Northern Basin and Range

Trout Creek Mountains
Northern Basin and Range Ecoregion Photo Credit: Rodney Klus, ODFW

Description

The Northern Basin and Range ecoregion covers the southeastern portion of the state, from Burns south to the Nevada border and from Fort Rock Valley east to Idaho. The name of this ecoregion describes the landscape, with numerous flat basins separated by isolated mountain ranges. This ecoregion encompasses several fault-block mountains, with gradual slopes on one side and steep basalt rims and cliffs on the other side. The Owyhee Uplands consist of a broad plateau cut by deep river canyons. Elevations range from 2,070 feet near the Snake River to more than 9,700 feet on the Steens Mountain.

In the rain shadow of the Cascade Mountains, the Northern Basin and Range is Oregon’s driest ecoregion, marked by extreme ranges of daily and seasonal temperatures. Much of the ecoregion receives less than 15 inches of precipitation per year, although mountain peaks may receive 30-40 inches per year. The extreme southeastern corner of the state has desert-like conditions, with annual precipitation of only 8-12 inches. Despite regional aridity, natural springs and spring-fed wetlands are scattered around the landscape. Runoff from precipitation and mountain snowpack often flows into low, flat playas where it forms seasonal shallow lakes and marshes. Most of these basins contained large, deep lakes during the late Pleistocene, between 40,000 and 10,000 years ago. As these lakes, which don’t drain to the ocean, dried through evaporation, they left salt and mineral deposits that formed alkali flats, extremely important stopover sites for migratory shorebirds as a rich source of invertebrate prey.

Sagebrush communities dominate the landscape. Due to the limited availability of water, sagebrush is usually widely spaced and associated with an understory of forbs and perennial bunchgrasses, such as bluebunch wheatgrass and Idaho fescue. The isolated mountain ranges have few forests or woodlands, with rare white fir stands in Steens Mountain and Hart Mountain. However, aspen and mountain mahogany are more widespread and can be found in the Trout Creeks, Steens Mountain, Pueblo Mountains, Oregon Canyon Mountain, and Mahogany Mountains, and juniper woodlands comprise a significant portion of the northern end of the ecoregion. In the southern portion of the ecoregion, there are vast areas of desert shrubland, called salt-desert scrub, dominated by spiny, salt-tolerant shrubs. Throughout the ecoregion, soils are typically rocky and thin, low in organic matter, and high in minerals.

The Northern Basin and Range ecoregion is sparsely inhabited, but the local communities have vibrant cultural traditions. The largest community is Ontario, with more than 11,000 people. Other communities include Nyssa, Vale, Burns, and Lakeview, with 1,930 to 3,250 people each. Land ownership is mostly federal and primarily administered by the BLM. Livestock and agriculture are the foundations of the regional economy. Food processing is important in Malheur County. Recreation is a seasonal component of local economies, particularly in Harney County. Hunting contributes to local economies, as does wildlife viewing, white-water rafting, and camping. Historically, lumber processing and harvesting from the nearby Blue Mountains was the basis of some local communities, particularly for Burns. However, these industries have declined with lower harvests from neighboring federal forests.

Characteristics

Important Industries

Livestock, forest products, agriculture, food processing, recreation

Major Agricultural Products

Alfalfa, wheat, hay, corn, oats, onions, sugar beets, potatoes

Important Nature-based Recreational Areas

Summer Lake Wildlife Area, Malheur Lake National Wildlife Refuge, Hart Mountain National Antelope Refuge, Steens Cooperative Management and Protection Area

Elevation

2,070 feet (Snake River) to 9,733 feet (Steens Mountain)

Important Rivers

Chewaucan, Donner und Blitzen, Malheur, Owyhee, Silvies

Conservation Issues and Priorities

Uncontrolled livestock grazing in the decades before enactment of the Taylor Grazing Act of 1934 caused serious long-term ecological damage throughout the ecoregion. Rangeland conditions have substantially improved since then in most areas, and grazing is managed sustainably in many parts of the ecoregion. However, some areas are still impacted. In addition, sensitive areas, such as riparian habitats and arid areas of sagebrush and salt desert, have been slow to recover.

