Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 344-370).

Thesis (Ph. D.) -- Lincoln University, 2008. / Also available via the World Wide Web.

Thesis (M.S.)--Ohio University, August, 2009. / Title from PDF t.p. Includes bibliographical references.

Thesis (PHD)--University of Montana, 2010. / Contents viewed on April 9, 2010. Title from author supplied metadata. Includes bibliographical references.

Thesis (M. Sc.) -- Lincoln University, 2009. / Also available via the World Wide Web.

Thesis (M.C.M.) -- Lincoln University, 2010. / Also available via the World Wide Web.

Thesis (M.S.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science Degree in Biology (Ecology track)." "A thesis entitled"--at head of title. Bibliography: leaves 38-46.

Invasive alien tree species have negative environmental and economic impacts throughout the world. For example, black wattle (Acacia mearnsii) threatens native habitats by competing with and so repressing or excluding indigenous vegetation: in this way it replaces grass communities, reduces biodiversity, and increases water loss from riparian zones, thereby fundamentally damaging the ecosystem. The Acacia mearnsii threat requires urgent attention: effective control and management is urgently required if these deleterious impacts are to be reversed or prevented. The present study was conducted in the Elliot and Ugie communities situated in the Sakhisizwe and Elundini Local Municipalities. The objective of this study was to design integrated, efficient and cost-effective methods to help farmers and members of these communities with control and management of alien plant invasions. Further the study aimed to evaluate the implementation and efficacy of Working for Water (WfW) initiatives in poverty alleviation, and skills development: in addition the study attempted to assess WfW inputs as regards relevant legislation aimed at combating major wattle invasions. Mixed methodological approaches were employed, utilizing both qualitative and quantitative techniques. Questionnaire surveys, semi-structured interviews, use of photos, content analyses of local documents and experimental field work were all employed in order to collect and interpret data for the study. The study reveals that mechanical control and rehabilitation in combating should provide efficient and cost-effective methods for proper management of rangelands. Moreover the National Department of Agriculture, Forestry and Fisheries (DAFF) should be urged to devise and enforce legislation that will help to ensure sustainable control and management of black wattle through conservation of the natural environment. Furthermore funds should be made available for wattle eradication programmes so as alleviate poverty by creating more job opportunities for members of poor communities.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Understanding the processes that drive the invasion of non-native species is often essential for effective management. This thesis focuses on Casuarina spp. – an economically and ecologically important tree genus with taxa that have been widely disseminated by humans. I explore the effects certain taxa can have on community dynamics in recipient environments, investigate the factors that mediate invasion of Casuarina species, and from this aim to develop recommendations for managing the group. First, I assessed the global introduction history, invasion ecology and the evolution of management approaches of Casuarina. Ten of the 14 species in the genus have been introduced outside their native ranges to over 150 countries, but only three species are recorded as naturalized or invasive. As with other groups there is a correlation between native range size and invasiveness – the three invasive species also have the largest introduced ranges. Propagule pressure explains much more of the variance in observed invasiveness between Casuarina taxa than any known combination of life-history traits. Large-scale plantings of casuarinas in some climatically suitable areas have not yet resulted in large-scale invasions; there is a substantial global Casuarina invasion debt. Experiences in Florida and the Mascarene Islands highlight that casuarinas have the potential to transform ecosystems with significant control costs. Despite modest progress with managing invasions in some areas, substantial problems remain. As with most other invasive tree taxa, complex conflicts of interest are particularly challenging. Second, I looked at mechanisms underlying naturalization and assessed invasion risk at a regional scale. Here, I examined Casuarina cunninghamiana invasions in the south-western Cape of South Africa – the part of the country with the largest contiguous area climatically similar to the native range of the species. Propagule pressure is a key driver of naturalization of C. cunninghamiana populations in climatically suitable areas. The species also naturalizes in regions with suboptimal bioclimatic conditions, but then only very near (<10 m) planted trees. Risk models indicate that C. cunninghamiana is likely to spread across a greater region of the Western Cape than it currently occupies. Naturalized populations of C. cunninghamiana are young and