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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

Boreal vegetation responses to forestry as reflected in field trial and survey data and the quality of cover estimates and presence/absence in vegetation inventory

Bergstedt, Johan January 2008 (has links)
Den här avhandlingen belyser hur avverkning och markberedning påverkar markfloran i den svenska barrskogen. Dessutom utvärderas två inventeringsmetoder som används inom växtekologin. Vid arbetet har både rikstäckande inventeringsdata och fältförsök använts och de likartade resultaten tyder på att rikstäckande inventeringar är en underutnyttjad resurs i forskningen. Ju större andel av träden som avverkas desto större blir förändringen av markflorans sammansättning. Vissa arter, som lingon, ljung, etc., verkar dock inte påverkas i nämnvärd omfattning, medan andra, som blåbär, minskar i relation till hur mycket som avverkats. Gräs och mjölkört ökar efter avverkning, dock visar sig vissa gräs och mjölkört inte reagera om inte avverkningen överskrider ett tröskelvärde på ca 80 %. Avverkning har en liten, men signifikant, effekt på antalet arter, medan artomsättning, d.v.s. arters etablering på och/eller försvinnande från provytorna, framförallt påverkas av andel gran innan avverkning, markens produktionsförmåga och först därefter av hur stor andel av träden som avverkas. Det var också uppenbart att markberedning har en stark effekt som skiljer sig från avverkning. Framförallt gynnas björnmossor av markberedning men även vårfryle, kruståtel och mjölkört. Arter som missgynnas av markberedning var bl.a., en levermossa, lingon, väggmossa och kråkbär. I växtekologi är visuell täckningsbedömning, d.v.s. hur stor del av en provyta som täcks av en växtart, och registrering av förekomst/icke förekomst, d.v.s. finns en växtart på en provyta eller inte, de två vanligaste metoderna vid vegetationsinventering. Vid registrering av förekomst/icke förekomst missas upp till en tredjedel av förekomsterna, vanligaste orsaken till missade registreringar verkar vara att man inte upptäcker arten snarare än att den inte kan identifieras. Det var stora variationer mellan arter, där arter med få exemplar på provytan missas oftare. Både den visuella täckningsbedömningen och förekomst/icke förekomst visar sig ha personberoende fel, d.v.s. att olika personer genomgående ger högre eller lägre värden än andra. Trots det personberoende felet visar sig täckningsbedömningar ha ett större informationsvärde än registrering av förekomst/icke förekomst när det gäller att särskilja olika typer av vegetation. Erfarenhet har en förvånansvärt liten effekt på kvaliteten av täckningsbedömningar. / This thesis has two main focuses; first, the response of forest ground layer flora on forestry, mainly harvesting and secondly, the quality of the vegetation assessment methods, cover estimates by eye and presence/absence data. The effect of harvesting intensity was evaluated with survey data from permanent plots as well as vegetation data from a field trial fourteen years after harvesting. Both data sets confirmed that response of ground layer flora increased with increasing logging intensity. Thereby, indicating that survey data is possible to use in research. From the survey data set, existence of a time lag was evident for several species and also a threshold level was evident in cutting intensity needed to affect a number of species. Logging had a modest, but significant positive effect on the change in species number per plot. Species turnover was influenced by the proportion of Picea abies in the tree canopy; site productivity; and logging intensity. In the field trial scarification had a strong effect that was different from the one created by cutting. In plant ecology cover estimate by eye and presence/absence recording are the two most frequent methods used. The methods were evaluated with survey data and a field trial. In the first data set vegetation was recorded independently by two observers in 342 permanent 100-m2 plots. Overall, one third of each occurrence was missed by one of the two observers, but with large differences among species. Species occurring at low abundance tended to be frequently overlooked. Observer-explained variance in cover estimates was <10% in 15 of 17 species. In the second data set, 10 observers independently estimated cover in sixteen 100-m2 plots in two different vegetation types. The bias connected to observer varied substantially between species. The estimates of missing field and bottom layer had the highest bias, indicating that missing layers are problematic to use in analysis of change. Experience had a surprisingly small impact on the bias connected to observer. Analyses revealed that for the statistical power, cover estimates by eye carries a higher information value than do presence/absence data when distinguishing between vegetation types, differences between observers is negligible, and using more than one observer had little effect.
2

