Grazing trials were conducted on irrigated fall/winter pastures near Maricopa, Arizona where 270 feeder lambs were stocked in 16-ha paddocks to explore the use of grazing behavior as an indicator of forage quantity and quality. Sheep behavior was monitored by filming the grazing periods with a VHS camera and recording the length of time that an individual spent at a feeding station, defined here as a feeding station interval. Other measurements included observed steps between feeding stations (step-sets), feeding stations min⁻¹, steps min⁻¹ and biting rate. As grazing progressed, lambs increased the number of feeding station intervals that were less than 5 seconds long and increased the number of feeding stations min⁻¹ significantly (p ≤ 0.05). Feeding stations min⁻¹ were negatively correlated (r ≤ -0.94) with crude protein, digestible energy and quantity of selected forage. Throughout the grazing trial lambs appeared to prefer the leaves to the stems. Steps min⁻¹ were only moderately correlated to forage quantity and quality. Bites min⁻¹ were not correlated to forage quantity and quality. Feeding stations min⁻¹ as a method of monitoring animal behavior during feeding periods might allow the manager to recognize nutritional limitations in the available forage and perhaps adjust management strategies accordingly.

The federal government has spent considerable sums of money to rehabilitate range lands administered by the Bureau of Land Management (BLM). These investments have had varying effects on the production and utilization of forage on these lands. One of the most surprising results, according to BLM officials, of the investments undertaken during the Vale Project has been the increased productivity of native lands in the Vale District of the BLM. This study was initiated to examine these effects and to evaluate the investments that have been undertaken during the project. The theoretical relationships that exist between the production, utilization, and administration of resources were developed to explain how various range improvements may affect forage production. This body of theory was also used to develop two hypotheses. The first hypothesis stated that increased forage production on native lands in the Vale District have resulted from increased forage production on improved areas. The second hypothesis stated that increased forage on improved areas have resulted from increased production of native areas in the Vale District. Parameters of a system of simultaneous equations were estimated by least squares using cost and forage response data obtained from BLM officials at the Vale District. Statistical tests, based on the preceding parameter estimates, indicated that forage production on native lands has been significantly affected by forage production on improved areas (first hypothesis). These tests also indicated that increased forage production on native areas has increased the production of forage on improved areas. Parameter estimates were also used to evaluate the returns necessary to earn a five percent return on the investments undertaken during the Vale Project. This evaluation indicated that an Animal Unit Month (AUM) of federal forage must be worth more than $6.00 for spray and seed areas, $5.00 for spray areas, $2.50 for native areas, $2.00 for plow and seed areas, and $1.00 for Old Rehab areas. Three major conclusions were derived from the results of this study. First, utilization rates have significant bearing on the returns that may be expected from an investment for range improvement. Second, investments that increase the production of forage in one area can affect the production of forage in other areas if utilization practices (management of the forage resource) such as those used by the BLM are followed. Third, many of the rehabilitation projects that have been undertaken by the BLM during the Vale Project have yielded less than a five percent return on the investments. / Graduation date: 1971

Between July and September, 1985, 70 ranchers, environmentalists and agency officials participating in three chartered Experimental Stewardship Program (ESP) areas were interviewed. Committee records and agency documents were also examined. As a result of the field work three conclusions were reached: (1) conflicts over grazing decisions have been significantly reduced by the stewardship process, (2) available data is insufficient to support conclusions about changes in the ecological status of the plant communities within the stewardship areas and (3) the annual economic value of rangeland recreation exceeds all other rangeland outputs on all three areas studied.

Lehmann lovegrass (Eragrostis lehmanniana Nees) is a warm-season bunchgrass native to South Africa which dominates many desert grasslands in southern Arizona. To determine why fire results in high seedling recruitment of this species, seedbank germination and field seedling emergence were measured in relation to (1) no treatment, (2) burning, (3) clipping and herbicide and (4) herbicide only. Treatments were replicated over 2 years on a stand of Lehmann lovegrass at the Santa Rita Experimental Range. Canopy removal, by either clipping or burning, significantly increased seedling emergence in seedbank bioassays prior to summer rains both years. Bioassay emergence was 826, 415, 350 and 199 seedling/m2 in 1988 from the dead-clip, burn, dead-standing and control treatments, respectively. Field seedling emergence was significantly increased with canopy removal both years and seedling densities were 281, 142, 3, and 0.1 seedlings/m2 for the dead-clip, burn, dead-standing and control treatments, respectively in 1988. The ability of this grass to reestablish after canopy disturbance may result from a greater range in sol temperatures and increases in red light reaching the seedbed.

