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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

Investigation of allelopathy in an invasive introduced tree species, Norway maple (Acer platanoides L.) /

Rich, Elizabeth L. Kilham, Susan Soltau. January 1900 (has links)
Thesis (Ph. D.)--Drexel University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 106-116).
2

Polygenic adaptation after a sudden change in environment

Hayward, Laura K. January 2020 (has links)
Polygenic adaptation in response to selection on quantitative traits is thought to be ubiquitous in humans and other species, yet this mode of adaptation remains poorly understood. We investigate the dynamics of this process, assuming that a sudden change in environment shifts the optimal value of a highly polygenic quantitative trait. We find that when the shift is not too large relative to the genetic variance in the trait and this variance arises from segregating loci with small to moderate effect sizes (defined in terms of the selection acting on them before the shift), the mean phenotype's approach to the new optimum is well approximated by a rapid exponential process first described by Lande (1976). In contrast, when the shift is larger or large effect loci contribute substantially to genetic variance, the initially rapid approach is succeeded by a much slower one. In either case, the underlying changes to allele frequencies exhibit different behaviors short and long-term. Over the short term, strong directional selection on the trait introduces small differences between the frequencies of minor alleles whose effects are aligned with the shift in optimum versus those with effects in the opposite direction. The phenotypic effects of these differences are dominated by contributions from alleles with moderate and large effects, and cumulatively, these effects push the mean phenotype close to the new optimum. Over the longer term, weak directional selection on the trait can amplify the expected frequency differences between opposite alleles; however, since the mean phenotype is close to the new optimum, alleles are mainly affected by stabilizing selection on the trait. Consequently, the frequency differences between opposite alleles translate into small differences in their probabilities of fixation, and the short-term phenotypic contributions of large effect alleles are largely supplanted by contributions of fixed, moderate ones.
3

How well does EIA project the biodivisity in Hong Kong?.

