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  • Thumbnail for An analysis of alternatives for water distribution between municipal and agricultural users of Colorado River water
    An analysis of alternatives for water distribution between municipal and agricultural users of Colorado River water by Hardin, Sally

    The Colorado River is often referred to as the “lifeblood” of the American Southwest, as it sustains rapidly growing cities, feeds millions of agricultural acres, and forms some of the world’s most incredible natural features. The Colorado River is also one of the most highly dammed, diverted, and otherwise regulated rivers in the world. In the last few decades, the demands on the flows of this river have begun to exceed its supply, which is threatened not merely by over-allocation but also by drought and climatic uncertainties. The river’s dwindling supplies are no longer enough to support the Southwest’s rapid population growth in municipal areas while simultaneously answering to the demands of the more senior water rights holders, the agriculturalists. This thesis is an exploration of the current contentions between agricultural and municipal users of Colorado River water, with a focus on the alternatives available to address these ongoing issues. Of many options, including increased infrastructure and various conservation measures, water banking has been identified as the strategy most socially, economically, and environmentally qualified to address these pervasive imbalances in water supply and demand of the Colorado River.

  • Thumbnail for Assessing the impact of mining on dissolved trace metal concentrations in surface water of the central Peruvian Andes
    Assessing the impact of mining on dissolved trace metal concentrations in surface water of the central Peruvian Andes by Boyes, Daniel Field

    Mining activity in the central Andes poses a serious threat to human health due to the release of heavy metals in surface water. Long-term exposure to elevated levels of heavy metals, including lead, cadmium, copper, and arsenic, are known to have severe detrimental effects on human health. Mining exposes large quantities of metal bearing rock, which oxidize in the presence of oxygen and water, releasing heavy metal ions into surface water. Surface water contamination in Perú as a result of mining operations is of particular concern due to a lack of regulation of large-scale mines. In order to determine the impact of mining on surface water heavy metal concentrations, water samples were collected in nine streams throughout our three watersheds in the central Peruvian Andes. Results showed [Mn] and [As] exceeded the EPA maximum allowable limits at 55% and 14% of sites, respectively. The [Mn] was significantly higher in impacted streams than non-impacted streams. The [As] was elevated in some non-impacted streams and below the EPA maximum allowable drinking water levels in some mine-impacted streams. While Mn appeared to be impacted by mining effluent, As seemed to have a natural groundwater source. This study suggests Mn and As pose a serious threat to human health in the regions of study. The [Zn], [Cu], and [Pb] seldom exceeded the EPA maximum allowable drinking water limit (5%, 3% and 5% of sites, respectively). Dry season [Zn], [Cu], and [Pb] do not appear to pose a serious threat to human health in these regions. Further research is needed to understand seasonal variations in both dissolved and particulate trace metal concentrations. Implementing a community-based water quality monitoring program in study regions may also afford local residents more autonomy and local knowledge regarding the impact of mining on heavy metal concentrations in their surface water.

  • Thumbnail for Carbon fluxes in the SiB3 model : evaluating the response of the terrestrial biosphere to significant drought
    Carbon fluxes in the SiB3 model : evaluating the response of the terrestrial biosphere to significant drought by Shiach, Ian Michael

    This study investigated the behavior of the terrestrial biosphere during times of significant drought, particularly in regard to carbon fluxes. The Simple Biosphere Model Version 3 (SiB3) was used to facilitate an investigation of ecosystem drought response. The Standardized Precipitation Index (SPI) was evaluated from 1983 to 2006 in order to produce historical drought maps, which were used to facilitate a subjective analysis of drought behavior and to identify geographic point locations in the SiB3 model for further temporal study. Standardized maps were produced for modeled physiological variables (gross primary productivity, respiration, net ecosystem exchange, and soil water stress factor) over time in order to determine general regional drought response patterns. Physiological response variable data for particular spatial locations was then analyzed over time during drought years for anecdotal comparison with observational study data. While the SPI, which standardizes precipitation, was predicted to be an indicator of ecosystem drought response, this did not appear to be the case. The droughts modeled in the SiB3 model, which included the droughts in the United States Southwest and Australia in 2002 and in Europe in 2003, were found to respond heterogeneously in terms of carbon fluxes to similar droughts. The U.S. Southwest and Australia appeared to respond to drought in a manner consistent with anecdotal evidence with regard to perturbations in gross primary productivity (GPP), ecosystem respiration, and net ecosystem exchange (NEE), while Europe appeared to respond in a manner dissimilar to published descriptions of that drought. The behavior of the soil water stress factor in Australia and Europe seemed to be incorrect as well. Precipitation input data, derived from a reanalysis dataset from the National Centers for Environmental Prediction (NCEP), the treatment by the SiB3 model of the soil water stress factor, and the possible heterogeneous vegetative response to seasonality between regions were identified as potential causes of these disparities.

