Thesis (M.App.Sc.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2001. / Bibliography: leaves 308-333.

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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

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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.

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