Arizona Wildlife Conservation Strategy

Grassland Systems Overview

North America’s central grasslands are considered one of the most threatened ecosystems in the world (Gauthier et al. 2003, Askins 2007). It is estimated that Great Plains and desert grasslands once covered more than 500 million acres across North America. Although this acreage has been reduced in recent centuries thanks to human encroachment, grasslands still play a critical role on a continental scale. Nearly 200 wildlife species use this immense sea of grass, spanning 11 states and includes parts of Arizona, Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming (WAFWA 2011). Conservation and sustainable use initiatives are becoming more strategic and comprehensive in nature, engaging multi-national focus between the United States, Mexico, and Canada.

Arizona’s grasslands are ecologically- and economically-important areas, providing habitat for wildlife, forage for livestock, pollinator habitat, soil stabilization, and a host of additional ecosystem services that support healthy human populations. The vast, open grassland landscapes are aesthetically pleasing, offer outstanding wildlife viewing, and provide valuable educational, recreational, and research opportunities.

In Arizona, grasslands once occurred across an estimated 18.2 million acres, or approximately one quarter of the state (Hendricks et al. 1985). While significant grassland habitat still exists across southeastern and northeastern areas of the state, lack of regular fires, high grazing pressure, and extended drought conditions, have led to shrub encroachment in some areas and desertification in others. According to an interagency ecological assessment led by TNC (Gori and Enquist 2003), 31% of Arizona’s former grasslands are in good condition with native perennial grasses and low shrub cover; 34% are shrub-invaded but have the potential to be restored; 26% have crossed a threshold where former grasslands have transitioned to shrubland; 9% are now dominated by exotic species; and 4% have low shrub cover but also little to no perennial grass.

Grasslands in Arizona occur primarily on State Trust, BLM, Tribal, and private lands, a significant portion of which is classified as working landscapes where livestock grazing is the primary land use. While grazing practices on many ranch lands and allotments have been modified in recent years to align with a more sustainable lands approach, overgrazing especially in arid environments can cause undesirable changes in the plant community, including decreased mulch cover, decreased water infiltration, compacted soil, increased water runoff, decreased plant vigor and production, and a drier microclimate at ground level (Severson and Medina 1983). In light of climate change and long-term drought, already stressed grasslands can be further impaired. In some places, introduced non-native plants (such as Lehmann lovegrass and cheatgrass) have invaded the natural vegetation and caused landscape-level changes that may be irreversible. In places where non-native grasses have become established, a frequent and intense fire regime develops, which furthers the spread and dominance of the non-natives.

In addition to grazing pressures, Arizona’s grasslands are at risk of loss to development, especially on private and State Trust lands which have no long-term conservation protection (Gori and Enquist 2003). This development not only results in habitat loss and fragmentation, but also prevents the use of fire in grasslands to maintain species diversity and prevent shrub encroachment (Gori and Enquist 2003).

Three types of grassland habitats occur in Arizona: semidesert grasslands, Plains and Great Basin grasslands, and subalpine grasslands.

Semidesert Grasslands

Semidesert grasslands occur in southeastern Arizona in areas with semi-arid soils associated with the Chihuahuan Desert ecoregion. They also occur in northwestern Arizona at the base of the Hualapai and Cerbat Mountains in the Kingman area, as well as in central Arizona along I-17 in Aqua Fria National Monument and the rolling hills outside of Camp Verde. Semidesert grasslands are the driest of any grassland habitat type in North America, receiving just 8 to 15 inches of precipitation annually. See the semidesert grassland habitat profile for further details.

Plains and Great Basin Grasslands

These grassland habitats are found mainly in northern Arizona in the Arizona/New Mexico Plateau ecoregion in shallow, mesic semi-arid soils. In the northeastern portion of the state, these grasslands cover relatively large areas east of Flagstaff, north and south of I-40. In north-central Arizona, Plains and Great Basin grasslands are found north of Williams on the Coconino Plateau as well as north of the Grand Canyon on the Kaibab Plateau. This habitat type receives an average of 17 inches of precipitation annually, the majority of which falls in the spring and summer. See the Plains and Great Basin grassland habitat profile for further details.

Subalpine Grasslands

Subalpine grasslands are limited in extent in Arizona, occurring in the White Mountains, on the Kaibab Plateau, and in a few areas in the sky islands region in southern Arizona. Supalpine grasslands are found in relatively flat areas, interspersed in mixed conifer and ponderosa pine forests. Forage value of grass species in this habitat type is high, making these grasslands an important resource for livestock as well as wildlife. See the subalpine grassland habitat profile for further details.

Conservation of Grasslands Systems

Restoring and enhancing grasslands in Arizona — and throughout much of North America — is challenging due to complex interactions among ecosystem components and cumulative effects of long-term stressors. However, in recent years, more and more research is providing valuable insights from which land managers can develop landscape- and regional-scale grassland habitat conservation projects.

In 2004, the Western Association of Fish and Wildlife Agencies (WAFWA) recognized the need for an increased conservation focus on grassland ecosystems because of historical impacts (e.g., agricultural conversion, infrastructure development, and urbanization) as well as more recent and on-going impacts facing these habitats (e.g., invasive species, energy development, climate change, and urban sprawl).

Meanwhile, in Arizona, the concern with the ecological status and sustainability of the state’s temperate grasslands has increased exponentially in recent years. In 2003, TNC completed a comprehensive grassland assessment for the Apache Highlands (APH) Ecoregion (U.S. and Mexico), an area that covers much of southeastern and central Arizona (Gori and Enquist 2003). Grasslands across the region were evaluated to characterize their condition, the extent of vegetation changes, and to identify the best remaining grasslands for restoration and conservation. The assessment concluded that changes to grassland vegetation have been extensive, due mostly to shrub encroachment and invasion of non-native grasses, emphasizing that grasslands are extremely vulnerable to development and most lack protective status.

Of the more significant findings in this report, most native grasslands within the U.S. portion of the APH Ecoregion with low shrub cover (the highest quality rating) are either private (44.3%) or State lands (23.3%). High quality native grasslands are less abundant on federal ownership (BLM and USFS), totaling only 17.1%. However, there is a very high percentage of native grasslands with restoration potential in public ownership (USFS 21.6% and BLM 15.4%), approximately 2.5 million acres. These lands represent the greatest opportunity for conservation efforts that will provide lasting benefits to future generations and wildlife populations. Lastly, there is a significant portion of native grassland with restoration potential on State Trust land (33.8%) that could be important if regional and statewide land use planning appropriated portions of these lands for conservation purposes.

Currently, AZGFD is working with several local, state, national and international initiatives that have implemented public/private partnerships to accomplish grassland conservation in Arizona:

Some of the broader and most relevant plans to grassland habitats or species (with web links) can be found in each of the grassland habitat profiles. Some examples include: 

Arizona Game and Fish Department:

 U.S. Department of Agriculture Forest Service:

 U.S. Bureau of Land Management: