The Irwin River catchment, located in the central western region of Western Australia, has been the scene of significant geomorphological change over both historical and geological timescales. This thesis focuses on the most recent of these changes, the anthropogenic imprint, through the development of a catchment-scale understanding of system behaviour. Analysis and modelling of changes in the hydrological behaviour of the system indicates that while the Irwin River has displayed a natural susceptibility to large flood events, these have been exacerbated by the widespread clearing of native vegetation throughout the catchment. As a result, when such events do occur, the catchment response is now larger, more direct and has a greater ability to cause erosion. However, the nature and detail of sediment yield processes and stream channel response varies markedly throughout the system. A series of representative channel reaches, as defined by their planform characteristics, geometry and architecture, are presented to illustrate spatial changes in stream channel behaviour. A distinct variation in river morphotypes is seen both downstream throughout the system as well as across the tributary sub-catchments of the Irwin River, Lockier River and Green Brook. This inter and intra sub-catchment variation in stream channel response can be attributed to changes in the boundary conditions and coupling mechanisms in operation throughout the Irwin River system. The pronounced spatial variability in response to human disturbance and the changing nature of catchment-scale connectivity seen in the Irwin River system differs markedly to that reported elsewhere in the literature. Appreciation of the variability in form, behaviour and evolutionary history throughout the Irwin River catchment not only provides the foundation for effective management but also contributes to a wider understanding of fluvial system behaviour. Unlike the majority of existing literature, which tends to identify and measure channel changes in a single catchment where historical variation to the sediment and discharge regime is well known, this study demonstrates the role of boundary conditions in determining the response of the fluvial system to changing environmental controls.

xvii, 382 p. : ill. (some col.), maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The debate concerning the role of natural versus anthropogenic burning in shaping the prehistoric vegetation patterns of the Willamette Valley of Oregon and Washington remains highly contentious. To address this, pollen and high-resolution charcoal records obtained from lake sediments were analyzed to reconstruct the Holocene fire and vegetation history, in order to assess the relative influence of climate variability and anthropogenic activity on those histories. Two sites provided information on the last 11,000 years. At one site at the northern margin of the Willamette Valley, shifts in fire activity and vegetation compared closely with millennial- and centennial-time scale variations in climate, and there was no evidence that anthropogenic burning affected the natural fire-climate linkages prior to Euro-American arrival. In contrast, the fire and vegetation history at a site in the central Willamette Valley showed relatively little vegetation change in response to both millennial- and centennial-scale climate variability, but fire activity varied widely in both frequency and severity. A comparison of this paleoecological reconstruction with archaeological evidence suggests that anthropogenic burning near the site may have influenced middle- to late-Holocene fire regimes. The fire history of the last 1200 years was compared at five sites along a north-south transect through the Willamette Valley. Forested upland sites showed stronger fire-climate linkages and little human influence, whereas lowland sites located in former prairie and savanna showed temporal patterns in fire activity that suggest a significant human impact. A decline in fire activity at several sites in the last 600 years was attributed to the effects of a cooling climate as well as the decline of Native American populations. The impacts of Euro-American settlement on the records include dramatic shifts in vegetation assemblages and large fire events associated with land clearance. The results of this research contribute to our understanding of long-term vegetation dynamics and the role of fire, both natural- and human-ignited, in shaping ecosystems, as well as provide an historical context for evaluating recent shifts in plant communities in the Willamette Valley. / Advisers: Cathy Whitlock, Patrick J. Bartlein

This study elucidates the underlying relationships for the distribution of oak landcover on bedrock and soil orders in two counties in Texas and one in Oklahoma. ESRI's ArcGis and ArcMap was used to create surface maps for Denton and Coke Counties, Texas and Choctaw County, Oklahoma. Attribute tables generated in GIS were exported into a spreadsheet software program and frequency tables were created for every formation and soil order in the tri-county research area. The results were both a visual and numeric distribution of oaks in the transition area between the eastern hardwood forests and the Great Plains. Oak distributions are changing on this transition area of the South Central Plains. The sandy Woodbine and Antlers formations traditionally associated with the largest oak distribution are carrying oak coverage of approximately 31-32% in Choctaw and Denton Counties. The calcareous Blackland and Grand Prairies are traditionally associated with treeless grasslands, but are now carrying oak and other tree landcover up to 18.9%. Human intervention, including the establishment of artificial, political and social boundaries, urbanization, farming and fire control have altered the natural distribution of oaks and other landcover of this unique georegion.