January 2001 (has links)
Chan Kit-ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 125-133). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.v / Table of Contents --- p.vi / List of Tables --- p.x / List of Figures --- p.xii / List of Plates --- p.xiii / List of Appendixes --- p.xiv / Abbreviations --- p.xv / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Organization of Study --- p.5 / Chapter 1.2.1 --- Stage One -Literature Review --- p.5 / Chapter 1.2.2 --- Stage Two - Review of EI A Reports and Case Studies of Ecological Mitigation/Compensation Measures --- p.5 / Chapter 1.2.3 --- Stage Three - Evaluation and Recommendations --- p.6 / Chapter 1.3 --- Chapter Outlines --- p.6 / Chapter CHAPTER 2 --- BACKGROUND OF STUDY / Chapter 2.1 --- Introduction --- p.9 / Chapter 2.2 --- Definitions --- p.9 / Chapter 2.3 --- The Ecological Impact Assessment Process --- p.10 / Chapter 2.3.1 --- Baseline Study and Scoping --- p.10 / Chapter 2.3.2 --- Impact Prediction and Evaluation --- p.11 / Chapter 2.3.3 --- Mitigation --- p.11 / Chapter 2.3.4 --- Environmental Monitoring and Auditing --- p.12 / Chapter 2.4 --- Ecological Impact Assessment in Hong Kong --- p.12 / Chapter 2.5 --- Problems of Ecological Impact Assessment --- p.16 / Chapter 2.6 --- Compensatory Mitigation --- p.19 / Chapter CHAPTER 3 --- METHDOLOGY AND STUDY AREA / Chapter 3.1 --- Introduction --- p.21 / Chapter 3.2 --- Critical Review of EIA Reports --- p.23 / Chapter 3.2.1 --- Methodology --- p.23 / Chapter 3.3 --- Case Studies of Compensatory Wetlands --- p.29 / Chapter 3.3.1 --- Selection of Ecological Compensation Projects --- p.29 / Chapter 3.3.2 --- Study Sites --- p.30 / Chapter 3.3.2.1 --- Climate --- p.30 / Chapter 3.3.2.2 --- Compensatory Fishponds at Au Tau Interchange --- p.32 / Chapter 3.3.2.3 --- Compensatory Mangrove at Main Drainage Channel --- p.34 / Chapter 3.3.2.4 --- Compensatory Mangrove at Kau Sai Chau --- p.36 / Chapter 3.3.3 --- Methods to Assess Ecological Functionality --- p.37 / Chapter 3.3.3.1 --- Bird Use of the Au Tau Compensatory Ponds --- p.39 / Chapter 3.3.3.2 --- Habitat and Vegetation Mapping --- p.41 / Chapter 3.3.3.3 --- Statistical Analysis --- p.43 / Chapter 3.3.4 --- Vegetation Performance and Soil Properties of Compensatory Mangroves --- p.45 / Chapter 3.3.4.1 --- Vegetation Sampling --- p.45 / Chapter 3.3.4.2 --- Statistical Analysis --- p.47 / Chapter 3.3.4.3 --- Soil Properties --- p.47 / Chapter 3.3.4.4 --- Statistical Analysis --- p.52 / Chapter CHAPTER 4 --- CRITICAL REVIEW OF ECOLOGICAL STATEMENTS / Chapter 4.1 --- Introduction --- p.53 / Chapter 4.2 --- Nature of the Projects Reviewed --- p.54 / Chapter 4.3 --- Quality of the Ecological Assessment --- p.56 / Chapter 4.3.1 --- Ecological Baseline Study --- p.56 / Chapter 4.3.2 --- Impact Predictions --- p.59 / Chapter 4.3.3 --- Mitigation --- p.63 / Chapter 4.3.4 --- Environmental Monitoring and Auditing --- p.67 / Chapter 4.3.5 --- Differences in Ecological Statements before and after EIAO --- p.67 / Chapter 4.4 --- Discussion --- p.69 / Chapter 4.4.1 --- Ecological Baseline Study and Scoping --- p.69 / Chapter 