Sagebrush

Shrub-Steppe

While looking at a sagebrush landscape, one visitor summed up the thoughts of many by saying, "There's nothing out there. It's dry and dead. A parking lot would be of more use." But life in the shrub-steppe is abundant; you just have to look with an educated eye


What is a shrub-steppe? Well, it’s pretty much what it sounds like—a mix of shrubs and "steppe." Steppe is a Russian word that means treeless plain. Shrub-steppe is a temperate, semi-arid landscape of shrubs and widely-spaced bunchgrasses. Typically, it also experiences hot, dry summers and low annual precipitation that usually comes in the form of snow.

On Columbia NWR, the dominant shrub is sagebrush, more specifically Wyoming big sagebrush. There are several species of sagebrush. All have deep taproots and spreading roots near the surface with which to gather water. Big sagebrush has a twisted trunk and many branches, pale grey leaves and tiny yellow flowers. It is an evergreen shrub, so it keeps some of its leaves year-round. The leaves have wider outer tips divided into three lobes (hence the scientific name Artemisia tridentata). Sagebrush can reach ages of over 100 years.

Have you ever smelled sagebrush after a rain? If not, you haven't fully experienced the high desert! Sagebrush has a powerful, pungent fragrance because of the presence of camphor, terpenoids and other volatile oils. It tastes incredibly bitter which, together with the odor, serves to discourage browsing by many herbivores.

What is sagebrush good for? Read on. 

Sagebrush

Sagebrush Is Important

As dry and brown as this habitat may appear in late summer, an amazing diversity of life thrives here. The shrub-steppe ecosystem harbors about 400 species of plants and 250 species of terrestrial vertebrates, the majority being birds and mammals, with approximately 100 and 70 species, respectively. Hoards of insects and reptiles also make their homes in sagebrush ecosystems.

Sagebrush is a keystone species that is, in part, an indicator of the health of the entire region it inhabits. For example, as sagebrush has diminished in cover and area, so have sage-grouse, pygmy rabbit, sage sparrow, black-tailed jackrabbit and sage thrasher populations. Healthy sagebrush habitat is characterized by an understory of bunchgrasses.

How is our sagebrush habitat doing? Read on. 

Wildfire

Sagebrush Habitat Is Diminishing

What? As you travel throughout the west, it seems like the sagebrush country is endless, vast, more than enough. The truth is that today only fragments of an immense sagebrush sea remains. It is considered to be one of the most imperiled of all ecosystems in the United States. Sagebrush has been cut to provide land for other purposes, such as agricultural cropland. During the middle decades of the 20th century, millions of acres were converted from sagebrush to nonnative grasslands for livestock forage production. More recently, extensive wildfires have converted millions of acres to nonnative annual grasslands. Now, plant and wildlife species that were formerly common and abundant have restricted ranges separated by an immense landscape of agricultural developments and nonnative grasslands. Sadly, only about 10% of the remaining sagebrush habitat is not damaged by weeds, fire, or other problems.

Cheatgrass and Fire

Cheatgrass (Bromus tectorum), a non-native  plant that appeared in North America at the end of the 1800s, has become a dominant plant in arid rangelands. Cheatgrass is aptly named as it robs farmers of their crops and wildlife of its habitat. It is the first grass to appear after the cold winter and uses up much of the soil's retained water before native bunchgrasses have a chance to grow. Because cheatgrass is an early grass, it also matures early in the season. Coupled that with the fact that it grows in a continuous carpet of grass, unlike native bunchgrasses that grow in clumps (thereby slowing the spread of fire), it provides abundant fuel for ferocious wildfires that start early in the season and ravage much of the sagebrush ecosystem. Although cheatgrass cannot compete with healthy native vegetation, fires bring competition to the seedling level where cheatgrass always wins. Over time, the range may become almost entirely cheatgrass-dominated.

Once cheatgrass fires have ravaged an area, it may take decades for native plants to recover, if they do at all. Sagebrush spreads by wind-blown seeds, so if there are no nurse plants over a large area, it has to come back by s . . . l . . . o . . . w . . . l . . . y spreading in from the edges.  Further hampering recovery is the arid environment; low moisture means that sagebrush grows and matures slowly, and a successful season for seed germination may only happen once a decade. It can take between 50 and 100 years for mature sagebrush to again dot the landscape after fire, and that's only if they are very lucky! Often, new cheatgrass (which does well after a fire!) fires will sweep through an area well before recovery can happen, ensuring that the landscape remains mostly cheatgrass. Once this fire cycle begins, many native wildlife species move on, looking for more accommodating homes.