Sagebrush habitats include all sagebrush steppe- and shrubland-dominated communities found east of the Cascade Mountains.
Big sagebrush steppe communities in the Blue Mountains ecoregion are similar to those of the Columbia Plateau. Sagebrush shrubland species vary by elevation and soils but include low sagebrush, silver sagebrush, rigid sagebrush, basin big sagebrush, Wyoming big sagebrush, mountain big sagebrush, threetip sagebrush, bitterbrush, and rabbitbrush. Soils vary in depth and texture but are non-saline.
Shrub-steppe habitats are open grass-dominated communities and are usually found on loamy, wind-deposited (loess) soils. In this ecoregion, shrub-steppe communities can be broadly divided into two elevational types. Within 10 miles of the Columbia River, sandy shrub-steppe communities occur on unstable, well-drained soils. These include grasslands dominated by needle-and-thread, shrub-steppe habitats dominated by bitterbrush and needle-and-thread grass or Indian rice grass, and sand dune communities characterized by sagebrush, bitterbrush, and western juniper. There is usually a component of bare ground or open sand present. Further from the Columbia River, big sagebrush steppe communities include basin big sagebrush, needle-and-thread grass, basin wildrye and bluebunch wheatgrass steppe, and Wyoming sagebrush and bluebunch wheatgrass (which formerly occupied the low-elevation, loess uplands in the Columbia Plateau).
The number of species and acreage dominated by sagebrush is lower in the East Cascades ecoregion than most other east side ecoregions, especially the Northern Basin and Range. Five of the eleven sagebrush species are found in the East Cascades ecoregion at various elevations and soil types. Low sagebrush generally grows less than 2 feet and is found from low to high elevations in shallow, rocky soils. Silver sagebrush grows 1-6 feet tall and enjoys wetter conditions than most sagebrush species. It is found throughout the ecoregion in seasonally-waterlogged soils. Basin big sagebrush generally grows from 5-7 feet tall and is an indicator of deep, well-drained soils. Mountain big sagebrush and Wyoming sagebrush grow from 2-4 feet and are found from mid to high elevations. The two species are difficult to tell apart and readily hybridize. Both are found along the north/south axis of the ecoregion, but Wyoming sagebrush is mainly found along the eastern edge.
Northern Basin and Range
Big sagebrush habitats include mountain, basin, and Wyoming big sagebrush shrublands and shrub-steppe. Structurally, these habitats are composed of medium-tall to tall (1.5-6 feet) shrubs that are widely-spaced with an understory of perennial bunchgrasses. Basin big sagebrush communities occur on deep silty or sandy soils along stream channels, in valley bottoms and flats, or on deeper soil inclusions in low sagebrush or Wyoming big sagebrush stands. Wyoming big sagebrush communities occur on shallower, drier soils. Mountain big sagebrush communities occur at montane and subalpine elevations on deep-soiled to stony flats, ridges, nearly flat ridge tops, and mountain slopes. The fire frequency in big sagebrush habitats ranges from 10-25 years for mountain big sagebrush and 50-100 years for Wyoming big sagebrush.
Although these particular sagebrush communities are considered the priorities for the Conservation Strategy, other sagebrush types also provide important habitat for wildlife and may need to be considered at the local and watershed scale, or for the conservation of particular species like the Greater Sage-Grouse. Low sagebrush habitats cover large areas of the Northern Basin and Range ecoregion. They are characterized by very shallow, poorly developed soils and dominated by low sagebrush, perennial forbs, and Sandberg’s bluegrass. Low sagebrush provides critical wildlife habitat for many sagebrush-obligate species. Because of the poor, shallow soils, low sagebrush communities are slow (150-300 years) to recover from significant soil disturbance or fire. Soil disturbance in these sites often results in establishment of invasive annual grasses.
Limiting Factors and Recommended Approaches
Limiting Factor: Altered Fire Regimes and Local Issues with Prescribed Fire
Fire suppression has resulted in undesirable changes in vegetation and contributes to increases in the intensity of wildfires. In some fire-suppressed areas, western junipers encroach into sagebrush habitats. Dense juniper stands are not suitable for species that require open sagebrush habitats. While a useful tool when tailored to local conditions, prescribed fire is not necessarily suitable for all sagebrush habitat types. Some sagebrush habitats, such as low sagebrush, are extremely slow to recover from disturbance such as prescribed fire. Fire, both prescribed and natural, can increase dominance by invasive plants.
