• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1225
  • 322
  • 157
  • 112
  • 73
  • 40
  • 17
  • 15
  • 15
  • 13
  • 12
  • 10
  • 9
  • 8
  • 6
  • Tagged with
  • 2408
  • 703
  • 516
  • 421
  • 421
  • 249
  • 245
  • 213
  • 203
  • 197
  • 177
  • 160
  • 157
  • 155
  • 153
  • 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.
151

Dispersal and remineralisation of biodeposits : ecosystem impacts of mussel aquaculture/

Giles, Hilke. January 2006 (has links)
Thesis (Ph.D.)--University of Waikato, 2006. / Includes bibliographical references (leaves 135-150)
152

Biogeochemical Response of a Northeastern Forest Ecosystem to Biosolids Amendments

Banaitis, Michael R. January 2007 (has links) (PDF)
No description available.
153

Arctic foxes as ecosystem engineers: benefits to vegetation and collared lemmings through nutrient deposition

Gharajehdaghipoor, Tazarve 14 January 2016 (has links)
I estimated the non-trophic effects of arctic fox (Vulpes lagopus) denning activities on soil nutrient dynamics, vegetation production and quality, snow cover thickness, and their primary terrestrial prey, collared lemmings (Dicrostonyx richardsoni), near Churchill, Manitoba in April, June and August 2014. Arctic foxes increased soil inorganic nitrogen and extractable phosphorous concentration on their dens. This increase in soil nutrient levels resulted in greater vegetation quantity (measured as biomass and cover) and quality (measured as nitrogen content) on dens. Increased vegetation cover, specifically Salix sp. and Leymus mollis cover, positively affected snow cover thickness on dens by trapping blowing snow. Increased snow cover thickness made dens attractive nesting sites to collared lemmings (measured as lemming nest counts). In addition, dens with lemming nests had greater snow cover thickness compared to dens without lemming nests. Greater vegetation quantity and quality on dens could also attract lemmings to dens for winter nesting. / February 2016
154

Competence development in marine protected area professionals: a case study of the South African Marine Protected Area Management Training Course (SAMPATC)

Lewis, Sebastian Giulio January 2012 (has links)
This study reviews a training programme on Marine Protected Area (MPA) management. It notes that although MPAs are well promulgated under legislation, reports have found that there are still key challenges facing the management of these areas. The research examines how the course was developed following the Lemm and Attwood (2003) report and designed to develop competences for effective MPA management. The aim is to identify how a MPA management training course produced competences apposite to the workplace settings of the participants. An interpretive case study method was used, in two phases. The first phase explored salient issues in MPA management in South Africa through analysis of the two key ‘state of MPA management’ reports and interviews with MPA professionals. The second was an analysis of the South African Marine Protected Area Management Training Course. This involved interviews with course designers, a review of the course materials, interviews with past course participants, and an analysis of course evaluations. Evidence emerged that supported the following findings: Challenges and problems facing MPA management still exist. Competence in key areas of MPA management was addressed in an effective work-integrated approach. Social learning was a key process in the development of these competences. The competences articulate well with the workplace of participants. Gaps exist between some of the management issues and the competences developed by the course, and some aspects of the course design are ineffective. From these findings it is concluded that: The course took up the majority of issues in MPA management through the development of key competences. The course design facilitated the development of these competences. The competences developed through the course are relevant to the workplace of MPA professionals. The research found that the course adequately addresses issues in MPA management through the development of competences. Some recommendations for improvements are made.
155

Exploring the well-being and ecosystem services relationship through the capability approach

Szaboova, Lukrecia January 2016 (has links)
This thesis investigates the relationship between ecosystem services and human well-being through a case study in Cornwall, UK. The study examines how aspects of the economic and socio-cultural environment interact and influence participants’ constructs of well-being, as well as mediate, through mechanisms of access, their ability to benefit from ecosystem services. The research design is informed by Sen’s capability approach as well as insights from literatures on access theory, human well-being, and ecosystem services. While Sen’s approach potentially offers a novel means to explore the ecosystem services and well-being relationship, it is currently underutilised in this research context. Adopting an in-depth qualitative research approach, data collection took place over 21 months with the same cohort of participants, who face various types of socio-economic disadvantage. Focus groups, life history interviews, photo elicitation, and semi-structured interviews were used to (a) elicit local constructs of well-being, (b) explore the role of ecosystem services for well-being, and (c) identify mechanisms of access that mediate participants’ ability to benefit from valued ecosystem services. The analysis shows that capabilities are interlinked and multidimensional. Therefore, existing socio-economic constraints have important implications for capability formation, and also lead to a series of trade-offs in converting capabilities into well-being. The findings deliver new insights into existing conceptualizations of the ecosystem services and well-being relationship, highlighting the role of cultural practices as sources of well-being, and identifying cultural ecosystem services as an overarching theme rather than a discrete service type. Four types of access mechanisms emerge from the data, including psychological mechanisms, demonstrating that physical distance is an insufficient indicator of exposure to ecosystem services. The thesis concludes by suggesting that developing a capability theory for ecosystem services could aid disaggregated analyses and deliver more nuanced insights into the complex links between ecosystem services and well-being, by shifting the focus from outcomes to opportunities and the processes that contribute to particular outcomes.
156

