Forage/Wildlife: Big sagebrush is perhaps the most important shrub on western rangelands. Evergreen leaves and abundant seed production provide an excellent winter food source to numerous species of large mammals including mule deer, black-tailed deer, white-tailed deer, elk, pronghorn antelope, bighorn sheep and jack rabbits. Nearly 100 bird species depend on sagebrush ecosystems for their habitat needs. Additionally, there are several animal species having an obligate relationship with big sagebrush including sage grouse, sharp tailed grouse, pygmy rabbits, sage thrashers, sage sparrows and Brewer’s sparrow. Sagebrush also provide habitat and food for hosts of invertebrates which in turn support birds, reptiles and small mammals. In addition to the numerous species of animals that depend on sagebrush for food and cover, there are several plant species having close relationships with sagebrush as well.
Sagebrush plants maintain high levels of most nutrients including crude protein (see table 1). This high forage value makes it especially useful for wildlife, and in some areas livestock, winter grazing. Separate studies indicated that sagebrush made up 78% of the annual diet for antelope in Wyoming and 59% of the winter diet of deer and elk near Gardiner, Montana. Sagebrush also makes up close to 100% of the winter diet of sage grouse and over 60% of their total annual diet. Use of sagebrush by livestock is limited and variable.
Animal preference of sagebrush varies with subspecies, populations and even individual plants due to chemical variation found in the foliage. Deer and elk tend to prefer mountain big sagebrush followed by Wyoming big sagebrush and finally basin big sagebrush. Although many range managers believe that deer and other large mammals prefer to browse shrubby members of the Rosaceae such as mountain mahogany (Cercocarpus), bitterbrush (Purshia) and cliffrose (Cowania) over big sagebrush, studies show sagebrush significantly more readily browsed.
Sagebrush’s value as thermal or security cover is also very high for wildlife. This includes nesting cover and escape cover for sage grouse, sharp tailed grouse, pheasants, chukar and other upland birds.
Table 1. Nutritive values as percent dry matter and percent in-vitro dry matter digestibility (IVDMD).
(Adapted from Welch, 2005)
Revegetation/reclamation: Because of its wide range of adaptation and ease of establishment, big sagebrush can be a very important species for use in revegetation efforts. Seedlings are able to compete with grasses and forbs as well as other shrubs allowing it to be used as a component of a wide range of seed mixes. Seedlings are very easy to establish when planted correctly (see “Establishment” section) and can be drill seeded or broadcast with near equal levels of success. Because sagebrush plants spread readily by seed, it can be seeded at relatively low rates and allowed to spread by natural recruitment.
Big sagebrush plants provide many additional benefits to the plant community. The dense canopy protects understory herbaceous plants from grazing. Healthy sagebrush communities provide a multi- tiered ecosystem with high levels of biodiversity. Big sagebrush plants also have a two-part root system with a deep tap root and a shallow, diffuse root system. Numerous studies have shown sagebrush plants create “hydraulic lift” where deep soil moisture is brought to near the soil surface by the tap root system during the day and then released into the upper soil at night. This water is then available to the diffuse root system of big sagebrush as well as to the roots of other understory plants. Sagebrush plants also increase water retention by trapping and holding windblown snow.
Big sagebrush subspecies are often useful indicators of soil characteristics. Generally, a subspecies indicates the soils at a site, thus proper identification of big sagebrush at a subspecific level can provide useful information on soils and ecological site characteristics. In some areas, however, such as those with glacial deposits, a separation based on soil characteristics is considerably more complex.
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