• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 306
  • 49
  • 32
  • 17
  • 15
  • 6
  • 5
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 525
  • 363
  • 173
  • 69
  • 68
  • 63
  • 61
  • 55
  • 51
  • 48
  • 47
  • 42
  • 40
  • 40
  • 39
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Conservation by Consensus: Reducing Uncertainty from Methodological Choices in Conservation-based Models

Poos, Mark S. 01 September 2010 (has links)
Modeling species of conservation concern, such as those that are rare, declining, or have a conservation designation (e.g. endangered or threatened), remains an activity filled with uncertainty. Species that are of conservation concern often are found infrequently, in small sample sizes and spatially fragmented distributions, thereby making accurate enumeration difficult and traditional statistical approaches often invalid. For example, there are numerous debates in the ecological literature regarding methodological choices in conservation-based models, such as how to measure functional traits to account for ecosystem function, the impact of including rare species in biological assessments and whether species-specific dispersal can be measured using distance based functions. This thesis attempts to address issues in methodological choices in conservation-based models in two ways. In the first section of the thesis, the impacts of methodological choices on conservation-based models are examined across a broad selection of available approaches, from: measuring functional diversity; to conducting bio-assessments in community ecology; to assessing dispersal in metapopulation analyses. It is the goal of this section to establish the potential for methodological choices to impact conservation-based models, regardless of the scale, study-system or species involved. In the second section of this thesis, the use of consensus methods is developed as a potential tool for reducing uncertainty with methodological choices in conservation-based models. Two separate applications of consensus methods are highlighted, including how consensus methods can reduce uncertainty from choosing a modeling type or to identify when methodological choices may be a problem.
132

Seasonal movement and activity patterns of the endangered geometric tortoise, Psammobates geometricus.

Van Bloemestein, Ulric Patrick January 2005 (has links)
Due to the critical status of Psammobates geometricus and the vulnerability of their habitat, there is a need to allocate areas for their protection. The aim of this study was to provide information on the space requirements and activity level of geometric tortoises to facilitate future conservation efforts.
133

Contextualising the role of zoos in conservation : an Australasian experience / Nicole Andrea Mazur.

Mazur, Nicole Andrea January 1997 (has links)
Bibliography: leaves 398-421. / xxxi, 421 leaves : ill. (chiefly col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The degree to which the conservation role of zoos can promote progressive environmental knowledge is debated. Generates data that zoo professionals can apply to future problem-solving and to increasing the relevance and effectiveness of zoo conservation policies for modern-day ecological problems. / Thesis (Ph.D.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1998
134

Habitat requirements and habitat use of the red-crowned toadlet Pseudophryne Australis and the giant burrowing frog Heleioporus Australiacus in the Sydney basin.

Andrew G, Stauber January 2009 (has links)
Habitat requirements and habitat use for Pseudophryne australis and Heleioporus australiacus were investigated to aid management of these threatened frogs around Sydney, Australia. Much of the work focussed on roads, commonly encountered features in the habitat of both species. The habitat requirements based on locality records of both frogs in the Sydney Basin were investigated at four spatial scales. Both species are habitat specialists. They showed a strong geological association with Hawkesbury Sandstone and occupy upper topographic areas with ephemeral watercourses of gentle gradients. Both frogs occur predominantly in areas of higher precipitation and milder temperature regimes compared to averages representative of the region. Leaf litter is an important feature of P. australis breeding sites, whereas H australiacus generally associate with crayfish burrows. Both species are dependent on natural vegetation with a complex structure. H australiacus have a relatively long larval period (3 - 12 months) and breed in ephemeral pools, exposing their tadpoles to the risk of dying due to early pond drying. In the laboratory, tadpoles responded to decreasing water levels by shortening their larval periods and metamorphosing earlier than siblings held at constant water level. Despite this plastic response, a number of pools in the field failed to produce metamorphs due to early drying, an observation also made on P. australis. Regular monitoring of breeding sites revealed increased reproductive success away from roads for both species probably because of relatively longer hydroperiods. Spatial distributions and associations with habitat features, and movement patterns of both frogs were further investigated using mark-recapture methods. Both species showed strong site fidelity. P. australis formed small aggregations and predominantly selected leaf litter piles despite their relatively low availability. Leaf litter piles in creeks moved over time and the animals moved with these piles. In contrast, H australiacus individuals formed no aggregations and showed no preference for any available structural vegetation type. Locations of individuals were independent of relative distances to creeks and artificial drains, but males appeared to be more common near culverts. However, individuals were randomly distributed in space and nearest-neighbour distances were high relative to individual movement distances, suggesting minimal overlap between relatively large home ranges. Radio-telemetry demonstrated that some H australiacus individuals burrow in the road environment. There they would be at risk of being dug up and possibly injured during road works. The results are discussed in relation to the spatial requirements of both species and the protection of utilised habitat features. Management options are suggested to mitigate the impacts of road works. Differences in spatial dynamics of both frogs with overlapping habitats highlighted in this study require species-specific management approaches.
135