INFLUENCES OF DISEASE-DRIVEN AMPHIBIAN DECLINES ON ECOSYSTEM STRUCTURE AND FUNCTION IN PANAMANIAN HEADWATER STREAMS

Rugenski, Amanda T. 01 December 2013 (has links)
Understanding relationships between biodiversity and ecosystem function is a critical challenge, particularly in freshwater ecosystems where species losses are occurring at unprecedented rates. There is a particular need to examine these relationships in natural settings at large spatial scales. Ongoing, disease-driven amphibian declines may influence the structure and function of stream ecosystems, but little is known of the potential roles of stream-dwelling tadpoles in consumer-resource dynamics, ecosystem functions such as decomposition, and ecosystem-level biogeochemical cycling. Tadpoles in tropical streams likely regulate flows and ratios of nitrogen (N), phosphorus (P), and carbon (C), influencing ecosystems by altering nutrient supplies to other animals and their food resources. I used ecological stoichiometry as a framework to assess how the sudden loss of consumer biodiversity in neotropical headwater streams affected ecosystem function. I quantified N and P excretion and C:N:P ratios of tadpoles, macroinvertebrates, and food resources in healthy sites (pre-decline) and sites where disease-driven amphibian declines had occurred (post-decline). I tested the hypothesis of consumer homeostasis (i.e., that organisms maintain consistent body nutrient ratios by altering excretion chemistry) over a range of taxa and size classes. I also used mesocosms in a natural stream setting to quantify the effects of grazing tadpoles, shredding macroinvertebrates and a combination of the two on leaf decomposition and associated microbial activity. Finally, I examined macroinvertebrate community structure and quantified biomass and nutrient storage in tadpoles, macroinvertebrates, and basal resources in pre-decline and post-decline sites. I also measured excretion rates, volumetric excretion, and nutrient turnover for both tadpoles and macroinvertebrates. Patterns of consumer-resource stoichiometry varied with the presence or absence of tadpoles. There were higher concentrations of C, N, and P in basal resources in pre-decline sites compared to post-decline sites, but little variation in elemental ratios among sites. Elemental composition and molar ratios in grazers and shredders varied, with pronounced differences in %N for gatherers and filterers across sites. Macroinvertebrate grazer elemental composition was higher for all elements and had lower C:N, N:P, and C:P molar ratios in pre-decline sites compare to grazers in post-decline sites, while shredders showed the opposite pattern. There were differences in both taxon-specific allometric and stoichiometric relationships in tadpoles and macroinvertebrates between pre- and post-decline sites. Body P content was a good predictor of tadpole P excretion and tadpoles in pre-decline sites excreted more P per unit body P than those in post decline sites. Individuals deviated from strict homeostasis, and the degree of deviation varied among taxa. Tadpoles also affected leaf decomposition by influencing microbial communities and altering shredding macroinvertebrate feeding. Higher respiration rates of leaf discs in chambers with tadpoles suggested that tadpoles enhanced microbial activity by excreting nutrients through feeding and excretion. Shredders alone had little effect on respiration rates, indicating that tadpoles play an important and unique role in enhancing microbial activity and litter decomposition. Leaf area loss was greatest when tadpoles and macroinvertebrates were together, indicating facilitation. Macroinvertebrates are important nutrient recyclers in neotropical headwater streams, but their role is greatly decreased in the absence of larval amphibians. I measured ~80% lower standing stocks and storage of C, N, and P in basal resources in post-decline compared to pre-decline sites. Storage of C, N, and P in both tadpoles and macroinvertebrates also decreased in post-decline sites. I also observed 98% decreases in tadpole nutrient excretion and egestion rates, and an additional decrease in macroinvertebrate excretion rates (~80%) for both N and P in post-decline versus pre-decline sites. These decreases led to >8,000% increase in the distance that it took tadpoles to turn over the ambient N pools in post-decline sites, and a 130% increase for macroinvertebrates. Similar patterns were evident for P turnover, with turnover distance increasing by 6,000% and 400% in post-decline sites for tadpoles and macroinvertebrates, respectively. My results indicate that N and P excretion by both tadpoles and macroinvertebrates constitute significant nutrient fluxes in these headwater streams. Both tadpole and macroinvertebrate communities were excreting nutrients at similar rates in pre-decline sites, suggesting that they were playing equally significant roles in their contribution to ecosystem demand. My results demonstrate that tadpoles are important consumers in Neotropical headwater streams and their loss significantly alters stream food webs and ecosystem functions.
157