Some areas are still recovering from intensive management in the past, damaged by misguided efforts to rehabilitate overgrazed, degraded rangelands and improve livestock grazing by planting crested wheatgrass, a non-native pasture grass. For example, in 1962 the BLM began a massive effort, the Vale Rehabilitation Project, to remove native sagebrush and establish crested wheatgrass. Over the course of 10 years, the Vale Rehabilitation Project seeded 250,000 acres to crested wheatgrass and used plowing, chaining, and herbicides, reducing sagebrush on as much as 506,000 acres. Modern day restoration efforts focus on returning these areas to healthy, native sagebrush habitat.

Invasive species and altered fire regimes are the greatest terrestrial conservation issues in this ecoregion. Overgrazing and fire suppression, followed by invasion of non-native annual grasses such as cheatgrass, have greatly altered natural fire cycles in many sagebrush steppe habitats. Landscapes formerly comprised of mosaics dominated by bunchgrasses and forbs are now heavily and disproportionately dominated by shrubs (mostly sagebrush) and exotic grasses and forbs. As a result of altered fire regimes, encroachment of juniper has displaced grasses and sagebrush, especially in the northern portions of the ecoregion. However, old-growth juniper naturally occurs in some areas, especially in rock outcrops where grasses and sagebrush are uncommon and where fire is less of a factor. These old-growth juniper are extremely beneficial to wildlife.

Greater Sage-Grouse are considered excellent indicators of sagebrush habitat quality. Current efforts to improve conditions for the Greater Sage-Grouse include comprehensive range-wide assessments and conservation planning.

Throughout the Northern Basin and Range ecoregion, water quality is impacted by high temperatures, and in some areas, by bacteria, pollutants, and aquatic weeds. Water is limited in the ecoregion, fully allocated in storage and other uses. Aquatic habitats are affected by altered channel and flow conditions, obstructions, and poor riparian condition. Efforts to assess the quality of aquatic habitats are ongoing, and priorities include assessment of the impact of federal dams on water quantity and obtaining an understanding of natural temperature and water quality dynamics in the ecoregion. Under climate change, drought conditions may become more frequent, resulting in reduced water availability for wetlands in important wildlife areas like Summer Lake, Lake Abert, and Malheur Lake.

Key Conservation Issues in the Northern Basin and Range ecoregion include Invasive Species, Water Quality and Quantity, and Disruption of Disturbance Regimes. In addition to the statewide issues, increasing demand for energy development, ongoing recovery from historical overgrazing, unregulated horse herds, uncontrolled use of off-highway vehicles, and increasing recreational demand are issues in this ecoregion.

Climate

The Northern Basin and Range terrain consists of tablelands, basins, plains, some mountains, and valleys. The climate is arid with both steppe and desert climates, hot summers, and cold winters. Mean annual precipitation varies from minimal in the low areas to considerable in the higher mountainous areas. Increasing temperatures will lead to hotter summers, warmer winters, and more precipitation falling as rain in the winter in the higher elevation areas.

Warming is projected in all seasons across the ecoregion, with the largest increases projected in summer. Summer average temperature is projected to increase by as much as 8°F for the 2040-2069 period and as much as 12°F for the 2070-2099 period under the high emissions scenario (SSP585; Figure 1). Increasing temperatures will lead to hotter summers, warmer winters, and more precipitation falling as rain in the winter in the higher elevation areas. Late summer total precipitation is projected to change depending on time-period and scenario. Cool season precipitation projections show an increase in precipitation of as much as 19% for the 2070-2099 period (Figure 2). Confidence is low, however, in the late summer projections. Growing degree days are projected to double by the 2070-2099 period for the Northern Basin and Range under a high emissions scenario (SSP585). Frost days are projected to decrease from 200 until there are fewer than 150 per year, on average, under the high emissions scenario (SSP585).