Habitat requirements and habitat use of the red-crowned toadlet Pseudophryne Australis and the giant burrowing frog Heleioporus Australiacus in the Sydney basin.

Stauber, Andrew G. January 2006 (has links)
Habitat requirements and habitat use for Pseudophryne australis and Heleioporus australiacus were investigated to aid management of these threatened frogs around Sydney, Australia. Much of the work focussed on roads, commonly encountered features in the habitat of both species. The habitat requirements based on locality records of both frogs in the Sydney Basin were investigated at four spatial scales. Both species are habitat specialists. They showed a strong geological association with Hawkesbury Sandstone and occupy upper topographic areas with ephemeral watercourses of gentle gradients. Both frogs occur predominantly in areas of higher precipitation and milder temperature regimes compared to averages representative of the region. Leaf litter is an important feature of P. australis breeding sites, whereas H australiacus generally associate with crayfish burrows. Both species are dependent on natural vegetation with a complex structure. H australiacus have a relatively long larval period (3 - 12 months) and breed in ephemeral pools, exposing their tadpoles to the risk of dying due to early pond drying. In the laboratory, tadpoles responded to decreasing water levels by shortening their larval periods and metamorphosing earlier than siblings held at constant water level. Despite this plastic response, a number of pools in the field failed to produce metamorphs due to early drying, an observation also made on P. australis. Regular monitoring of breeding sites revealed increased reproductive success away from roads for both species probably because of relatively longer hydroperiods. Spatial distributions and associations with habitat features, and movement patterns of both frogs were further investigated using mark-recapture methods. Both species showed strong site fidelity. P. australis formed small aggregations and predominantly selected leaf litter piles despite their relatively low availability. Leaf litter piles in creeks moved over time and the animals moved with these piles. In contrast, H australiacus individuals formed no aggregations and showed no preference for any available structural vegetation type. Locations of individuals were independent of relative distances to creeks and artificial drains, but males appeared to be more common near culverts. However, individuals were randomly distributed in space and nearest-neighbour distances were high relative to individual movement distances, suggesting minimal overlap between relatively large home ranges. Radio-telemetry demonstrated that some H australiacus individuals burrow in the road environment. There they would be at risk of being dug up and possibly injured during road works. The results are discussed in relation to the spatial requirements of both species and the protection of utilised habitat features. Management options are suggested to mitigate the impacts of road works. Differences in spatial dynamics of both frogs with overlapping habitats highlighted in this study require species-specific management approaches.
136

Space use and resource selection by Eastern spotted skunks in the Ouachita Mountains, Arkansas

Lesmeister, Damon Brock. January 2007 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 31, 2008) Includes bibliographical references.
137

Effects of land-based pollution on Indonesian coral reefs : biodiversity, growth rates, bioerosion, and applications to the fossil record /

Edinger, Evan Nathaniel. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (p. 223-258). Also available via World Wide Web.
138

Golden-cheeked warbler nest success and nest predators in urban and rural landscapes

Reidy, Jennifer L. January 2007 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 1, 2007) Includes bibliographical references.
139

Using insect responses to anthropogenic disturbance to improve land management and conservation planning decisions

Sanford, Monte Paul. January 2007 (has links)
Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "December 2007." Includes bibliographical references. Online version available on the World Wide Web.
140

Translocation of the Eastern Bristlebird and factors associated with a successful program

Bain, David. January 2006 (has links)
Thesis (Ph.D.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 124-146.

Page generated in 0.0638 seconds