Five techniques were used to predict the potential biogeography of the four alien plant species, Acacia longifolia, Acacia mearnsii, Opuntia ficus-indica and Solanum sisymbrifolium. Prediction was based on five environmental factors, median annual rainfall, co-efficient of variation for rainfall, mean monthly maximum temperature for January, mean monthly minimum temperature for July and elevation. A geographical information system was used to manage the data and produce the predictive maps. The models were constructed with presence and absence data and then validated by means of an independent data set and chisquared tests. Of the five models used, three (the range, principal components analysis and discriminant function analysis) were linear while the other two (artificial neural networks and fuzzy logic) were non-linear. The two non-linear techniques were chosen as a plant's response to its environment is commonly assumed to be non-linear. However, these two techniques did not offer significant advantages over the linear methods. The principal components analysis was particularly useful in ascertaining the variables that were important in determining the distribution of each species. Artifacts on the predictive maps were also proved useful for this purpose. The techniques that produced the most statistically accurate validation results were the artificial neural networks (77% correct median prediction rate) and the discriminant function analysis (71% correct median prediction rate) while the techniques that performed the worst were the range and the fuzzy classification. The artificial neural network, discriminant function analysis and principal component analysis techniques all show great potential as predictive distribution models.

Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed substrate fragments can readily root and establish. Subsequently, torpedograss thrives when subjected to inundations to 75 cm and survives prolonged exposure to depths greater than 1 m. These findings suggest that fluctuating water levels contribute to torpedograss dispersal and colonization patterns and that low water levels increase marsh area susceptible to invasion. The competition study found that spikerush grown in monoculture produces significantly more biomass when continually inundated to shallow depths (10 to 20 cm) than when subjected to drier conditions (-25 cm) or greater inundations (80 cm). In contrast, torpedograss establishes more readily on exposed substrate (-25 to 0 cm) compared to inundate substrates. During the first growing season biomass production increases as substrate exposure interval increases. However, during the second year, established torpedograss produces more biomass when grown on intermittently wet (0 cm) compared to permanently dry (-25 cm) or intermittently inundated (10 cm) substrates. No difference in production was observed between substrates permanently inundated (10 cm) and any other regime tested. During the first two years of torpedograss invasion, regardless of treatment, spikerush suppresses invasion and torpedograss had little effect on established spikerush, indicating that spikerush-dominated areas are capable of resisting torpedograss invasion. Even so, disturbances that might cause mortality of long hydroperiod species, such as spikerush, may create open gaps in the native vegetation and thus facilitate torpedograss establishment and expansion.

Ecological niche modelling is a method designed to describe and predict the geographic distribution of an organism. This procedure aims to quantify the species-environment relationship by describing the association between the organism’s occurrence records and the environmental characteristics at these points. More simply, these models attempt to capture the ecological niche that a particular organism occupies. A popular application of ecological niche models is to predict the potential distribution of invasive alien species in their introduced range. From a biodiversity conservation perspective, a pro-active approach to the management of invasions would be to predict the potential distribution of the species so that areas susceptible to invasion can be identified. The performance of ecological niche models and the accuracy of the potential range predictions depend on the quality of the data that is used to calibrate and evaluate the models. Three different types of input data can be used to calibrate models when producing potential distribution predictions in the introduced range of an invasive alien species. Models can be calibrated with native range occurrence records, introduced range occurrence records or a combination of records from both ranges. However, native range occurrence records might suffer from geographical bias as a result of biased sampling or incomplete sampling. When occurrence records are geographically biased, the underlying environmental gradients in which a species can persist are unlikely to be fully sampled, which could result in an underestimation of the potential distribution of the species in the introduced range. I investigated the impact of geographical bias in native range occurrence records on the performance of ecological niche models for 19 invasive plant species by simulating two geographical bias scenarios (six different treatments) in the native range occurrence records of the species. The geographical bias simulated in this study was sufficient to result in significant environmental bias across treatments, but despite this I did not find a significant effect on model performance. However, this finding was perhaps influenced by the quality of the testing dataset and therefore one should be wary of the possible effects of geographical bias when calibrating models with native range occurrence records or combinations there of. Secondly, models can be calibrated with records obtained from the introduced range of a species. However, when calibrating models with records from the introduced range, uncertainties in terms of the equilibrium status and introduction history could influence data quality and thus model performance. A species that has recently been introduced to a new region is unlikely to be in equilibrium with the environment as insufficient time will have elapsed to allow it to disperse to suitable areas, therefore the occurrence records available would be unlikely to capture its full environmental niche and therefore underestimate the species’ potential distribution. I compared model performance for seven invasive alien plant species with different simulated introduction histories when calibrated with native range records, introduced range records or a combination of records from both ranges. A single introduction, multiple introduction and well established scenario was simulated from the introduced range records available for a species. Model performance was not significantly different when compared between models that were calibrated with datasets representing these three types of input data under a simulated single introduction or multiple introduction scenario, indicating that these datasets probably described enough of the species environmental niche to be able to make accurate predictions. However, model performance was significantly different for models calibrated with introduced range records and a combination of records from both ranges under the well established scenario. Further research is recommended to fully understand the effects of introduction history on the niche of the species. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Zoology and Entomology / unrestricted

No description available.

