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  • 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.
101

Population biology of the <em>Primula sibirica</em> group species inhabiting frequently disturbed seashore meadows: implications for management

Rautiainen, P. (Pirjo) 29 March 2006 (has links)
Abstract Many plant species inhabiting the seashore meadows of the Bothnian Bay, especially early successional ones, have become threatened. Isostatic land uplift creates virgin land for early successional species to colonise. However, at the same time it gradually elevates the habitat and eventually makes the habitat unsuitable for them. Disturbances of the waterfront may slow down succession and create new empty sites. In order to persist on the shores, pioneer species have to be able to colonise new sites by seeds, vegetative propagules or growth. In this thesis I studied the status of an endangered early successional grass species, A. fulva var. pendulina, at the Liminka Bay. According to a matrix population model based on eight years of observations (1992–1999), the population seemed not to be in immediate danger of extinction. However, simulations based on four-year field observations (2000–2003) indicated that if the current trend continues, the species will decrease considerably in area in the next 30 years. In the field studies no seedlings or viable seeds of A. fulva were found. In spite of this, high genotypic diversity was found in the A. fulva population, suggesting that sexual reproduction has taken place at some time during the history of the population. Analysis of the population structure revealed a low level of genotypic differentiation between subpopulations and significant sub-structuring within subpopulations. The overall pattern of genetic variation suggests that the population has characters of both stepping-stone and metapopulation models. The results of the study on the ability of a seashore plant Potentilla anserina ssp. egedii to change its allocation of resources to sexual and vegetative reproduction according to competitive stress implied that the species can modify the allocation of resources to different life-history traits. For a plant living in disturbance-prone environment, it may be beneficial to be able to rapidly track the competition-free space formed by disturbances by changing its reproductive pattern. Management studies on three endangered seashore plant species showed that deterioration of suitable habitats of A. fulva and Primula nutans var. jokelae could be slowed down by management, and the vegetative and/or sexual reproduction of these species was enhanced. However, in the case of Puccinellia phryganodes, no positive response to management was observed.
102

The ecology and conservation of the white-winged nightjar Caprimulgus candicans

Pople, Robert Grant January 2003 (has links)
In the tradition of previous studies of threatened species, this thesis was undertaken with the aim of improving our understanding of the ecology of the White-winged Nightjar Caprimulgus candicans, and providing the information necessary to facilitate conservation efforts on its behalf. In 1998-2001, I studied a population of White-winged Nightjars at Aguará Ñu, an area of cerrado habitats within the Reserva Natural del Bosque Mbaracayù, eastern Paraguay. Over the course of three fieldwork seasons, I captured and ringed a total of 49 nightjars (34 adults and 15 young birds). Young females first bred at approximately one year old, while still in pre-definitive plumage. Young males exhibited a form of delayed plumage maturation, whereby they only attained definitive plumage following a prolonged moult spanning much of their first potential breeding season. No evidence was obtained to suggest that they succeeded in breeding while in this conspicuously intermediate state of moult. Considerable variation was noted in the plumage whiteness of definitive males, but no clear evidence was found for consistent age-related increases in white. During the breeding season, males defended small aggregated display territories, at which they conducted nuptial display flights between late August and early January. Female nightjars were responsible for all the parental care, and apparently visited male display arenas solely to obtain copulations. Chick paternity data confirmed that the study population was polygynous, with patterns of male aggregation suggestive of an exploded lek or 'landmark' mating system. Radio-telemetry studies showed that nightjars utilised home ranges of at least 20 to 40 hectares during the eight to ten months for which they were monitored. Home ranges contained a disproportionately large amount of young campo cerrado vegetation, but no forest or old campo cerrado habitats. When selecting foraging sites within their ranges, nightjars preferred younger and avoided older campo cerrado vegetation; wet grassland was utilised roughly in proportion to its availability. Observed patterns of habitat selection were potentially explained by the greater abundance of insect prey in younger habitats. When selecting daytime roost sites, nightjars preferred vegetation of intermediate age, reflecting their need for a balance between cover and ease of access. A more general analysis of patterns of sexual dimorphism within the Caprimulgidae showed that, although almost 80% of nightjar species exhibit some dimorphism of plumage whiteness, the study species was by far the most extreme case. The striking plumage of the male was partly explained by a strong positive relationship between wing white and openness of breeding habitats within the family. However, this failed to explain the complete absence of white in the female plumage, or the extent of white dimorphism shown by the species. The most likely explanation would appear to be that extreme plumage dimorphism occurred in conjunction with the evolution of polygyny and female-only care in this open-country species. The implications of these findings for the conservation of the White-winged Nightjar are highlighted, and recommendations are proposed for future work and conservation action.
103

