Rotational Cattle Grazing to Restore Degraded Chihuahuan Desert Grasslands and Promote Watershed Health

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Describing the Mimms Ranch in Marfa, Texas, the authors write, “The Foundation aims for practical conservation, with the belief that restored grasslands improve overall watershed health, resources for native wildlife, and continued support of ranching.”

NOTE: this article was originally published to https://usbr.maps.arcgis.com/apps/MapSeries/index.html?appid=f1d4efbfdb33474cbf7bfc3c20dabb9a

 

As settlement spread across the west, changes in land-use and disturbance regimes often resulted in degradation of native grasslands.

 

The loss of functional grasslands meant reduced carbon sequestration, loss of wildlife habitat, and negative impacts on watersheds. The Dixon Water Foundation (the Foundation) works to promote healthy watersheds through sustainable land management. Since 2008, the Foundation has owned the Mimms Unit ranch, which is a working cattle ranch and a demonstration ranch on a high Chihuahuan Desert grassland northwest of Marfa, Texas. The ranch utilizes different grazing regimes to study the use of livestock as a tool in grassland restoration in a dry climate.

The ranch consists of pastures that examine three different grazing management techniques: continuous, rotational, and areas where grazing is entirely excluded. Rotationally grazed pastures are divided into paddocks that are heavily grazed for a short amount of time and left to rest for an entire growing season. Rotations are alternated so that paddocks are not always grazed at the same time each year. This rotational technique attempts to allow paddocks to rest and generate new growth, while mimicking the grazing patterns of bison herds that would have historically passed through the landscape.

This promotes healthy soils, but also reduces runoff and erosion. As the cattle are rotated, the disturbed pastures are allowed to rest and recover, generating vegetative cover that traps moisture. The foundation also hosts educational programming to demonstrate the economic and environmental benefits of their practices. A large fire burned through the Mimms in 2011, essentially resetting the property. Thus, all observations on ecosystem response have occurred post-fire.

Key Issues Addressed

Early European settlers of West Texas eliminated bison herds in a quest to push Native Americans off of the land. The removal of bison from the landscape left plentiful rangelands that were subsequently heavily stocked with cattle by the late 1800s. Overgrazing resulted in conversion of grasslands to bare ground.

Bare ground increases runoff of precipitation, further degrading soil quality and causing accelerated flows that carry more sediment and degrade creeks and rivers downstream. The loss of grasslands deprived native wildlife of habitat, created unproductive ranchlands, and inhibited aquifer recharge and carbon sequestration. The Dixon Water Foundation works to restore grasslands by employing grazing techniques that mimic historical bison movements. This approach allows for long periods of rest and recovery after short periods of heavy disturbance, and has been able to reverse century-old problems in a relatively short amount of time. The Foundation aims for practical conservation, with the belief that restored grasslands improve overall watershed health, resources for native wildlife, and continued support of ranching. The Mimms Unit range ranch is used to demonstrate the benefits of sustainable land management, which is communicated through public outreach and educational programming at the ranch.

Project Goals

  • Rehabilitate grasslands to improve watershed health and to provide habitat for wildlife
  • Use sustainable ranching to maintain healthy grasslands over the long term
  • Provide educational and research opportunities to share information on the benefits of regenerative livestock management

 

Cattle Grazing for Restoration: Dixon Water Foundation uses cattle grazing as the principle restoration technique. American conservationist, Aldo Leopold, recommended strategic cattle grazing as a tool for land management; cattle are already present on many ranches and present a large-scale restoration opportunity that maintain value of working lands.

Monitoring for Success: Vegetation is monitored through transect surveys by Sul Ross State University Students, in-house point monitoring by the Dixon Water Foundation, and regular visual assessments by ranch employees.

Collaborative Partnerships: The Foundation partners with wildlife researchers from universities and state agencies, and has worked with the Rio Grande Joint Venture, the Bird Conservancy of the Rockies, The Borderlands Research Institute at Sul Ross State University, and Natural Resource Conservation Service. These partnerships have created opportunities for researchers to explore a variety of topics such as small mammal response to fire and grassland bird and over-winter home range and survival. Foundation members have served on the management boards of regional non-profit conservation groups. The Foundation offers an internship program through the Sul Ross University Ranch Management Program, which began in 2018.

