Spelling suggestions: "subject:"1arget species"" "subject:"darget species""
11 |
Strengthening Urban Green: Using Green Infrastructure for Biodiversity Improvement in Boston's Highly Fragmented Urban EnvironmentsMantle, Christopher L 01 January 2010 (has links) (PDF)
Increasing recognition of the worlds' expanding population and current global rural-to-urban migration necessitates a better understanding and integration of urban ecological process into the framework for urban design (Sandström, 2006). Incorporating ecological processes such as resilience and dispersal into urban design requires special attention be paid to green infrastructure for the preservation and restoration of biodiversity. In addition, biodiversity improvement promotes related ecosystem services (Opdam et al., 2006) and advocates biodiversity conservation and strengthening as a key part of the development of sustainable urban landscapes.
This research developed a replicable and broadly applicable method for determining the ability of green infrastructure to increase abundance of the three target species, and by extension, biodiversity. By applying the urban biodiversity assessment method, green infrastructure can be designed to build neighborhood scale urban ecological networks, specifically designed for the target species in Boston’s highly fragmented urban landscapes.
Green infrastructures such as urban parks, riparian corridors, street trees, and unused abandoned land have the ability to serve as important reserves of biodiversity. Using the spatial pattern analysis program FRAGSTATS, the assessment of green infrastructure demonstrates its potential for increasing biodiversity of three target species (Red-tailed Hawk, Song Sparrow, and Variegated Fritillary). The comparative analysis of the existing green infrastructure with the proposed scenarios will determine their potential for species-specific neighborhood scale biodiversity improvement. Additionally, the comparison of the proposed scenarios and their rating helps provide valuable information regarding the spatial configuration of green infrastructure and the effect that it can have on target species.
|
12 |
Response of selected non-target Lepidoptera, Coleoptera and Diptera species to Cry1Ab protein expressed by genetically modified maize / Annemie ErasmusErasmus, Annemie January 2010 (has links)
The environmental impacts of genetically modified (GM) crop plants such as Bt (Bacillus
thuringiensis) maize have not yet been fully assessed in South Africa. Bt maize designed
to express Bt endotoxin for control of Busseola fusca (Fuller) (Lepidoptera: Noctuidae)
and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is planted on approximately
1.103 million hectares in South Africa. The monitoring of GM crops after release is
important in order to assess and evaluate possible environmental effects. No risk
assessment for Bt maize was done in South Africa before its release in 1998 and no
targeted post-release monitoring of possible resistance development or impact on non-target
species have been done. Awareness has risen in South Africa through research
highlighting the possible effects GM crops may have. The aim of this study was to
determine, through feeding experiments, the effects of Bt maize on selected non-target
Lepidoptera, Coleoptera and Diptera species that occur in maize agro-ecosystems in
South Africa. Results provide information for use in future risk assessment studies on Bt
maize and indicate which species could possibly be of importance in post-release
monitoring of Bt maize. Priority insect species were identified and laboratory- and semifield
experiments were conducted to evaluate the effect of Bt maize on these species. In
the light of the reportedly lower toxicity of Bt maize to certain noctuid borers, the effect
of Bt maize was evaluated on Sesamia calamistis (Hampson), Agrotis segetum (Denis &
Schiffermüller), and Helicoverpa armigera (Hubner). Feeding studies were also
conducted to determine the effect of Bt maize on non-target Coleoptera, i.e.
Heteronychus arator Fabricius (Coleoptera: Scarabaeidae) and Somaticus angulatus
(Fahraeus) (Coleoptera: Tenebrionidae). The effect of indirect exposure of the stem borer
parasitoid Sturmiopsis parasitica (Curran) (Diptera: Tachinidae) to Bt toxin was
evaluated to determine if there is any effect when it parasitizes Bt-resistant B. fusca
larvae that have fed on Bt maize. Results from the study conducted with S. calamistis
indicated that Bt maize of both events (Bt11 and MON810) were highly toxic to S.
calamistis. The behavioural characteristic of S. calamistis to feed behind leaf sheaths and
to enter stems directly did not result in escape of exposure to the toxin. Larval feeding on
leaf sheaths therefore resulted in the ingestion of sufficient toxin to kill larvae before they entered maize stems. Results showed that the effect of Cry1Ab toxin on the biology of A.