Figure 1. Model median historical (1950-2010) and future projections of summer maximum temperature change for three periods (2010-2039, 2040-2069, 2070-2099) under a high emission scenario (SSP585) for the Northern Basin and Range. Future projections show increasing temperatures through the century for the entire Northern Basin and Range ecoregion (Raymond and Fusco, 2024).
Figure 2. Model median historical (1950-2010) total late summer precipitation and projected percent change for three future periods (2010-2039, 2040-2069, 2070-2099) under a high emission scenario (SSP585) for the Northern Basin and Range. Future projections show varied changes in late summer precipitation across the Northern Basin and Range ecoregion through the next century. For the 2070-2099 period, projections show an increase in precipitation for the southern are of the Northern Basin and Range ecoregion (Raymond and Fusco, 2024).

 

Limiting Factors and Recommended Approaches

Limiting Factor: Altered Fire Regimes

CMP Direct Threats 7.1, 8.1, 8.2, 11.3, 11.4

Most sagebrush-dominated areas were once a mosaic of successional stages, from recently burned areas dominated by grasses and forbs to old, sagebrush-dominated stands that had not burned for 80 to 300 years. However, fire suppression and intensive grazing practices have reduced this mosaic and resulted in large areas dominated by invasive annual grasses, particularly cheatgrass, or older big sagebrush with a dense understory of invasive annual plants.

Changing climate conditions, including warming temperatures and more frequent and severe droughts, are contributing to increased frequency of fires, resulting in landscapes that are susceptible to the spread of western juniper and cheatgrass. Areas dominated by cheatgrass or other invasive annual grasses are more susceptible to fire ignition and reburning. Juniper invasion and encroachment of other woody vegetation provides fuel for wildfires, leading to higher intensity burns. Large fire events often destroy sagebrush, which are very slow to recover, leaving behind habitat that is no longer suitable for sagebrush-obligate species such as Greater Sage-grouse and pygmy rabbit. Big sagebrush communities with non-native invasive annuals in the understory will not recover from fire without significant intervention.

Recommended Approach

Under current vegetation management conditions, fire is damaging to sagebrush stands. Reintroduction of natural fire regimes may be difficult, and risks loss of sagebrush habitat. In many areas prescribed fire may be impractical. Use mechanical treatment methods that minimize soil disturbance to help remove encroaching juniper and annual invasive grasses that contribute to more frequent, higher-intensity fires. Chemical or biological management techniques can also be explored. In sagebrush habitats that are moderately impacted by invasive annual grasses, use of herbicides may help preserve sagebrush and increase fire resiliency. Engage in research on the efficacy and impacts of new herbicides to control nonnative vegetation.

Where appropriate, reintroduce natural fire regimes using site-appropriate prescriptions that limit risk of sagebrush loss, account for the historical fire regime, and encourage native plant regeneration. Use prescribed fire to create a patchy mosaic of successional stages and avoid large, prescribed fires.

Limiting Factor: Water

CMP Direct Threats 7.2, 11.4

Water Quantity is a limiting factor for fish and wildlife. Changing climate conditions are leading to rising temperatures and altered patterns of precipitation, which affect water availability across different times of year. In streams, seasonal low flows can limit habitat suitability and reproductive success for many fish and wildlife species. Although many communities in this ecoregion are small, increases in the demand for water for crop irrigation and livestock production, coupled with increasing drought conditions, mean the supply of groundwater is decreasing. Already an arid ecoregion, increases in drought conditions have also resulted in the loss of some marshes and alkali lakes—areas that are critical for wildlife, particularly migrating birds. Water quality can also limit species and habitats. Warming waters provide conditions for increased bacterial growth which can impact fish and wildlife, as well as drinking water supplies.