4.4.2 --- Impact Predictions --- p.71 / Chapter 4.4.3 --- Environmental Mitigation and Monitoring --- p.72 / Chapter CHAPTER 5 --- PROMISES AND REALITIES OF ECOLOGIAL COMPENSATORY SCHEMES / Chapter 5.1 --- Introduction --- p.76 / Chapter 5.2 --- Mangrove Communities at KSC and MDC --- p.77 / Chapter 5.2.1 --- Vegetation Performance --- p.77 / Chapter 5.2.2 --- Soil Properties --- p.81 / Chapter 5.2.3 --- Discussion of the Overall Performance --- p.85 / Chapter 5.3 --- Compensatory Fishponds --- p.91 / Chapter 5.3.1 --- Bird Use at Au Tau Compensatory Fishponds --- p.91 / Chapter 5.3.2 --- Total Bird Counts --- p.93 / Chapter 5.3.3 --- Species Composition --- p.94 / Chapter 5.3.4 --- Avian Density --- p.96 / Chapter 5.3.5 --- Species Diversity --- p.101 / Chapter 5.3.6 --- Discussion of Au Tau Compensatory Ponds --- p.102 / Chapter 5.4 --- Discussion --- p.107 / Chapter CHAPTER 6 --- CONCLUSION / Chapter 6.1 --- Major Findings --- p.111 / Chapter 6.2 --- Discussion of Findings --- p.114 / Chapter 6.3 --- Recommendations --- p.119 / REFERENCES --- p.125 / APPENDIXES --- p.134
4

A comparison of three rapid evaluation procedures for pine savanna wetlands

Henderson, Cynthia Joan. January 2001 (has links)
Thesis (M.S.)--Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.
5

Derivation of near-shore bathymetry from multispectral satellite imagery used in a coastal terrain model for the topographic analysis of human influence on coral reefs /

Hogrefe, Kyle Richard. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.
6

Environmental impacts and the ecology of sponges and ascidians in south-eastern Australian coastal lakes and lagoons

Barnes, Peter Brendan. January 2009 (has links)
Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 146-171.
7

Ecological modeling of the lower trophic levels of Lake Erie

Zhang, Hongyan, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 211-226).
8

Set-back distances to protect nesting and roosting seabirds off Vancouver Island from boat disturbance

Chatwin, Trudy 16 September 2010 (has links)
In order to set guidelines that promote responsible wildlife viewing, I quantified the effects of boat-based disturbance to seabirds off Vancouver Island. Field trials recorded the approach distance at which roosting and nesting birds responded to either a motor boat or a kayak. Probability of agitation response was used to evaluate disturbance. At a distance of 40 m nesting Double-crested Cormorants, Pelagic Cormorants, Glaucous-winged Gulls, Pigeon Guillemots and Black Oystercatchers had less than an 8% chance of being agitated with either a kayak or motorboat approach. Roosting birds had longer response distances. Harlequin Ducks were particularly sensitive with a 25% probability of agitation at distances less than 50 m. Agitation distances were reduced by habituation to boat traffic. A set-back guideline of 50 m would protect most nest and roost sites in the study area while allowing viewers to appreciate seabirds. Some sensitive sites would require 70 m set-backs.
9

Ecological impact assessment: post-project analysis of pipeline installation.