segetum larvae and moths were largely insignificant. Whorl leaves were observed to be
an unsuitable food source for H. armigera larvae and larval growth was poor. No larvae
survived to the pupal stage on any of the Bt maize treatments. When feeding on maize
ears H. armigera larval mass increased on non-Bt maize whereas no increase occurred on
Bt maize. The feeding study conducted with Coleoptera showed that the effect of Bt
maize on H. arator and S. angulatus was insignificant and no differences were observed
in any of the parameters measured for the two species. Although not always significant,
the percentage parasitism of Bt-consuming host larvae by S. parasitica was always higher
compared to host larvae that fed on non-Bt maize. It could be that Bt toxin affects B.
fusca fitness to such an extent that the immune systems of host larvae were less effective.
The different parameters tested for S. parasitica indicated only one case where fly
maggots originating from diapause host larvae feeding on non-Bt maize had a greater
mass compared to host larvae that fed on Bt maize. The same applied to S. parasitica
pupal length. For other parameters tested there were no significant differences. Sesamia
calamistis is stenophagous and occurs in mixed populations with other borer species. It
was therefore concluded that the ecological impact of local extinctions of S. calamistis
caused by Bt maize is not expected to be great. Bt maize will most likely not have any
significant effect on the control of A. segetum under field conditions. The feeding study
conducted with H. armigera quantified the effects of Bt maize on this species and
provided important information on the potential of Bt maize as protection against this
polyphagous pest. However, the likelihood of H. armigera becoming an important
secondary pest is high. It can be concluded that the Cry1Ab toxin targeting lepidopteran
pests will not have adverse effects on H. arator or S. angulatus. Although some adverse
effects were observed on S. parasitica mass and pupal length it is most likely that this
will not contribute to adverse effects in the field, but that there rather be synergism
between Bt maize and S. parasitica. An ecological approach was followed in which the
potential effects of exposure of priority species to Bt toxin in maize was investigated. A
series of selection matrixes were developed in which each of the above mentioned
species was ranked for its maximum potential exposure to Bt toxin by assessing it
occurrence, abundance, presence and linkage in the maize ecosystem. Through the use of these selection matrixes, knowledge gaps were identified for future research and to guide
the design of ecologically realistic experiments. This study contributes to knowledge
regarding the possible effects of Bt maize on the most economically important non-target
pests in South Africa. There is, however, a need to evaluate other non-target species in
feeding studies, as well as in field studies. From this study it can be concluded that some
species can be eliminated from further testing since Bt maize had no adverse effect while
more research have to be conducted on other species. / Thesis (Ph.D. (Environmental Science)--North-West University, Potchefstroom Campus, 2010.
|
13 |
Response of selected non-target Lepidoptera, Coleoptera and Diptera species to Cry1Ab protein expressed by genetically modified maize / Annemie ErasmusErasmus, Annemie January 2010 (has links)
The environmental impacts of genetically modified (GM) crop plants such as Bt (Bacillus
thuringiensis) maize have not yet been fully assessed in South Africa. Bt maize designed
to express Bt endotoxin for control of Busseola fusca (Fuller) (Lepidoptera: Noctuidae)
and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is planted on approximately
1.103 million hectares in South Africa. The monitoring of GM crops after release is
important in order to assess and evaluate possible environmental effects. No risk
assessment for Bt maize was done in South Africa before its release in 1998 and no
targeted post-release monitoring of possible resistance development or impact on non-target
species have been done. Awareness has risen in South Africa through research
highlighting the possible effects GM crops may have. The aim of this study was to
determine, through feeding experiments, the effects of Bt maize on selected non-target
Lepidoptera, Coleoptera and Diptera species that occur in maize agro-ecosystems in
South Africa. Results provide information for use in future risk assessment studies on Bt
maize and indicate which species could possibly be of importance in post-release
monitoring of Bt maize. Priority insect species were identified and laboratory- and semifield
experiments were conducted to evaluate the effect of Bt maize on these species. In
the light of the reportedly lower toxicity of Bt maize to certain noctuid borers, the effect
of Bt maize was evaluated on Sesamia calamistis (Hampson), Agrotis segetum (Denis &
Schiffermüller), and Helicoverpa armigera (Hubner). Feeding studies were also
conducted to determine the effect of Bt maize on non-target Coleoptera, i.e.
