During the Paleoproterozoic Era (ca. 2.5 Ga to 1.6 Ga), Earth underwent dramatic changes to its tectonic and atmospheric parameters. These changes included: the formation and breakup of the supercontinent Nuna (Columbia) and the gradual rise in atmospheric oxygen levels. The gradual rise in atmospheric oxygen, referred to as the Great Oxidation Event (GOE), altered the behaviour of silicate mineral weathering, and permitted the formation of new types of economic uranium deposits. Beaverlodge Lake, Northwest Territories (NT), allows for the study of a weathering profile and uranium mineralization post GOE. At Beaverlodge Lake, NT, a regolith is preserved in a rhyodacitic porphyry of the ca. 1.93 Ga Hottah plutonic complex, which is unconformably overlain by the ca. 1.9 Ga quartz arenite of the Conjuror Bay Formation. Coincident with the unconformity is a past-producing uranium deposit (called the Tatie U deposit), which was mined out in the 1930s. Other uranium showings have been discovered at Beaverlodge Lake including the Bee showing. The initial purpose of this project was to examine the regolith through field, petrography, electron microprobe analysis (EMPA), whole-rock geochemistry, and mass balance calculations. The weathering profile shows an increase in Al2O3, Fe2O3T, K2O, P2O5, Ba, and Rb, a loss in SiO2, Na2O, MgO, and Sr, and constant and low abundance of CaO. Titanium remains constant in the weathering profile. Rare earth element (REE) analysis reveals remobilization of light REE (LREE) on a micrometer scale, but no cerium anomaly is preserved in the weathering profile. The weathering profile displays characteristics similar to other post GOE paleoweathering profiles developed on felsic parental material. The timing of uranium mineralization at Tatie and Bee was constrained by in-situ U-Pb uraninite dating by Secondary Ion Mass Spectrometer (SIMS), which yielded two variably discordant ages of 1370.2 ± 7.9 Ma and 407 ± 21 Ma. In addition, REE contents of uraninite were determined by in-situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Results revealed two types of uraninite mineralization are preserved at Beaverlodge Lake and they consist of synmetamorphic at Bee and basement-hosted unconformity-type at Tatie similar to those in the Athabasca Basin. The ca. 1370 Ma uraninite (Tatie) is characterized by an asymmetric bell-shaped REE pattern centered on Tb to Er where LREEs are depleted compared to heavy REEs (HREE). The ca. 407 Ma uraninite at Bee has low La concentrations and a flat to slightly negative REE pattern. The Mesoproterozoic age is similar to a Pb loss age of ca. 1400 Ma found in the Athabasca Basin. The younger Devonian age may be related to meteoric fluids cycling and uranium remobilization during the Phanerozoic.

Understanding the use of habitat by large carnivores in the presence of ever increasing anthropogenic disturbance is crucial to managing threatened species. In the foothills of the Rocky Mountains in west-central Alberta, Canada the grizzly bear (Ursus arctos) faces such disturbance, and is especially susceptible due to their low fecundity and large home ranges. Grizzly bear mortality increases with proximity to human disturbance, leading to the conclusion that anthropogenic forest disturbance is incompatible with successful grizzly bear habitat The purpose of this research is to evaluate grizzly bear habitat use as it relates to forest disturbance. The general approach was to quantify grizzly bear habitat use and compare to an expectation of use calculated through conditional randomization. The research involved two distinct analyses. First, grizzly bear use of natural edges (transitions between land cover classes) and anthropogenic landscape edges (roads, pipelines, and forest harvests) was quantified and compared between seasons and sex. Females were found to use anthropogenic edges more than natural edges, whereas males used natural edges more. Despite the increased mortality threat arising from increased human access around anthropogenic disturbances, female grizzly bears are using anthropogenic edges more than natural edges, meaning anthropogenic edges may not be incompatible with successful grizzly bear populations. Knowing that female grizzly bears use anthropogenic edges more allows managers to limit access to areas with specific edges desirable to female bears. While creating more disturbances is not the solution to managing for better grizzly bear habitat, limiting human access to areas of beneficial edge could decrease mortality risk. Knowing that grizzly bears use edges, the second analysis quantified use of forest disturbances of varying ages, and determined what disturbance characteristics drive grizzly bear selection of forest disturbances. A 40-year forest disturbance dataset was generated through image differencing of the tasselled cap angle transformation of Landsat imagery (MSS, TM, ETM+). Disturbances were grouped into decades, and compared. Disturbances were labelled as selected or not selected through a randomization process, and selected disturbances were compared to not-selected disturbances using four landscape metrics: disturbance size, disturbance elevation, average tasselled cap transformation greenness, and distance from disturbance to nearest human settlement along a road network. Results indicate that bears select for larger disturbances in all seasons. Females select for disturbances with low remotely-sensed greenness in all seasons, where males select for disturbances with low remotely-sensed greenness in the spring and fall, but high remotely-sensed greenness in the summer. Females select for disturbances at a consistent elevation, whereas males show seasonal variation. Both sexes avoid the most recent disturbances from the 2000s. Females show greater selection of disturbances in the summer and fall, whereas males select disturbances in the fall the least. Knowing that bears select for large disturbances, and females select disturbances at a consistent elevation, forest managers can limit human access to these areas in order to limit human and bear interactions and reduce mortality risk. / Graduate

