Current models of rangeland system dynamics were evaluated in Cosapa, a pastoral community on the Bolivian altiplano. Two specific models were tested: the "equilibrium" model, which assumes biotic interactions dominate rangeland dynamics and lead to system stability , and the "nonequilibrium" model, in which stochastic, abiotic factors control systems such that equilibrium is never attained. A livestock development project (called "Project Alpaca ") working in the community was then assessed in terms of how its assumptions of system dynamics compared with empirical findings. The goal of Project Alpaca was to increase incomes for camelid (i.e., llama and alpaca) herders on the Bolivian altiplano by improving the processing, production, and marketing of alpaca wool. Project implementation was carried out by an indigenous herders' association, with funds provided for construction of a modern alpaca wool processing plant and technical interventions at the farm level. Specific research objectives were to determine which conceptual model of system dynamics (equilibrium or nonequilibrium) best approximated the vegetation and livestock dynamics in Cosapa, and determine the impacts of technical innovations introduced by Project Alpaca . Vegetation dynamics were assessed by comparing plant species composition and production between grazed and ungrazed sites. Pastoral management strategies, livestock population dynamics between 1982 to 1995, and project impacts were assessed using a household survey. Results from the vegetation analyses showed that grazing protection had little impact on plant productivity, but reduced species diversity in wetland areas. The vegetation thus exhibited nonequilibrial characteristics. Regarding livestock dynamics, populations were relatively stable (over 13 years), although mortality was affected by severe drought, suggesting a combination of equilibrial and nonequilibrial interactions . Project Alpaca assumed an equilibrium model by emphasizing system stability and production maximization. The technical interventions showed positive, negative, and neutral associations with animal productivity. Construction of fenced exclosures on communal land has increased conflicts over land tenure rights, and may marginalize poorer households and increase social stratification . Development recommendations include shifting efforts away from intensification interventions that limit movement and flexibility, and strengthening social and economic networks that buffer the impacts of system variability.

Western prairie clover [Dalea ornata (Douglas ex Hook.) Eaton & J. Wright] is a perennial legume that occurs in the northern Great Basin, Snake River Basin, and southern Columbia Plateau, whereas Searls prairie clover [Dalea searlsiae (A. Gray) Barneby], also a perennial legume, occurs in the southern Great Basin and surrounding areas. Understanding the genetic and ecotypic variation of these prairie clovers is a prerequisite for developing populations suitable for rangeland revegetation in the western USA. DNA sequences of internal transcribed spacer (ITS/5.8S) and trnK/matK were used to study the phylogeny of these species. The species were distinguished by DNA sequences from both regions and conserved haplotypes were observed between and within species. Common-garden plots of 22 collections of western prairie clover from Idaho, Oregon, and Washington and 20 collections of Searls prairie clover from Utah and Nevada were established in northern Utah for phenotypic evaluation. Significant variation was detected among the collections for all traits measured in the common gardens for both species. Flowering date was correlated with collection-site temperature and elevation in western prairie clover collections, whereas biomass-related traits were closely related with collection-site precipitation in Searls prairie clover. Population structure from amplified fragment length polymorphism (AFLP) markers resulted in two distinct, genetically differentiated groups and a third admixed group in western prairie clover, and flowering date played a significant role in discriminating those genetic-based groupings of collections. For western prairie clover, two populations are recommended for development, one from the Deschutes River watershed and another from the remaining collections. For Searls prairie clover, two genetically different groups of collections were identified from southern Utah and eastern Nevada and from northwestern Utah. Three western Nevada collections exhibited close association with eastern Nevada and southern Utah groups for AFLP-markers but with collections from northwestern Utah for phenotypic traits. Strong isolation by distance was observed for Searls prairie clover collections suggesting that genetic drift and gene flow are major factors for determining population structure in this species. As a result, two regional seed sources should be developed for Searls prairie clover, one from northwestern Utah and the other from eastern Nevada and southern Utah.