Recommended Approach

Provide incentives and information about water usage and sharing during low flow conditions (e.g., late summer). Promote water management actions that enable climate resilience and adaptation. Invest in watershed-scale projects for cold water and flow protection. Increase awareness and manage timing of applications of potential aquatic contaminants. Improve compliance with water quality standards and pesticide use labels administered by the DEQ and EPA. Work on implementing Senate Bill 1010 (Oregon Department of Agriculture) and DEQ Total Maximum Daily Load water quality plans.

Limiting Factor: Invasive Species

CMP Direct Threat 8.1, 8.2

Non-native annual grasses, particularly cheatgrass and medusahead, have rapidly expanded in the Northern Basin and Range, displacing desirable forage for wildlife and livestock. These invasive plants disrupt native communities, diminish populations of at-risk native species, and threaten the economic productivity of resource lands. The spread of invasives like cheatgrass and medusahead can also increase the frequency, intensity, and spread of fires, replacing sagebrush and native bunchgrasses, which are adapted to infrequent, patchy fires.

While not nearly as extensive as invasive plants, non-native animals have also impacted native fish and wildlife populations. For example, invasive carp in Malheur Lake have damaged one of the most important waterfowl production areas in Oregon, altering ecological dynamics through predation and altering water quality by disturbing sediments. Brown bullhead have also spread throughout the ecoregion, competing with native species for limited resources or preying on native species and/or their eggs or young. Unregulated horse herds are a concern in many areas, competing with native wildlife for vegetation and access to limited water sources, spreading invasive plant seeds via their manure, and trampling sensitive habitats.

Changing climate conditions and fire suppression have also led to the expansion of western juniper throughout the ecoregion. Western juniper is a native species, andold growth juniper trees in rocky outcrops offer benefits to native wildlife. However, the expansion of western juniper in the Northern Basin and Range has degraded some grassland, sagebrush, riparian, large-diameter juniper, and aspen habitats. Western juniper expansion may reduce water availability in many seasonal and some perennial streams. In riparian areas, junipers replace deciduous shrubs and trees that are more beneficial to riparian wildlife. In many of the grassland and sagebrush habitats, 20–30-year-old juniper trees form dense stands that are not suitable for many wildlife species that require the open sagebrush or grassland habitats that are now in decline. These dense stands also act as fuel for wildfire, contributing to large, high-intensity fires that destroy sagebrush habitat.

Recommended Approach

Controlling western juniper in newly invaded areas benefits wildlife and other habitat values. Early control of newly invaded young trees before woodlands become established is often the most successful approach. Develop markets for small juniper trees as a special forest product to reduce restoration costs. Maintain large-diameter juniper trees in the native rocky outcrops and ridges, which are important nesting habitat for passerines and raptors. In some areas, fire can be used to control young juniper. Carefully evaluate sites to determine if prescribed fire prescribed fire is appropriate, considering the landscape context, vegetation types, and risk of sagebrush loss.

Emphasize prevention, risk assessment, early detection, and quick control to prevent new invasive species invasive species from becoming fully established. Use multiple site-appropriate tools (e.g., mechanical, chemical, and biological) to control the most damaging invasive species. Prioritize efforts to focus on key invasive species in high priority areas, particularly where Key Habitats and Species of Greatest Conservation Need occur. Cooperate with partners through habitat programs and county weed boards to address invasive species problems. Carefully manage wildfires in cheatgrass-dominated areas. Promote the use of native “local” stock for restoration and revegetation where native species have the greatest potential to successfully establish. In some cases, use “assisted succession” strategies, applying low seed rates of non-invasive non-native plants in conjunction with native plant seeds as an intermediate step in rehabilitating disturbances in sagebrush communities.

Promote dialogue between wildlife managers, landowners, and land managers to develop horse management plans based on common priorities. Promote outreach to explain the issue to the public and the impacts of unregulated herds on wildlife and habitat.

