Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 243 for “"Invasions"”.
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Biological invasions in brackish waters
Invasive non-native species (NNS) cause deleterious ecological, economic, social impacts worldwide. Brackish waters are transitional areas subject to invasion by taxa that may subsequently spread into adjacent freshwater and marine systems. The tendency for ports to be situated in brackish …
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Seaweed Invasions and Novel Chemical Defences
Biological invasions pose a risk to the biodiversity and the functioning of ecosystems in invaded areas. The reasons why some introduced species become dominant and widespread in their new environments is still largely an unsettled question. It has commonly been predicted that introduced plants …
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Effects of Plant Invasions on Birds Breeding In Desert Grasslands
… past 150 years, encroachment by woody plants and invasions by nonnative grasses have altered the structure and composition of plant communities that once dominated desert and semidesert grasslands. These plant invasions have reduced the quantity and quality of habitat for many grassland-associated …
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BUILDING FRAMEWORKS FOR UNDERSTANDING INVASIONS AND EXTINCTIONS FOR BIODIVERSITY SCIENCE
Scientists have long been interested in mechanisms that increase and decrease biodiversity on Earth and the effects they have on organisms’ interactions and functions. Global biodiversity loss is now outstripping accumulation and far exceeds expected background levels and has drawn comparisons to …
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Exploring the mechanisms and impacts of plant invasions in grasslands
… that a more nuanced understanding of plant invasions is needed to protect biodiversity and ecosystem functions in an era of rapid global change.
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Ecological impacts of biological invasions on native birds in Africa
The impacts of biological invasions on native avian diversity have been the subject of many studies in Africa. However, a holistic synthesis of available information from different taxa and their impacts on native birds is lacking. From published information, I analysed the negative and positive …
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Scientific and educational strategies a sustainable port activity against biological invasions
Una gran parte de la población mundial habita hoy en día en el entorno costero debido a la amplia variedad de recursos ecosistémicos que este ofrece. Los ecosistemas marinos pueden ser empleados como fuente de alimentos o energía, y suponen un recurso económico importante. El crecimiento de la …
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Fish invasions in the Mid-Atlantic region of the United States
… patterns and assessed determinants of fish invasions in the Mid-Atlantic region of the United States. Data on nonnative fish distributions were obtained from the United States Geological Survey's Nonindigenous Aquatic Species Database (NASD). Nonnative fishes are introduced by a variety of …
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Geological recognition of abrupt marine invasions in two coastal areas of Portugal
Abrupt marine invasions such as tsunamis and storms are particularly devastating for coastal areas. They may also leave a permanent record in the sedimentary deposits which is the principal focus of this thesis. In historical times the most destructive tsunami that affected Europe was the AD 1755 …
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Use of genetic methods for determining patterns and processes during marine biological invasions
… genetic methods to the study of marine bioinvasions in the last two decades. This work aims to build on and extend current advances in the use of molecular techniques for understanding marine bioinvasions, and in particular invasive ascidians. Part One (Chapters Two and Three) contains …
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The mathematical modeling and analysis of nonlocal ecological invasions and savanna population dynamics
… needed for rapid response, accurately modeling invasions remains a high priority for resource managers. To achieve this goal, we begin by revisiting a particular class of deterministic contact models obtained from a stochastic birth process for invasive organisms. We then derive a deterministic …
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Using patchy plant invasions to understand how diffuse interactions modify facilitation and competition
<p>Indirect interactions among plants promote conditionality in competitive outcomes that affect plant community structure and function. I utilized spatially patchy distributions of two invasive exotic plants, <i>Centaurea stoebe</i> and <i>Bromus tectorum</i>, to explore conditionality in plant …
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Using patchy plant invasions to understand how diffuse interactions modify facilitation and competition
<p>Indirect interactions among plants promote conditionality in competitive outcomes that affect plant community structure and function. I utilized spatially patchy distributions of two invasive exotic plants, <i>Centaurea stoebe</i> and <i>Bromus tectorum</i>, to explore conditionality in plant …
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Chaos and Cossacks, two fatal vendettas : the invasions of Russia in 1708 and 1812
Introduction: There were two invasions of Russia by foreign powers in the early eighteenth and nineteenth centuries. Charles XII of Sweden entered Russia in 1708 and was destroyed in battle outside Poltava in 1709. Napoleon invaded in 1812 and was back in France before the end of that year, having …
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Applications of DNA-barcoding in the identification and understanding of grass invasions in Southern Africa
… threats to global biodiversity. Alien plant invasions also have serious economic impact in terms of the delivery of ecosystem goods and services. Studies of biological invasions in southern Africa have tended to overlook grasses (family Poaceae), although there are many naturalised species in …
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The influence of an ecosystem engineer on nutrient subsidies and fish invasions in southwestern Montana
… native fish species threatened by nonnative invasions.</p> <p>I showed that beaver impoundments enhanced aquatic resource availability to terrestrial consumers. Beaver impounded watersheds had increased densities of emerging aquatic macroinvertebrates and higher levels of aquatic carbon in …
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The influence of an ecosystem engineer on nutrient subsidies and fish invasions in southwestern Montana
… native fish species threatened by nonnative invasions.</p> <p>I showed that beaver impoundments enhanced aquatic resource availability to terrestrial consumers. Beaver impounded watersheds had increased densities of emerging aquatic macroinvertebrates and higher levels of aquatic carbon in …
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Multidimensional Spatial Characterization of Plant Invasions in 'El Pinacate y Gran Desierto de Altar' Biosphere Reserve
… effects than global warming. Exotic plant invasions threaten biodiversity and ecosystem viability worldwide. Their effects in the Sonoran Desert ecosystems are a growing concern among ecologists and land managers. We hypothesized that highly dynamic desert environments are unstable, …
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Effects of pine invasions on ground-dwelling ants on the southern slopes of the Swartberg Mountains
Ant and plant assemblages in patches of Pinus species trees in mountain fynbos and renosterbos (Elytropappus rhinocerotis) shru.bland were investigated in order to detennine whether there were differences in ant and plant species richness, abundance and cover between patches of pines and the …
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