Se reconstruirmos elas virão? abelhas e vespas solitárias que nidificam em cavidades preexistentes em matas ciliares restauradas no cerrado do Sudeste do Brasil.

Araújo, Gustavo Júnior de January 2015 (has links)
Submitted by Filipe Nepomuceno (filipearn@yahoo.com.br) on 2015-12-01T13:22:05Z No. of bitstreams: 2 license_rdf: 22190 bytes, checksum: 19e8a2b57ef43c09f4d7071d2153c97d (MD5) DISSERTAÇÃO_AbelhasVespasSolitárias.pdf: 8557441 bytes, checksum: 592d20da2a3487a05b33d7d7cce3a5bc (MD5) / Rejected by Gracilene Carvalho (gracilene@sisbin.ufop.br), reason: a pedido on 2015-12-01T13:25:27Z (GMT) / Submitted by Filipe Nepomuceno (filipearn@yahoo.com.br) on 2015-12-01T13:29:53Z No. of bitstreams: 2 license_rdf: 22190 bytes, checksum: 19e8a2b57ef43c09f4d7071d2153c97d (MD5) DISSERTAÇÃO_ReconstruimosVirãoAbelhas.pdf: 8557441 bytes, checksum: 592d20da2a3487a05b33d7d7cce3a5bc (MD5) / Rejected by Gracilene Carvalho (gracilene@sisbin.ufop.br), reason: substituir o arquivo on 2015-12-02T14:53:29Z (GMT) / Submitted by Filipe Nepomuceno (filipearn@yahoo.com.br) on 2015-12-02T15:04:06Z No. of bitstreams: 1 DISSERTAÇÃO_ResconstruirmosVirãoAbelhas.pdf: 15205054 bytes, checksum: 5139b7c46cdb34bab29fd55cdf98162a (MD5) / Approved for entry into archive by Gracilene Carvalho (gracilene@sisbin.ufop.br) on 2015-12-02T15:07:45Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO_ResconstruirmosVirãoAbelhas.pdf: 15205054 bytes, checksum: 5139b7c46cdb34bab29fd55cdf98162a (MD5) / Made available in DSpace on 2015-12-02T15:07:45Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO_ResconstruirmosVirãoAbelhas.pdf: 15205054 bytes, checksum: 5139b7c46cdb34bab29fd55cdf98162a (MD5) Previous issue date: 2015 / As matas ciliares compõem uma vegetação característica de margem de corpos d’água, apresentando importantes funções ecossistêmicas, impedindo o assoreamento de rios, lagos e lagoas, promovendo a estabilidade nos ambientes aquáticos, atuando como corredores ecológicos e funcionando como importantes áreas de refúgio para diversas espécies da fauna. Nesse trabalho avaliou-se o sucesso da restauração de quatro fragmentos de mata ciliar, no entorno do Reservatório da Usina Hidrelétrica de Volta Grande situada entre os estados de Minas Gerais e São Paulo comparando-as com um fragmento que passou por processo de sucessão natural. Utilizou-se como indicador a comunidade de abelhas e vespas solitárias que nidificam cavidades preexistentes. Avaliou-se a relação entre largura, período de recuperação, matriz adjacente e a estrutura da vegetação sobre a riqueza, abundância, composição e rede de interação com parasitas de ninhos. As matas ciliares restauradas apresentaram uma riqueza (s=20) e abundância (n=368) maiores em relação a vários outros levantamentos em áreas primárias. A área referência e as áreas com maior largura apresentaram uma maior riqueza de abelhas e as áreas mais novas apresentaram maior abundância de vespas. A maior quantidade de fragmentos de cerrado na matriz determinou a maior riqueza e abundância de abelhas e vespas. Quanto maior a complexidade estrutural da vegetação nos fragmentos mais diversificada é a comunidade e diferentes espécies responderam de forma diferente a essa complexidade. As abelhas e vespas solitárias que nidificam em cavidades preexistentes se mostraram excelentes preditoras de qualidade ambiental, demonstrando que o processo de restauração das matas ciliares está caminhando para o sucesso por disponibilizar ambientes para a ocupação da fauna e estar recuperando dos serviços ecossistêmicos perdidos. __________________________________________________________________________________________ / Riparian forests play an important role in the preservation of water bodies and, in maintaining biodiversity, act as refuges for many species or can be used as ecological corridors. The restoration of these environments is critical to the recovery of pollinator communities. In this work we study the role of restored riparian forest on the riverbanks of the Volta Grande Reservoir (MG and SP) in maintaining bees and wasps communities that nest in preexisting cavities so as to verify if here is difference in richness, abundance and composition throughout the seasons (dry and wet), if there is a relationship between richness and abundance of these individuals and their parasites and the degree of specialization of parasites in relation to the hosts. Were recorded 12 species of wasps, eight of bees and nine species of parasites of the orders Coleoptera, Diptera, Hymenoptera in addition to mites and fungi. The wasps Trypoxylon nitidum (Smith, 1856), Pachodynerus grandis Willink & Roig-Alsina, 1998 and the bee Centris (Heterocentris) analis (Fabricius, 1804) were the most abundant. Areas with longer time of restoration showed higher species richness. However the abundance was higher in most recent areas. The composition of bees and wasps assembly has not changed between the four seasonal periods evaluated, although it has changed between sampling areas. The richness and abundance were higher in warmer and rainy periods. The rate of bee mortality was 45.68% and 48.62% for the wasps. Richness parasites correlated positively with the richness and abundance of bees and wasps. The network of host- parasite interaction has a modular configuration with generalists and specialists. Recovered riparian forests are providing environmental conditions necessary for the maintenance of bees and wasps communities that nest in preexisting cavities.
158

