• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • Tagged with
  • 8
  • 8
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

The effects of forest fragmentation on leaf-litter invertebrates in Central Amazonia

Didham, Raphael K. January 1996 (has links)
No description available.
2

Chytridiomycosis in amphibian populations in the Western Cape, South Africa

Hopkins, Samantha January 2002 (has links)
Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / There have been many cases reported of amphibian populations declining. These are often due to anthropogenic factors such as habitat destruction and pollution. However, some declines have not had an obvious cause and many of these have been investigated and found to be due to pathogenic disease. Batrachochytrium dendrobatidis is a recently described pathogen of frogs. The population declines that have been associated with chytridiomycosis have occurred in relatively undisturbed areas such as national parks. The declines tend to occur at higher altitudes or in colder climates. This is thought to be because of the frog immune system being slower at lower temperatures. Chyt1id fungus has been found in frog populations throughout the world. Little research has been carried out in Africa although, chytridiomycosis has already been seen in Kenya and South Africa. In this project frogs were sampled from selected transects in the Western Cape and three sites in the Northern Cape. The effect of altitude on the occurrence of infection was tested in the Western Cape. It was found that 18 frogs were infected in the Western Cape and the effect of altitude was not significant. Large numbers of dead and dying frogs were found in two of the Northern Cape sites and the incidence of chytridiomycosis was high in these populations. Chytrid was found in two Bufogariepensis from the Eastern Cape and in Xenopus petersii from Kasanka National Park, Zambia. More research is needed on chytridiomycosis in these populations. The frogs in the Western Cape seem to survive with chytrid fungus infection whereas, the frogs in the Northern Cape are dying. This suggests another factor acting on the Northern Cape frog populations.
3

A Fine Balance

Vice President Research, Office of the January 2009 (has links)
Climate change is putting the Earth’s biodiversity in serious jeopardy. UBC’S Biodiversity Research Centre is aiming to understand the impact of this shift.
4

Biodiversity in fragmented boreal forests : assessing the past, the present and the future

Berglund, Håkan January 2004 (has links)
<p>The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes. </p><p>Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. Data from 46 patches (0.2-12 ha) showed that most species were rare. However, species richness and composition patterns exhibited a high degree of predictability, which strengthen the possibility to apply biodiversity indicators in old-growth forest stands. Area was a key factor. The increase in species richness starts to level out at 2-3 ha. Large patches host more Red-list species in their interiors than do small ones, i.e. stand size is an important qualitative aspect of old-growth habitat. Nestedness emerged in relation to area but also in equal-sized plots. Structural complexity and habitat quality were important for species richness and compositional patterns, and small habitats of high quality could harbor many rare species. Monitoring of wood-fungi on downed logs showed that species diversity on downed logs changed over periods of 5-10 years and that the occurrences of annual species were unpredictable. It is suggested that monitoring of species with durable fruit bodies (mainly polypores) is likely to be a feasible approach to obtain comparable data over time.</p><p>Assessments of biodiversity of WKHs were performed in two areas with contrasting histories of forest exploitation, namely in south boreal and north boreal Sweden. Analyses of the history of 15 south boreal WKHs showed that fire-suppression, selective logging until mid-20th century and abandonment by modern forestry has shaped their forest structure. These WKHs are not untouched forests, they lack key structural components and harbor few Red-list species. Artificial interventions to restore natural processes and patterns are needed to further increase their suitability for threatned species. Modeling analyses of species richness in 32 WKHs in north boreal Sweden, some of which have not been isolated by modern forestry until recently, indicated an excess of crustose lichen species, i.e. WKHs may face delayed species extinctions. By contrast, the results indicate that wood-fungi have tracked the environmental changes. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs may explain the diffeence between species groups. The results indicate that population densities of Red-list species were low, which may result in further depletion of species diversity.</p><p>Continuing species declines and extinctions are likely if not conservation of WKHs are combined with other considerations in th managed forest landscape. Both WKHs and their surroundings must be managed and designed to maintain biodiversity over time. For a successful future conservation of boreal forest biodiversity monitoring of WKHs must be combined with monitoring of refeence areas. </p>
5

Biodiversity in fragmented boreal forests : assessing the past, the present and the future