Den Europeiska idegranens återväxtproblematik / The regeneration issues of European Yew (Taxus baccata)

Ermalm, Sandra January 2020 (has links)
Abstract I hela Europa har idegranen problem med återväxten. Olika återväxthämmande faktorer påverkar föryngringen i olika stadier, och det är aldrig bara en anledning till att föryngringen inte lyckas. Idegranen är skuggtålig men behöver ljus. Den gynnas av lövfällande bestånd då den drar nytta av vårens öppna krontak. I bristen på ljus stannar de yngre plantorna av i utvecklingen, dessa dör eller äts upp och föryngringen uteblir. Nästan alla naturligt förekommande äldre plantor (&gt; 2 år) betas. Bete av idegran är idag ett stort problem för föryngringen då rådjurens matsmältning klarar av idegran. I Stockholms norra skärgård är det framför allt betet som hämmar plantornas utveckling. Idegranen har problem med sin återväxt och detta sägs vara ett karaktärsdrag för arten.
104

Population dynamics of the threatened staghorn coral, Acropora cervicornis, and the development of a species-specific monitoring protocol

Goergen, Elizabeth 03 May 2018 (has links)
Historically, Acropora cervicornis was found in high densities on many Caribbean, Florida, and Gulf of Mexico reefs. A disease outbreak in the late 1970s and 80s caused up to 99% loss of A. cervicornis cover at some sites, leaving populations sparsely distributed throughout its range and typically found as isolated colonies. Even though populations are depauperate causing a decrease in sexual reproduction, its fast growth rate and ability to reproduce through asexual fragmentation affords this species the potential for quick recovery and population growth. However, limited to no natural recovery has been documented. Many of these populations are poorly studied because most monitoring programs are not designed to capture A. cervicornis’ unique life history characteristics. Its patchy distribution, complex growth form, frequent fragmentation, and dislodgment present a challenge for long term tracking. Furthermore, its ability to exist from small isolated colonies to semi-continuous patches spanning hectares makes defining individuals to assess abundance, survival, health, and growth a difficult task. The aim of this dissertation was to develop a species-specific monitoring protocol to describe the abundance and cover of A. cervicornis and the effects of disease, predation, and disturbance events across space and time. The monitoring protocol was developed and used across three sub-regions of the Florida Reef Tract (Broward County, Middle Keys, and Dry Tortugas). Several permanent 3.5 m radial plots were installed across multiple sites in each sub-region. A species census, percent cover, and demographic data of a sub-set of colonies were collected three times per year (winter, summer, and fall) from 2008-2016. These results were then used to assist in designing and testing optimal outplant strategies. Outplanting occurred at seven sites in Broward County, FL between 2012- 2015. Experiments were designed to assess the effects outplant colony density, host genotype, colony size, and attachment technique had on colony survival, growth, and health. The monitoring protocol was successfully used for identifying spatial and temporal patterns and trends in cover, disease, and predation on A. cervicornis across a range of population sizes. Percent cover of living A. cervicornis declined significantly during the duration of the project. Disease prevalence and occurrence was highest during the summer. Colony size and volume increased with depth and were the largest in the Broward County sub-region. Disease caused the most mortality, however fireworms were the most prevalent cause of recent mortality. Disease and predation were more prevalent on masses (individuals larger than 1.5 m in diameter). The outplant experiments showed that colony survival and health were greatest when colonies had greater than 15 cm in total tissue and in densities less than 1 col/m2. Host genotype and outplant site had variable effects on survival and growth. Outplanted colonies quickly acclimated to their environment and increased colony abundance within sites by fragmentation. Prevalence of disease and predation were lower on outplanted colonies than wild colonies. Frequent disturbances such as tropical storms, hurricanes, and disease events caused increased, prolonged, and widespread mortality and fragmentation, however periods void of disturbances resulted in recovery and growth. Therefore, reducing the effects of climate change and determining and decreasing the causes of disease could promote species recovery. In the meantime, population enhancement by outplanting is a viable way to assist species conservation and recovery.
105

A critical review of the South African freshwater angling legislative framework / Morné Viljoen.

