• A theoretical basis for study and management of trampling by cattle

  Guthery, F. S.; Bingham, R. L. (Society for Range Management, 1996-05-01)

  Cattle trampling of endangered plants, certain animal species, and ground nests may be a management concern on rangeland. Researchers need theoretical models of trampling loss to assist in design of studies and interpretation of results. Managers can use such models to assist in grazing management decisions. We present null (random background) models for predicting probability of trampling loss, explore the effects of failure of assumptions underlying these models, and develop alternative models for dealing with nonrandom grazing and nonrandom placement of vulnerable objects. The null models predict that if time-based stocking rate (head-days ha-1) is held constant and 1 pasture is grazed under several rotation schedules (a study design used to simulate rotational grazing), or if 1 pasture is divided into n paddocks through which 1 herd rotates, the probability of trampling is operationally constant. This qualitative prediction holds when grazing is nonindependent and nonrandom, competing risks exist, and objects subject to trampling are dispersed nonrandomly. Quantitative predictions of the null models do not hold under nonrandom grazing, which is expected to reduce probability of trampling. Researchers can use predictions of the models as a priori hypotheses. If empirical results deviate from the predictions, then researchers should search for the underlying cause-effect mechanisms. For management, the models indicate that trampling varies with livestock density and time grazed but is independent of herd rotation.
• A digital technique for recording of plant population data in permanent plots

  Roshier, D.; Lee, S.; Boreland, F. (Society for Range Management, 1997-01-01)

  A mobile system to rapidly record demographic and spatial data of plant populations on permanent plots has been developed based on digital image processing equipment for personal computers. It offers considerable savings in field and data handling time and can record data from large plots. This system will facilitate broader application of plant demographic studies to arid and semi-arid ecosystems.
• Wildlife numbers on late and mid seral Chihuahuan Desert rangelands

  Nelson, T.; Holechek, J. L.; Valdez, R.; Cardenas, M. (Society for Range Management, 1997-11-01)

  Seasonal wildlife observations were made along transects on 2 pastures in late seral and 2 pastures in mid seral condition in southcentral New Mexico in non-drought and drought years (1993, 1994). Remaining climax vegetation was about 64% and 57% on late seral pastures. About 37% and 32% of the climax vegetation remained on mid seral pastures. Total wildlife and total bird sightings/km2 during the study period were higher (P < 0.10) on the mid compared to late seral rangelands. The same number of wildlife species were seen on the late and mid seral pastures. Sightings of scaled quail (Callipepla squamata Vigors), mourning doves (Zenaida macroura Linnaeus), prong-horn (Antilocapra americana Ord), and desert cottontails (Sylvilagus auduboni Mearns) showed no differences (P> 0.10) between late and mid seral condition rangelands. Black-tailed jackrabbit (Lepus californicus J.A. Allen) numbers were higher (P
• Viewpoint: Ungulate herbivory, willows, and political ecology in Yellowstone

  Kay, C. E. (Society for Range Management, 1997-03-01)

  Contentions that willows (Salix spp.) on Yellowstone National Park's northern range have declined because of climatic change, fire suppression, reduced chemical defenses, or other natural factors are not supported by available data. Instead, willows have declined due to repeated browsing by an unnaturally large elk population. By established standards Yellowstone contains some of the worst overgrazed willow communities in the entire West, but that was not true in earlier times. Prior to park establishment, predation by Native Americans kept elk and other ungulate numbers low which, in turn, prevented herbivores from impacting Yellowstone's plant communities, as those animals do today. Finally, the condition of willows in the park is also a test of Yellowstone's "natural regulation" program, and that paradigm must also be rejected.
• Viewpoint: The present status and future prospects of squirreltail research

  Jones, T. A. (Society for Range Management, 1998-05-01)

  Squirreltail's [Elymus elymoides (Raf.) Swezey + Sitanion hystrix (Nutt.) J.G. Smith] ready germination, rapid reproductive maturity, capacity for cool-temperature growth, self-pollinated mating system, excellent seed dispersal mechanisms, fire tolerance, and genetic diversity make it a promising candidate for assisting ecological restoration of rangelands dominated by exotic weedy annual grasses such as medusahead wildrye [Taeniatherum caput-medusae (L.) Nevski] and cheatgrass (Bromus tectorum L.). Squirreltail is a short-lived perennial and generally early seral in successional status. It comprises a complex of several subspecies whose ecological amplitudes are poorly understood. Wildfire or prescribed burning may provide opportunities for seeding squirreltail or augmenting existing populations. Grazing deferment is important for a successful transition from an annual to a perennial-dominated grassland. Reduction in frequency of annuals may facilitate natural or artificial establishment of desirable mid- or late-seral grasses, forbs, and shrubs. Currently, squirreltail seed supplies originate from wildland harvests. Reduced cost, dependable supply, and improved quality of seed will require development of efficient commercial seed production practices. Experience in restoration may reveal the suitability of squirreltail plant material for assisted succession as well as expose its weaknesses. Such information will allow researchers to improve plant materials and methods for increased future success.

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