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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.
71

none

Lue, Tai-feng 05 August 2007 (has links)
none
72

Meadow restoration on former agriculture land in southwestern Ontario, Canada

Balsdon, Jennifer Hsien-ther January 2013 (has links)
Best practices for Restoration Ecology have been largely derived from case studies. Novel Ecosystems is an approach that has the possibility of providing the field of restoration research with both structure and a road map for ecological recovery. In December 2015, Ontario Parks will be ceasing the lease of approximately 122 ha of farmland within Boyne Valley Provincial Park. My thesis aims to bridge the gap between social and ecological systems and build a resilient restoration project at Boyne Valley Provincial Park. My approach integrated the best case scenarios from each the social and ecological aspects to determine a restoration plan. From the social aspect, I chose the method photo-elicitation to bridge the communication gap between myself, the researcher, and the interviewees. Semi-structured interviews were conducted with six major stakeholders including a farmer who is currently leasing land within Boyne Valley Provincial Park, a frequent hiker of the Ontario Parks’ trail system, an academic researcher for Ontario Parks, and three Ontario Parks’ personnel to understand the different landscape preferences of stakeholders within Boyne Valley Provincial Park. From the ecological aspect, I examined the success of restoration for the first year after a fall planting in terms of species richness and percent cover for all species, including native species (planted and not planted) and non-native species across three fields with different initial conditions. To test which species should be used as the initial ground cover after farming has ceased, I looked at the survivorship and growth of five species: Danthonia spicata, Elymus trachycaulus ssp. trachycaulus, Sporobolus cryptandrus, Monarda fistulosa and Penstemon hirsutus. My recommendations for restoration at Boyne Valley Provincial Park include implementing the restoration efforts at a smaller scale to start. The remaining fields should continue to be farmed until restoration can commence or mowed at least four times a year before seeds are formed. Open communication should continue between all stakeholders. Soil preparation should include tilling the soil prior to planting only if the land was left abandoned (e.g. old-field). A plant composition survey should be conducted prior to restoration – more particularly in hay fields - to determine if native meadow species are found. If native meadow species are present (e.g. Sisyrinchium montanum) that would not survive tilling, a no-till planting method may be a better option than tilling. Acknowledging these are early results, my initial recommendation based on survivorship and growth for the first year after planting would be to use plant plugs for Elymus trachycaulus ssp. trachycaulus and a combination of plant plugs and seeds for Monarda fistulosa and Penstemon hirsutus. Future studies should incorporate other herbaceous species to increase the biodiversity while choosing flowers that bloom at different times. Additionally, pilot studies should be completed at all Ontario Parks locations where agriculture leases are ending to develop restoration methodologies that are applicable across Ontario. Information on each of the species to be planted should be distributed to the farmers that border Ontario Parks’ boundaries. This information should include at minimum the species life history, dispersal mechanisms, and a photograph. The research in this thesis outlines initial restoration efforts to guide restoration recommendations for the first year after land abandonment. Much longer-termed research is necessary to understand community dynamics and potential recovery of system.
73

