In the 1950s and 1960s, Western agencies seeded crested wheatgrass for grazing; by 1970s, it had altered 6.4 million acres of sagebrush, many never recovered

During the 1950s and 1960s, land management agencies across the western United States carried out extensive programmes with the aim of reducing sagebrush cover and establishing grasslands that could provide forage for livestock. Crested wheatgrass, a perennial grass introduced from Eurasia, was one of the principal plants used for this programme. This plant species established relatively easily and tolerated aggressive grazing.According to the US Forest Service, seeding with non-native grasses, primarily crested wheatgrass, had affected around 6.4 million acres of sagebrush land by the 1970s.This programme’s legacy continues to impact vegetation across the American West, with the agency reporting that many affected sites have not yet recovered their past ecological characteristics. Though it is important to note that the figure does not mean that all 6.4 million acres were converted in the same way or have remained unrecovered.Why agencies opted to plant crested wheatgrassSagebrush steppe ecosystems cover vast parts of the western United States, especially the Intermountain region. These landscapes contain a mixture of shrubs, native grasses and wildflowers and provide habitat for wildlife, including greater sage-grouse and pygmy rabbits. Livestock grazing, drought, and other forms of disturbances that occurred in the late 19th century through the early 20th century diminished native herbaceous plants across many landscapes. Several attempts were made to stabilise these degraded soils, maximise livestock forage, and maintain basic vegetative cover under what was then termed agricultural restoration. The US Forest Service suggested that overgrazing was not solely responsible for all the transformations occurring in sagebrush lands.Crested wheatgrass turned into a favoured option because it was relatively easy to establish, tolerated grazing and could produce substantial forage. Researchers James A. Young and Raymond A. Evans documented its growing use in the Intermountain region during the decades following its introduction. After World War II, advances in both methods and machinery for sowing crested wheatgrass led to its widespread use on range restoration sites. Seeding also helped control other plants and improve grazing conditions.Millions of acres experienced lasting changesSince the 1930s, methods such as prescribed burns, herbicides, mechanical treatment, and grass seeding have been used in order to reduce the area covered by sagebrush. Such actions were most intensive in the 1950s and 1960s, and the goal was usually to convert brush land into grassland that would be appropriate for livestock grazing. The US Forest Service claims that grass seeding, mainly non-native species, especially crested wheatgrass, affected about 6.4 million acres of sagebrush land by the 1970s. Such statistics relate to the land affected by grass seeding but not converted into one kind of grass.Crested wheatgrass can establish itself in dense colonies and thereby become a competitor to other plants and inhibit the development of native grass and flowers. Once established, it dominates native vegetation and actively arrests the return of local flora, especially in places where sagebrush seeds are unavailable.The consequences extend beyond changes in plant composition. Sagebrush provides food and shelter for wildlife adapted to shrubland habitats, while a grass-dominated site can offer a different structure and range of resources. For example, greater sage-grouse depend on shrublands for parts of their lifecycle. Thus, when shrublands are replaced by extensive grasses, this can lead to a loss of suitable habitat in some areas. The extent of the effect will vary depending on the area affected and the habitat needs of the species involved.Why recovery remains challengingRestoring native vegetation in established crested wheatgrass stands can be challenging because the grass competes with newly introduced plants. A 2021 study published in Restoration Ecology tested chemical and mechanical treatments intended to suppress crested wheatgrass before native species were seeded. The authors of the paper state that these approaches failed to provide better establishment of the natives. At the end of the experiment, the density of seedlings was almost the same for all the treatments, suggesting that suppression of the grass was not enough to ensure successful restoration.However, minimal recovery occurs only under highly specific environmental constraints. According to the U.S. Forest Service, sagebrush occasionally establishes sparse footholds within ageing stands of crested wheatgrass, though these isolated instances do not equate to a systemic return of the native steppe. Results of restoration efforts will depend on things like seed availability, climate, grazing, and the techniques used to prepare the site. The application of crested wheatgrass has become one of the last resorts in the contemporary approach to erosion control, where soil stabilisation is given priority or where invasion by non-native grasses is being prevented.You use AI every day. Now get your AI Quotient. Take the AIQ test.