Um jeito amazônida de ser mundo. A Amazônia como metáfora do ecossistema comunicacional: uma leitura do conceito a partir da região

Colferai, Sandro Adalberto 30 October 2014 (has links)
Submitted by Gabriele Rodrigues (gabriele_r.valentim@hotmail.com) on 2016-08-19T15:09:26Z No. of bitstreams: 1 Tese - Sandro Adalberto.pdf: 1553386 bytes, checksum: 54fdfd124268d5aad722d23156b114ef (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-08-19T15:10:04Z (GMT) No. of bitstreams: 1 Tese - Sandro Adalberto.pdf: 1553386 bytes, checksum: 54fdfd124268d5aad722d23156b114ef (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-08-19T15:10:23Z (GMT) No. of bitstreams: 1 Tese - Sandro Adalberto.pdf: 1553386 bytes, checksum: 54fdfd124268d5aad722d23156b114ef (MD5) / Made available in DSpace on 2016-08-19T15:10:40Z (GMT). No. of bitstreams: 1 Tese - Sandro Adalberto.pdf: 1553386 bytes, checksum: 54fdfd124268d5aad722d23156b114ef (MD5) Previous issue date: 2014-10-30 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis presents an interdisciplinary interpretation of the concept of Communicational Ecosystem taking the Amazon as an explanatory metaphor for what triggers theoretical frameworks that converge to a complex and new paradigmatic approach to knowledge production and dialogical postures in dealing with the relations between the local and the universal. The argumentation comes from a recovery of the concept of Communicational Ecosystem institutionalized in the Brazilian academic research and it is appropriated in the communicational field in the Amazon under proper interpretation keys. From this, the proposal by which the concept refers to the multiplicities that traverse the human being, the nature and the technical means of communication and information that completely comprise the Communicational Ecosystem are organized in this thesis. This thesis is about an ecosystem approach that considers corporeality of relations and subjectivities driven in society, taking them as inseparable instances amplified by technologies that extend human innervations beyond the corporeal boundaries. At this point, the experiences of Amerindian populations, especially indigenous peoples of Amazonia and traditional communities of the region, which have different relation with the environment, comparing with westerner communities, are the point of contact between the concept and the everyday common practices: the Amazon, being a region of the planet where it is clearly perceived the recursive relationships between humans, nature, and - by the increasing presence - information and communication technologies, it becomes explanatory metaphor of the Communicational Ecosystem / Esta tese apresenta uma leitura interdisciplinar do conceito de Ecossistema Comunicacional tomando a Amazônia como metáfora explicativa, para o que aciona arcabouços teóricos que convergem para uma abordagem complexa e novo paradigmática da produção de conhecimento e para posturas dialógicas ao tratar das relações entre o local e o universal. A argumentação parte de uma recuperação do conceito de Ecossistema Comunicacional institucionalizado na pesquisa acadêmica brasileira e apropriado no Campo da Comunicação na Amazônia sob chaves interpretativas próprias. A partir daí, na tese, se organiza a proposta pela qual o conceito se refere às multiplicidades que atravessam o ser humano, a natureza e as tecnologias da comunicação e informação que, inapartáveis, compõem o Ecossistema Comunicacional. Trata-se de uma abordagem ecossistêmica que considera a corporalidade das relações e as subjetividades acionadas em sociedade, tomando-as como instâncias inseparáveis amplificadas pelas tecnologias que estendem as inervações humanas para além dos limites corpóreos. Neste ponto as vivências de populações ameríndias, especialmente de povos indígenas da Amazônia e de populações tradicionais da região, que se relacionam com o ambiente de maneiras diversas das ocidentais, são o ponto de contato entre o conceito e as práticas ordinárias cotidianas: a Amazônia, por ser uma das porções do planeta onde se percebe claramente as recursivas relações entre ser humano, natureza e – pela crescente presença – tecnologias da comunicação e informação, torna-se metáfora explicativa do Ecossistema Comunicacional.
159