An evaluation of ecological stoichiometry in pelagic systems

2012 June 1900 (has links)
Ecological stoichiometry is the study of the balance of chemical substances in ecosystems. In freshwaters, research has focused on how the ratios of carbon, nitrogen and phosphorus in organisms and their environment affect ecosystem processes. Because autotrophs have variable stoichiometry, particulate C:N:P ratios are used to assess nutrient availability in lakes. Zooplankton have relatively fixed stoichiometry and so differences between their body stoichiometry and the stoichiometry of their food can constrain their growth. Ecological stoichiometry predicts that zooplankton with low C:P body ratios (e.g., Daphnia) will be limited by the P content of their food in lakes where seston C:P is high. The stoichiometric theory of consumer-driven nutrient recycling (CNR) predicts that the stoichiometry of a consumer will influence the stoichiometry of the nutrients they regenerate through such processes as egestion and excretion. In lakes, zooplankton with a low body N:P are expected to regenerate nutrients in a high N:P ratio, potentially shifting nutrient limitation of the food web from N to P limitation. I used data from 99 Canadian lakes to test the following: a. Are particulate C:P and N:P ratios consistent with other P deficiency indicators? b. Do seston C:P and N:P ratios affect zooplankton community composition? c. Does zooplankton community composition affect plankton P limitation as predicted by CNR? Particulate C:P and N:P ratios generally agreed with other P deficiency indicators, except dissolved phosphate turnover times (TTPO4). C:P and N:P suggested P sufficiency more often than TTPO4, possibly because these two indicators respond to P deficiency over different time scales. Most zooplankton biomass parameters were negatively related to seston C:P ratios consistent with improved food quality at lower seston C:P. There was, however, no evidence that Daphnia were more strongly affected than any other zooplankton. Turnover times of particulate P in the whole plankton assemblage were not related to zooplankton community structure parameters. However, particulate P turnover in the >200 µm size fraction increased with increasing zooplankton biomass. There was no evidence for a particular effect of Daphnia on particulate P turnover. Phosphorus deficiency indicators showed a trend of relaxing P deficiency as zooplankton biomass and the proportion of Daphnia increased. This contradicts the predictions of CNR which suggest that Daphnia should cause greater P deficiency in lakes.
74

Selecting species as indicators of ecological integrity a conceptual model based on mammals of Algonquin Provincial Park, Ontario, Canada /

Kassel, Samantha J. January 1998 (has links)
Thesis (M.E.S.)--York University, 1998. / Typescript. Includes bibliographical references (leaves 93-104). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27357.
75

Assessing the symbiotic dependency of grain and tree legumes on N2 fixation for their N nutrition in five agro-ecological zones of Botswana

Pule-Meulenberg, F, Dakota, FD January 2009 (has links)
Abstract To assess the symbiotic dependency of grain and shrub/tree legumes within five agro-ecological zones of Botswana, fully expanded leaves of the test species were sampled from about 26 study sites within Ngwaketse, Gaborone, Central, Ghanzi and Kalahari agro-ecological zones. Isotopic analysis revealed significant differences in 1)15N values of the grain legumes [cowpea (Vigna unguiculata L. Walp), Bambara groundnut (Vigna subterranea L. Verde.), and groundnut (Arachis hypogaea L.)] from the 26 farming areas in both 2005 and 2006. Estimates of %Ndfa of leaves also showed significant differences between farming areas, with cowpea deriving more than 50% of its N nutrition from symbiotic fixation. In terms of distribution, many more symbiotic shrub/tree species were found in the wetter Ngwaketse agro-zone compared to the fewer numbers in the drier Kalahari region. Acacias were the more dominant species at all sites. Leaf 1)15N values of shrub/tree species also varied strongly across Botswana, with 11 out of 18 of these legumes deriving about 50%, or more, of their N from symbiotic Nz fixation. Acacia caffra, in particular, obtained as much as 93.6% of its N nutrition from symbiotic fixation in the wetter Ngwaketse agro-zone. This study has shown that grain legumes sampled from farmer's fields in Botswana obtained considerable amounts of their N from symbiotic fixation. We have also shown that shrub and tree legumes probably play an important role in the N economy of the savanna ecosystems in Botswana. However, the decline in the number of functional Ny-fixing shrub/tree legumes along an aridity gradient suggests that soil moisture is a major constraint to Nz fixation in the tree legumes of Botswana.
76

Assessing the symbiotic dependency of grain and tree legumes on N2 fixation for their N nutrition in five agro-ecological zones of Botswana