The variability in utilization estimates using seasonal production data from clipped sideoats grama plants was studied in southeastern Arizona. Three intensities of clipping at four seasons were studied. Regrowth was also examined. Current growth was highest in October and lowest in June, whereas, standing dead material was lowest in February and highest in June. By April 1986, 39% of peak current growth was already produced. Total peak standing crop occurred in October. The sum of current growth and regrowth from heavy clipping was greater than for plants clipped heavily only in October. The opposite was true for moderate and control clippings. Actual utilization was calculated using peak current growth as a basis for calculating percentage utilization. Relative utilization was based on standing crop at each season of clipping treatments. Generally, relative utilization estimates overestimated utilization when compared to actual utilization estimates based on current growth.

Geographic analysis procedures and multiple linear regression techniques are applied to the problem of generalizing forage production and utilization information from sample point data. The study involves the application of these procedures to predict the spatial variability of mean production and utilization of Digitaria californica on the Santa Rita Experimental Range near Tucson, Arizona. Analysis of ten-year means from data collected between 1957 and 1966 indicate that variability in production is a function of mean summer precipitation and elevation. Variability in utilization is found to be a function of land slope and distance from livestock water. Geostatistical procedures are used to estimate mean summer precipitation. A geographic information system (GIS) is used to automate multiple linear regression functions for points in a raster data structure. The geographic analysis procedures are used to describe the spatial variability of the data in a mapped form. Management applications of the approach are demonstrated.

Penetrometer soil strength and the depth of packstock hoofprints were studied in two subalpine meadows in an attempt to develop a method for determining the seasonal readiness of wilderness meadows for packstock grazing at Sequoia & Kings Canyon National Parks, California. Soil and vegetation parameters (bulk density, water content, percent gravel, sand, silt, clay, and organic matter, above-ground biomass, and below-ground biomass in two diameter size classes) were also studied in order to understand their influence on soil strength and hoofprint depth. Of the four penetrometer tip sizes tested on a Lang penetrometer, a 9/16" diameter tip was found to be a good predictor of hoofprint depth. Both 9/16" soil strength and hoofprint depth were well predicted by soil water content and meadow vegetation type.

The grazing system I studied is intended to promote sustainable elk (Cervus elaphus) and cattle use, attracting elk to cattle-grazed pastures, thus resting the others. My objective was to determine whether the grazing system (1) promotes sustainable levels of forage use and (2) rests half the pastures each year. The grazing system did promote sustainable forage use but did not rest half the pastures; elk used all study pastures. Elk grazing patterns depended more on cover and topography than the grazing system. Essential to the study of grazing interactions are reliable utilization data. My objective was to compare forage use estimates obtained with the paired-plot and 2 height-weight methods (i.e., using on-site height-weight regression curves and the United States Forest Service height-weight gauge). Height-weight methods produced lower but more precise use estimates than the paired-plot method. Height-weight estimates did not differ significantly when calculated with on-site curves or the USFS gauge.

Thesis (M.S.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 135-141). Also available via the World Wide Web.

Ground cover, species composition, average distance between perennial plants, standing biomass, frequency of bare quadrats, and site stability rating were evaluated as predictor variables in determining the degree of site protection from accelerated soil erosion on a clay loam upland range site. Interpretations of range condition, species diversity, and the WEPP model predicted sediment yield were analyzed to determine their usefulness in detecting a threshold of site protection. Standing biomass, basal cover, average distance between plants and frequency of bare quadrats demonstrated strong correlations to the site stability rating and were useful in examining thresholds of site protection. The WEPP model was useful in determining a threshold of protection with the site stability rating. The diversity index and range condition rating showed poor relationships with the stability indices and plant community attributes measured. Thus, individually, these ratings do not provide and adequate assessment of the degree of site protection.