Many recent studies have demonstrated that propagule pressure is a useful predictor of patterns of invasions by non-native species. However, most of these studies have used only current, not historical, data to estimate propagule pressure. Recognizing the potential importance of propagule pressure over time, I used surrogate variables that represent both past and present propagule pressure, for example, the length of time a surrounding area had been developed. I quantified the relationships between these surrogate variables and the distribution and abundance of non-native woody plant species in central Texas. I constructed statistical models predicting native and non-native species richness and the occurrence of five common species using a set of six ecological and five development-related predictor variables. I compared all models using the corrected Akaike information criterion (AICc). Overall, age of residential development surrounding native woodlands was the best predictor, other than community type, of non-native species richness. As expected, areas near older developments had more non-native species than areas near newer developments. Surprisingly, age of development and average city age, two different measures of the length of time that landscaping (a major source of propagules of non-native woody species in this region) had been present nearby, were much better predictors than distance to source populations. Age of development and average city age (weighted by distance from the site) were also both correlated with distance to source populations; this may be true in other systems as well. This suggests that the reason distance to source population has been a successful predictor of invasion may be because it is a surrogate for an underlying causal variable, length of time of exposure to source populations. Future studies of non-native invasions would benefit from taking into account both past and present propagule pressure: age of residential development and city age could be useful surrogates in other systems. / text

Thesis (Ph. D., Entomology)--University of Idaho, August 2008. / Major professor: Mark Schwarzländer. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (M.S.)--Villanova University, 2009. / Biology Dept. Includes bibliographical references.

Thesis (M.S. in botany)--Washington State University, May 2007. / Includes bibliographical references (p. 29-35).

Thesis (Ph. D.)--Oregon State University, 1998. / Typescript (photocopy). Includes bibliographical references (leaves 182-194). Also available via the World Wide Web.

Thesis (M.S.)--University of Wisconsin -- La Crosse, 2009. / Includes bibliographical references (leaves 42-46)

Thesis (Master of Conservation Science)--Cape Peninsula University of Technology, 2018. / Introduction pathways of fungal pathogens in South Africa are far less quantified in the literature than those for plants, animals and human infectious diseases. Phytopathogens continue to be introduced to South Africa via several pathways at an unprecedented rate. A number of these species pose a significant threat to South African ecosystems and biodiversity. Despite this, fungal pathogens could also be beneficial when they are used as bio-control agents to control alien invasive plant species. Nevertheless, recent studies revealed pathogens are most likely to be studied after they have caused a detrimental impact on the environment. Invasive fungal pathogens, such as Phytophthora cinnamomi (Oomycota) do not only pose a threat to native species of the family Proteaceae but could also potentially be bio-control agents for emerging alien plant invaders. In this thesis, firstly, I review current knowledge of phytopathogenic fungi introduction pathways in South Africa; secondly, I aim to understand the importance of fungi in limiting plant invasions using Banksia as a case study in the Cape Floristic Region. In chapter two I investigate introduction pathways and dispersal vectors that facilitate the spread of fungal pathogens. I compiled comprehensive list of fungal pathogens in South Africa, and evaluated the dispersal vectors and introduction pathways for each species. I found fifty five casual species, three naturalised species, six invasive species and thirty six pathogens for which invasion status was not classified due to insufficient data. Agriculture is responsible for the introduction of most fungal pathogens in South Africa. Wind was identified to be the prominent dispersal vector facilitating the spread of pathogens. I conclude that knowing introduction pathways of pathogens and their dispersal vectors will assist in developing quarantine protocols that could improve bio-security. Lastly, I provide recommendations for the national invasive microbe species list. In chapter three the study investigates the variability in mortality rate of Banksia species in the Cape Floristic. Species abundance was calculated across known Banksia populations in the Cape Floristic Region to determine survival and mortality rates. Soil and leave samples were taken from Banksia plants to evaluate potential microbial pests that were present. Also, acetone leaf extracts of twelve Banksia species were screened for antimicrobial activity against P. cinnamomi (Oomycota). Lastly, a post-border risk assessment was conducted for 14 Banksia species− present in South Africa − using the Australian Weed Risk Assessment protocol, to evaluate potentially invasive species. The results indicated that survival and mortality rate varied across species; I found the two invasive species, B. integrifolia and B. ericifolia to have the highest survival rate. Phytophthora cinnamomi was the most prominent isolated fungal pathogen sampled from Banksia species roots. The detection of antifungal activities in the minimum inhibitory concentration (MIC) bioassay provided evidence that some Banksia species (B. ericifolia, B. integrifolia, B. hookeriana and B. formosa) have antimicrobial chemical constituents that could possibly inhibit infection and colonisation by P. cinnamomi. The weed risk assessments conducted on Banksia species showed five species pose a high risk of invasion while seven species required further evaluation. I conclude that P. cinnamomi could potentially regulate invasive Banksia species such as B. speciosa with minimal antimicrobial activity against the pathogen. I recommend an in-situ and ex-situ inoculation trials of Banksia species against P. cinnamomi to be conducted to evaluate pathogenicity, under different watering regimes since the pathogens proliferation is favoured by soils that are high in moisture. I present the main conclusions from this thesis in chapter four and provide recommendations for management and invasive species legislation.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 82-89.

Thesis (M. Sc.(Zoology and Entomology))--University of Pretoria, 2009. / Summary in English.

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Mar. 9, 2010). Includes bibliographical references.