Pule-Meulenberg, F, Dakora, FD 01 January 2009 (has links)
Abstract To assess the symbiotic dependency of grain and shrub/tree legumes within five agro-ecological zones of Botswana, fully expanded leaves of the test species were sampled from about 26 study sites within Ngwaketse, Gaborone, Central, Ghanzi and Kalahari agro-ecological zones. Isotopic analysis revealed significant differences in 1)15N values of the grain legumes [cowpea (Vigna unguiculata L. Walp), Bambara groundnut (Vigna subterranea L. Verde.), and groundnut (Arachis hypogaea L.)] from the 26 farming areas in both 2005 and 2006. Estimates of %Ndfa of leaves also showed significant differences between farming areas, with cowpea deriving more than 50% of its N nutrition from symbiotic fixation. In terms of distribution, many more symbiotic shrub/tree species were found in the wetter Ngwaketse agro-zone compared to the fewer numbers in the drier Kalahari region. Acacias were the more dominant species at all sites. Leaf 1)15N values of shrub/tree species also varied strongly across Botswana, with 11 out of 18 of these legumes deriving about 50%, or more, of their N from symbiotic Nz fixation. Acacia caffra, in particular, obtained as much as 93.6% of its N nutrition from symbiotic fixation in the wetter Ngwaketse agro-zone. This study has shown that grain legumes sampled from farmer's fields in Botswana obtained considerable amounts of their N from symbiotic fixation. We have also shown that shrub and tree legumes probably play an important role in the N economy of the savanna ecosystems in Botswana. However, the decline in the number of functional Ny-fixing shrub/tree legumes along an aridity gradient suggests that soil moisture is a major constraint to Nz fixation in the tree legumes of Botswana.
77

Subsistence and land-use amongst resettled indigenous people in the Paraguayan Chaco : a participatory approach

Leake, Andrew Paul January 1998 (has links)
The lack of data on subsistence and land-use patterns often impedes the design of ecologically sustainable, culturally appropriate, socially acceptable and politically feasible approaches to the legalisation of land tenure among indigenous peoples. With specific reference to Amerindians of the Gran Chaco, this thesis shows the extent to which a participatory research methodology can empower indigenous peoples in generating, articulating and communicating data which are vital to the support of their land claims. Fieldwork was conducted with Angaite Indians of the Paraguayan Chaco between 1994 and 1996. Participatory research methods included a census of ten villages (pop. 1,005), drawings of subsistence activities, a survey of material possessions, a time-allocation study, self-kept records of food intake, anthropometric measurements of children, self-kept records on wildlife use (in ten villages), and Indian-made maps of land-use. Satellite imagery provided the basis for the geographic analysis of landuse patterns at local and regional scales. The Angaite own some land but are surrounded by privately owned cattle ranches. Their actual land and resource-use patterns extend over an area ten times greater than that to which they are legally entitled. Although horticulture and paid labour are now the mainstay of the Indian subsistence economy, hunting and fishing continue to provide over 90% of their meat consumption. Hunting patterns are shown to affect a large number of animals but only a small number of species. Land-use is focused on the communal exploitation of resources at key sites spread over broad areas of land. This concept is not catered for in the current Paraguayan legislation, which is based on the principle of giving families a plot of land to farm. On the basis of data generated by the Angaite, this study underlines the need for a radical rethinking of how Indian land-rights might be legalised in a manner which enhances the ecological sustainability of their respective lifestyles. Fundamental to that rethinking is the empowerment of indigenous peoples to express and communicate their own views on their own needs for land.
78

Ecosystem services and the Central Texas Greenprint for Growth : valuing nature through collaborative land conservation