Limiting Factor: Energy Development

CMP Direct Threat 3.3

Climate change and global economies are increasing pressure for renewable energy development, including solar energy. Solar energy projects offer environmental benefits but also have significant impacts on wildlife and their habitat. Many solar energy facilities have large footprints. Federal requirements for facilities to be fully fenced make any remaining habitat within a solar field inaccessible to most terrestrial wildlife species, which results in lost habitat and may disrupt critical movement and migration pathways. Solar facilities are also a collision risk for birds, as reflection of sunlight off the panels may cause solar fields to resemble large water bodies. The area is increasingly challenged with the need to balance the state’s interest in clean energy development with local natural resource conservation needs. The Northern Basin and Range ecoregion offers excellent renewable energy resources, but the ecoregion is particularly sensitive to local impacts on sagebrush and other habitats.

Recommended Approach

Plan energy projects carefully, using the best available information and early consultation with biologists. Use available tools and resources found in the Land Use Changes and Climate Change KCIs and ODFW Compass. Consider the broader landscape context when planning new development, including habitat connectivity, cumulative impacts, fish and wildlife species presence, and mapped or modeled suitable habitat. Use wildlife-permeable fencing or allow egress to permit passage for medium-sized animals through solar fields.

Limiting Factor: Recreational Activity

CMP Direct Threats 1.3, 4.1, 6.1

Increasing demands for recreational access can disturb animals and degrade habitats. Activities like hiking, biking, hunting, fishing, and foraging, and off-road vehicle use can create sensory stressors for wildlife, with sound, light, and unusual smells that may deter species from moving through certain areas. Human recreation may contribute to destruction of sensitive vegetation, harassment of wildlife from off-leash pets, spread of invasive species, and contamination of areas with refuse. Use of off-highway vehicles (OHVs) is particularly prevalent in the Northern Basin and Range. When limited and controlled, OHV use can be compatible with wildlife conservation. Illegal use, however, is prevalent, and highly detrimental. In general, OHV use can damage soils, impact sensitive riparian, aquatic, and upland habitats, spread invasive plant seeds, affect wildlife behavior and distribution, and increase the risk of wildfires. Although OHV use is limited to designated roads in some sensitive landscapes, there is little to no enforcement due to lack of funds and law enforcement personnel.

In addition to OHV use, other recreational use, such as camping, soaking in hot springs, rock climbing, and parasailing, is increasing. Use at some sites, such as the Alvord Desert, is high, and often damaging to sensitive desert playa habitat. Although recreational use is still light in comparison to more populated ecoregions, social media is driving increased use of several areas in the ecoregion. This increased recreational pressure could intensify impacts to wildlife and magnify disturbance in areas previously little-used by people.

Recommended Approach

Work cooperatively with land managers and OHV groups to direct use to maintained trails in low-impact areas and improve enforcement of existing rules. Support educational efforts to promote low-impact recreational use such as the Tread Lightly! Program. Monitor the impacts of OHV use on priority areas. Support efforts to effectively manage OHV use on public lands, particularly in highly sensitive habitats, and restore damaged areas.

Proactively consider potential impacts to wildlife and habitats when developing or promoting recreational opportunities to encourage compatible uses. Monitor recreational patterns and trends. Institute road and/or area closures to protect species during sensitive times of year and decommission roads when possible. In high use areas, establish permitted entry systems to decrease recreational pressure.

Limiting Factor: Ongoing Recovery from Historical Overgrazing

CMP Direct Threats 2.3, 7.3, 8.1

Prior to limitations that were initiated on public lands in the mid-1930s, livestock grazing had a profound influence on landscapes throughout the Northern Basin and Range ecoregion. Many areas experienced serious ecological damage. Conditions on rangelands in general have improved substantially over the past half-century as a result of improvements in livestock management, and most ecosystems are recovering. However, some habitats have been slow to recover, such as some riparian areas areas and sagebrush communities, especially where cheatgrass and other invasive annual grasses have invaded.

Recommended Approach

Continue to proactively manage livestock grazing and restore degraded habitats. Minimize grazing during restoration of highly sensitive areas, such as wetlands and riparian areas.

Species of Greatest Conservation Need

Conservation Opportunity Areas