I described recreational use in mountain sheep (Ovis canadensis mexicana) habitat in the Pusch Ridge Wilderness (PRW), Tucson, Arizona. I also examined human attitudes held by PRW recreationists and homeowners within 1 mile (1.6 km) of PRW boundary towards several mountain sheep management options. I used geographic information system modeling and social science survey methodology. Recreational use along two trails that traverse mountain sheep habitat was frequent (66 individuals/day use Pima Canyon trail, 26 individuals/day use Romero Canyon trail) and primarily limited to the lower 3 miles (4.8 km) of the trails. Compliance with existing dog leash regulations is low (41.8% on Pima Canyon trail, 62.8% on Romero Canyon trail). Recreationists and homeowners within 1 mile (1.6 km) of PRW support the elimination of dogs within PRW and support planned burns of PRW to improve mountain sheep habitat. Recreationists and homeowners also support closing all or parts of PRW to protect the long term viability (>100 years) of the sheep population. Homeowners within 1 mile (1.6 km) of PRW primarily enjoy passive recreational use of PRW (i.e, viewing the wilderness).

D.Litt.et Phil. (Sociology) / Please refer to full text to view abstract

A thesis submitted to the Faculty of Science, School of Geography and Environmental Studies, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, October, 2017. / The purpose of this study was to examine how subsistence farmers in the Delta State of Nigeria employed their asset portfolios i.e. human, financial, social, natural and physical capitals to build their adaptive capacity and resilience to climate variability and change. The study was also interested in understanding the extent to which climate change risk communication facilitated the protection and adaptation of subsistence farmer’s assets in the face of extreme weather warnings. Primary data were obtained using the Participatory Climate Change Adaptation Appraisal (PCCAA), which comprises both the asset vulnerability analytical and the asset-based adaptation operational frameworks. The systems thinking approach, together with the asset vulnerability analytical framework were also used as an operational vulnerability framework to highlight the myriad factors undermining the rural poor from maximising their asset portfolios during food production. Focus group discussions and semi-structured interviews facilitated the use of the PCCAA tools. Meteorological data reinforced subsistence farmer’s perception (62%) that there has been an increase in temperature within the last decade, which have adversely affected on groundnut production. The farmers (92%) also listed heavy rainfall event and flooding as a climatic variable that impede their ability to produce cassava throughout the year. This is because their farmlands, which are generally low-lying, are always inundated for approximately four months every year. Nonetheless, the farmers still engaged in cassava production annually by adopting a strategy indigenously referred to as elelame (follow-water-go). It is important to mention that in spite of the rapidly changing climate, the subsistence farmers did not rely on Seasonal Climate Forecast (SCF) in order to determine the appropriate time to grow their food. Instead, they relied on their Indigenous Knowledge Systems (IKS) not limited to cloud observations, croaking of frogs and peculiar sounds made by the swamp chickens. However, the farmers acknowledged that their IKS have not been as reliable as it has always been in the past decades. Nonetheless, the farmers underlined being misled by an inaccurate scientific forecast in 2013 and, a lack of trust in the source of the forecast are some of the reasons they continue to rely primarily on IKS. With climate change expected to continue occurring at unprecedented levels in Nigeria, it is crucial to build subsistence farmers trust in SCF while simultaneously not undermining the value of their IKS. This is because there is growing consensus that if subsistence farmers continue to rely on IKS alone, the key assets that play a huge role in food production will likely be eroded. This will adversely hamper households’ ability to continue obtaining the livelihood they aggressively pursue. Thus, a useful starting point will be to generate a “unified” forecast whereby SCF compensates for the limitations of farmer’s IKS. However, for the unified forecast to make meaningful contributions to the ways in which farmers produce their food and protect their assets in anticipation of an extreme weather forecast, it must be communicated through the various mediums that the farmers rely upon to receive vital pieces of information. Keywords: Indigenous knowledge systems, seasonal climate forecast, climate change risk communication, Delta State, Nigeria. / LG2018

Human influence on the environment is becoming increasingly pervasive across the globe, and can drastically impact ecological patterns and processes. For many terrestrial wildlife species, human influence can fragment critical habitat, increase mortality, and threaten habitat connectivity and ultimately the persistence of wildlife populations. This dissertation aims to use multiple conservation ecology methods and tools to test the impact of human influence on the population dynamics of a large carnivore in a human-dominated landscape. To assess the impact of human activity on carnivore ecology, a series of empirical studies were conducted on a small population of American black bear (Ursus americanus) in the Western Great Basin, USA. A long-term dataset including geographic locations of animal habitat choices as well as mortality locations were used in multiple statistical models that tested the response of black bears to human activity. These analyses were conducted at multiple spatial and temporal resolutions to reveal nuances potentially overlooked if analyses were limited to a single resolution. Individual studies, presented as dissertation chapters, examine the relationships between human activity and carnivore ecology. Collectively, the results of these studies find black bear ecology to be highly sensitive to the magnitude and spatial composition of human activity in the Lake Tahoe Basin, observable at both coarse and fine spatial resolutions. The results presented in this study on the influence of human activity on large carnivore population dynamics allow for a more thorough understanding of the various ways common conservation ecology methods and tools can be used to evaluate human-wildlife relationships.