Borowski, Robert Henry 18 February 2011 (has links)
This project explores the potential for integrating an ecosystem service approach with the Central Texas Greenprint for Growth process, a continuing and active stakeholder supported voluntary conservation effort The report provides an overview of the Greenprint process, ecosystem services, and the participatory stakeholder method of social network analysis or mapping. Each of these methods may be used to explore opportunities to enhance the collaborative land conservation planning activity in Central Texas. Conservation goals identified in the Greenprint process are evaluated in terms of ecosystem service and methods for measuring more complete environmental value can be identified. This evaluation focuses on three out of the six goals that the stakeholders have identified as having importance: protect water quality and quantity, preserve farms and ranchlands, and protect cultural resources. Community-based environmental planning or adaptive management processes such as the Greenprint process requires effective communication methods to address complex issues among diverse stakeholders. Social network mapping and analysis are illustrated as a method to evaluate how stakeholders communicate information about ecosystem services. A limited social network analysis is conducted as a pilot study with a stakeholder group in Bastrop, Texas. Natural resource professionals have used social network analysis to understand the structure of relationships and the pathways of communication in community planning processes. I will review this method and its potential for application. Through questionnaires, data gathered at a stakeholder meeting and is used to develop a preliminary social network matrix to demonstrate the method. It is envisioned that the report would advance understanding of how an ecosystem service approach can enhance an active ecological planning process and landscape scale conservation. / text
79

Meadow restoration on former agriculture land in southwestern Ontario, Canada

Balsdon, Jennifer Hsien-ther January 2013 (has links)
Best practices for Restoration Ecology have been largely derived from case studies. Novel Ecosystems is an approach that has the possibility of providing the field of restoration research with both structure and a road map for ecological recovery. In December 2015, Ontario Parks will be ceasing the lease of approximately 122 ha of farmland within Boyne Valley Provincial Park. My thesis aims to bridge the gap between social and ecological systems and build a resilient restoration project at Boyne Valley Provincial Park. My approach integrated the best case scenarios from each the social and ecological aspects to determine a restoration plan. From the social aspect, I chose the method photo-elicitation to bridge the communication gap between myself, the researcher, and the interviewees. Semi-structured interviews were conducted with six major stakeholders including a farmer who is currently leasing land within Boyne Valley Provincial Park, a frequent hiker of the Ontario Parks’ trail system, an academic researcher for Ontario Parks, and three Ontario Parks’ personnel to understand the different landscape preferences of stakeholders within Boyne Valley Provincial Park. From the ecological aspect, I examined the success of restoration for the first year after a fall planting in terms of species richness and percent cover for all species, including native species (planted and not planted) and non-native species across three fields with different initial conditions. To test which species should be used as the initial ground cover after farming has ceased, I looked at the survivorship and growth of five species: Danthonia spicata, Elymus trachycaulus ssp. trachycaulus, Sporobolus cryptandrus, Monarda fistulosa and Penstemon hirsutus. My recommendations for restoration at Boyne Valley Provincial Park include implementing the restoration efforts at a smaller scale to start. The remaining fields should continue to be farmed until restoration can commence or mowed at least four times a year before seeds are formed. Open communication should continue between all stakeholders. Soil preparation should include tilling the soil prior to planting only if the land was left abandoned (e.g. old-field). A plant composition survey should be conducted prior to restoration – more particularly in hay fields - to determine if native meadow species are found. If native meadow species are present (e.g. Sisyrinchium montanum) that would not survive tilling, a no-till planting method may be a better option than tilling. Acknowledging these are early results, my initial recommendation based on survivorship and growth for the first year after planting would be to use plant plugs for Elymus trachycaulus ssp. trachycaulus and a combination of plant plugs and seeds for Monarda fistulosa and Penstemon hirsutus. Future studies should incorporate other herbaceous species to increase the biodiversity while choosing flowers that bloom at different times. Additionally, pilot studies should be completed at all Ontario Parks locations where agriculture leases are ending to develop restoration methodologies that are applicable across Ontario. Information on each of the species to be planted should be distributed to the farmers that border Ontario Parks’ boundaries. This information should include at minimum the species life history, dispersal mechanisms, and a photograph. The research in this thesis outlines initial restoration efforts to guide restoration recommendations for the first year after land abandonment. Much longer-termed research is necessary to understand community dynamics and potential recovery of system.
80

Assessing coral stress responses at the level of gene expression

Morgan, Michael Boyce 05 1900 (has links)
No description available.

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