Comparing the Use of Abundance and Consistent Occupancy Measures to Predict Local Species Persistence

Grouios, Christopher 03 January 2011 (has links)
I compared the utility of two continuous time-series data measures for applied conservation biology by investigating how well each could predict future local persistence of a diverse set of bird species. I used 37 years of data from the North American Breeding Bird Survey to calculate abundance from yearly point-counts and permanence (i.e., consistent occupancy over time) from yearly presence-absence data in the early portion of the study period, then used the later portion of data to empirically evaluate how well each measure predicted persistence two decades into the future. I found that permanence could only match the ability of abundance to accurately predict local species persistence if multiple within-year repeated observations contributed to its calculation. Neither measure was effective at predicting persistence for regionally rarer species. I suggest the yearly and within-year repeated collection of abundance estimating data for use in applied conservation biology to best ensure biodiversity persistence.
3

Comparing the Use of Abundance and Consistent Occupancy Measures to Predict Local Species Persistence

Grouios, Christopher 03 January 2011 (has links)
I compared the utility of two continuous time-series data measures for applied conservation biology by investigating how well each could predict future local persistence of a diverse set of bird species. I used 37 years of data from the North American Breeding Bird Survey to calculate abundance from yearly point-counts and permanence (i.e., consistent occupancy over time) from yearly presence-absence data in the early portion of the study period, then used the later portion of data to empirically evaluate how well each measure predicted persistence two decades into the future. I found that permanence could only match the ability of abundance to accurately predict local species persistence if multiple within-year repeated observations contributed to its calculation. Neither measure was effective at predicting persistence for regionally rarer species. I suggest the yearly and within-year repeated collection of abundance estimating data for use in applied conservation biology to best ensure biodiversity persistence.
4

Rememoráveis: uma poética visual sobre a ausência e o imaginário

Campos, Luiz Claudio Ferreira January 2009 (has links)
233f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-09T16:24:49Z No. of bitstreams: 3 luisclaudiocampospt3.pdf: 36751 bytes, checksum: 27aaa05485cc7fa2baab48e3c6e9cdec (MD5) luisclaudiocampospt2.pdf: 3344070 bytes, checksum: afef5aa5743eb9dda302f662f97af4df (MD5) luisclaudiocampospt1.pdf: 1763833 bytes, checksum: 964d965a231058dac57f07466ea525d6 (MD5) / Approved for entry into archive by Lêda Costa(lmrcosta@ufba.br) on 2013-04-18T12:35:54Z (GMT) No. of bitstreams: 3 luisclaudiocampospt3.pdf: 36751 bytes, checksum: 27aaa05485cc7fa2baab48e3c6e9cdec (MD5) luisclaudiocampospt2.pdf: 3344070 bytes, checksum: afef5aa5743eb9dda302f662f97af4df (MD5) luisclaudiocampospt1.pdf: 1763833 bytes, checksum: 964d965a231058dac57f07466ea525d6 (MD5) / Made available in DSpace on 2013-04-18T12:35:54Z (GMT). No. of bitstreams: 3 luisclaudiocampospt3.pdf: 36751 bytes, checksum: 27aaa05485cc7fa2baab48e3c6e9cdec (MD5) luisclaudiocampospt2.pdf: 3344070 bytes, checksum: afef5aa5743eb9dda302f662f97af4df (MD5) luisclaudiocampospt1.pdf: 1763833 bytes, checksum: 964d965a231058dac57f07466ea525d6 (MD5) Previous issue date: 2009 / A pesquisa sistematiza o processo de confecção de objetos com abordagem diferenciada sobre relíquia, memória e história, na intenção de transpor limites ao uso de materiais e técnicas de arte, conceituando em reflexões prático-teóricas lembranças e recordações, portanto uma poética que traz a “ausência” do imaginário, tecido de memória, distância, passado e saudade. A importância de se trabalhar com relíquias em linguagens artísticas reside na visibilidade da aproximação das distâncias entre o passado e o presente, trazendo ao contemporâneo o significado do passado como alicerce de nossas ações. Tomando como base o processo de criação na construção da obra de arte discutido por Cecília Salles, assumo o conceito de criação em rede como, forma de compreender as implicações em adotar essa perspectiva ao pensar na prática artística. Esses modos de “pensar” e “fazer” serviram de guia e, até mesmo, contribuíram para que a escolha dos materiais na elaboração das obras acontecesse a partir do momento que o suporte pudesse dialogar com o conceito. Imaginei cada obra e as registrei em estudos, desenhos, rascunhos que serviram para elaborar as peças. As modificações sofridas durante a gênese de uma delas é a evidência de que esse processo é ativo e repleto de diversas possibilidades. Fatos lembrados e vividos foram agregados às obras, de forma consciente ou não, transformando as peças marcadas pela ausência de temporalidade no pensamento e ato criador em registros do passado. Tomo Santo Agostinho e Henri-Louise Bergson como Filósofos norteadores para compreender as questões relacionadas ao tempo e a memória. Em momentos específicos recorro a Merleau-Ponty (aspectos fenomenológicos) e Gaston Bachelard (aspectos relacionados ao mobiliário). Faço aproximações e distanciamentos com obras de artistaspesquisadores, como Joseph Cornell, Farnese de Andrade, Sebastião Pedrosa, Graziano Spinosi, Anish Kapoor, Eriel Araújo, Graça Ramos e VigaGordilho. As reflexões e a prática no atelier apontaram caminhos e possíveis soluções que abraçam o dialogo com o espectador para conquista de novos conhecimentos. A síntese das pesquisas foi mostrada na exposição Rememoráveis, com a apresentação de três objetos e seis instalações. / Salvador
5