Carefully evaluate sites to determine if prescribed fire is appropriate. Consider landscape context and landscape diversity when planning conservation actions. Be particularly cautious in low productivity needlegrass sites where recovery times are prolonged or in sites with invasive annual grasses. If determined to be ecologically beneficial, reintroduce natural fire regimes using site-appropriate prescriptions. Use prescribed fire to create a mosaic of successional stages and avoid large prescribed fires. In areas where prescribed fire is undesirable or difficult to implement, use mechanical treatment methods such as mowing to maintain shrub cover at desired levels. To control encroaching junipers, use chipping or cutting for firewood. Develop markets for small juniper trees as a special forest product to reduce restoration costs. Maintain juniper trees with old-age characteristics, which are important nesting habitat for birds and other wildlife.
Limiting Factor: Invasive Species
Depending on the area, invasive plants, such as yellow-star thistle, knapweeds (diffuse, spotted, and purple), rush skeleton weed, spikeweed, leafy spurge, and perennial pepperweed, invade and degrade sagebrush habitats. The introduction and spread of the invasive species cheatgrass and medusahead can increase the frequency, intensity, and extent of fires. Sagebrush and native bunchgrasses are adapted to infrequent, patchy fires, so they are eliminated by hot fires. The dominance of invasive species thus increases, further increasing wildfire risk.
Emphasize prevention, risk assessment, early detection, and quick control to prevent new invasive species from becoming fully established. Prioritize control efforts and use site-appropriate methods to control newly-established species for which management can be most effective (e.g., leafy spurge and perennial pepperweed). Cooperate with partners through habitat programs and County Weed Boards to address invasive species problems. Reintroduce shrubs, grasses, and forbs at control sites through seeding and/or planting. In some cases, it may be desirable to use “assisted succession” strategies, using low seed rates of non-invasive, non-native plants in conjunction with native plant seeds as an intermediate step in rehabilitating disturbances to sagebrush habitat. Prevent and control wildfires in areas where cheatgrass dominates in the understory. Conduct research to determine methods to manage established species such as cheatgrass and medusahead. Minimize soil disturbance in high priority areas to prevent establishment of invasive species.
Limiting Factor: Damage to Microbiotic Soil Crusts
In the Columbia Plateau and Blue Mountains ecoregions, unmanaged grazing can damage soil crusts, which leads to soil erosion, changes in plant species composition and structure, and degradation by invasive plants.
Because most of the Columbia Plateau ecoregion is privately-owned, voluntary cooperative approaches are the key to long-term conservation in this ecoregion. Use tools such as financial incentives, technical assistance, regulatory assurance agreements, and conservation easements to achieve conservation goals. Continue to work with public land managers to ensure grazing is carefully managed. Conduct research and develop incentives to determine grazing regimes that are compatible with a variety of conservation goals.
Limiting Factor: Conversion to other Land Uses
In the Columbia Plateau ecoregion, remnant shrub-steppe habitats are subject to conversion to agriculture. In the Blue Mountains and East Cascades ecoregions, rapidly growing human populations near Bend, Redmond, and Madras, and slowly but steadily growing populations near Baker City and La Grande, are resulting in land use conversion, habitat loss, and habitat fragmentation.
Use tools such as financial incentives and conservation easements to conserve priority sagebrush habitats. For example, re-establishing the shrub component of lands enrolled in the Conservation Reserve Program has helped to restore habitat structure. Work with community leaders and agency partners to ensure that development is planned and consistent with local conservation priorities. Support and implement existing land use regulations to preserve farm and range land, open spaces, recreation areas, and natural habitats from incompatible development.
Limiting Factor: Loss of Habitat Connectivity
In the Columbia Plateau, shrub-steppe habitats often occur in small patches, such as roadsides and field edges. These patches are valuable habitat for some species, especially some plants. However, small size and poor connectivity of remnant patches limit dispersal for sagebrush-associated species.
Maintain high priority patches and improve connectivity. (KCI: Barriers to Animal Movement)