The Important Bird Areas (IBAs) network of BirdLife International aims to identify sites that are essential for the long-term conservation of the world’s avifauna. A number of global change events have the potential to negatively affect, either directly or indirectly, most bird species, biodiversity in general and associated ecological processes in these areas identified as IBAs. To assist conservation decisions, I assessed a suite of ten landscape scale anthropogenic pressures to 115 Important Bird Areas (IBAs) in South Africa, both those currently placing pressures on IBAs and those that constitute likely future vulnerability to transformation. These threats are combined with irreplaceability, a frequently used measure of conservation importance, to identify the suite of IBAs which are high priority sites for conservation interventions: those with high irreplaceability and are highly vulnerable to anthropogenic threats. A total of 22 (19%) of the South African IBAs are highly irreplaceable and are highly vulnerable to at least some of the pressures assessed. Afforestation, current and potential future patterns of alien plant invasions affect the largest number of highly irreplaceable IBAs. Only 9% of the area of highly irreplaceable IBAs is formally protected. A total of 81 IBAs (71%) are less than 5% degraded or transformed. This result, together with seven highly irreplaceable IBAs found outside of formally protected areas with lower human densities than expected by chance provides an ideal opportunity for conservation interventions. However, all the pressures assessed vary geographically, with no discernible systematic pattern that might assist conservation managers to design effective regional interventions. Furthermore, I used the newly emerging technique of ensemble forecasting to assess the impact of climate change on endemic birds in relation to the IBAs network. I used 50 endemic species, eight bioclimatic envelope models, four climate change models and two methods of transformation to presence or absence, which essentially creates 2400 projections for the years 2070-2100. The consensual projection shows that climate change impacts are very likely to be severe. The majority of species (62%) lose climatically suitable space and 99% of grid cells show species turnover. Five species lose at least 85% of climatically suitable space. The current locations of the South African Important Bird Areas network is very likely ineffective to conserve endemic birds under climate change along a “business a usual” emissions scenario. Many IBAs show species loss (41%; 47 IBAs) and species turnover (77%; 95 IBAs). However, an irreplaceability analysis identified mountainous regions in South Africa as irreplaceable refugia for endemic species, and some of these regions are existing IBAs. These IBAs should receive renewed conservation attention, as they have the potential to substantially contribute to a flexible conservation network under realistic scenarios of climate change. Considering all the global change threats assessed in this study, the Amersfoort-Bethal-Carolina District and the Grassland Biosphere Reserve (IBA codes: SA018; SA020) are the key IBAs in South Africa for conservation prioritisation. / Dissertation (MSc)--University of Pretoria, 2008. / Zoology and Entomology / unrestricted

MSc (Microbiology) / Department of Microbiology / See the attached abstract below.

Michaela Kubátová Alien species of plants and biotic resistence of invaded communities This study is about problems and questions of alien plants and their relation to native communities in their new range. Ecologists are increasingly aware that soil organisms may affect plant communities because they are part of the processes that affect them. The soil organisms may affect the success of alien species invasion. Each species of plants differ in interaction with soil organisms, these interactions can result in specific feedback that will influence the future growth of other plants. According to Darwin's naturalization hypothesis related species should have similar enemies. This implies less successful invasion of alien plants at home with relatives. The practical part consists of two experiments. Using plant-soil feedback I studied under controlled conditions the importance of kinship of native plants and their soil organisms on the growth of three species of alien plants Impatiens, Parviflora, Stenactis annua and Epilobium ciliatum. There were used soil samples from localities with related and unrelated species; the soil was used as inoculums for growing first-generation plants, where there were original related, unrelated and alien plants. In the second phase only alien species were grown. Part of...