Increasing levels of conflict between brown bears and rural people have been reported for Yusufeli (Artvin, Turkey). This study aimed to document the conflict, understand human attitudes and responses, determine local habitat use and daily activity patterns of bears, and evaluate available damage prevention techniques. The study was conducted within landscapes at different scales, ranging from a core area defined by a large valley system to the whole of Artvin Province. Data on close encounters, injuries and damages caused were collected through government records, published literature and open-ended interviews with the locals. Bear presence and activity were monitored through various techniques, including the capture and radio-collaring of one individual. Population density was found to range between 11-27 adult bears/100 km2. Bear activity increased during hyperphagia, with many daytime observations. Interviews (n=67) showed that almost all (95%) locals believed that bears have become more of a problem lately. Only 6% supported full protection while 38% conditionally accepted it. On more than two-thirds of close encounters, the bear and person(s) involved departed without any harm. Rare bear attacks on humans, usually provoked, sometimes caused non-fatal injuries. Several bears were found to be shot and killed within the study area in 2002-2005. Damages were mostly in late summer on field crops and orchards, and in spring on beehives. Precautions taken by villagers differed in effectiveness against bears. Bears caused a minimum of US$21,500 worth damages annually at Yusufeli County. Implementation of modern techniques of exclusion and scaring would reduce human-bear conflict in the region.

Thesis (Ph.D.). / Written for the Dept. of Geography. Title from title page of PDF (viewed 2008/05/09). Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1997. / Vita. Includes bibliographical references (p. 99-105).

No description available.

Large carnivores in the United States are making a comeback following decades of systematic eradication. Black bears (Ursus americanus), cougars (Puma concolor), and gray wolves (Canis lupus) may recolonize the midwestern United States provided there is substantial suitable habitat. However, viability of large carnivore populations is as dependent on social acceptance as on biological factors. I developed individual and combined models of suitable habitat for black bears, cougars, and wolves in 18 midwestern states using geospatial data, expert-opinion surveys, and multi-criteria evaluation. I also assessed attitudes and perceptions of Illinois citizens about large carnivores via a mail-in survey. Experts indicated land cover was the most important variable for predicting potential habitat for black bears and cougars; human density was the most influential variable for wolves. Large, contiguous areas of suitable habitat comprised 35%, 21%, and 13% of the study region for wolves, bears, and cougars, respectively. About 12% of the region was considered suitable for all 3 species. Arkansas, Minnesota, Texas, and Wisconsin had the highest proportions (>40%) of suitable habitat for black bears; Arkansas, Michigan, Missouri, Texas, and Wisconsin had the most (≥20%) suitable cougar habitat; and only 4 states in the study region contained <29% suitable wolf habitat. Models were validated by comparing suitability values of independent sets of known carnivore locations to those of random locations, and models appeared accurate. More than 70% of survey respondents (n = 791) were male and their average age was 60; 55% were hunters. Approximately 40% were unsure about the population status of large carnivores in Illinois; of the remaining respondents, most (ranging from 20% for black bears to 41% for cougars) believed the presence of all 3 species had increased over the past decade. More residents supported protection (43%) and increasing numbers of large carnivores (39%) than opposed them (26%), although support for black bears was slightly higher than for cougars and wolves. Rural residents and livestock owners were the most likely to want carnivore numbers to decrease and least likely to support their protection; higher levels of education corresponded to positive attitudes toward large carnivores. My research provides the foundation for well-informed management plans, policy decisions, and educational initiatives for large carnivores in midwestern states where large carnivore populations have been absent for decades.

