Comprehensive Study Guide to Rangeland Management, Livestock Production, and Wildlife Ecology
Principles of Ranching and Animal Selection in Rangelands
Ranching is defined as the practice of raising livestock on rangelands to meet the diverse food and material needs of human populations. For ranching to be successful, it requires a comprehensive knowledge base encompassing range management, animal husbandry, and financial management. A critical component of successful management is selecting animals that are efficient and productive within the specific constraints of a given rangeland. The responses of livestock are determined by three primary factors: animal kind (species), animal breed, and animal class.
Several environmental and socioeconomic factors influence animal selection for rangeland operations. These include topography, climate, and the type of vegetation available. Topography specifically dictates the species of animal suitable for a landscape; for example, goats and sheep are best suited for sloping and rocky terrain, whereas cattle and horses perform better on flatter ground. Other factors include water requirements, presence of predators, pests and diseases, and economic and social considerations.
Livestock Physiology and Water Requirements
Water requirements vary significantly among livestock species. Cattle and horses typically require water daily, whereas sheep and goats have lower requirements, often needing water only every . However, these frequencies are influenced by the salt content of the forage and available water. Higher salt content in rangeland forage necessitates an increase in water intake. For instance, sheep grazing saltbush may require water . Sheep and goats generally possess a higher tolerance to salt compared to cattle; consequently, cattle grazing in areas with high total dissolved solids (such as certain regions of New Mexico) would likely need to drink more frequently.
Economic Considerations and Management Strategies
There are distinct economic and social trade-offs when choosing between different types of livestock. Cattle raising possesses advantages such as lower labor requirements and a reduction in predator-related problems. In contrast, sheep offer the advantage of producing two distinct products: wool and meat. Historically, goats have yielded higher economic returns in environments where oaks dominate the vegetation. A combination of cattle and wildlife has been shown to yield the highest overall economic returns on many rangelands.
Common-use grazing, or the practice of grazing multiple species on the same range, offers several benefits. It may substantially increase livestock production and promotes a better distribution of animals across the landscape. This practice allows for a wider variety of available plant species to be grazed, leading to improved uniformity of rangeland use. Furthermore, it allows for income diversification, making the ranch less dependent on a single animal product, and reduces the risk associated with poisonous plants and species-specific diseases.
In terms of reproductive management, implementing a breeding season provides specific advantages. These include increased weaning weights and the production of more uniform calves. This shortened window also assists managers in identifying low-producing cows more effectively.
Managing Toxic Plants and Noxious Invasions
Livestock health can be severely compromised by toxic plants. Nitrate accumulation is a major threat, found in plants such as oat hay, alfalfa, barley, wheat, sorghum, corn, sudangrass, Johnsongrass, and beets. Weeds like carelessweed, kochia, pigweed, Russian thistle, nightshade, bull thistle, Canadian thistle, sunflower, and bindweed also accumulate nitrates. Ingestion of these plants disrupts the blood's ability to carry oxygen, leading to death by asphyxiation.
Milkweeds represent another risk as they produce resins that affect the muscular and nervous tissues of livestock. While the USDA National Resource Conservation Service (NRCS) may offer incentives to promote milkweed for monarch butterfly habitats to help rebuild the population, ranchers must be cautious. Large numbers of milkweeds in a pasture can be toxic if overconsumed. However, if a portion of the rangeland is not being used for livestock, participating in such programs can supplement ranching income.
Other toxicities include mesquite consumption, which may cause "wooden tongue" or paralyzed tongues in livestock. Managers can prevent poisoning by maintaining high-quality forage so animals are not forced to eat toxic species, providing adequate salt (as a lack of salt can cause animals to eat abnormally), and using weed control to remove poisonous plants. Avoid putting animals on range with poisonous plants when they have been on dry feed or are otherwise deprived of forage.
Noxious plant invasions are caused by several factors: overgrazing by domestic livestock, landscape fragmentation and denudation due to human population growth, and seed transport by grazing and small animals.
Wildlife Ecology and Habitat Heterogeneity
There is an increasing concern for wildlife on US rangelands, driven by a higher human population with greater affluency demanding more recreation. Society is also increasingly interested in how food production impacts the environment. Wildlife populations are primarily regulated by the quality and quantity of available habitat.
Habitat heterogeneity—the existence of two or more different types of habitat in an area—is a central concept in wildlife management. High heterogeneity is characterized by a mosaic of different plant heights and litter layers; for example, one area might be grazed heavily with short grass, while another is avoided and remains tall. Low heterogeneity occurs when the entire pasture possesses uniform vegetation height and litter. Heterogeneity is created through the combination of grazing, fire, and the activity of burrowing mammals. Grazing is considered the practice with the greatest potential for managing heterogeneity because it is the most common use of rangelands in the Great Plains.
Livestock grazing influences wildlife habitat both directly and indirectly. Direct impacts include the removal or trampling of vegetation used as food and the defoliation of food sources, along with overgrazing of riparian areas. Indirect impacts include changes in vegetation composition and a reduction in plant species diversity. While heavy grazing typically reduces calf and lamb crops and can negatively affect wildlife through reduced cover and increased social stress, moderate grazing generally supports more diverse wildlife populations than heavy grazing or no grazing at all.
Ecological Interactions and Specific Habitats
Specific wildlife species require different vegetation structures within the rangeland:
- Bare Ground: Ideal for mountain plover, horned lark, and common nighthawk.
- Sparse Vegetation: Ideal for long-billed curlew, chestnut-collared longspur, horned lark, mountain plover, common nighthawk, grasshopper sparrow, and western meadowlark.
- Thick Vegetation: Ideal for grasshopper sparrow, western meadowlark, lark sparrow, and dickcissel.
- Shrubby Areas: Ideal for lark sparrow, dickcissel, field sparrow, and loggerhead shrike.
The "edge effect" occurs where two habitats meet. Higher wildlife populations are often found in these areas because many species require multiple vegetation types to meet their needs. For example, mule deer in New Mexico prefer habitats with high diversity over short distances. Conversely, practices like planting shelterbelts (rows of trees) can be detrimental to rangeland natives. While they encourage deer and turkeys, they provide perches for raptors and shelter for mammalian predators, which fragments the habitat and reduces the productivity of avian species native to the rangelands.
Small mammals like jackrabbits and prairie dogs are often viewed negatively by ranchers due to forage competition. However, they provide positive impacts such as speeding up soil development, aiding mineral cycling, and contributing to the formation of organic matter. Research indicates that cattle production is not necessarily compromised when rangelands are managed for heterogeneity and diverse wildlife habitats.
Environmental Pressures and Improvement Practices
Environmental factors like drought can be devastating, reducing forage production by more than compared to the annual average. During drought or periods of low forage availability, there are more similarities in the diets of various animal species, increasing competition.
Range improvements, such as properly planned brush control, can increase the capacity of rangeland for both livestock and wildlife. Prescribed burning is another tool used to improve forage, reduce litter, enhance wildlife habitat, and reduce fuel loads to prevent catastrophic wildfires. Fire also reduces the labor costs of handling livestock. The three elements required for combustion are fuel, oxygen, and heat. Heat is the element managers can manipulate by selecting specific weather conditions for the burn. High-intensity rangeland fires can impact predation; for example, removing vegetation can increase the visibility of sheep to predators. Additionally, as the steepness of a slope increases, the rate of fire spread increases.
Regulatory and Legal Frameworks
Policy also plays a role in rangeland management. The Wild Free Roaming Horse and Burro Act of 1971 acts to protect wild horses and burros specifically on public lands within the United States.