Invasiva främmande arter är ett av de största hoten mot biologisk mångfald samt att de medför stora ekonomiska kostnader. Kommunerna spelar en viktig roll gällande tillsyn och bekämpning av invasiva främmande arter då de ofta är fastighetsägare och ansvarar för stora arealer. Med ett varmare klimat kan många arter som varit ett problem i varmare länder och i södra delarna av Sverige bli ett problem även på nordligare breddgrader. Det kan därför vara viktigt att kommunerna har ett väl fungerande arbete med etablerade arter och en beredskapsplan mot de arter som kan komma att bli ett problem i framtiden.  Syftet med denna studie var att identifiera vilka invasiva främmande arter som förekom i Värmlands län, samt vilka potentiella problemarter som skulle kunna etablera sig med ett förändrat klimat. Studiens avsikt var även att undersöka kommunernas arbete med de invasiva främmande arter som var etablerade på kommunal mark samt identifiera hinder för agerande mot dessa. För kartläggning av artförekomst i Värmland användes data från SLU ArtDatabankens Artportal. För att undersöka vilka arter som kunde bli ett problem i Värmland med ett varmare klimat användes också Artportalen för att identifiera artförekomst i de södra delarna av Sverige (Skåne). Data mellan åren 2016–2021 analyserades och visualiserades i kartor. Värmlands arbete med arterna undersöktes genom en semistrukturerad intervju med naturvårdshandläggare på länsstyrelsen samt att enkäter sändes ut till samtliga kommuner.   Resultatet visade att av de arter som var med på EU:s förordning fanns förekomster av sex arter i Värmland. Utöver arterna på förordningen fanns andra problemarter som även dessa räknades som invasiva. Enligt data i artportalen hade Skåne, som historiskt sett haft en varmare medeltemperatur, en större förekomst av invasiva arter. Ett varmare klimat skulle kunna gynna etablering av dessa arter även i Värmland, dessutom skulle spridningsintervallen på redan etablerade arter kunna öka.  Merparten av kommunerna hade dock inget förebyggande arbete mot potentiella problemarter. Undersökningen gav intrycket att arbetet är på uppgång men att det fortfarande fanns en utvecklingspotential. Det fanns ett behov för samverkan mellan kommunerna och tydligare och frekvent information till allmänheten. Det fanns även ett behov för fler resurser. / Invasive alien species are one of the biggest threats to biodiversity and they entail large economic costs. Since 2015, there is an EU regulation on the prevention and management of the introduction and spread of invasive alien species. The municipalities' work has a central role in the control of invasive species as they are often property owners and responsible for large areas. With a warmer climate, many species that have been a problem in warmer countries and in the southern parts of Sweden can become a problem even in more northern latitudes. It may therefore be important that the municipalities have a well-functioning work with established species and a contingency plan against the species that may become a problem in the future. The purpose of this study was to identify which invasive alien species occurred in Värmland County and which potential problem species that could establish with a changing climate. The purpose of the study was also to examine the municipalities' work with the invasive alien species that were established and to identify obstacles to action against them. Data from SLU ArtDatabanken's Art Portal were used to map species occurrence in Värmland. To investigate which species could be a problem with a warmer climate, the Species Portal was also used to identify species occurrences in the southern parts of Sweden (Skåne). Data between the years 2016–2021 were analyzed and visualized in maps. Värmland's work with the species was investigated through a semi-structured interview with nature conservation officers at the County Administrative Board and questionnaires were sent out to all municipalities. The results showed that of the species that were included in the EU regulation, there were occurrences of six species. In addition to the species in the regulation, there were other problem species that were also considered invasive. According to data in the species portal, Skåne, which had a warmer average temperature, had a greater incidence of invasive species. A warmer climate could favour the establishment of these species also in Värmland. Most of the municipalities, however, had no preventive work against potential problem species. The survey gave the impression that the work has started but that there was still a development potential. There was a need for collaboration between the municipalities and more frequent information to the public. There was also a need for more resources.

Parkslide är en främmande invasiv växt som ohämmat sprider sig på bekostnad av närliggande vegetation och den biologiska mångfalden. Genom att undersöka möjligheten att ta vara på Parkslides egenskaper och skapa någonting användbart för vårt samhälle, utan negativ påverkan på människa, djur och framtid, så kan det i sin tur skapa en möjlighet för en hållbar utveckling. Ett annat sätt att se på befintligt råmaterial, som en del i en cirkulär ekonomi. Rapporten diskuterar resurs och värde med intention att minska användandet av nya material och byta ut dessa till mer hållbara lösningar.Genom faktainsamling och en materialdriven designprocess utforskas Parkslide som material, vilket resulterar i materialprover som öppnar upp möjligheterna för framtida marknader. / Japanese knotweed is an Invasive Alien plant that is widely spread, at the expense of nearby vegetation, which has a negative impact on the biodiversity. By examining the possibilities to use Japanese Knotweed and its characteristics, as something valuable and useful, it can result in opportunities for a sustainable development in the society. We can change the way we view the plant and possibly make it a part of a circular economy. This work will discuss resource and value with the intention to reduce the use of new materials and switch those to a more sustainable solution.Through literature studies, interviews, survey and a Material Driven Design process I will explore Japanese Knotweed as a material, which results in material samples and discussion. This opens up the possibilities for future markets.

This study analyzes newspaper coverage of immigration reform in mainstream newspapers prior to, and following the debate in June 2007. The newspaper text is analyzed using metaphor interpretation supported by content analysis. The quantitative result categorizes the identified metaphors in three distinct metaphor categories about: immigrants and immigration, immigration policy and enforcement, and metaphors about the debate and immigration issue itself. The relative distribution of metaphors among categories is provided. Using an open coding process, emergent metaphor categories are identified. The qualitative findings describe metaphors and schemas that were potentially activated by particular metaphorical phrases in this context. Lastly, this research compares the similarities and differences of the immigration debate of the early 20th century with the contemporary U.S. and European debate.