Heteronychus arator Fabricius (Coleoptera: Scarabaeidae) and Somaticus angulatus
(Fahraeus) (Coleoptera: Tenebrionidae). The effect of indirect exposure of the stem borer
parasitoid Sturmiopsis parasitica (Curran) (Diptera: Tachinidae) to Bt toxin was
evaluated to determine if there is any effect when it parasitizes Bt-resistant B. fusca
larvae that have fed on Bt maize. Results from the study conducted with S. calamistis
indicated that Bt maize of both events (Bt11 and MON810) were highly toxic to S.
calamistis. The behavioural characteristic of S. calamistis to feed behind leaf sheaths and
to enter stems directly did not result in escape of exposure to the toxin. Larval feeding on
leaf sheaths therefore resulted in the ingestion of sufficient toxin to kill larvae before they entered maize stems. Results showed that the effect of Cry1Ab toxin on the biology of A.
segetum larvae and moths were largely insignificant. Whorl leaves were observed to be
an unsuitable food source for H. armigera larvae and larval growth was poor. No larvae
survived to the pupal stage on any of the Bt maize treatments. When feeding on maize
ears H. armigera larval mass increased on non-Bt maize whereas no increase occurred on
Bt maize. The feeding study conducted with Coleoptera showed that the effect of Bt
maize on H. arator and S. angulatus was insignificant and no differences were observed
in any of the parameters measured for the two species. Although not always significant,
the percentage parasitism of Bt-consuming host larvae by S. parasitica was always higher
compared to host larvae that fed on non-Bt maize. It could be that Bt toxin affects B.
fusca fitness to such an extent that the immune systems of host larvae were less effective.
The different parameters tested for S. parasitica indicated only one case where fly
maggots originating from diapause host larvae feeding on non-Bt maize had a greater
mass compared to host larvae that fed on Bt maize. The same applied to S. parasitica
pupal length. For other parameters tested there were no significant differences. Sesamia
calamistis is stenophagous and occurs in mixed populations with other borer species. It
was therefore concluded that the ecological impact of local extinctions of S. calamistis
caused by Bt maize is not expected to be great. Bt maize will most likely not have any
significant effect on the control of A. segetum under field conditions. The feeding study
conducted with H. armigera quantified the effects of Bt maize on this species and
provided important information on the potential of Bt maize as protection against this
polyphagous pest. However, the likelihood of H. armigera becoming an important
secondary pest is high. It can be concluded that the Cry1Ab toxin targeting lepidopteran
pests will not have adverse effects on H. arator or S. angulatus. Although some adverse
effects were observed on S. parasitica mass and pupal length it is most likely that this
will not contribute to adverse effects in the field, but that there rather be synergism
between Bt maize and S. parasitica. An ecological approach was followed in which the
potential effects of exposure of priority species to Bt toxin in maize was investigated. A
series of selection matrixes were developed in which each of the above mentioned
species was ranked for its maximum potential exposure to Bt toxin by assessing it
occurrence, abundance, presence and linkage in the maize ecosystem. Through the use of these selection matrixes, knowledge gaps were identified for future research and to guide
the design of ecologically realistic experiments. This study contributes to knowledge
regarding the possible effects of Bt maize on the most economically important non-target
pests in South Africa. There is, however, a need to evaluate other non-target species in
feeding studies, as well as in field studies. From this study it can be concluded that some
species can be eliminated from further testing since Bt maize had no adverse effect while
more research have to be conducted on other species. / Thesis (Ph.D. (Environmental Science)--North-West University, Potchefstroom Campus, 2010.
|
14 |
Entwicklung eines statistischen Habitateignungsmodells zur räumlichen Vorhersage der Vorkommenswahrscheinlichkeit des Wachtelkönigs (<i>Crex crex L.</i>) im Nationalpark Unteres Odertal / Ein landschaftsökologischer Beitrag zum Schutz einer gefährdeten Vogelart / Development of a statistical habitat model for the spatial prediction of corncrakes (<i>Crex crex L.</i>) occurrence in the Lower Oder Valley National Park, Germany / A landscape ecological contribution to the conservation of a threatened bird speciesJust, Peter 25 January 2006 (has links)
No description available.