Russian knapweed (Acroptilon repens) is an invasive perennial forb that has become well established in much of the western United States and Canada since the late 1800s. Aminopyralid is a relatively new pyridine carboxylic acid herbicide registered for use on rangelands and has provided excellent control of Russian knapweed in many studies. Research trials were conducted on two adjacent plot sites at Dinosaur National Monument to evaluate the effects of a single spring goat grazing paired with a fall application of aminopyralid at 0, 53, 70, 88, and 105 g ae ha-1 on Russian knapweed control. Russian knapweed density, canopy cover, and biomass were reduced to 0 or near 0 by all rates of aminopyralid, regardless of grazing treatment. Conversely, desirable grass cover and biomass increased at all rates of aminopyralid regardless of grazing treatment. Aminopyralid provided excellent control of Russian knapweed at all rates tested. Desirable perennial grass species have the potential to be injured when growth regulator herbicides are used for broadleaf weed control. Greenhouse trials performed at Utah State University and field trials performed in Logan, UT from 2009&ndash2011 evaluated tolerance and response of six native perennial bunchgrasses to growth regulator herbicides. Grasses used in the study included tall wheatgrass, bluebunch wheatgrass, Great Basin wildrye, Indian ricegrass, big bluegrass, and bottlebrush squirreltail. Two rates each of aminopyralid, aminocyclopyrachlor, and clopyralid were evaluated. Herbicide test rates were based on the labeled rate for control of Russian knapweed and other creeping perennials. Tolerance to herbicides varied among grass species. Petri&ndashdish trials showed reductions in root length by all three herbicides in all six speceis 14 days after treatment (DAT). Shoot length was significantly reduced by both rates of aminopyralid (123 and 246 g ae ha-1) and 280 g ai ha-1 of amincyclopyrachlor. The same species were evaluated in the field and greenhouse in response to postemergence applications of the same herbicides. Of the six grass species tested, &lsquoSherman&rsquo big bluegrass appeared to be highly tolerant to aminopyralid, clopyralid, and aminocyclopyrachlor, and &lsquoMagnar&rsquo Great Basin wildrye and Anatone bluebunch wheatgrass appeared to be the most sensitive to aminopyralid and aminocyclopoyrachlor in both the field and the greenhouse.

The interaction of land-use and climate can cause non-linear “state” changes in ecosystems, characterized by persistent differences in structure and function. Changes in land-use and climate on the Colorado Plateau may be driving many ecosystems toward undesired states where energy-intensive measures are required to return to previous states. Landscape classification systems based on “ecological potential” offer a robust framework to evaluate ecological conditions. Ecological sites are a popular landscape classification system based on long-term ecological potential and are widely used throughout the western US. Ecological sites have been described extensively for rangelands and woodlands on DOI Bureau of Land Management lands; however, they have yet to be described on USDA Forest Service (USFS) lands. In this thesis, I describe a statistical approach to ecological site delineation and the development of state-and-transition models, diagrams that illustrate ecosystem dynamics and responses to disturbances. In Chapter 2, I used a large inventory dataset and multivariate statistical procedures to classify plots based on life zone, soils, and potential vegetation, effectively delineating statistical ecological site-like groups. Most of the statistical ecological sites matched ecological sites already described by the USDA Natural Resources Conservation Service (NRCS). Additionally, I described one new ecological site that has not been described by the NRCS in the Colorado Plateau region. In Chapter 3, I examined empirical evidence for alternative states in mountain ponderosa pine (Pinus ponderosa Lawson & C. Lawson) and upland piñon-juniper ecosystems. Using multivariate statistical procedures, I found that plots cluster into groups consistent with generalized alternative states identified in a priori conceptual models. Additionally, I showed that ponderosa pine clusters were true alternative states and piñon-juniper clusters were not true alternative states because they were confounded by similarities in climate. Ponderosa pine clusters were differentiated by overstory ponderosa pine density and corresponded to three states: current potential, high fuel load, and reduced overstory. These results illustrate the range of ecosystem variability that is present throughout the study area and present evidence for alternatives states caused by historical land-use. This project is the first to propose ecological sites and state-and-transition models on USFS lands in this region. These techniques could be applied to areas that do not have formally described ecological sites and state-and-transition models and could help identify ecological sites that may have been overlooked using other means of delineation. Additionally, these methods can be used to evaluate the range of ecological variability throughout an area of interest and to improved understanding of ecosystem dynamics.

The first chapter of this thesis reviews applications of satellite remote sensing and geographical information systems (GIS) in wildlife studies. The simpler uses of remote sensing are for habitat mapping, often using satellite imagery classified for other natural resources. More sophisticated applications incorporate remotely sensed data into a GIS for the digital manipulation of data planes. The most advanced applications are those which use remote sensing and GIS in models predicting habitat quality or population levels. The second chapter reports how brightness values of six Landsat Thematic Mapper (TM) bands were used in multiple linear regressions to predict percent cover of six rangeland components. Regression equations were applied to TM imagery to create cover maps for live shrub, dead and live shrub, sagebrush, forb/grass, forb, and bare ground/rock. Accuracy was assessed at two levels and ranged from 55 to 90%. The third chapter presents results of sage grouse surveys used with satellite data and GIS to assess habitat use patterns. Habitats used by grouse were compared to availability in the landscape for continuous images of rangeland cover variables, for discrete images of rangeland classes, and for habitat diversity values. Overall, results were comparable to those in studies using traditional methods.