January 2001 (has links)
Leung Hoi-gok. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 188-205). / Abstracts in English and Chinese. / Abstract --- p.i / 槪論 --- p.iv / Acknowledgements --- p.vi / List of Tables --- p.vii / List of Figures --- p.viii / List of Plates --- p.ix / List of Appendices --- p.x / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- The Problems --- p.6 / Chapter 1.3 --- Conceptual Framework --- p.10 / Chapter 1.4 --- Significance of the Study --- p.15 / Chapter 1.5 --- Scope of Study --- p.17 / Chapter 1.6 --- Organization of the Thesis --- p.19 / Chapter CHAPTER 2 --- STUDY AREA / Chapter 2.1 --- Physical Setting of Hong Kong --- p.22 / Chapter 2.2 --- "Towngas Pipeline Project, the Land Section" --- p.25 / Chapter 2.3 --- Study Plots --- p.30 / Chapter 2.4 --- Observation on the Site --- p.39 / Chapter 2.5 --- Post-planting Care --- p.40 / Chapter CHAPTER 3 --- SOIL PROPERTIES AND IMPACTS BY PIPELINE CONSTRUCTION / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Methodology --- p.47 / Chapter 3.2.1 --- Sampling --- p.47 / Chapter 3.2.2 --- Bulk density --- p.48 / Chapter 3.2.3 --- Soil texture --- p.43 / Chapter 3.2.4 --- Soil reaction --- p.49 / Chapter 3.2.5 --- Organic carbon --- p.49 / Chapter 3.2.6 --- Total Kjedahl nitrogen (TKN) --- p.50 / Chapter 3.2.7 --- Available phosphate --- p.50 / Chapter 3.2.8 --- "Exchangeable K, Ca and Mg" --- p.50 / Chapter 3.3 --- Statistical Analysis --- p.51 / Chapter 3.4 --- Results --- p.51 / Chapter 3.4.1 --- Soil texture --- p.51 / Chapter 3.4.2 --- Bulk density --- p.53 / Chapter 3.4.3 --- Soil pH --- p.53 / Chapter 3.4.4 --- Soil organic matter --- p.55 / Chapter 3.4.5 --- Total Kjeldahl nitrogen --- p.55 / Chapter 3.4.6 --- Available phosphorus --- p.59 / Chapter 3.4.7 --- "Exchangeable potassium, calcium and magnesium ions" --- p.59 / Chapter 3.5 --- Discussion --- p.64 / Chapter 3.5.1 --- Nutrient content of shoulder and proper soils --- p.64 / Chapter 3.5.2 --- Causes for the change of soil properties --- p.72 / Chapter 3.5.2.1 --- Construction of the pipeline --- p.72 / Chapter 3.5.2.2 --- Influence of localized factors --- p.74 / Chapter 3.5.3 --- Recommendations on soil management --- p.75 / Chapter 3.6 --- Conclusion --- p.77 / Chapter CHAPTER 4 --- SPECIES SELECTION IN RESTORATION PLANTING / Chapter 4.1 --- Introduction --- p.79 / Chapter 4.2 --- Methodology --- p.83 / Chapter 4.2.1 --- Vegetation sampling --- p.83 / Chapter 4.3 --- Results --- p.85 / Chapter 4.3.1 --- Species composition of the undisturbed habitats --- p.85 / Chapter 4.3.2 --- Species composition of the restored vegetation --- p.88 / Chapter 4.4 --- Discussion --- p.95 / Chapter 4.4.1 --- Inadequate baseline and impact prediction in project EIA --- p.95 / Chapter 4.4.2 --- Restoration strategy --- p.98 / Chapter 4.4.3 --- Species selection in restoration planting --- p.101 / Chapter 4.4.4 --- Compatibility of species in restoration planting --- p.105 / Chapter 4.5 --- Conclusion --- p.110 / Chapter CHAPTER 5 --- GROWTH PERFORMANCE OF VEGETATION AND NATURAL INVASION IN THE SITES / Chapter 5.1 --- Introduction --- p.112 / Chapter 5.2 --- Methodology --- p.117 / Chapter 5.3 --- Results --- p.119 / Chapter 5.3.1 --- Growth performance of shrubs and trees --- p.119 / Chapter 5.3.2 --- Ground cover --- p.131 / Chapter 5.3.3 --- Species invading the pipeline corridor --- p.132 / Chapter 5.4 --- Discussion --- p.133 / Chapter 5.4.1 --- Growth performance of the restored saplings --- p.133 / Chapter 5.4.2 --- Site constraints --- p.135 / Chapter 5.4.3 --- Natural invasion on the pipeline corridor --- p.140 / Chapter 5.5 --- Conclusion --- p.141 / Chapter CHAPTER 6 --- RESTORATION TECHNIQUES AND MANAGEMENT / Chapter 6.1 --- Introduction --- p.144 / Chapter 6.2 --- Overview of the Project EIA --- p.146 / Chapter 6.2.1 --- Guidelines for site preparation --- p.146 / Chapter 6.2.2 --- Planting techniques of the restored vegetation --- p.148 / Chapter 6.2.3 --- Maintenance and aftercare --- p.149 / Chapter 6.3 --- Evaluation on Restoration Techniques and Aftercare --- p.149 / Chapter 6.3.1 --- Site preparation --- p.149 / Chapter 6.3.2 --- Restoration techniques of the vegetation --- p.151 / Chapter 6.4 --- Conclusion --- p.153 / Chapter CHAPTER 7 --- IMPROVEMENT ON ECOLOGICAL IMPACT ASSESSMENT / Chapter 7.1 --- Introduction --- p.154 / Chapter 7.2 --- Integrative Discussion --- p.156 / Chapter 7.2.1 --- Scoping and focusing procedures --- p.156 / Chapter 7.2.2 --- Impact assessment --- p.160 / Chapter 7.2.3 --- Impact mitigation --- p.161 / Chapter 7.2.4 --- Monitoring and auditing --- p.165 / Chapter 7.2.5 --- Guidelines of restoration in the technical memorandum of EIAO --- p.167 / Chapter 7.3 --- Conclusion --- p.169 / Chapter CHAPTER 8 --- CONCLUSION / Chapter 8.1 --- Summary of Findings --- p.171 / Chapter 8.2 --- Implications of the Study --- p.179 / Chapter 8.2.1 --- Criteria for the selection of species in restoration --- p.179 / Chapter 8.2.2 --- Silvicultural knowledge of native species --- p.180 / Chapter 8.2.3 --- Soil impact assessment for project involving soil alternation --- p.182 / Chapter 8.2.4 --- Improvement on environmental monitoring and auditing --- p.182 / Chapter 8.3 --- Limitation of the Study --- p.183 / Chapter 8.4 --- Suggestion for Further Studies --- p.185 / REFERENCES --- p.188 / APPENDICES --- p.206
10