Room for Wildlife: Much of the native grasslands in the Chihuahuan Desert have been lost to conversion and fragmentation. Restoration and conservation of these grasslands improves habitat quality for local wildlife such as small mammals, and for pronghorn, which use portions of the Mimms as fawning grounds. Additionally, these desert grasslands provide habitat for over-wintering migratory birds.

Binational Collaboration: Proximity to the international border has allowed ranch managers to visit and share ideas with ranches in Mexico that are using similar management techniques.

Community Outreach: The Mimms Ranch is located just on the edge of the town of Marfa, Texas, facilitating access for events, workshops, and use of the interpretive trail. The interpretive trail extends 2.5 miles from the ranch entrance to an overlook in the grasslands. Informative signs posted along the path describe the grasslands ecosystems and ranching practices. The ranch has hosted other groups from across the Southwest to come and share their own management stories. Closeness to the town also allows for managers to have more interactions and communication with others in the local ranching community.

Lessons Learned

  • Forbs and ground cover are able to establish during rest periods in rotationally grazed pastures. Forbs send down taproots, which increases permeability and infiltration, and leads to less runoff and erosion. They are also good forage for wildlife.

  • Stocking density and recovery periods need to be continually monitored and adjusted based on local conditions. Dixon Water Foundation owns an additional property in North Central Texas which receives more annual precipitation and can therefore host a higher stocking density. This increased grazing pressure helps keep the tall grass prairies from being colonized by undesirable woody plants. However, in the drier conditions of the Chihuahuan Desert in West Texas, stock densities need to be tailored to an often less productive range. Areas that are stressed by drought conditions and are subsequently grazed too heavily can be converted back to bare ground.

  • New growth is selected for and grazed in continually grazed pasture. Less palatable plants go ungrazed, which, in turn, causes them to become tougher and less desirable to cattle. Similarly, in exclosure pastures, ungrazed plants that mature can begin to lose palatability and nutritional value. In rotational grazing pastures, new growth is heavily selected, but for shorter periods of time, allowing recovery during rest.

  • Since many of the grass species at the ranch evolved with large grazing ungulates (i.e. bison), the removal of exposed growth stimulates the plant to produce more growth. Grasses within ungrazed exclosure pastures turn gray and decadent. Uniform surface soils resulting from a lack of disturbance by ungulates, shed water, increasing runoff and erosion potential.

  • Perennial grasses have expanded to cover previous bare ground around ephemeral springs and riparian areas as a result of rotational grazing.

  • In continually grazed pastures, Russian thistle is selectively consumed, and therefore removed, when it is young. Alternatively, rotational grazing has allowed Russian thistle to mature and blow into riparian areas where it creates natural dams that slow water and increase infiltration. While this is a non-native species, it has shown some benefits at Mimms Ranch. It should be noted that in some areas of Far West Texas, mature Russian thistle can also blow into fence lines, such as netwire fencing, which can have a negative impact by creating dense barriers to wildlife movement.

  • The Mimms Ranch hosts events where a hiking trail is open to the public. This public engagement has helped facilitate communication and education about grazing techniques, soil health, and watershed health in the desert Southwest and has reached a broad spectrum of people, from hikers to students, conservation professionals, landowners, and researchers.

  • The need to regularly access and move cattle requires roads. Trails sometimes result from cattle and horse use, potentially leading to erosion. Access points should be considered in design of this type of grazing system.

Next Steps

  • Grazing management will continue. This type of restorative management needs to be applied over a long period of time in order to give the land the chance to respond and observe long-term effects.

  • The Foundation will continue to seek ways to engage agencies and the public about sustainable grazing practices that maintain working lands while benefiting native wildlife species.

  • The Mimms Ranch is open to further research from universities in order to expand the scientific evaluation of these techniques and to encourage discussion and adaptive management. Dixon Water Foundation has provided funding for research conducted on the property and plans to continue this practice.

  • Managers will continue to monitor the ecosystem response to grazing and will adjust stocking densities as necessary.

  • It is important to ranch managers to communicate with others applying similar techniques in the Chihuahuan Desert and southwestern desert ecoregions. The Foundation seeks to continue and expand these relationships both regionally and internationally.

  • Dixon Water Foundation may employ hay bail grazing in heavily degraded areas. This supplemental feeding would allow cattle to fertilize the soil and break up compacted surface soil layers in areas that currently offer little to no nutritional plants.

 

Collaborators

  • Rio Grande Joint Venture

  • Bird Conservancy of the Rockies

  • Borderlands Research Institute

  • Natural Resources Conservation Service

Resources

 

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