Plains and Great Basin Grasslands

Plains and Great Basin grasslands are found at elevations between 5,000 to 7,000 ft. Perennial, sod-forming grasses dominate this habitat type with blue, black, and sideoats grama being the most abundant. Other important grasses include buffalo-grass, Indian rice grass, Galleta grass, prairie junegrass, plains lovegrass, vine mesquite grass, Texas timothy, and alkali sacaton. Common forbs are primrose, bahia, four-o’clock, gaura, mallow, aster, scurfpea, and coneflower (Brown 1994). Historically, this habitat type consisted of large areas of nearly uninterrupted grass and forb species with low shrub cover, and included most of the grasslands of the Colorado Plateau in northeastern Arizona. This habitat’s distribution is limited in southeastern Arizona.

Plains and Great Basin grasslands in Arizona have changed significantly over the past century. The area occupied by these grasslands are in good condition across about 31% of their distribution. A high amount of the overall area, roughly 60%, has been invaded by shrubs with some potential to be restored or has transitioned into shrubland. The remaining 9% is dominated by shrubs or non-native grasses or suffers from severe erosion (TNC 2021; Schussman and Gori 2004). For example, when in close proximity to pinyon-juniper woodland, these grasslands are subject to encroachment and, in cases where essential ecosystem processes are not restored, conversion has resulted. Grazing pressures from livestock and wildlife can contribute to alterations in the vegetation composition and structure as well, though appropriate management may reduce negative impacts and even stimulate positive ecological responses (Finch 2004; Souther et al. 2019). Human encroachment is also adding pressure to these habitats as these low-lying valley bottoms are attractive for housing development, a rising trend that will only grow with increasing populations in Arizona.

Several SGCN occur in this habitat type that are not found elsewhere in the state or in only one or a few habitat types, such as Sonoran tiger salamander, eastern yellow-bellied racer, Arizona grasshopper sparrow, Gunnison’s prairie dog, and black-footed ferret.

Significant Habitat Features

The following describes habitat features or microhabitats that are unique to this habitat type and are of particular importance to certain species:

Ciénegas and other small and shallow water bodies provide habitats for the reproduction and recruitment of amphibian and invertebrate species, including Chiracahua leopard frog and Sonoran tiger salamander. These vital habitat are also an important water resource for other species. Ciénegas are particularly important in the grasslands of southeastern Arizona.
Springs exist on the landscape when water pressure in the aquifer pushes water through cracks or tunnels and flows naturally to the surface. These springs create isolated pockets of habitat for a variety of aquatic species, such as the northern leopard frog found in Truxton Spring.
Temperate grasslands are typically found between desert and forest habitat with grasses as the dominant vegetation type. Tree and shrub species can be found interspersed on the landscape. Examples of SGCN that occur in these habitat feautes include American pronghorn and plains leopard frog. Plains and Great Basin grasslands are the Aubrey Valley, Seventyfour Plains, north of the Great Basin conifer woodlands habitat in the White Mountains, Antelope Flat, and Cataract Ranch.

Strategy Species

The following list represents SGCN in this habitat type that AZGFD actively manages or are watching closely due to some level of concern:

Sensitive Plant Species

The following list represents plant species that are known to occur in this habitat type:

Holmgren (paradox) milk-vetch, Diamond Butte milkvetch, Sarah's wild buckwheat, Huachuca water-umbel, Holmgren's stickleaf, September 11 stickleaf, beardless cinchweed, Paradine (Kaibab) plains cactus, Fickeisen plains cactus, Peebles Navajo cactus, Siler pincushion cactus, Higgins' Phacelia, Hughes' Phacelia, Huachuca Mountain milkwort, Arizona rose sage, Siler fishhook cactus, Canelo Hills ladies'-tresses

Additional Influential Species

The following are other wildlife species, native and non-native, that can have particular influence in this habitat type. Influential species can affect SGCN and their habitats directly and indirectly, for example altering predator/prey interactions, overgrazing, outcompeting natives, creating microhabitats, and others.

Amphibians

Mexican Spadefoot, Plains Spadefoot

Birds

Lark Sparrow, Rock Wren, Western Meadowlark

Invertebrates

Monarch

Mammals

American Pronghorn, Kit Fox, Mule Deer, Rocky Mountain Elk

Plants

Rusby’s milkwort, Tusayan Flameflower, Varied Fishhook Cactus

Reptiles

Prairie Rattlesnake

Threats

The following describes the primary threats facing this habitat type, adapted from Salafsky et al. (2008). First-level threats (i.e. Agriculture, Climate Change) represent broad categories while second-level threats reflect more specific stressors to the system. For detailed information on threats to this habitat type and conservation actions being taken, see Chapter 8: Threats and Conservation Actions.

1. Agriculture

1.3: Livestock farming and ranching

Agricultural practices (primarily livestock grazing) can adversely affect grasslands through loss of plant cover, erosion, and conversion to non-native species. Excessive stocking rates in combination with fire suppression have led to decreased plant diversity and cover for wildlife. Groundwater pumping is also affecting water levels.

2. Biological Resource Use

2.1: Unlawful take of terrestrial animals

2.2: Unlawful take of terrestrial plants

Unlawful collection of terrestrial animals or plants can be detrimental to populations that have slow recruitment. When healthy, mature wildlife are taken out of season, population numbers are reduced due to the loss of the viable reproductive animal(s).

3. Climate Change and Severe Weather

3.1: Habitat shifting and alteration

3.2: Droughts

3.3: Temperature extremes

Climatological warming trends favor shrub species over perennial grasses and desert grasslands are likely to transition to desertscrub. Changes in precipitation, hydrological, and temperature regimes may result in increased frequency, magnitude, and intensity of droughts, dust storms, floods, and other extreme weather events which have the potential to impact wildlife populations through changes to suitable habitat.

4. Residential and Commercial Development

4.1: Housing and urban areas

4.3: Tourism and recreation areas

As Arizona’s population continues to expand, demand for housing and employment centers pose threats to habitat through direct loss of habitat, and indirect impacts such as habitat fragmentation, loss of wildlife resources, light and noise pollution, and disturbance to wildlife from human and pet recreation outside the built environment.

5. Disease, Pathogens, and Parasites

5: Disease, Pathogens, and Parasites

Species in this habitat can be affected by a variety of diseases, including plague, rabies, hantavirus, rabbit hemorrhagic disease which can cause significant mortalities and drastic population declines to keystone species. There is also the threat of decreased reproduction and recruitment of young.

7. Human Intrusions and Disturbance

7.1: Recreational activities

Recreational activities, such as unlawful OHV use, can damage habitats by altering or damaging vegetation. In upland areas poorly-managed OHV use can cause erosion. These types of alterations can negatively affect species abundance and distributions.

8. Invasive and Other Problematic Species

8.1: Invasive non-native species

8.2: Problematic native species

Invasive and problematic species compete with native fauna, over-utilize native species, and cause habitat damage. Overgrazing and invasive insects also impact this habitat type, resulting in increased woody debris, decrease in diversity of species, and increasing the potential for large and severe fires.

9. Natural System Modifications

9.1: Fire and fire suppression

The lack of wildfires on the plains and great basin grassland landscape has resulted in the encroachment of pinyon pine and juniper tree species. Where fire has occurred, non-native plant species are competing with natives.

11. Transportation and Service Corridors

11.1: Roads and railroads

Transportation corridors through grasslands can be a direct threat to species. Vehicles traveling those roads can be a significant cause of mortality while also creating noise and visual disturbance which alters wildlife behavior. Road construction and maintenance may result in the direct loss of habitat and disrupt migration corridors.

Conservation Actions

The following describes specific conservation actions that can be taken to reduce or eliminate threats to this habitat type, adapted from Salafsky et al. (2008). Level 1 conservation actions (i.e. Land and Water Protection) represent broad categories of potential actions, while the Level 2 conservation actions (i.e. Resource and habitat protection) are more specific.

