for Scouler willow on 4 sites in Montana [224]:
Nutritional analysis of Scouler willow in Idaho shows that protein and digestibility remain high through the end of September. Seasonal changes in these nutritional attributes are summarized below [36]:
COVER VALUE:Willows may produce dense thickets, making them valuable cover and nesting habitat for birds and small mammals and providing shade for fish in streams and ponds [8,89]. Willows are also valuable for cavity nesting woodpeckers [89]. Scouler willow provides both visual and thermal cover for deer and elk, and nesting habitat, cover, and food for nongame birds, upland game birds, and small mammals [40,41,95,103,107,140,256]. In riparian areas, it provides shade, cooling stream temperatures and providing escape cover for fish [79]. The degree to which Scouler willow provides cover for wildlife species is as follows [52,130]:
VALUE FOR REHABILITATION OF DISTURBED SITES:Scouler willow is effective in revegetating canyons disturbed by flooding water and debris. It is especially successful in establishing in riparian areas and at the base of dry slopes with sufficient moisture [38]. Willows contribute to streambank stability [79], and Scouler willow is useful for stabilizing steep, erodible banks on drier sties above river courses [62,256] and is recommended for riparian revegetation projects [37]. It may also be useful for rehabilitating recreation areas; 90% rooting success has been achieved for planted cuttings [220]. Scouler willow may provide site protection for conifer seedlings [226,227,228,256]. It provides light cover for the establishment of larch and Engelmann spruce after disturbance, encouraging revegetation [218,226,228]. Scouler willow may also enhance Douglas-fir regeneration by providing a suitable microclimate for seedlings [111,218]. It provides "safe-site" cover to improve tree seedling establishment in revegetating grand fir habitat types; it is rated neutral to moderately efficient based on the ratio of "safe-site" cover to the percentage of seedlings occurring there [78]. However, Scouler willow is a formidable competitor of ponderosa pine, which must outgrow Scouler willow to survive. High densities of Scouler willow may preclude ponderosa pine success following disturbance because it is shaded out by the height and lateral spread of Scouler willow [227,228]. Scouler willow has received the following ratings for reclamation suitability [256]:
OTHER USES AND VALUES:Willows are useful for erosion control and windbreaks [8], and provide medicine for many ailments including indigestion, worms, and stomach complaints [121]. It is the source of "diamond wood", used in carving and furniture making [256]. Scouler willow was used by Native Americans for traps, snares, sweathouse frames, burden baskets, toys, musical instruments, and medicine [203].
MANAGEMENT CONSIDERATIONS:The deep root system, multiple stems, and ability to resprout from a subterranean root crown rather than surface resprouting may increase Scouler willow's tolerance to disturbance [24]. Fire can be used to maintain shrub productivity on seral brushfields and encourage shrub dominance after harvest. Tree establishment can be encouraged by excluding wildfire, using site preparation methods that do not encourage grass or shrub species, and planting and seeding pioneer species under the shade of killed shrubs [222]. Prescribed fire has been used to stimulate sprouting of Scouler willow that has grown out of reach of big game browsers [130,131,135]. In burned areas, the current annual growth of willows is considerably higher than in control areas, and fire increases both browse production and availability [18]. Prescribed fire was used in the 1960's to rejuvenate northern Idaho brushfields for elk winter range [136]. When prescribed burning causes greater than 50% canopy mortality, substantially higher current annual growth (CAG) of Scouler willow is produced. CAG of vigorously growing plants has a higher nutritive value and nutrient concentration than mature, slower growing plants [183]. Big game prefer browsing on the current annual growth of burned willows than that of unburned willows [18]. Utilization by elk demonstrated an obvious preference for the sprouts of burned Scouler willow following mechanical treatment and understory burning; the surviving plants were substantially more vigorous, with greater live biomass and better palatability than the unburned plants [15,16,23,131]. Scouler willow experiences a dramatic increase in available browse production immediately following burning, the result