Viljoen, Morné January 2010 (has links)
Prior to 1993, freshwater angling in South Africa had been governed by the respective nature conservation legislation of the four South African provinces, the four “independent homelands" and the six so-called Bantustans. In 1993 a South Africa with nine provinces was created, of which only Limpopo and Mpumalanga promulgated its own laws governing freshwater angling. From 2008 angling for listed threatened and protected freshwater fish species has been regulated by the National Environmental Management: Biodiversity Act, supplemented by the Threatened or Protected Species Regulations. In addition, it is anticipated that the Alien and Invasive Species Regulations, which will regulate angling for listed alien and invasive freshwater fish, will be promulgated in the near future. The result is that freshwater angling is currently being governed by a plethora of pre-1993 provincial, homeland and Bantustan legislation, two post-1993 provincial acts, as well as post-1993 national legislation. In this dissertation the South African freshwater angling legislative framework was critically analysed. It was found that the multitude of fragmented and complex laws, created 15 “angling provinces” which leads to confusion amongst anglers and government officials alike. In the process legal certainty and reasonableness, cornerstones of a sound legal system, are being compromised, indigenous freshwater fish are not adequately protected and alien or invasive freshwater fish are not properly managed. In the light of the above, and after taking comments by anglers and enforcement officials into account, recommendations are made for an improved legislative framework for freshwater in South Africa. It is recommended that all freshwater fish species be managed and/or protected on a catchment basis, as opposed to the current provincial basis. This will ensure legal certainty and reasonableness and that all indigenous freshwater fish which are subject to the similar threats are protected adequately and uniformly. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2010.
106

A critical review of the South African freshwater angling legislative framework / Morné Viljoen.

Viljoen, Morné January 2010 (has links)
Prior to 1993, freshwater angling in South Africa had been governed by the respective nature conservation legislation of the four South African provinces, the four “independent homelands" and the six so-called Bantustans. In 1993 a South Africa with nine provinces was created, of which only Limpopo and Mpumalanga promulgated its own laws governing freshwater angling. From 2008 angling for listed threatened and protected freshwater fish species has been regulated by the National Environmental Management: Biodiversity Act, supplemented by the Threatened or Protected Species Regulations. In addition, it is anticipated that the Alien and Invasive Species Regulations, which will regulate angling for listed alien and invasive freshwater fish, will be promulgated in the near future. The result is that freshwater angling is currently being governed by a plethora of pre-1993 provincial, homeland and Bantustan legislation, two post-1993 provincial acts, as well as post-1993 national legislation. In this dissertation the South African freshwater angling legislative framework was critically analysed. It was found that the multitude of fragmented and complex laws, created 15 “angling provinces” which leads to confusion amongst anglers and government officials alike. In the process legal certainty and reasonableness, cornerstones of a sound legal system, are being compromised, indigenous freshwater fish are not adequately protected and alien or invasive freshwater fish are not properly managed. In the light of the above, and after taking comments by anglers and enforcement officials into account, recommendations are made for an improved legislative framework for freshwater in South Africa. It is recommended that all freshwater fish species be managed and/or protected on a catchment basis, as opposed to the current provincial basis. This will ensure legal certainty and reasonableness and that all indigenous freshwater fish which are subject to the similar threats are protected adequately and uniformly. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2010.
107

"Ungerska för rötternas skull" : Språkval och identitet bland andragenerationens ungrare i Sverige och Finland

Straszer, Boglárka January 2011 (has links)
This thesis is a comparative sociolinguistic study which describes and compares language choice among people with Hungarian background in Sweden and Finland and studies their views on the importance of the Hungarian language and Hungarian cultural heritage for identity. The future prospects of language maintenance and language shift and differences between the Swedish-Hungarians and the Finnish-Hungarians are discussed. A survey was completed among 50 Swedish-Hungarian informants and 38 Finnish-Hungarian informants during 2006. The survey was supplemented by in-depth interviews with 15 informants during 2007. The majority language, either Swedish or Finnish, is much more active in the second-generation Hungarians’ lives than Hungarian is. Hungarian is mostly used in the domain of family relations. The language choices made today are dependent on the informant’s situation during childhood, particularly the parents’ usage of the language and the ability to learn and use Hungarian, chiefly gained through contact with the parents’ mother country and other Hungarian speakers. For some informants, having Hungarian roots forms the sole foundation for belonging, while for others it is this heritage combined with the culture, the ability to use the language or specific character traits. The Hungarian background is most often seen as a treasure offering diversity in life. Finnish-Hungarians are generally more positive about their Hungarian background, have better competence in the language and a greater awareness of the culture than Swedish-Hungarians. The Hungarian language plays a central though often symbolic role. The most important conditions for minority language preservation are language competence together with the desire and opportunity to use it; whereof the largest deficit among second-generation Hungarians is knowledge of the Hungarian language. Only one-fourth of the informants have all of the conditions necessary to be able to maintain the language, which means that Hungarian is an endangered minority language in Sweden and Finland.
108

"Ungerska för rötternas skull" : Språkval och identitet bland andragenerationens ungrare i Sverige och Finland.