As an ecological disturbance agent, wildfire is highly responsive to spatial and temporal variables. At the landscape scale, the spatiotemporal characteristics of fire are influenced by climate, which is non-stable and subject to oscillations, and by weather, which affects the intensity of burning and the severity of fire effects over short time periods. Like wildfire, vegetation communities and fuels are similarly influenced and modified by climate and weather, which configure not only the type of burning possible at any given time, but also the fire effects produced by burning. Furthermore, ignition sources, both natural and anthropogenic, vary over space and time, whether they are from natural ignitions in response to weather and climate factors, and anthropogenic ignitions, which are much less constrained. Within a given physiographic setting, the spatiotemporal conditions of wildfire can be understood as fire regimes, which can be expressed in terms of typical fire frequency, season of burning, ignition source, duration, fire size, patch size, fire rotation, and return interval. As a dynamic assemblage, vegetation communities, combustible fuels, ignition sources, and fire regimes are arrayed over topographic features at landscape scales. Humans are able to affect various and multiple components of this dynamic assemblage. Humans have the most direct control over ignitions, both in terms of adding ignitions to the weather and climate-modulated background of natural ignitions, or by suppressing anthropogenic ignitions and suppressing fires that do start. Humans can also manipulate vegetation communities and fuel complexes, either promoting or diminishing the chance for fires to burn and spread. Humans have far less control over weather and climate, although the enhanced greenhouse effect is beginning to be expressed in terms of climate change and unusually extreme weather, including weather variables that drive fire growth and spread, including low humidity, high temperatures, and increased winds. The objectives of this dissertation were to: (1) investigate the influences of several waves of human occupation on temporal fire regime characteristics in the Chiricahua Mountains across major topographic settings and forest types, and to detect cessation of widespread, low-intensity wildfire in specific locations; (2) account for the mechanisms by which the U.S. state has managed fires by managing anthropogenic ignitions, which has contributed to long-term deviation in formerly frequent fire regimes; (3) examine the effects from the return of large and severe wildfire following decades of fire prevention and suppression by categorizing the ecological trajectories of montane forests following mixed-severity reburning; and (4) understand how the post-disturbance recovery of burned areas is influenced by the response of shrub species to variations in fire severity, with the post-fire regeneration strategies of shrub species driving differences in patch structure and total cover. Major findings and contributions of this research include identifying distinct anthropogenic influences on temporal fire regime characteristics in several forest types in an Arizona Sky Island, including shortened fire frequencies during times of conflict between Apaches and colonizing forces. We found that periods of conflict with Spanish and later American militaries exerted an influence on fire frequencies, with higher-elevation forests burning more frequently than pre-Apache periods or during episodes of peacetime. We also find that single-tree fires, which are likeliest to express anthropogenic ignitions, do not significantly correspond to multi-year patterns in climate (Appendix A). We found that the U.S. state used Smokey Bear and other wildfire prevention media as a pyropolitical instrument aimed at simultaneously managing people, landscapes, and flammable forests, in the process binding proper fire behavior to notions of citizenship, territory, and ecology. The wildfire prevention campaign, with Smokey Bear as its avatar, was successful because it remained flexible in the face of social, economic, and environmental change within the United States, but the ultimate result of this success is an environmental feedback loop by which fire prevention and suppression produce the need for ever-greater state response (Appendix B). We found that mixed-severity reburning has differential effects on various structural and demographic components of vegetation communities, with trees, shrubs, and regeneration responding differently according to plant functional traits. Although the effects of recent disturbance tend to overwrite prior disturbance, mixed severity fire produces different response in plant communities than single events. Repeated high and moderate severity fire suppress tree regeneration and shift the community to shrub dominance, with recovery in pine-oak vegetation types dominated by resprouting species and by resprouting species in mixed conifer. Unburned areas contain different vegetation communities, with pine-oak forests increasing the proportions of fire-intolerant species typical of mixed conifer, as well as oaks and other potentially shrubby species growing as trees (Appendix C). Finally, we found that the proportion of the landscape dominated by shrub cover and the structure of shrub patches is influenced strongly by fire severity, with high severity burns producing the largest shrub patches as well greater area:stem ratios. Unburned areas have the lowest amount of shrub cover, and shrub patches tend to be single-stemmed, indicating that sufficiently long fire-free periods can produce monopodial trees that would otherwise grow in shrub form. The effects of antecedent disturbance can be seen in shrub patch structure, suggesting that the organizing effects of fire can persist for decades (Appendix D). Together, this body of work underscores the means by which human activities interact with the natural world to produce historic fire regimes, and the ecological communities that arise following long periods of fire regime disruption.