North American River Otter (<i>Lontra canadensis</i>) Presence and Habitat Analysis in Florida as Compared to Historical Data

Wilber, Samantha 05 November 2015 (has links)
North American river otters are considered common in the state of Florida, but their populations have not been studied since the 1980’s. Since that time, Florida’s human population has more than doubled, and many natural areas of Florida have been developed. The aim of this study was to determine the presence or absence of river otters at locations in Florida which they historically inhabited. Forty-six sample sites where otters were historically found were obtained from the Florida Museum of Natural History Mammals Master Database (FMNH MMD). These sites were condensed to two focus areas, in and around Alachua and Collier Counties, where the sites were most highly clustered. Each site was surveyed to determine the presence or absence of river otters and to determine the suitability of the site’s environment for otter habitation. Sites with favorable habitat features for otters were surveyed a second time. River otters were not found at any site. Only 9 of the 46 sites had permanent water and only 8 of those had other habitat features preferred by otters. Therefore, only 17.39% of sites that historically supported otters likely still have the ability to do so. Loss of water over time is most likely the result of human disturbances such as the draining, damming, and canalizing of wetlands. As a result of this loss of natural habitat, river otters have become increasingly common in urban areas wither preferred habitat features, even if they are man-made. The increased presence near humans may have led to the apparently inaccurate assumption that otters are common, and, therefore, do not need protection.
6

Efeito da Presença/Ausência de Modelos na Formulação de Regras e Resolução de Problemas

Rocha, Letícia Nunes 30 May 2012 (has links)
Made available in DSpace on 2016-07-27T14:19:56Z (GMT). No. of bitstreams: 1 Leticia Nunes Rocha.pdf: 697434 bytes, checksum: 34284c59faa2286d63eff01af4a6082e (MD5) Previous issue date: 2012-05-30 / The aim of this study was to evaluate the effect of the presence/absence variables about the behavior model to solve problems and formulate rules. Twenty-four participants (6 in each of the experiments I and II and 12 in experiment III) were exposed to a task that was to organize a sequence of colors. The first experiment consisted of three conditions: a) presence of the model at the moment to answer, b) absence of the model and detailed instructions, c) absence of the model. Experiment II was almost identical to the previous one, except in the second condition, where the models were present and the participant had detailed instructions. Yet the experiment III was conducted with two groups of participants. In Group A, the models were present of the answer of the participant, in contrast to Group B, where the models were absent. In this experiment no participant had access to any instruction. The results suggest that the presence of the model facilitates the behavior for the solution of problems. / O objetivo do presente estudo foi avaliar o efeito das variáveis presença/ ausência de modelo sobre o comportamento de resolver problemas e formular regras. Vinte e quatro participantes (6 nos experimentos I e II e 12 no Experimento III) foram expostos a uma tarefa que consistia em organizar uma sequência de cores. O Experimento I era constituído de três Condições: a) presença do modelo no momento do responder; b) ausência do modelo + instruções detalhadas; c) ausência do modelo. O Experimento II era praticamente idêntico ao anterior, exceto que na segunda condição, onde os modelos estavam presentes e o participante dispunha de instruções detalhadas. Já o Experimento III, foi realizado com 2 grupos de participantes. No Grupo A, os modelos estavam presentes no momento do participante responder, ao contrario do Grupo B, onde os modelos estavam ausentes. Neste Experimento nenhum participante tinha acesso a qualquer instrução. Os resultados sugerem que a presença do modelo facilita o comportamento de resolução de problemas.
7