Straszer, Boglárka January 2011 (has links)
This thesis is a comparative sociolinguistic study which describes and compares language choice among people with Hungarian background in Sweden and Finland and studies their views on the importance of the Hungarian language and Hungarian cultural heritage for identity. The future prospects of language maintenance and language shift and differences between the Swedish-Hungarians and the Finnish-Hungarians are discussed. A survey was completed among 50 Swedish-Hungarian informants and 38 Finnish-Hungarian informants during 2006. The survey was supplemented by in-depth interviews with 15 informants during 2007. The majority language, either Swedish or Finnish, is much more active in the second-generation Hungarians’ lives than Hungarian is. Hungarian is mostly used in the domain of family relations. The language choices made today are dependent on the informant’s situation during childhood, particularly the parents’ usage of the language and the ability to learn and use Hungarian, chiefly gained through contact with the parents’ mother country and other Hungarian speakers. For some informants, having Hungarian roots forms the sole foundation for belonging, while for others it is this heritage combined with the culture, the ability to use the language or specific character traits. The Hungarian background is most often seen as a treasure offering diversity in life. Finnish-Hungarians are generally more positive about their Hungarian background, have better competence in the language and a greater awareness of the culture than Swedish-Hungarians. The Hungarian language plays a central though often symbolic role. The most important conditions for minority language preservation are language competence together with the desire and opportunity to use it; whereof the largest deficit among second-generation Hungarians is knowledge of the Hungarian language. Only one-fourth of the informants have all of the conditions necessary to be able to maintain the language, which means that Hungarian is an endangered minority language in Sweden and Finland.
109

Spolupráce dobrovolníka, klienta a o.s. Lata - Programy pro ohroženou mládež / Cooperation between the volunteer, the client and o.s. Lata - Programy pro ohroženou mládež

Kniha, Michal January 2012 (has links)
Cooperation between the volunteer, the client and o. s. Lata - Programy pro ohroženou mládež Abstract: The thesis deals with issues of a voluntary work on field of programmes focused on working with threatened children, adolescents and young adults by form one to one. It's focused on a mentors project running by the citizens' association LATA - Programmes for Threatened Adolescents. It pays attention especially to factors, which can influence the relationship between a volunteer, a client and an organization. It follows up mainly involved volunteers, it puts an aim to description of ways, how the volunteers percieve their work with clients and their organization. Research part of the thesis is focused on analysis of volunteers' statements and has an ambition to catch and reveal important factors, which affect their activities in the organization. This thesis conducts a survey, what motivation and aim the volunteers have, how they percieve their relationships with clients, what helps them to maintain a mentoring role and how they percieve at all the organization they work in
110

An evaluation of the conservation of New Zealand's threatened biodiversity : management, species recovery and legislation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Auckland, New Zealand

Seabrook-Davison, Mark Nicholas Hawdon January 2010 (has links)
Content removed from thesis due to copyright restrictions: Seabrook-Davison, M. N. H., Weihong, J. J. & Brunton, D. H. (2010). "Survey of New Zealand Department of Conservation staff involved in the management and recovery of threatened species." Biological Conservation, 143: 212-219. doi: 10.1016/j.biocon.2009.10.005. Seabrook-Davison, M. N. H., Ji, W. & Brunton, D. H. (in press). "New Zealand lacks comprehensive threatened species legislation -- comparison with legislation in Australia and the USA." Pacific Conservation Biology, 16. / It is only recently that New Zealand wildlife managers have become aware of both the taxonomic range of New Zealand’ indigenous biodiversity and the number of species threatened with extinction. The entire New Zealand archipelago has been described as a biodiversity hotspot; a term with both negative and positive connotations as although its biodiversity is unique and diverse, it has lost three quarters of its primary vegetation and much of its remaining endemic biota is in decline. This thesis evaluated aspects of New Zealand’s approach to the management of biodiversity with an emphasis on methods used in the recovery of threatened species. Possible solutions are presented that New Zealand could investigate to improve the delivery of species recovery. A survey was conducted amongst Department of Conservation (DOC) staff to investigate management tools available to them. Results suggest that inadequate resources, staff shortages and an overwhelming workload have resulted in a failure to achieve comprehensive recovery of threatened species. A review of New Zealand wildlife conservation legislation and a comparison with the USA Endangered Species Act 1973 and Australian Environment Protection and Biodiversity Conservation Act 1999, suggests that a lack of dedicated threatened species legislation is hindering the effective recovery of New Zealand’s threatened species. The thesis concludes that New Zealand has the advantage of a large conservation estate but lacks an integrated national management approach to the conservation of its biodiversity. Considerable improvement of the management and recovery of threatened species can be achieved with the enacting of dedicated threatened species legislation. Keywords: Threatened species, biodiversity, biodiversity hotspot, conservation, management, recovery plans, recovery groups, Department of Conservation, legislation, threat classification system, listing, ecological function, ecosystem services, staff survey, New Zealand

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