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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.
1

Grazing and drought in tallgrass prairie: the role of belowground bud banks in vegetation dynamics

VanderWeide, Benjamin Lee January 1900 (has links)
Doctor of Philosophy / Department of Biology / David C. Hartnett / Grazing and drought are instrumental in the development and maintenance of perennial grasslands. In this research I tested the belowground bud bank contribution to tallgrass prairie resistance and resilience when perturbed by grazing and drought. First, I tested the bud bank role in vegetation response to and recovery from severe drought (Chapter 2). I compared above- and belowground responses of experimentally droughted plots to ambient controls and irrigated plots during two years of severe drought and two years of recovery. I found that although aboveground net primary productivity declined 30-60% during drought, bud bank density and demography were insensitive to drought. These results suggest that grassland resistance and resilience when perturbed by drought may be mediated by stability of belowground bud banks. Second, I investigated vegetation and soil nutrient legacies following release from long-term grazing (Chapter 3). I documented a relatively rapid shift in aboveground vegetation within four years of grazer exclusion, with productivity, stem density, and diversity becoming relatively more similar to ungrazed than grazed prairie. The density and composition of the belowground bud bank and soil seed bank shifted more slowly, remaining more similar to grazed than ungrazed prairie. Responses of soil nutrients to removal of grazers varied, and in some cases was affected by recent fire history. These results demonstrate the contribution of belowground propagules to the maintenance of a diverse plant community both during grazing and after grazers are removed. Finally, I examined short-term vegetation responses to both drought and grazing (Chapter 4). Despite extreme drought and simulated grazing that reduced productivity and increased mortality of individual stems, the dominant C4 grasses maintained a stable bud bank. Aboveground net primary productivity and bud bank density of sedges and forbs, however, were reduced by both drought and grazing. This differential response of species to extreme drought and grazing led to shifts in community composition and species diversity over one growing season. Across drought and grazing treatments, live rhizome biomass was highly correlated with bud bank density and may be a useful, more easily measured index of bud bank density.
2

Black and minority ethnic young people : exploring the silences in the Scottish Highlands

Cacho, Patricia January 2016 (has links)
In this thesis I analyse the dynamics of youth, race and rurality by considering the life experiences of young people in relation to race and racism through a small –scale study I have conducted over eight months. The study also investigates the aspirations of eight black and minority ethnic young people living in the Scottish Highlands. The study found that young people’s experiences of racism and racial microaggressions were exacerbated by a ‘conspiracy of silence’ in which institutional actors such as service providers, who are there to support and encourage young people, have knowingly, or inadvertently, contributed to undermining, marginalising and excluding black and minority ethnic young people through misunderstanding or misrecognition of experiences of racialisation in rural areas. I observed how these minority young people engaged in strategies of resistance and resilience as a prevalent response when negotiating racist experiences and racial microaggressions. It was further evident that the deficient practices of institutional actors, such as teachers, youth workers and most service providers play a tangible role in perpetuating racism and racial discrimination in the Highlands. The study recommends that to reduce bias and discrimination against black and minority ethnic pupils requires a range of strategies ranging from enhancing teacher confidence in teaching and addressing different forms of racism, a need for teachers to have training on anti-racist education and pedagogical approaches, recruitment of black and minority ethnic practitioners for different service provision, recognition and promotion of the benefits of multilingualism and opportunities for white majority pupils to have greater exposure to diversity in rural Scotland.
3

Qualidade do solo e pedofauna em sistemas tradicionais e agroflorestais / Soil quality and pedofauna in tradictional and agroflorestries systems