Percorrendo o conjunto da obra do artista Tony Smith: entre a década de 1960 à 1970 / The present thesis proposes a trajectory through the work collection created by the north-american artist Tony Smith from 1960 to 1970

Dalacorte, Tereza Cristina Faria 15 September 2017 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-03-29T11:22:56Z No. of bitstreams: 2 Dissertação - Tereza Cristina Faria Dalacorte - 2017.pdf: 4102159 bytes, checksum: fd7c2399b73c06baadf93f9849ec03f5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-03-29T11:40:39Z (GMT) No. of bitstreams: 2 Dissertação - Tereza Cristina Faria Dalacorte - 2017.pdf: 4102159 bytes, checksum: fd7c2399b73c06baadf93f9849ec03f5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-03-29T11:40:39Z (GMT). No. of bitstreams: 2 Dissertação - Tereza Cristina Faria Dalacorte - 2017.pdf: 4102159 bytes, checksum: fd7c2399b73c06baadf93f9849ec03f5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-09-15 / The present thesis proposes a trajectory through the work collection created by the North- American author Tony Smith from 1960 to 1970. The examination of this interval of his artwork is developed based on a bibliographical approach of the life and work of the same era in terms of the aesthetic and historical time in North-America. In addition, this thesis also investigates the interrelation of the analytical aspects of the theme and attempts make a critical review or essay on the topic, as it proposes not only an objective analysis of the subject but also a consideration on the poetic observed in the in the studied artworks. This reflection is built according to the paradox presence/absence of the artworks in the space they occupy. Such cogitation also takes into consideration the fact that the blackness of these artwork volumes could possibly confront their own existences. Finally, this research concentrates on the analysis of the expansion of Tony Smith's artwork in relation to both architectonic and urban spaces, with implications on their possible dialects and/or confrontations. / O projeto desta dissertação propõe um percurso pelo conjunto da obra do artista norte-americano Tony Smith produzidas entre a década de 1960 à 1970. Este recorte é desenvolvido mediante uma abordagem bibliográfica das obras e vida do artista inter-relacionado ao contexto estético e histórico norte-americano do período. No entanto o projeto é também uma inter-relação entre análise e ensaio, pois aqui desenvolvemos não apenas um levantamento objetivo como tambémuma reflexão a respeito da poética a qual percebemos nas obras analisadas. Tal reflexão é construída segundo o paradoxo presença e/ou ausência das obras no espaço que as contêm, considerando também que o negrume de suas volumetrias possivelmente confrontariam sua própria existência. A pesquisa se estende ainda na análise da expansão das obras e sua relação com o espaço arquitetônico e urbano, implicando suas possíveis dialéticas e/ou confrontos.
8

Observer error in identifying species using indirect signs: analysis of a river otter track survey technique