  • Thumbnail for Coccinellid predation on Aphis helianthi : diffusive instability and pattern formation in predator-prey systems
    Coccinellid predation on Aphis helianthi : diffusive instability and pattern formation in predator-prey systems by Kidney, Daniel

    Spatial context in predator-prey systems has proven to have important dynamical consequences. Instabilities and spatial pattern formation driven by diffusion (Turing pattern formation) have been extensively observed and theorized on, but empirical examples of Turing pattern formation in ecological systems are few. In this study we construct and analyze a reaction-diffusion equation model of the aphid species Aphis helianthi under predation by two species of ladybugs: Coccinella septempunctata and Hippodamia convergens. The structure and parametrization of the model is entirely field derived and in analysis of model output it is compared extensively to field observations. This system fits the well known framework for diffusive instability and pattern formation: an activator-inhibitor system in which the inhibitor (predator) diffuses substantially faster than the activator (prey). Theory predicts that under these conditions the inhibitor will fail to strike a normal equilibrium with the activator; rather diffusing away from activator outbreaks too quickly to contain them, subsequently over-inhibiting the surrounding lower densities of activator (undermatching). This usually results in a patchy, bimodal distribution of prey resulting from cubic density dependence driven by undermatching. Aphid population distribution in the field is clearly bimodal and patchy. We looked for several indications of diffusive instability in field data; bimodality, cubic density dependence, and undermatching were all found. The focus of this paper is on a mathematical model we developed from field data to gain insight into the workings of the system. I found the model matched field data very well and corroborated the hypothesized functioning of a diffusive instability. I explored the role of self attraction (aggregation) among ladybugs. Aggregation is not considered a hallmark of diffusive instability but in this case it created some preytaxis in ladybugs (allowing aphids to act as an activator). Preytaxis by aggregation is slow though, which allowed some aphid populations to avoid detection long enough to reach the high attractor of cubic density dependence. Finally I considered the nature of space in our system. Although our model is constructed in Euclidean space it demonstrates some features of a network. Network structured systems manifest Turing patterns primarily as bimodal distributions. They also facilitate understanding of ladybug behavior and may increase efficiency of computer model execution.

  • Thumbnail for Examining the response of soil nutrients to mastication treatments in Colorado's Front Range ponderosa pine forests
  • Thumbnail for Managing the human-wildlife interface in the Lake Manyara National Park region of Tanzania
    Managing the human-wildlife interface in the Lake Manyara National Park region of Tanzania by Ritland, Karen Elizabeth

