• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• PALATABILITY
• NUTRITIONAL VALUE
• COVER VALUE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES AND VALUES
• MANAGEMENT CONSIDERATIONS

IMPORTANCE TO LIVESTOCK AND WILDLIFE:

Antelope bitterbrush is important browse for wildlife and livestock [3,15,30,56,106,169,176,228]. Pronghorn [110,174,207,215,245], mule deer [110,147,223,226,237,239], elk [121], bighorn sheep, and moose utilize antelope bitterbrush extensively [5,169,227]. Mule deer use of antelope bitterbrush peaks in September, when antelope bitterbrush may compose 91 percent of the diet [11]. Winter use is greatest during periods of deep snow [201]. In northwestern Nevada and northeastern California, antelope bitterbrush is a critical winter food for mule deer. Domestic livestock and mule deer may compete for antelope bitterbrush in late summer, fall, and/or winter [56]. Cattle prefer antelope bitterbrush from mid-May through June and again in September and October [201]. Antelope bitterbrush seed is a large part of the diets of rodents [229], especially deer mice and kangaroo rats [85,88,110,114,176].

Antelope bitterbrush supports several insect populations [92,99,100,105], some of which eat the seeds or cotyledons [86, 99, 159]. Especially important are Pogonomyrmex ants, which stash seeds and are important to natural regeneration [61,85], and tent caterpillars, which often cause antelope bitterbrush die-back [126,145,176,198].

PALATABILITY:

Antelope bitterbrush is palatable to all types of livestock and wildlife. It is often critical browse for mule deer in winter [16,109,146,148,180,205,227].

The palatability of antelope bitterbrush has been rated as follows [110,113,143,196,219]:

                 CA           ID           MT           NV           
domestic sheep   good         poor-fair    ----         good         
mule deer        very good    very good    very good    very good                                  
elk	         ----         fair-good    very good    ----         
moose            ----         ----         ----         ----     
mountain sheep   ----         ----         moderate     ----        
pronghorn        very good    very good    very good    very good    
cattle           good         good         good         good        

                 UT           WY
domestic sheep   good         ----
mule deer        very good    very good                                             
elk	         ----         very good
moose            ----         very good
mountain sheep   ----         ----
pronghorn        very good    very good
cattle           good         good

NUTRITIONAL VALUE:

Total digestible nutrient levels of bitterbrush range from 39.7 to 54.8%, slightly less than the probable requirements for wintering sheep and mule deer and less than the values for big sagebrush and juniper species [201]. Dry-matter in vitro digestibility averages 25.4% [41]. Crude protein can reach 14% or higher in the leaves in early summer [11,17,25,118,205,206], but is around 7.9% in winter [67]. Winter protein content is generally below requirements of mule and white-tailed deer [11,15,201,227,231,234]. Twigs have lowest carbohydrate values in June and July and highest in November [102]. Antelope bitterbrush contains calcium, phosphorus, carotene, and fat [118,201,205]. It is an important source of carotene for rodents [85,169]. Winter phosphorus content is 0.13%, short of the 0.24% requirement for mule deer [201].

In natural and thinned Oregon ponderosa pine stands, the nutritional quality of antelope bitterbrush was as follows [69]:

Nutrient group  Nutritional content in  Nutritional content under
                natural stands (%)      thinned saplings (%)

N-free extract   50.31                   47 
crude protein    9.76                    9.4
crude fat        5.8                     4.9
crude fiber      21.64                   27
ash              4.2                     3

Digestible content (%) of antelope bitterbrush for mule deer was 
as follows [105]:

State       Crude protein  Crude fat  Crude fiber  N-free extract 
Colorado    8.7            7.5        22.8         57.7
California  9.4            4.9        ----         ----
Utah        7.4            5.4        30.6         53.6

COVER VALUE:

Ungulates, birds, and rodents use antelope bitterbrush for cover [26,79,107,178]. Mule deer preferred antelope bitterbrush habitat during winter in central Washington, maybe because of height and large crown of antelope bitterbrush [48]. Pronghorn prefer shrubs up to two feet tall (0.6 cm), so tall, decadent, fire-excluded stands of antelope bitterbrush are not good pronghorn habitat [245]. Sage grouse use short (12-inch (30.5 cm)) antelope bitterbrush for cover in Idaho [135,152], Oregon [188], and Wyoming [136]. Antelope bitterbrush and other shrubs provide important cover for Lewis' woodpeckers [138].