Soil moisture deficits often hinder rangeland revegetation efforts. Due to sheer numbers and germination timing, invasive annual species can easily outcompete those of desired seeded species for resources, including water. One way to increase seedling establishment may be to increase the amount of water available to seeded species. Superabsorbent polymers (SAPs) can absorb and release hundreds of times their weight in water and slowly release it. Concentrated SAP bands at or near seedling rooting depth may act as a soil water reservoir for germinating seedlings and increase rangeland seedling establishment. The objective of these studies was to evaluate the effect of banded SAP on soil moisture and seedling establishment through a series of eight glasshouse and field trials with different combinations of: species, SAP band rate, SAP band placement depth, seeding rate, fertilizer application, and seedling distance from the SAP band. Two grasses, bottlebrush squirreltail (Elymus elymoides) or Siberian wheatgrass (Agropyron fragile) were used as test species in all studies but one. In that study six species commonly used in rangeland restoration [bottlebrush squirreltail, crested wheatgrass (Agropyron cristatum (L.)), Lewis flax (Linum lewisii Pursh), yellow sweet clover (Melilotus officinalis), Wyoming big sagebrush (Artemisia tridentata Nuttall ssp. wyomingensis Beetle Young), and forage kochia (Kochia prostrata (L.) Schrad.)] were used. Concentrated band of SAP at rates up to 6000 kg ha-1 were placed below the seeds at depths ranging from the soil surface to 15 cm deep or mixed into the top 8 or 15 cm of soil. Measurements varied with trial. Soil moisture measurements included gravimetric water content, volumetric water content, and/or soil matric potential. Seedling growth parameters included seedling time to emerge, number emerged, longevity, percent of seedlings alive, shoot length, blade count, root length, root biomass, shoot biomass, and/or root:shoot ratio. Banded SAP at high rates increased usable soil moisture up to 49 days in the glasshouse and in spring of the first year after installation in the field. Rates ? 1500 kg ha-1 increased seedling longevity up to 12 days in the glasshouse but resulted in raised and cracked soil. This negatively impacted seedling survival in the field but not the glasshouse and may also reduce the amount of available soil moisture over time. Banded SAP at rates < 1500 kg ha-1, intended to reduce soil cracking, had no impact on soil moisture or live seedlings in the field. Further work is needed to investigate alternative application methods, such as blending the SAP into the soil.

In recent years, the importance of sagebrush to shrub-steppe ecosystems and associated plant and animal species has been recognized. The historical removal of herbaceous species by excessive and uncontrolled livestock grazing on many of our sagebrush ecosystems has resulted in a stagnant state where dense, competitive stands of sagebrush prevent herbaceous species from recovering. Most early research on sagebrush control was directed toward eradication to increase herbaceous forage for livestock production, rather than sagebrush thinning to improve shrub vigor and understory production for wildlife habitat and community diversity. Mechanical treatments have the ability to retain shrub and herbaceous components, while improving diversity within degraded sagebrush communities. This study evaluated the effects of 6 mechanical treatments and revegetation of a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) community in northern Utah that were treated in the fall of 2001 and spring of 2002 (aerator only). Disking and imprinting killed 98% of the sagebrush and significantly (p < 0.05) lowered cover and density of sagebrush more than any other treatment. Disking and imprinting was the only mechanical treatment to reduce cover and density of residual understory species, but also to successfully establish seeded grasses. One-way Ely chaining, 1-way and 2-way pipe harrowing, and aerating in the fall and spring reduced sagebrush cover from greater than 20% to less than 5% and reduced density by about half. Two years after mechanical treatment surviving sagebrush had greater leader and seed stalk growth than untreated sagebrush. Choice of a mechanical treatment to increase and diversify the perennial herbaceous component and retain the shrub component of sagebrush communities depends on the amount of residual herbaceous species, as well as economics. Chaining is potentially most economical for diversifying communities with a residual herbaceous perennial component. It is uncertain whether successful revegetation from disking and imprinting was a result of significant reduction in sagebrush, residual perennial herbaceous species, or both. Response of sagebrush communities with a very limited perennial herbaceous understory needs to be tested to determine how much and what kind of mechanical reduction in sagebrush is needed for successful revegetation.