Rapid bioassessment of the ecological integrity of the Lourens, Palmiet and Hout Bay Rivers (South Western Cape, South Africa) using aquatic macroinvertebrates

Ollis, Dean Justin 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The primary aim of this study was to assess and compare the ecological integrity of the Lourens, Palmiet and Hout Bay Rivers (South Western Cape, South Africa) by examining the macroinvertebrate community structure at a series of representative sampling sites along the course of each river, using the South African Scoring System - Version 5 (SASS-5) rapid bioassessment method. Secondary aims included an examination of the effects of seasonal variability, biotope availability and site-specific environmental variables on the macroinvertebrate community structure at sampling sites, as well as the preliminary testing of the Integrated Habitat Assessment System (IHAS) for aquatic macroinvertebrates. According to results obtained, the ecological integrity of sampling sites in the Mountain Stream Zone of the three rivers was consistently good. The Hout Bay River in the upper portions of the Orange Kloof Reserve was particularly near-pristine, with this area having been identified in this study as a potential biodiversity ‘hot-spot’ for aquatic macroinvertebrates. Downstream of the Mountain Stream Zone, there was a significant deterioration in the ecological integrity of all three rivers due to a number of probable causes. Results based on recorded SASS Scores and Average Score per Taxon (ASPT) values, using ‘biological bands’ generated from reference sites in the South Western Cape, were generally similar to and supported by the corresponding multivariate analyses undertaken. From the results of the various analyses undertaken in this investigation and some of the problems encountered in interpreting the data, a number of recommendations are made regarding future bioassessment studies based on the SASS within the national River Health Programme (RHP). To test the IHAS, secondary data were obtained from reference sites in the Mpumalanga and Western Cape Provinces of South Africa. Assuming that SASS Scores at reference sites are the highest scores attainable, one would expect to find a positive relationship between SASS Scores and IHAS scores at reference sites. The assumption in this investigation was that this relationship should be linear. Non-parametric correlation analyses were undertaken between SASS-4/5 Scores and IHAS scores, using Kendall’s Rank-correlation Coefficient (τ), with separate analyses undertaken for different geomorphological zones and biotope groups. Correlations between SASS Scores and IHAS scores were generally weak (τ-values mostly < 0.3) and unsatisfactory, with no significant correlations (p < 0.05) for two-thirds of the data sets analysed and a wide degree of scatter generally observed amongst data points in respective scatter plots. The performance of the IHAS varied between geomorphological zones and biotope groups, with the Foothill: Gravel-bed Zone in Mpumalanga showing the best results, particularly when the stones-in-current biotope group was analysed separately. Further testing of the IHAS is required to confirm its relative performance in different bioregions/ecoregions, geomorphological zones and biotope groups, which should be undertaken as a priority research area within the RHP. Unsuccessful attempts to test the IHAS by means of multiple regression analyses were undertaken, suggesting that such techniques should be avoided in further testing of the IHAS. / AFRIKAANSE OPSOMMING: Die hoofdoel van hierdie studie was om die ekologiese toestand van die Lourens-, Palmiet- en Houtbaairiviere (Suidwes Kaap, Suid Afrika) te bepaal en te vergelyk deur die bestudering van die makroinvertebraatgemeenskapstruktuur by verteenwoordigende monsterpunte langs die riviere, met gebruik van die “South African Scoring System” – Weergawe 5 (SASS-5) snelle biologiese bepalingsmetode. Sekondêre doelwitte het die bepaling van die gevolge van seisoenele veranderlikheid, biotoop beskikbaarheid en ligging-bepaalde omgewingsveranderlikes op die makroinvertebraatgemeenskapstruktuur by monsterpunte ingesluit, asook die inleidende toetsing van die “Integrated Habitat Assessment System” (IHAS) vir watermakroinvertebrate. Volgens die resultate verkry, was die ekologiese toestand van monsterpunte in die Bergstroomsone van die drie riviere konsekwent goed. Die Houtbaairivier in die boonste gedeelte van die Oranjekloofreservaat was veral feitlik onversteurd en hierdie streek is in die studie as ‘n potensiaal biodiversiteit “hot-spot” vir watermakroinvertebrate geidentifiseer. Stroomafwaarts van die Bergstroomsone was daar ‘n beduidende verswakking in die ekologiese toestand van al drie riviere, as gevolg van ‘n aantal moontlike oorsake. Resultate gebaseer op bepaalde “SASS Scores” en ‘Gemiddelde Waarde per Takson’ (“Average Score per Taxon” - ASPT) waardes, met gebruik van ‘biologiese bande’ wat van verwysingsmonsterpunte in die Suidwes Kaap afgelei is, was oor die algemeen soortgelyk aan en gestaaf deur die ooreenstemmende multiveranderlikke (“multivariate”) statistiese analises wat gedoen is. Uit die resultate van die verskeie analises wat in hierdie ondersoek gedoen is en sommige van die probleme wat in die dataverklaring gevind is, is ‘n aantal aanbevelings gemaak met betrekking tot toekomende biologiese bepalingstudies vir die nasionale Riviergesondheidsprogram (“River Health Programme” - RHP) wat op die SASS gebaseer is. Om die IHAS te toets is sekondêre data van verwysingsmonsterpunte in die Mpumalanga en Wes Kaap Provinsies van Suid Afrika verkry. As aangeneem word dat die “SASS Scores” by verwysingsmonsterpunte die hoogste moontlike tellings is wat bereik kan word, sou ‘n positiewe verwantskap tussen “SASS Scores” en IHAS tellings by verwysingsmonsterpunte verwag word. Die veronderstelling in hierdie studie was dat dié verwantskap lineêr moet wees. Nie-parametriese korrelasieanalise tussen “SASS-4/5 Scores” en IHAS tellings is gemaak, deur gebruik van Kendall se Rangkorrelasiekoëffisiënt (τ), met afsonderlike analises vir verskillende geomorfologiese sones en biotoopgroepe verrig. Korrelasies tussen “SASS Scores” en IHAS tellings was algemeen swak (τ-waardes < 0.3) en onbevredigend, met geen beduidende korrelasies (“p” < 0.05) vir twee-derdes van die datastelle wat geanaliseer is nie en ‘n wye verspreiding tussen datapunte in die onderskeie “scatter plots” wat waargeneem is. Die funksionering van die IHAS was verskillend tussen geomorfologiese sones en biotoopgroepe. Die beste resultate is vir die Voorheuwel: Gruisbeddingsone in Mpumalanga verkry, veral indien die klippe-in-stroom biotoopgroep afsonderlik geanaliseer is. Verdere toetsing van die IHAS is nodig om die relatiewe funksionering in verskillende biostreke/”ecoregions”, geomorfologiese sones en biotoopgroepe te bevestig en dit behoort voorangs te geniet binne die RHP. Pogings om die IHAS deur middel van veelvoudige regressie analise te toets het misluk, wat aandui dat sulke tegnieke vermy moet word in verder toetsing van die IHAS.

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