VALUE FOR REHABILITATION OF DISTURBED SITES:

Antelope bitterbrush has been used extensively in land reclamation [30,44,93,95,100,165,168,202]. It is a pioneer species on some harsh sites. Antelope bitterbrush enhances succession by retaining soil and depositing organic material [12,36,104,166,169,176], and, in some habitats and with some ecotypes, by fixing nitrogen [89]. Antelope bitterbrush is important for watershed erosion control in central Washington [218].

Direct seeding of antelope bitterbrush has had mixed results [134]. Establishing antelope bitterbrush from planted seeds is difficult and requires optimum seedbed preparations including good weed control [83]. Seedling survival can be very low [91,127,194], particularly when antelope bitterbrush competes with cheatgrass [55,122,184,251]. Antelope bitterbrush is responsive to seeding in pinyon-juniper communities but is less successful in big sagebrush and mountain brush types [165]. Scholten [201] planted antelope bitterbrush in Idaho using several methods, with success ranging from 0 to 7% with direct seeding and from 19 to 69% with greenhouse seedlings. Everett and others [87] reported 79% antelope bitterbrush seedling survival 3 years after planting on an untreated acid spoil site in California. They concluded that antelope bitterbrush is a good choice for revegetating similar sites. Propagation from stem cuttings may prove more useful for rehabilitation projects [134]. Everett [86] successfully used containerized plants to revegetate arid roadcuts in Nevada. Survival rates on north and south slopes averaged 70%. Knapp [137] found natural antelope bitterbrush establishment on abandoned mining town sites was poor. He attributed the limited establishment to the weight of antelope bitterbrush seeds, which are too heavy to be easily transported or windblown to disturbed areas, and to the lack of favorable soil conditions. His study did not directly evaluate either of these factors.

OTHER USES AND VALUES:

No entry

MANAGEMENT CONSIDERATIONS:

Antelope bitterbrush is moderately browse tolerant [30,47,101,160,169]. Zacek and others [253] describe antelope bitterbrush a community "decreaser" under browsing pressure. Domestic sheep may be particularly damaging to antelope bitterbrush since they prefer young and small plants [176]. Almost 40 years after two years of heavy domestic sheep grazing in Oregon, no young antelope bitterbrush were present on grazed sites [76]. However, some authors claim that browsing helps maintain an antelope bitterbrush community's seral stage and therefore increases shrub vigor [183, 222]. In an 8-year study in southwestern Colorado, mortality was higher in unclipped and 80% clipped antelope bitterbrush compared to intermediate treatments of 20, 40, and 60% clipped antelope bitterbrush [203]. Monsen [164] found livestock browsing decreased the number of antelope bitterbrush that established or survived over 32 years in south-central Idaho. Kindschy [133] found that cattle grazing of grasses opened an area in southeastern Oregon and aided antelope bitterbrush establishment, whereas fewer plants established in ungrazed areas.

Antelope bitterbrush varies for many traits including sprouting, cold and elevation tolerance, nitrogen fixing, seed dormancy, palatability, nutritional content, drought resistance, form, and size. Because of this variation, it is important that the ecotype selected as a seed source matches the intended environment [66,192,162,163,210,241].

Antelope bitterbrush seedlings apparently have little resistance to damping off, particularly in greenhouse environments [100,172,202].

Related categories for SPECIES: Purshia tridentata | Antelope Bitterbrush