    Managing the human wildlife interface in Northern Tanzania has become a challenge as human settlements are expanding into zones that have been designated to serve as wildlife corridors and habitats for the region’s wildlife, whose natural habitats are dwindling. This region’s dynamic history has lead to a current population of wildlife that is not representative of its historically lower levels. These high wildlife populations and expanding human populations have forced an increased demand on limited resources. This project studies the human-wildlife interface in Mto wa Mbu, the ward that is a part of the wildlife corridor bordering the northern tip of Lake Manyara National Park. Lake Manyara National Park is a part of the Tarangire-Manyara ecosystem in Northern Tanzania and is an example of a protected area that is vital to mammal populations. It is critical for wildlife to have access to substantial protected regions and migration corridors in order to maintain stable and healthy populations. Both the buffer zones of each protected area and the corridors of protected areas are crucial to the integrity of the biodiversity in the region. This region is also essential to human livelihoods due to its fertile soil as well as proximity to a major road for trade and travel. This project assesses the conflicting goals of the human stakeholders as well needs of wildlife and uses of the area through surveys and geographical analysis. Much of the data and conclusions that were reached in this study parallel the work by Lisa Naughton-Treves, Adrian Treves, and M. Wallgren: all major authors in the field of human wildlife conflict and human wildlife conflict mitigation. In this study, there is direct competition between wildlife of the park and livestock, which aligns with the results of Wallgren et al. (2008). Primates are the most willing of large mammals to go into zones of high impact, but the largest animals are reported by locals to do the most damage, paralleling the conclusions Naughton-Treves et al. (2007). Pastoralists and agriculturalists view the human wildlife interface in different ways due to their different lifestyles and practices, however both believe that short term and immediate solutions are the first step towards solving human wildlife conflict, also found by Treves et al. (2006). This project illustrates the complexity of the interface between wildlife and various human stakeholders and how essential it is to understand the various points of view for planning and conflict mitigation. The goal of this project is to understand this interface thoroughly enough to suggest potential solutions for mitigating the conflicts caused by limited critical resources.

  • Thumbnail for Methods for distributing appropriate sustainable energy technology in developing nations : a comparative analysis
    Methods for distributing appropriate sustainable energy technology in developing nations : a comparative analysis by Weiss, Tim McDow

    This thesis seeks to determine the most effective means of distributing appropriate sustainable energy technology to individuals that have no access to energy services. There are approximately 1.4 billion people around the world that are ‘energy-impoverished.’ ASETs are small-scale clean energy technologies that fill the immediate energy needs of these individuals. There are, however, seven fundamental barriers limiting the dissemination of these technologies. These barriers result from the microeconomic and sociological conditions of these populations. This thesis analyzes 12 unique distribution models from companies, nonprofit organizations, and universities, and shows how each model performs relative to these barriers. Following this analysis, I propose the most effective means of distribution ASET to energy-impoverished populations. Title on PDF: Methods for distributing appropriate sustainable energy technologies in developing nations : a comparative analysis

  • Thumbnail for Micrometeorological feedbacks at treeline : are the trees at the leading edge responsible for increased local temperatures?
    Micrometeorological feedbacks at treeline : are the trees at the leading edge responsible for increased local temperatures? by Anderson, Joshua

    Mounting research on alpine treeline advance suggests that global and regional temperatures do not completely explain changes in treeline elevation and distribution. Rather, micrometeorological feedbacks may play an important role in treeline advance by increasing local temperatures. On Pikes Peak, the comparison of a transition zone microclimate at treeline to an adjacent rockslide microclimate at the same elevation showed that the transition zone microclimate heats more quickly and to a higher maximum temperature than the rockslide. Observed differential heating is particularly prevalent in the near-surface soil temperature, an important location for seedling establishment and growth. During the June observation period, daytime temperature maximums in the transition zone soil were 7C warmer on average than in the rockslide. Local warming at the treeline’s leading edge suggests that the presence of trees increases soil heat flux through a variety of mechanisms. Canopy warming, varying soil moisture, and sheltering are each considered independently as possible causes of differential heating. First, I investigate the possibility that heat captured in the canopy warms the transition zone microclimate. However, this theory is unsupported by data showing daytime canopy transpiration and cooling, and infrared photos revealing that the canopy is significantly cooler than the rockslide during the day. Second, I explore whether higher soil moisture in the transition zone is responsible for differential heating via increased conduction. However, soil moistures are actually lower in the treeline microclimate, suggesting that low soil moisture may be a characteristic of warming rather than its cause. Third, I look at the idea that trees shelter the microclimate from wind and hence reduce heat loss. While sheltering effects show some relationship with differential heating, there is no consistent correlation between high wind and differential heating. While this analysis does not offer a clear cause of differential warming, a better understanding of the treeline system is gained, and suggestions are made for how and where to look for warming feedbacks in the future. Thus, while results are inconclusive, warming feedbacks at treeline that increase soil temperatures during the critical growing season should be further considered as factors in treeline advance.