Jamili Silva Fialho 22 February 2013 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A prÃtica da agricultura tradicional pode degradar a qualidade dos recursos naturais e por isso se tornar insustentÃvel, o que leva a necessidade de uma abordagem ecolÃgica, possibilita a escolha de manejos agrÃcolas que associem a produÃÃo de alimentos e a conservaÃÃo dos recursos naturais, como acontece nos sistemas agroflorestais. A simplificaÃÃo do agroecossistema reduz a diversidade, afetando a biota e a qualidade do solo. Assim, objetivou-se: i) avaliar indicadores da qualidade e Ãndices da qualidade, resistÃncia e resiliÃncia do solo, ii) avaliar a diversidade da pedofauna dos agroecossistemas e iii) identificar as relaÃÃes entre a flora nos perÃodos seco e chuvoso com a riqueza da pedofauna. Foram estudados os sistemas agroflorestais do tipo agrossilvipastoril, silvipastoril e o tradicional, atualmente em uso e apÃs diferentes perÃodos de pousio; alÃm de um sistema menos impactado (MATA). A qualidade do solo (QS) foi avaliada por indicadores quÃmicos e fÃsicos de solo e calculados os Ãndices de qualidade, resistÃncia e resiliÃncia. A pedofauna foi coletada, nos perÃodos seco e chuvoso, usando armadilhas de queda, identificando-se os grupos taxonÃmicos e posterior determinaÃÃo da riqueza, densidade, diversidade e uniformidade. As Ãreas sob sistemas agroflorestais mantiveram a QS, o pousio recuperou e o tradicional a reduziu, sendo menos resiliente e resistente. No perÃodo seco, os sistemas agroflorestais apresentaram baixas diversidade e uniformidade, porÃm riquezas semelhante à MATA, enquanto que as Ãreas em pousio apresentaram altas diversidade e uniformidade. Houve semelhanÃas de diversidade e uniformidade entre as Ãreas sob cultivo tradicional e MATA. No perÃodo chuvoso, os sistemas agroflorestais apresentaram densidade e riqueza semelhantes à MATA. As Ãreas tradicionais em pousio apresentaram densidade, riqueza, diversidade e uniformidade semelhantes à MATA. Conclui-se que os sistemas agroflorestais sÃo sustentÃveis, seis e nove anos de pousio sÃo suficientes para retomar a condiÃÃo do sistema menos impactado e manejo tradicional reduz a qualidade, resistÃncia e resiliÃncia do solo. Os sistemas agroflorestais apresentam diversidade e uniformidade da pedofauna semelhantes ao ambiente menos impactado quando hà disponibilidade hÃdrica. A riqueza das espÃcies arbÃreas e a sazonalidade climÃtica determinam a riqueza da pedofauna. / Traditional agriculture can degrade natural resources becoming unsustainable. Hence, ecological approaches on agriculture enable the choice of agricultural management,which associates food production and the maintenance of natural resources, as agroforestry systems. The simplified agroecosystem reduces diversity, causing deleterious effects on soil biota and on soil quality,. Thus, the aim of this work was: i) to assess quality indicators and soil quality, resistance and resilience indexes, ii) to evaluate the diversity of edaphic fauna of agroecosystems and iii) to identify flora and dry and rainy seasons to edaphic fauna abundance. Agrosilvopastoral, silvopastoral, and traditional agroecosystems were studied, under use and under different periods of fallow, besides the natural vegetation (MATA). Soil quality (QS) was analyzed according to some indicators and from them quality, resistance and resilience indexes were calculated. Edaphic fauna was collected under dry and rainy seasons, using PITFALL TRAPS. The fauna was identified under taxonomic groups and the indexes: abundance, density, diversity, and uniformity here determined. The relation between fauna and flora and the seasons was analyzed using general linear models. Agroforestries maintained QS, traditional system under fallow recovered it, and the traditional system reduced it and it was less resilient and resistant. In the dry season, agroforestries showed low diversity and uniformity, therefore presenting similar abundance to MATA, while areas under fallow showed high diversity and uniformity. There were similarities in diversity and uniformity between traditional system and MATA. In the rainy season, agroforestries showed density and abundance similar to MATA,. Traditional systems under fallow showed density, abundance, diversity, and uniformity similar to MATA. It is possible to conclude that agroforestry systems are sustainable. Six and nine years of fallow are enough to recover the condition of natural vegetation. Traditional management reduces quality, resistance and resilience of soil. Agroforestries show diversity and uniformity of pedofauna similar to the natural vegetation when water is available. The abundance of trees and weather seasonality determine the abundance of pedofauna.
4

INVESTIGATING THE EFFECTS OF “NEIGHBOURHOOD REVITALIZATION” ON RESIDENTS’ DESTIGMATIZATION PRACTICES, HEALTH AND WELLBEING IN TORONTO’S REGENT PARK COMMUNITY

Cahuas, Madelaine C. 10 1900 (has links)
<p>Social housing residents’ lived experiences and understandings of their neighbourhood and home are key factors influencing their health and wellbeing, but remain under-examined in the urban redevelopment literature. This thesis investigates the ways in which people living in Toronto’s Regent Park, Canada’s oldest and largest social housing development undergoing “neighbourhood revitalization,” experience their community and respond to neighbourhood stigma. Drawing on Lamont’s (2009) destigmatization practices concept, the aim of this study was to understand “neighbourhood revitalization” as a place destigmatization strategy that may influence the ways in which residents engage in personal destigmatization practices as well as affect their perceived health and wellbeing. Semi-structured interviews were carried out with 15 Regent Park residents and NVivo 9 software was used for data analysis. Findings show that participants utilize various counter-narratives as destigmatization practices that challenge dominant narratives and stereotypical representations of their neighbourhood. However, since re-housing in revitalized buildings, participants’ narratives describing their neighbourhood have changed and may further stigmatize some Regent Park residents. Counter-narratives may be implicitly linked to resiliency and wellbeing, while place destigmatization through revitalization was strongly associated to residents’ perceived improvements in health and wellbeing. The findings of this thesis may contribute to the developing literature on the impacts of urban redevelopment on residents’ health and wellbeing.</p> / Master of Arts (MA)

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