of shrub removal and resprouting that reduces the height and increases the availability of browse [130,134,139,140,263]. In one study, Scouler willow reached 10 feet in height 4 years after burning, with 80% of twig production available for elk browse. However, repeated treatment may be necessary to maintain browse availability [132]. Scouler willow browse production increased from 6.5 to 44.1 kg/ha 3 to 7 years after wildfire in Alaska. The increase in production was due to an increase in the number of shrubs during the 1st 5 years and an increase in the number of twigs per shrub during all 7 years. Stems were available after the first 2 years; 4 years postfire, browse production in the burned area was twice that in the unburned area; and at 7 years postfire browse was 5 times greater. Browse production is likely to peak at 10-15 years and decrease by 20 years postfire [264]. Scouler willow responds well to both fall and spring burning; however, fall burning eliminates the following winter's food supply for animals. Spring burns regrow rapidly, with 5 foot (1.5 m) sprouts common by summer on burns in Idaho [130]. It has shown no decreased vigor from burning at 5 year intervals [135]. Brushfield burning to improve elk winter range in Idaho has often occurred during the spring or fall. However, another very important browse species, redstem ceanothus, is not always replaced by seedlings under these treatments because the seedcoat required high soil temperatures to crack and allow germination. Therefore, for winter range improvement, summer prescribed fires may need to be considered [259]. Willows produce, within limits, denser growth when they are browsed [8], with browsed stems branching laterally [253]. Browsing stimulates production of Scouler willow, though continuous browsing over several years may eventually deplete plant or soil reserves resulting in an eventual decline in productivity [263]. Following wildfires in Alaska, Scouler willow resprouts have suffered intense browsing by snowshoe hares, which often migrate to burned areas to feed. In some locations, 100% of the current annual growth of sprouts was removed for 2 succeeding winters [253,263]. This impact normally lasts for only a few years. Flowering and fruit production of Scouler willow are affected by heavy browsing, possibly resulting in low seedling success and recruitment, and browsing may suppress sprouting [24,34]. In burned and unburned clearcuts, grazed sites had no Scouler willow present, while ungrazed sites had 5 to 7% Scouler willow cover 11 years after treatment [61]. Where it is subject to overbrowsing, the loss of Scouler willow may result in substantial losses to elk herds [73]. Mechanical thinning may prevent suppression of Scouler willow in Douglas-fir/ponderosa pine forests [87]. Scouler willow increased in biomass and vigor in response to thinning in a Douglas-fir/ponderosa pine stand in Montana, indicating a positive response to overstory reduction [24]. Winter carrying capacity for mule deer may be substantially increased after mechanical treatment due to the establishment and growth of Scouler willow [87]. It is difficult to achieve control of Scouler willow using mechanical treatment due to the resprouting of damaged shrubs, and clearcutting can result in major canopy increases. Chemical treatments may be required if managing for ponderosa pine establishment due to its inability to compete with Scouler willow [227,228]. Herbicide treatments of Scouler willow aimed at increasing sprouting and maintaining production at a height available to big game have erratic and complex results; the production of sprouts did not persist, but the reduction in crown height did persist [143]. Scouler willow is highly sensitive to light applications of 2,4-D and 2,4,5-T. With 2,4-D, basal sprouting was proportional to crown kill; the maximum crown height was reduced and the proportion of live crown within reach of deer and elk increased accordingly. Sprout production was most favored by treatment in August and least by treatment in October; plant kill was highest following September treatment [173]. In other studies, crown volume and cover of Scouler willow were reduced by 50% after herbicide treatment [157]. Herbicide control of Scouler willow may be effective in allowing Douglas-fir to regenerate in the seral brushfields of Idaho [92]. Percent control of Scouler willow with different herbicides ranges from 33 to 100% [158,159,160,161].
Related categories for SPECIES: Salix scouleriana | Scouler Willow |
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