Evans, Jonah Wy 17 September 2007 (has links)
Indirect signs of species presence (e.g., tracks, scats, hairs) are frequently used to detect target species in occupancy, presence/absence, and other wildlife studies. Indirect signs are often more efficient than direct observation of elusive animals, making such signs well suited for long-term and broad-scale monitoring programs. However, error associated with misidentification of indirect signs can be high, and should be measured if meaningful inferences about population parameters are to be made. This study addressed the need for systematic approaches to estimate and minimize variation due to observer error in identifying indirect signs. I reanalyzed data from 4 replicates of a presence/absence survey of northern river otters (Lontra canadensis) that had been conducted by Texas Parks and Wildlife Department (1996-2003). Sixteen observers had recorded tracks at sample points under bridges (n = 250) distributed throughout 27 counties in the Piney-Woods ecoregion of east Texas. My objectives were to 1) determine if observers were a source of bias in the survey, 2) estimate the proportion of error associated with track identification skill, and 3) evaluate the use of an international certification procedure that measured observer tracking skill. The null hypothesis that observers had no effect on the variation in reported sign was rejected. Indeed, binary logistic regression tests indicated that observers were significantly associated with variation in reported track presence. Observers were not randomly distributed among bridge sites, and therefore were significantly correlated with 4 habitat variables that may have influenced heterogeneity in otter occupancy and probability of detection (watershed, vegetation-type, water-type, bridge-area). On average, experienced observers (n = 7) misidentified 44% of otter tracks, with a range of 0% to 100% correct detection. Also, 13% of the tracks of species determined to be 'otter-like' were misidentified as belonging to an otter. During the certification procedure, participants misidentified the tracks of 12 species as otter. Inaccurate identification of indirect signs is a likely source of error in wildlife studies. I recommend that observer skill in identification of indirect signs be measured in order to detect and control for observer bias in wildlife monitoring.
9

Eliciting Expert Knowledge for Bayesian Logistic Regression in Species Habitat Modelling

Kynn, Mary January 2005 (has links)
This research aims to develop a process for eliciting expert knowledge and incorporating this knowledge as prior distributions for a Bayesian logistic regression model. This work was motivated by the need for less data reliant methods of modelling species habitat distributions. A comprehensive review of the research from both cognitive psychology and the statistical literature provided specific recommendations for the creation of an elicitation scheme. These were incorporated into the design of a Bayesian logistic regression model and accompanying elicitation scheme. This model and scheme were then implemented as interactive, graphical software called ELICITOR created within the BlackBox Component Pascal environment. This software was specifically written to be compatible with existing Bayesian analysis software, winBUGS as an odd-on component. The model, elicitation scheme and software were evaluated through five case studies of various fauna and flora species. For two of these there were sufficient data for a comparison of expert and data-driven models. The case studies confirmed that expert knowledge can be quantified and formally incorporated into a logistic regression model. Finally, they provide a basis for a thorough discussion of the model, scheme and software extensions and lead to recommendations for elicitation research.
10

Ecological knowledge towards sustainable forest management:habitat requirements of the Siberian flying squirrel in Finland

Hurme, E. (Eija) 18 November 2008 (has links)
Abstract Maintaining biodiversity in boreal forest landscapes in conjunction with forestry is a challenging task. This requires ecological understanding that is based on empirical research. In this thesis, I examined spatial and temporal occupancy patterns as well as predictability of the occurrence of the Siberian flying squirrel (Pteromys volans L.) in Finland. I used thematic maps which matched habitat requirements of the flying squirrel in forested landscapes and data on species presence and absence, which were gathered in suitable forest habitats. The results of this thesis provide applications for landscape management. First, the preferred habitat characteristics of the flying squirrel were linked to available forest data. In addition, some predictive habitat models could be used to estimate the distribution of the flying squirrel within a region. Second, based on a five year study the forests were classified as continuously occupied, continuously unoccupied and variable-occupancy patches. The dynamic occupancy pattern emphasizes the need for repeated surveys to also locate the seldom-used suitable habitats in a landscape. Third, a comparison of simulated future scenarios in long-term forest planning suggested that flying squirrel habitat might be maintained without considerable loss of timber in a landscape. Thus, a combination of ecological and economic goals in forestry planning is an encouraging alternative. Fourth, there were more polypore species in forests occupied by the flying squirrel. This suggests that conservation of the flying squirrel habitats would protect other naturally co-occurring species, and thus the flying squirrel could be assigned as an umbrella species in mature spruce-dominated forests. Based on these findings, I suggest that the flying squirrel could be used as one of the target species for forest management in boreal forest landscapes. Further research challenges are related to the examination of habitat thresholds and to the projection of future scenarios where ecological, economic and social aspects are combined to assist in complex decision making processes.

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