  • Thumbnail for Relict tallgrass prairie of the Upper Black Squirrel Creek drainage, El Paso County, Colorado : change since the 1940's
    Relict tallgrass prairie of the Upper Black Squirrel Creek drainage, El Paso County, Colorado : change since the 1940's by Tsocanos, Sebastian A. E.

    In the mid 1940s remnant tallgrass prairie near Colorado Springs was recognized in vegetation studies on the plains. Tallgrass prairie is unusual in the arid Great Plains, and is of significant conservation value, particularly given the past and present pressures of urban expansion, intense grazing, and water development. Our study examined the question of whether this community type still exists in the region, if the extent of the community type has changed since then, and whether the species composition has changed. We found that while true tallgrass prairie vegetation is no longer dominant at many of the sites used in the original studies, patches of true tallgrass prairie still occur in the area. The extent of tallgrass prairie in the vicinity has clearly declined over the past 70 years. The vegetation of remaining patches is composed of very similar species to those originally documented. We found that the dominant vegetation is still characteristic of true tallgrass prairie. Among the important grasses were prairie dropseed, indian grass, little bluestem), and big bluestem. Important widespread forbs indicative of true tallgrass prairie included american licorice (Glycyrrhiza lepidota), stiff goldenrod (Oligoneuron rigidum), white heath aster (Symphyotrichum ericoides), and purple prairie clover (Dalea purpurea) among many others. We determined that overall precipitation and temperature in the locality has not changed dramatically since the 1940’s. The alluvial aquifer across much of the area is evidently little changed, but hydrology on a site-by-site basis is poorly understood. While the continued existence of some true tallgrass prairie communities here is reassuring, their diminished extent is cause for concern, especially given increasing pressure from urban expansion, livestock grazing, invasive species, and water development. The uncertain status of future temperature and precipitation, as well as the maintenance of critical surface and subsurface hydrologic regimes is also of concern.

  • Thumbnail for Spatial patterns and typology changes of an advancing treeline on Pikes Peak, CO
    Spatial patterns and typology changes of an advancing treeline on Pikes Peak, CO by Elwood, Kelsey Kjestine

    Alpine treeline is a valuable indicator of climate change because of its sensitivity to temperature. On Pikes Peak (Southern Rocky Mountains, Colorado), tree density and elevation in the forest-tundra ecotone has increased in the last century, corresponding with a 2°C increase in regional growing-season temperature. The purpose of this study was to provide a detailed analysis of the process of treeline advancement. Spatial clustering within age classes and elevational bands was used to identify harsh environments and track the upper climatic boundary of tree establishment. Overall, clustering (Ripley’s K, p < 0.01, based on boot-strapping) was more prominent at lower elevations and for older cohorts, indicating the upward migration of the climatic boundary. However, the climatic boundary may be advancing more quickly than treeline as the moving edge changed from a clustered to a randomly dispersed distribution over time: from 1868-1940 the moving edge was clearly clustered, from 1941-1976 it showed mixed results, and from 1977-2010 it displayed a random spatial pattern. Treeline advancement also demonstrated a reach-and-fill pattern, with sudden advancement of treeline, followed by a few decades of infill at lower elevations. The reach-and-fill pattern repeated three times in the last 120 years, with exponential increases in tree density, especially in the last 40 years. The recent explosion of growth and the quickly advancing climatic boundary match temporally with a shift from an abrupt to a diffuse edge typology. To my knowledge, this is the first study that examines in detail the process of changing treeline typology of an advancing treeline.

  • Thumbnail for THE ANTS GO MARCHING A Study of Formicidae Movement Between and Within Yucca Plants
    THE ANTS GO MARCHING A Study of Formicidae Movement Between and Within Yucca Plants by O'Brien, Rebecca