Towards a conceptual framework for social-ecological systems integrating biodiversity and ecosystem services with resource efficiency indicators

Eisenmenger, Nina, Giljum, Stefan, Lutter, Franz Stephan, Marques, Alexandra, Theurl, Michaela C., Pereira, Henrique M., Tukker, Arnold 25 February 2016 (has links) (PDF)
In this article we develop a comprehensive conceptual framework for resource efficiency indicators with a consistent link of resource use to the socio-economic system and activities therein as well as to the natural system and its ecosystem functioning. Three broad groups of indicators are defined: (1) resource use indicators representing pressures on the environment; (2) resource efficiency indicators relating resource use indicators to the socio-economic side; and (3) environmental impact indicators linking resource use impacts on the state of the natural system. Based on this conceptual framework we develop a structure for possible resource efficiency indicators and conduct a RACER evaluation on the Relevance, Acceptance, Credibility, Easiness and Robustness of indicators. With the RACER evaluation, we identify areas where indicators are well established and available as well as areas where indicators still need further development or even need to be designed first.
160

The impact of native and exotic plants on soil biodiversity and ecosystem function

Bird, Stephanie January 2016 (has links)
Soil biodiversity is an often overlooked component of global biodiversity, despite being important for supporting soil ecosystem services, notably decomposition processes. As the UK becomes increasingly urbanised, knowledge is required to help gardeners maximise urban green space resources for biodiversity. It is often assumed that non native vegetation has negative impacts on biodiversity, however, this hypothesis has not been tested for soil biodiversity. The overarching aims were to establish whether the geographical origin of vegetation affected soil faunal assemblages and decomposition rates for a UK soil. Traditional taxonomic methods and a molecular phylogenetic approach were used to characterise the Collembola communities of plots planted with vegetation from three geographical regions: ‘Native’, ‘Near native’ and ‘Exotic’. For comparison, additional soil cores were collected from the amenity grassland sites adjacent to the experimental plots, a lowland heath and a semi-natural woodland. No difference was found either in terms of the taxonomic diversity (1-D & H’) or phylogenetic diversity (PD & MPD) for the Collembola, under the different vegetation treatments, although differences in abundance were observed for some taxa (Acari & Collembola). Decomposition rates were assessed for each plot, using both twig (B. pendula) and leaf (Q. robur) litter bags for the soil mesofauna and bait lamina strips for earthworm activity; none of these parameters showed evidence of a vegetation origin effect on decomposition processes. The greatest differences were found when all sites were considered, with distinct Collembola communities found at each of the habitats; the semi-natural habitats had greater Collembola species diversity than the experimental plots, however, the decomposition rates of the latter were significantly higher. The implications of all results have been discussed with regards to the management of gardens for soil biodiversity, reaching the conclusion that vegetation origin is not of paramount importance.

Page generated in 0.0945 seconds