|
15 |
Règles d’assemblages et restauration écologique des communautés végétales herbacées méditerranéennes : le cas de la Plaine de La Crau (Bouches-du-Rhône, France) / Assembly rules and ecological restoration of mediterranean herbaceous communitiesCoiffait-Gombault, Clémentine 07 December 2011 (has links)
Les écosystèmes herbacés méditerranéens, caractérisés par une importante biodiversité, ont subi de considérables changements d‟usage. Désormais, leur conservation est devenue insuffisante au regard de l‟augmentation des dommages causés par les activités humaines. La restauration écologique apparaît donc comme un outil approprié pour participer à leur préservation. Des recherches préalables sur les différents compartiments de l‟écosystème ainsi que sur les facteurs responsables de l‟assemblage de leurs communautés avant et après dégradations sont donc nécessaires afin de mettre en place des méthodes de restauration adaptées à ces écosystèmes. Ainsi, en utilisant comme modèle biologique les Coussouls de Crau et leurs friches post-culturales (Bouches-du-Rhône, France), représentatif de nombreux écosystèmes steppiques méditerranéens, nous avons choisi de déterminer et d‟étudier les principaux filtres potentiellement responsables de l‟organisation de cette communauté végétale. Le pâturage ovin, les changements trophiques du sol, les phénomènes de compétition et la capacité de reproduction et/ou de dispersion des espèces, identifiés lors d‟une première étude sur la régénération de la steppe, ont ainsi été étudiés dans trois expérimentations différentes. Deux protocoles de restauration écologique in situ (transfert de foins et semis d‟espèces structurantes) et un protocole d‟expérimentation ex-situ testant les interactions d‟une sélection d‟espèces de la steppe ont permis de réaliser ces recherches. Nos principaux résultats montrent que les filtres de reproduction/dispersion, le niveau trophique du sol, la compétition et le régime de perturbations récurrentes lié au pâturage ovin ont un rôle déterminant dans les changements de la composition et de la structure de la communauté et ils expliquent ainsi en partie le ralentissement de sa dynamique successionnelle vers la steppe de référence. Nous avons également pu démontrer que ces filtres interagissaient entre eux. Au niveau de la recherche appliquée, les protocoles testés favorisent le retour de la végétation steppique, néanmoins la composition des parcelles restaurées reste toujours très différente de l‟écosystème de référence à très court terme (deux à trois années après la restauration). Cela démontre que même si nous comprenons mieux aujourd‟hui les facteurs expliquant l‟organisation de cette communauté, il est cependant toujours difficile de la restaurer dans son intégralité car il n‟est pas aisé de manipuler et de trouver un équilibre entre l‟action de ces différents facteurs. Il est donc désormais plus que nécessaire de poursuivre ces recherches fondamentales et appliquées notamment au niveau des processus de maturation et de structuration des vieilles communautés végétales herbacées. / Mediterranean herbaceous ecosystems which are characterized by a high biodiversity have been submitted to a lot of changes in use. Their conservation is not sufficient enough and ecological restoration seems to be an adapted solution to improve conservation efforts as it can mitigate damages induced by human activities. To develop restoration methods adapted to these ecosystems, preliminary researches on the different communities composing an ecosystem and the filters which are responsible for community assemblage before and after disturbance are necessary. Representative of numerous Mediterranean steppe ecosystems, the “Coussouls de Crau” and their ex-arable-fields (Bouches-du-Rhône, France) are the biological models used to identify and study the principal filters potentially responsible for organizing the plant communities. Sheep grazing, trophic changes, competition and reproduction and /or species dispersal, were identified in a first study on steppe regeneration; these filters were then the core of the following three research experiments. We carried out two in-situ restoration protocols (hay transfer and sowing foundation species) and one ex-situ experiment testing interactions between a selection of steppe species. The main results show that reproduction, seed dispersal, soil trophic level, competition, extensive sheep grazing are filters which have a determinant role in structuring the communities, in determining plant composition and partly in explaining the slow dynamics towards the reference steppe. Also, we show that filters interact between them. For applied restoration, the tested methods promote steppe vegetation come back, but in the short term (two or three years after restoration), the composition of restored areas remains different to the reference ecosystem. Even if we understand better the different factors which explain community organization, these results demonstrate that it is difficult to restore it integrally because it is not easy to manipulate and find an equilibrium between the different filters actions. Now it is necessary to continue these fundamental and applied researches, in particular on the maturation and structure of the old herbaceous plant communities.