    Ants and aphids are involved in a mutualistic relationship whereby the aphids produce a sugary waste product which the ants then harvest as food. We were interested in exploring the dynamics of this relationship, and specifically how ant movement was influenced by the distribution of aphids and the distribution of members of their own species. For this study, we focused on the interactions between the two insects on the flowering racemes of yucca glauca in the Rocky Mountains region. Ant populations showed patterns of both single and double attractors, with the number of attractors likely driven by aphid number (we did not have sufficient data to confirm this statistically). Although aphids proved to be a factor in determining the number of attractors, they were not significant in determining the number of ants on a plant or the number of ants entering or exiting that plant. Playing a much larger role in determining arrivals and departures was the number of focal ants, with increased numbers of focal ants lead to increased numbers of arrivals and departures from the plant. The number of ants on the nearest neighbor also impacted ant movement, but it influenced only arrival rates and not departure rates. The degree to which neighboring plants showed similar dynamics varied greatly between plants, but there were certain plants which correlated to a particularly great degree with their neighbors. These plants tended to be those with the most aphids.


    Aldo Leopold’s land ethic takes root in both metaphor and empathy. The use of metaphor and empathy in cultivating the land ethic has profound implications for our relations with the environment, both personal and political. I hope to show that these implications are positive and help us to realize the ethical extension vital to ensuring human harmony with nature. In pursuit of this, I first provide a deeper look into metaphor, empathy, alterity, and their overlap. I then put these ideas into the context of Leopold’s land ethic as described in A Sand County Almanac. Then I dissect the philosophical implications of metaphor and empathy in an environmental ethic. Finally, I suggest representation as a pragmatic instantiation of the ethic prescribed by metaphor and empathy. At the end of all, I think, is a compelling case made for the vital integration of more subjective modes of inquiry into the realm of ethics.

  • Thumbnail for The History and Future Prospects of Colorado Conservation Easements
    The History and Future Prospects of Colorado Conservation Easements by Stewart, Allison A

    Understanding the history, purpose, requirements and benefits of conservation easements provides the necessary background for a grasp of what land trust organizations are currently doing, and can do, to ensure that perpetuity of conservation is upheld. An explanation of the dynamic reality and of the challenges of conservation easements that are posed by global climate change is emphasized. The intent is to comprehensively develop the concept of conservation easement, to illuminate the inherent benefits and challenges of permanent land conservation, and then identify a series of suggestions. Recognizing the ways in which conservation easements can be strengthened, mostly by changing the language, is a noble step toward improving the environment and hopefully will contribute to a stronger, healthier, and more sustainable environment for the future.

  • Thumbnail for The Law of the Colorado River: A Rigid Relic or a Flexible Foundation for the Future
    The Law of the Colorado River: A Rigid Relic or a Flexible Foundation for the Future by King, Warren Scott

    The Colorado River Compact was signed in 1922 in an attempt to regulate and manage the Colorado River and its tributaries. Since its implementation a series of laws and court opinions have come together to make up a comprehensive set of guidelines that now govern the river system. Despite the litany of legislation surrounding the Colorado River, 21st century issues such as regional climate change, population growth, increasing salinity and sediment levels, and minority interest water rights issues continue to plague those reliant on Colorado River water. The fundamental question now facing those charged with the responsibility of governing the River is, “Is the Law of the River adequate for dealing with these 21st century issues?”. I contend that the Law of the River, including its keystone piece of legislation, the 1922 Colorado River Compact, is neither inherently rigid or flexible. Instead the Law of the River is as flexible or as rigid as the contracting parties allow it to be.

  • Thumbnail for The Nitrogen Cycle in the Central Peruvian Andes
    The Nitrogen Cycle in the Central Peruvian Andes by Woolley, McKenzie L.

    The central Peruvian Andes is a region of varied geology and land use, likely affecting the surrounding watersheds in a variety of ways. Abnormally high levels of nitrite were measured in several streams in the Lake Junin and Cordillera Blanca regions. These high nitrite concentrations could be explained by several mechanisms: an artifact of sampling and storage, nutrient limitation, oxygen limitation, reduced reactions with hydroxyl radicals due to a reduction in Fenton oxidation reactions, pollution from Mn, As or NO2- or any combination of these factors. High nitrite levels are of concern because they can cause methemoglobinemia, a potentially fatal condition for infants or people with weak immune systems. Further studies are needed to better understand the cause behind the unusually high concentrations of nitrite in these streams, as well as the overall input of the cycle of nitrogen.