Berglund, Håkan January 2004 (has links)
The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes. Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. Data from 46 patches (0.2-12 ha) showed that most species were rare. However, species richness and composition patterns exhibited a high degree of predictability, which strengthen the possibility to apply biodiversity indicators in old-growth forest stands. Area was a key factor. The increase in species richness starts to level out at 2-3 ha. Large patches host more Red-list species in their interiors than do small ones, i.e. stand size is an important qualitative aspect of old-growth habitat. Nestedness emerged in relation to area but also in equal-sized plots. Structural complexity and habitat quality were important for species richness and compositional patterns, and small habitats of high quality could harbor many rare species. Monitoring of wood-fungi on downed logs showed that species diversity on downed logs changed over periods of 5-10 years and that the occurrences of annual species were unpredictable. It is suggested that monitoring of species with durable fruit bodies (mainly polypores) is likely to be a feasible approach to obtain comparable data over time. Assessments of biodiversity of WKHs were performed in two areas with contrasting histories of forest exploitation, namely in south boreal and north boreal Sweden. Analyses of the history of 15 south boreal WKHs showed that fire-suppression, selective logging until mid-20th century and abandonment by modern forestry has shaped their forest structure. These WKHs are not untouched forests, they lack key structural components and harbor few Red-list species. Artificial interventions to restore natural processes and patterns are needed to further increase their suitability for threatned species. Modeling analyses of species richness in 32 WKHs in north boreal Sweden, some of which have not been isolated by modern forestry until recently, indicated an excess of crustose lichen species, i.e. WKHs may face delayed species extinctions. By contrast, the results indicate that wood-fungi have tracked the environmental changes. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs may explain the diffeence between species groups. The results indicate that population densities of Red-list species were low, which may result in further depletion of species diversity. Continuing species declines and extinctions are likely if not conservation of WKHs are combined with other considerations in th managed forest landscape. Both WKHs and their surroundings must be managed and designed to maintain biodiversity over time. For a successful future conservation of boreal forest biodiversity monitoring of WKHs must be combined with monitoring of refeence areas.
6

Sediment Removal from the San Gabriel Mountains

Ferguson, Mary C 01 May 2012 (has links)
The issue of sediment removal from the San Gabriel Mountains has been a complex issue that has created problems with beach replenishment, habitat destruction and the need to spend millions of dollars at regular intervals to avoid safety hazards. Most recently 11 acres of riparian habitat, including 179 oaks and 70 sycamores, were removed for sediment placement. Other sites including Hahamongna Watershed Park and La Tuna Canyon also face a similar fate. This thesis questions: How did we get to this point of destroying habitat to dump sediment which is viewed as waste product? What are the barriers for creating long term solutions and progressive change? What are some other options? And how should we move forward? The issues with sediment management have stemmed from regulatory compliance issues, adversarial relationships within agencies and among NGO's and the public, and the lack of a comprehensive long-term plan to prevent further habitat loss and other sediment removal issues. A recommendation includes looking at a community forestry model to include a wide cross-section of the community, NGO's and government agencies to come up with a long term comprehensive and progressive solution.
7

An exploration of the impacts of socio-economic activities on the loss of biodiversity in the Maseru and Berea districts of Lesotho

Sekamane, Thabang 01 1900 (has links)
Text in English / Biodiversity is a fundamental characteristic of life on Earth and encompasses the whole range of variation in living organisms. Lesotho has been subjected to tremendous biodiversity change over the last two centuries, primarily due to socio-economic activities. A number of socio-economic factors have contributed to the loss of biodiversity. However, worldwide experience has shown that, the consequences emanating from loss of biodiversity are sometimes irreversible as some species are threatened by extinction. The study aimed at exploring the impacts of socio-economic activities that result in loss of large game animals, predators and indigenous plants species in Lesotho. To serve this objective, both quantitative and qualitative research methodologies were used to collect data. Quantitative research method was used in pre-post tests whilst qualitative research method was used in interviews and focus group discussions to collect data. The finding and results of the study show that, impacts of human vectors such as immigration, migration, settlement, economic and recreation activities in Lesotho have the impacts to the loss of large game animals, predators and indigenous plants. It is imperative therefore, for Lesotho to find ways to establish more parks and botanic gardens that could offer opportunities for re-introduction of species in Lesotho, thus, adding value to the existing parks. / Environmental Sciences / M. Sc. (Environmental Management)
8

An exploration of the impacts of socio-economic activities on the loss of biodiversity in the Maseru and Berea districts of Lesotho

Sekamane, Thabang 01 1900 (has links)
Text in English / Biodiversity is a fundamental characteristic of life on Earth and encompasses the whole range of variation in living organisms. Lesotho has been subjected to tremendous biodiversity change over the last two centuries, primarily due to socio-economic activities. A number of socio-economic factors have contributed to the loss of biodiversity. However, worldwide experience has shown that, the consequences emanating from loss of biodiversity are sometimes irreversible as some species are threatened by extinction. The study aimed at exploring the impacts of socio-economic activities that result in loss of large game animals, predators and indigenous plants species in Lesotho. To serve this objective, both quantitative and qualitative research methodologies were used to collect data. Quantitative research method was used in pre-post tests whilst qualitative research method was used in interviews and focus group discussions to collect data. The finding and results of the study show that, impacts of human vectors such as immigration, migration, settlement, economic and recreation activities in Lesotho have the impacts to the loss of large game animals, predators and indigenous plants. It is imperative therefore, for Lesotho to find ways to establish more parks and botanic gardens that could offer opportunities for re-introduction of species in Lesotho, thus, adding value to the existing parks. / Environmental Sciences / M. Sc. (Environmental Management)

Page generated in 0.1258 seconds