1. Land and Water Protection

1.2: Resource and habitat protection

Identify wildlife corridors essential to the movement of species between high-quality habitat blocks. Create wildlife corridors that are identified via acquisition and/or conservation easements. Identify new wildlife corridors essential to movements between high quality habitat blocks. (Threats 1.3, 4.1, 11.1)

2. Land and Water Management

2.2: Invasive/problematic species control

2.3: Habitat and natural process restoration

Improve the quality of altered ecosystems by restoring and maintaining native plant species. This can be done by utilizing fire, improving diversity, eradication of invasive species, coordinating with partners to protect and maintain native grassland characteristics and wildlife habitat requirements, research, and maintenance once work is performed. (Threats 1.3, 3.1, 8.1, 9.1)
Increase habitat connectivity by removing barriers and impediments to species movement. (Threats 1.3, 4.1)
Control the spread of invasive and problematic species by implementing biological, mechanical, and chemical methods. (Threat 8.1)

3. Species Management

3.1: Management of specific species of concern

3.2: Species recovery

3.3: Species reintroduction

Survey and monitor species and habitats to determine status and conditions so that resources can be appropriately allocated. Evaluate the effectiveness of management actions, adapting the approach as necessary. Develop predator control strategies to enhance fawn recruitment. (Threat 8.2)
Ensure viable populations of at-risk species (prairie dogs and black-footed ferrets) through captive breeding, artificial propagation and/or gene banking. (Threat 5)
Conduct research with new methods to help lower the spread of plague on the landscape. Reduce the prevalence of external parasites carrying plague on the landscape to bolster prairie dog and ferret populations. (Threat 5)

4. Education and Awareness

4.3: Awareness and communication

Engage communities to incorporate natural resource values and open spaces into long-term planning; increase public awareness of AZGFD’s nongame conservation efforts to gain the support of non-traditional constituencies. (Threat 4.1)
Collaborate with developers, the Arizona Corporation Commission, and federal state, and local governments to raise awareness of impacts to wildlife and habitat from renewable and non-renewable energy development. (Threats 6.2, 6.3)
Partner with NGOs and OHV user groups to raise awareness about damages to sensitive habitats resulting from recreational activities. (Threat 7.1)
Expand wildlife viewing programs to improve associated infrastructure (signs, platforms, etc.) and to reach larger and more diverse audiences. (Threats 4.3, 7.1)
Mitigate transportation impacts by constructing wildlife crossing structures, avoiding wildlife corridors, and signage, etc., when major roadway/highway construction will be occurring. (Threat 11.1)

5. Law and Policy

5.2: Policies and regulations

5.4: Compliance and enforcement

Partner with NGOs and OHV user groups to track OHV use and damage of cross-country travel; improve coordination with partners through multi-agency regional to discuss priorities; conduct statewide law enforcement patrols targeting illegal OHV use as well as targeted saturation patrols in areas identified as critical habitat that are being adversely impacted by recreational activities. (Threat 7.1)

7. External Capacity Building

7.2: Alliance and partnership development

Collaborate with partners at different scales (e.g., statewide, regional, national, and international) to develop and implement management plans, conservation agreements, recovery actions, research, management recommendations, and determine specific management efforts to improve and coordinate landscape-scale efforts for long-term conservation of SCGN wildlife. (Threats 3.2, 3.3)
Improve coordination with partners to identify priorities and how the AWCS can be used to facilitate project planning and implementation. (Threats 1.3, 4.1, 11.1)

Conservation in the Context of Climate Change

The following describes some of the conservation strategies that may mitigate the effects of a changing climate for this habitat type. Strategies have been adapted from guidelines by the Association of Fish and Wildlife Agencies (AFWA 2009).

Conserve a variety of habitats that support healthy populations of fish and wildlife as climate changes.
Identify and improve the connectivity of natural landscapes to better link wildlife populations and allow for range shifts.
Maintain existing and identify new wildlife waters for drought mitigation.
Conserve a variety of habitats that support healthy populations of wildlife as the climate changes.
Collect specimens or samples for taxonomic analysis, genetics, research, and/or disease testing.
Conduct research targeting species and habitat types likely to be vulnerable to climate change impacts.
Implement long-term monitoring protocols for vulnerable species and habitats to inform adaptive management.

Other Conservation Actions

The following describe other routine or on-going conservation actions AZGFD regularly performs in this habitat type:

Monitor pronghorn movements and wildlife connectivity in Big Chino Valley.
Conduct surveys and monitor populations of SGCN as specified in work plans and job statements. Survey other influential species within the habitat to minimize negative impacts to habitat and species.
Fund or work with partners to conduct conservation-related species research.
Manage recreational activities and OHV use of grassland habitat to minimize negative impacts to habitat and associated species.
Collect specimens or samples for taxonomic analysis, genetics, research, and/or disease testing.