It is unclear whether accounting for the number of rare taxa or differentiating live (cells with visible chloroplasts) and dead (empty cells) diatoms would enhance the accuracy and precision of diatom-based stream bioassessment. My dissertation research examines whether the number of rare taxa and percentage (%) live diatoms can be used as indicators of human disturbance in streams/rivers. To address my objectives, I analyzed two datasets collected at different spatial scales. The large scale dataset was collected over the course of five years and included more than 1300 sites and over 200 environmental variables from 12 Western US states (US EPA's Environmental Monitoring and Assessment Program). The small scale dataset included 25 streams from the Oregon Coast Range. My findings revealed that rarity definition is important in bioassessment. Rural taxa richness (number of taxa with high occurrence and low abundance) was the only rarity metric that distinguished least disturbed (reference) sites from the most disturbed (impacted) ones. Neither of the other two rarity metrics, satellite (taxa with low occurrence and abundance) and urban (taxa with low occurrence and high abundance) taxa richness, was able to do that. Results from regression tree analysis revealed that rural taxa richness increased with human disturbance, but it was significantly higher at impacted sites only in the Mountains ecoregion (t-test, p0.05). Percentage live diatoms distinguished reference from impacted sites only in the Mountains ecoregion (t-test, p=0.02) and somewhat in the Plains (t-test, p=0.05). However, % live diatoms exhibited opposite patterns in the two ecoregions. They increased with disturbance in the Mountains and decreased in the Plains. The results from the small scale study in the Oregon Coast Range revealed similar species compositions between live and live+dead diatom assemblages (non-metric multidimensional scaling) and similar relationships with their environmental variables (linear fitting). Both assemblages correlated well with in-stream physical habitat conditions (e.g., channel dimensions, substrate types, and canopy cover). Both rural taxa richness and % live diatoms can be used as indicators of human disturbance in streams/rivers, especially in the Mountains ecoregion, dependent on specific assessment objectives.

It is widely believed that Australian Aboriginals utilised fire to manage various landscapes however to what extent this impacted on Australia???s ecosystems remains uncertain. The late Pleistocene/Holocene fire history from three sites within the Sydney Basin, Gooches Swamp, Lake Baraba and Kings Waterhole, were compared with archaeological and palaeoclimatic data using a novel method of quantifying macroscopic charcoal, which is presented in this study. The palynology and other palaeoecological proxies were also investigated at the three sites. The Gooches Swamp fire record appeared to be most influenced by climate and there was an abrupt increase in fire activity from the mid-Holocene perhaps associated with the onset of modern El Ni??o dominated conditions. The Kings Waterhole site also displayed an abrupt increase in charcoal at this time however there was a marked decrease in charcoal from ~3 ka. Lake Baraba similarly had displayed low levels of charcoal in the late Holocene. At both Kings Waterhole and Lake Baraba archaeological evidence suggests intensified human activity in the late Holocene during this period of lower and less variable charcoal. It is hence likely that at these sites Aboriginal people controlled fire activity in the late Holocene perhaps in response to the increased risk of large intense fires under an ENSO-dominated climate. The fire history of the Sydney Basin varies temporally and spatially and therefore it is not possible to make generalisations about pre-historic fire regimes. It is also not possible to use ideas about Aboriginal fire regimes or pre-historic activity as a management objective. The study demonstrates that increased fire activity is related to climatic variation and this is likely to be of significance under various enhanced Greenhouse scenarios. There were no major changes in the composition of the flora at all sites throughout late Pleistocene/Holocene although there were some changes in the relative abundance of different taxa. It is suggested that the Sydney Sandstone flora, which surrounds the sites, is relatively resistant to environmental changes. Casuarinaceae was present at Lake Baraba during the Last Glacial Maximum and therefore the site may have acted as a potential refugium for more mesic communities. There was a notable decline in Casuarinaceae during the Holocene at Lake Baraba and Kings Waterhole, a trend that has been found at a number of sites from southeastern Australia.

No description available.