The effects of scale influence all aspects of spatial analysis and should be expressly considered early in research planning. Remotely sensed images provide unique landscape perspectives and possess several features amenable to dealing with scale. In particular, images can be segmented into image objects representative of landscape features and structured as nested hierarchies for evaluating landscape patterns across a range of scales. The objectives of this research are to evaluate methods for: 1) characterizing candidate image objects to inform the selection of user-supplied segmentation parameters and 2) exploring the multi-scale structure of landscape patterns for defining and describing potentially important scales for conducting subsequent geospatial and ecological investigations. I followed a recursive strategy to develop an image hierarchy using a corrected version of the normalized difference vegetation index (NDVIc) derived from a Landsat ETM+ satellite image over a complex, forested landscape at Lava Cast Forest (LCF), Oregon. At each scale level, I calculated an objective function based on within-object variance and spatial autocorrelation to distinguish between alternative image objects created with the region-merging segmentation algorithm available in the Definiens Developer 7 software. Segmentation quality was considered highest for results exhibiting the lowest overall within-object variance and between-object spatial autocorrelation. I then applied geographical variance analysis to calculate the independent contribution and relative variability of each level in the hierarchy to evaluate the scene's spatial structure across scales. My results reveal overall trends in image object spatial variance consistent with scaling theory, but suggest judging image object quality without sampling the entire range of segmentation parameters is insufficient. Statistical limitations of the spatial autocorrelation coefficient at small sample sizes constrained the number of possible hierarchy levels within the image spatial extent, preventing identification of larger-scale landscape patterns. Geographical variance analysis results show patterns in vegetation conditions at LCF possess a multi-scaled structure. Three levels exhibiting high variance relative to the entire hierarchy coincide with abrupt transitions in the slopes of within-object variance and spatial autocorrelation trends, which I interpreted as scale thresholds potentially important for relating landscape patterns and processes. These methods provide an objective, object-oriented approach for addressing scale issues within heterogeneous landscapes using remote sensing.

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 220-234).

Thesis (Ph. D.)--Dept. of Economics and Dept. of Sociology/Criminal Justice & Criminology. University of Missouri--Kansas City, 2005. / "A dissertation in economics and social science." Advisor: Peter J. Eaton. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed March 12, 2007. Includes bibliographical references (leaves 301-324). Online version of the print edition.

Thesis (Ph.D.)--Victoria University of Wellington, 2010. / Includes bibliographical references.

No description available.

The ecological role of apex predators in ecosystems is increasingly recognized not only as a result of their affects on prey species, but also on the numbers and behaviour of other predator species within their guilds. In an African context, dominant apex predators such as lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) have been implicated in limiting endangered intraguild species such as wild dogs (Lycaon pictus) via direct intraguild interactions, such as interference and predation. As a result of this it has been predicted that spatial and temporal refugia are critical for wild dogs to co-exist with lions and spotted hyaenas. Whether such refugia are actually present within small protected areas, such as Hluhluwe iMfolozi Park (HiP), within which these three species co-exist, has been questioned. For wild dogs, interference or predation refugia may be equated to areas or periods which contain a relatively low level of encounter probability with spotted hyaenas and lions respectively. By combining well established field research techniques, such as radio telemetry and audio playbacks, with novel geographic information system tools, I investigated the two key drivers of the probability of encounter with spotted hyaenas and lions, namely density and utilization intensity. Results from the analyses showed that substantial spatial and temporal variation existed in the utilization intensity of lions, as well as the density of both lions and spotted hyaenas, at short and intermediate time scales, in HiP. The spatial scale across which these patterns resolved appear to be well suited to the movement capabilities of wild dogs. This indicated that wild dogs may be able to exploit such areas of temporary lower density and/or utilization intensity, suggesting the dynamic nature of refugia involved in the interactions within these two species-pairs. Results from the lion analyses further suggest that groups rather than individuals are the basic units around which intraguild interactions of social predator and prey species should be investigated, and that social grouping in combination with predator territoriality may stabilize intraguild interactions. An important prediction emerging from this work is that wild dogs, or other subordinate African large predator species, may be forced to trade-off safety from hyaena interference vs. safety from lion predation. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009. / National Research Foundation, The Green Trust (WWF–SA), The Wildlands Conservation Trust, University of KwaZulu-Natal, The Endangered Wildlife Trust, Smithsonian Institution, Sichel Family Endowment, Friends of the National Zoo, THRIP, Wild about Cats, Hluhluwe Tourism Association, Bateleurs, Third World Academy of Science, The Wild Dog Foundation, and The Sally Club.

Understanding the mechanisms that control the rate and trajectory of primary succession can lead to insights for ecosystem rehabilitation. Proposed mechanisms include life history traits and nutrient limitation. To explore how these mechanisms can drive successional dynamics, I devised a stoichiometric ecosystem-level model that considered the role of nitrogen and phosphorus limitation in plant primary succession in conjunction with life history traits. This model was applied to the plant community on Mount St. Helens to check the validity of the mechanisms. The results show the competitive hierarchy of plants at the local scale can be explained by nutrient limitation and plant stoichiometry. At regional scales, life history traits interact with local processes to shape community structure and successional dynamics. At all scales, the presence of Lupinus lepidus, a nitrogen-fixer, significantly altered community dynamics and succession. This study suggests that primary succession can be examined within the framework of ecological stoichiometry. / Ecology

Thesis (Ph. D.)--University of Adelaide, Dept. of Environmental Science and Management, 1999? / Includes bibliographical references (leaves 132-153).

Thesis (M.A.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 76-85). Also available via Humboldt Digital Scholar.

Thesis (M. Sc.)--Acadia University, 1997. / Includes bibliographical references. Also available on the Internet via the World Wide Web.