Cattle grazing has been a historic use of rangelands in Utah since Pioneer settlement in the mid 1800's. Wright fishhook cactus is a small globose cactus endemic to an area of 280,000 ha in south-central Utah and was listed as endangered in October of 1979, by the U.S. Fish and Wildlife Service (USFWS). By 2010, concerns were expressed that soil compaction in proximity to the cactus posed a threat to this species, though there was no empirical data to support such concern. In order to assess the impact of cattle traffic on Wright fishhook cactus, we used an imprint device to simulate a cow track's impact. We applied a treatment of either zero, one, or four hoof imprints within 15 cm evenly of 146 cacti within the same population cluster on the same day. We monitored subsequent plant survival as well as reproductive success. Each cactus in the study was visited multiple times and all developed seed was collected. We found that cattle traffic of any amount had no effect on plant survival or seed production and therefore concluded that cattle traffic poses no threat to Wright fishhook cactus. The status of this cactus yields no justification for changing the historic land management use of cattle grazing on these rangelands. Seedbank abundance and location has not been examined for any species within the genus Sclerocactus. Over a one-day period, we took 500 soil samples from various locations near the cactus and potential nurse-plants. We found that approximately 1% of annual seed production makes it into the seedbank, a number in line with other species in the Cactaceae family. Seedbank densities were highest immediately adjacent to, and downslope from, parent plants. Understanding the dynamics of the seedbank of this species could lead to more informed management practices.

Master of Science / Department of Agronomy / Walter H. Fick / Patch-burn grazing is a relatively new concept in terms of rangeland management. While numerous benefits have been associated with this system, in the tallgrass prairie of Kansas, cattle production and sustainability of rangeland are critical. In 2006, 253 ha at the KSU Bressner Range Research Unit in Woodson County, Kansas were subjected to spring patch-burn grazing (using one-third portions) and traditional full-burn grazing. Each treatment within the split-block design was replicated four times for 3 years. The objectives were to evaluate whether livestock performance would be compromised under this grazing system, to monitor the health of the rangeland, and to observe the usefulness of this tool as a potential control of the invasive plant sericea lespedeza [Lespedeza cuneata (Dumont) G. Don]. In regards to cattle performance, burn treatments had no significant difference in average daily gain (p≥0.10) in any of the 3 years. On average, cattle utilized 61% of the current year’s forage production in patch-burned portions, which was higher (p≤0.10) than that of unburned (30%) and full-burn (41%) portions. Results of the botanical composition show forb and woody plant composition did not differ between treatments, however differences (p≤0.10) were present in grass composition. Total annual grasses increased 19.1 percentage units under patch-burn and 2.1 units under full-burn, while total perennial grasses decreased 18.4 and 1.1 units, respectively. When evaluated by treatment area (one-third portion), results indicated that the 3-year cycle did allow enough time for recovery. At 2 years after treatment (2-YAT), no significant difference in composition(p≥0.10) was present between initial patch-burn portions and the full-burn pastures. Finally, in only 1 year of the study did cattle statistically consume a greater percentage of sericea lespedeza plants (p≤0.10) in the patch-burned portions (92%) than in full-burned pastures (35%). Biomass utilization did not differ (p≥0.10) between burn treatments. Surprisingly, there was a trend for the number of plants in the sampled areas of the patch-burn portions to decrease throughout the cycle. However, at the conclusion of the 3-year cycle, sericea densities did not differ(p≥0.10) between treatments. Patch-burn grazing shows promise as a potential management tool for Kansas land managers.

Environmental issues are often complex with many different constituents operating according to a broad range of communication techniques. In order to foster negotiations, different perspectives need to be articulated in lucid ways sensitive to various viewpoints and circumstances. In my thesis I investigate how certain approaches to environmental discourse effect dialogue and negotiation. My first two chapters focus on environmental problems surrounding rangeland ecology along the U.S./Mexico border; whereas the last two chapters explore more theoretical conflicts concerning the philosophy of nature. Throughout the thesis I show the significance of nonhumans (prairie dogs, cattle, biological assessment sheets, environmental laws, etc.) in the human community. Only by considering the roles of nonhumans do we broaden and enrich the conversation between ourselves concerning environmental issues.