A study of the mineralogy of a suite of specimens, collected by Dr.C.Riley from the Bonanza silver deposit, has been made. Particular attention is paid to the silver mineralization and the origin of the dendritic structure. A brief examination of the wall rock alteration is included. The mineralogy of the deposit is relatively simple, consisting of the following metallic minerals in their order of abundance: native silver, magnetite, hematite, tetrahedrite, argentite, chalcopyrite, and an unknown mineral. Pitchblende and cobalt-nickel minerals are absent. Magnetite and hematite are restricted to the wall rock and are not associated with the other metallic minerals. The magnetite is believed to be of pyrometasomatic origin and related to a granodiorite intrusion, while the other metallic and gangue minerals are considered to be of hydrothermal origin. The gangue minerals consist of quartz, sericite, and carbonate. Ninety-five percent of the native silver occurs as dendrites and the other five percent as replacement of tetrahedrite and chalcopyrite. Core replacement by the silver is well developed. The dendritic structure of the silver is inherited from quartz through replacement. In a quartz gangue this structure appears to be controlled by rows of specially oriented, doubly terminated, quartz prisms, while in a sericitic gangue the euhedral quartz grains, arranged in a rude dendritic pattern, are the controlling factor. The mineral deposits of the Echo Bay area are compared with similar deposits throughout the world. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A grizzly bear habitat classification was developed by modifying and expanding the climax-based Biogeoclimatic Ecosystem Classification (BEC) to accommodate serai vegetation. Locations of radio-collared bears were assigned to a large number (N=110) of structurally and floristically unique habitats. An interpretive classification of 14 Bear Habitat Units (BHUs) was derived from the taxa of the BEC system; units were amalgamated on the basis of grizzly bear habitat value and similarity of response to forest management practices. Fifteen climax forest, three subalpine, three wetland, and three avalanche chute units were identified and described in the lower Kimsquit River. Two adult female grizzly bears (numbers 08 and 25) were monitored for 1238 and 1196 days, respectively, from April 1982 to October 1985 and had multi-annual minimum convex polygon (MCP) home ranges of 85 km² (N=23 6), and 60 km² (N=241). River floodplain BHUs were used most heavily by bears 08 and 25 during their active seasons (65% of locations and 51% of time for bear 08; 75% of locations and 63% of time for bear 25) followed by avalanche chutes and sidehill climax and old-growth forests. Rank testing between quality/quantity indices (food plant nutrient content, biomass, berry abundance) and grizzly bear use indicated that movements were generally correlated with food availability at the higher, or BHU, level of the classification (rs=0.61 and 0.83, p<.05 for bears 08 and 25, respectively). Salmon (Oncorhynchus spp.) and insects were the only common non-plant items in a diet of over 3 0 species, although food habits differed between bears. It is concluded that, although food plays a critical role in habitat selection of coastal grizzly bears, a relatively rich environment precludes the need for individuals to forage optimally at a micro-habitat level. Except for the early spring and late fall, food can be found in a number of units that collectively meet life requisites. These analyses were used in combination with other use and habitat quality information to develop seasonal habitat values. Assigned values allowed predictions about the effects of forest management practices on habitat capability. / Forestry, Faculty of / Graduate