|
16 |
Impact of a landing obligation on coupled dynamics ecosystem-fishers : individual-based modelling approach applied to Eastern English Channel / Impact d'une obligation de débarquement sur les dynamiques couplées écosystème-pêcheurs : approche par modélisation individu-centrée appliquée à la Manche OrientaleBourdaud, Pierre 23 January 2018 (has links)
L'objectif de cette thèse était d'anticiper les effets de l'Obligation de Débarquement (OD) mise en place en UE depuis début 2015 en Manche Orientale (MO). Pour accomplir ces objectifs, il a été prévu de : i) mieux comprendre la distribution spatiale saisonnière d'espèces commerciales à l'aide d'observations embarquées sur des navires commerciaux, ii) les comparer avec la distribution de l'effort de pêche à fine échelle des chalutiers de fonds (OTB), et iii) développer un modèle individu-centré de dynamique des flotilles, DSVM, à intégrer avec le modèle écosystémique OSMOSE pour simuler l'OD. L'utilité des données d'observations embarquées a été prouvée pour une majeure partie des espèces échantillonnées, en utilisant une validation par la bibliographie et un indicateur géostatique. Ensuite la comparaison de l'effort de pêche à fine échelle a fourni une amélioration de la quantification de l'effort de pêche effectif et mis en valeur l'importance de la seiche et du rouget barbet pour la distribution des OTB en MO. De plus, l'intensité de ciblage des OTB a été quantifiée en octobre à l'aide d'un nouvel indicateur, et démontré l'intérêt pour les mêmes espèces, mais aussi la contrainte d'un faible quota de cabillaud pour les pêcheurs. Les résultats du couplage OSMOSE-DSVM montrent que k'OD aurait des effets négatifs à court terme pour le revenu des pêcheurs, induits par le déplacement de l'effort de pêche afin d'éviter les dépassements de quota, mais serait profitable à moyen terme. Cependant, l'OD provoquerait une hausse de la pression de prédation produite par le cabillaud et le merlan sur les autres espèces, ce qui n'améliorerait pas l'état global de l'écosystème. / The objective of this thesis was to anticipate the effects if the EU Landing Obligation (LO) implemented since the beginning of 2015 in the Eastern English Channel (EEC). To achieve these objectives, it was planned to : i) better understand seasonal spatial distribution of commercial species using on-board commercial vessels observation data, ii) compare them with the final scale fishing effort distribution of EEC bottom otter trawlers (OTB), and iii) develop an individual-based model of fleet-dynamics, DSVM, to be integrated within the ecosystem model OSMOSE to simulate a LO. The usefulness of on-board observation data was proved for a main part of a species sample, using validation from the literature and a geostatistical indicator. Then the comparison of fine scale fishing effort provided an improvement of the quantification of effective fishing effort and emphasized the importance of cuttlefish and red mullet for the global distribution of EEC OTB. In addition, the targeting intensity of OTB was quantified in October using a newly-developed indicator, and demonstrated the attractiveness of the same species, but also the constraint of low cod quota for fishers. Results of the OSMOSE-DSVM coupling show that the LO would have short-term negative effects on fishers' revenue, induced by a large reallocation of their fishing effort to avoid quota over-shooting, but would be profitable in the medium-term. However, the LO would induce an increase of the predatory pressure operated by cod and withing on the other species, which would not improve the overall ecosystem health.
|
17 |
Vegetation succession in old fields at broad landscape scales / Vegetation succession in old fields at broad landscape scalesJÍROVÁ, Alena January 2012 (has links)
This thesis is focused on succession in old fields in Central Europe. Repeated sampling, analysis of surrounding vegetation and soil measurements were conducted in the Bohemian Karst Landscape protected area. Samples from the Doupovské hory Mountains and the rest of the Czech Republic were added to discover basic principles of old field succession at the larger scale of landscapes.
|
Page generated in 0.0695 seconds