expanding. The capacity of the species to resprout and attain reproductive maturity at an early age suggests that this species could become a widespread and damaging invader in South Africa. We conclude with some recommendations for management, and argue that if particular steps are taken (e.g. the immediate removal of all female plants from proximity to dams and water-courses; all future sales and plantings to be restricted to male plants) then it might be possible to safely utilise the species in future. Third, I examined the invasion dynamics of a single Casuarina species at the landscape scale. I explored how interactions between disturbance and invasion govern successional trajectories, using the remarkable invasion of C. equisetifolia on the volcanic island of Réunion. Invasive populations of C. equisetifolia have increased substantially in extent over 40 years. Lava flows have facilitated the spread of C. equisetifolia and invasion of this species has radically changed successional trajectories, increasing the rate of succession sevenfold. This case mirrors work done on Morella faya and Falcataria moluccana on Hawa'ii, which shows the extent to which invasive species can alter ecosystem function and benefit from natural disturbances generated by volcanic lava flows. The continued spread of C. equisetifolia poses a major threat to the small area of remaining native lowland rainforests on Réunion which cover < 2 % of their original extent. The studies in this thesis have uncovered patterns, processes and invasion risks for invasive trees that are not well represented in the literature. Some insights derived from well-studied tree genera, such as Acacia and Pinus, seem to apply fairly well to tree invasions in general. However, special ecological features of Casuarina species and the ways they are used by humans call for unique considerations when piecing together changing global distributions and creating effective strategies for management. / AFRIKAANSE OPSOMMING: ‘n Deeglike begrip van die prosesse wat die indringing van uitheemse spesies fasiliteer is noodsaaklik vir effektiewe besturing. Hierdie tesis fokus op Casuarine spp. – ‘n ekonomiese en ekologiese belangrike boom genus, met menigte spesies binne hierdie genus wyd verspreid deur mense. Ek ondersoek die effekte wat sekere taksa kan hê op die gemeenskap dinamika in die ontvanger omgewing, sowel as die faktore wat Casuarina indringing bemiddel, en deur hierdie doelwitte beoog ek om aanbevelings te maak aangaande die effektiewe bestuur van hierdie groep. Eerstens evalueer ek die invoerings geskiedenis van die genus wêreldwyd, die indringer ekologie en ook die evolusie van bestuurs benaderinge ten opsigte van Casuarina. Tien van die 14 spesies binne hierdie genus is ingevoer na meer as 150 verkillende lande buite hul inheemse streek, maar slegs drie van hierdie spesies word beskou as genaturaliseerd of indringers. Soos met ander groepe is daar ‘n korrelasie tussen inheemse streeks-grote en indringerheid – die drie indringer spesie het ook die grootste ingevoerde streke. Propaguul druk verduidelik die meerderheid van die variasie in die waargeneme indringer Casuarina taksa as enige ander kombinasie van lewens geskiendenis eienskappe. Groot skaalse plantasies van casaurina taksa in sommige klimaat geskikste areas het nog nie na groot skaalse indringing gelei nie; daar is wêreldwyd ‘n aansienlike Casuarina indringer skuld. Ervarings in Florida en die Mascarene Eilande beklemtoon dat casuarinas die potensiaal het om ekosisteme te transformeer met geweldige beheer omkostes. Ten spyte van redelike vordering aangaande die besturing van indringers in sekere areas, is daar steeds aansienlike probleme. Soos met meeste ander indringer boom taksa, is die botsing van belange veral uitdagend. Tweedens, het ek die meganismes van die naturalisasie bemiddel as ook indrigner risiko op die plaaslike skaal ondersoek. In hierdie deel het ek Casuarina cunninghamiana indringers in die Suid-Wes Kaap van Suid-Afrika ondersoek – die deel van die land met die grootste aangrensende area wat ‘n ooreenstemmend klimaat het met die inheemse areas van die spesie. Propaguul druk is ‘n belangrike drywer vir die naturalisasie van C. cunninghamiana populasies in areas met ‘n geskikte klimaat. Hierdie spesie het ook genaturaliseer in areas met suboptimale klimaats kondisies, maar slegs baie naby (<10m) aan plantasies. Risiko modelle dui aan dat C. cunninghamiana die potensiaal het om te versprei na ander dele van die Wes-Kaap waar dit huidiglik afwesig is. Natuurlike populasies van C. cunninghamiana is jonk en in die proses van uitbreiding. Die kapasiteit van die spesie om te hergrooi en voortplantings volwassenheid op n vroeë ouderdom te beriek stel voor dat hierdie spesie ‘n wyd verspreide en skadelike indringer kan word. Ons sluit af met aanbevelings vir effektiewe bestuur en stel voor dat indien sekere stappe geneem word (bv. ontmiddelike verwydering van die vroulike plante naby damme en water areas; alle verdere verkope beperk word tot manklike plante), dit moontlik sal wees om hierdie spesie op ‘n omgewings-veilige manier te gebruik. Derdens het ek die indringing dinamika van ‘n enkele Casuarina spesie on landskap skaal ondersoek. Ek het verken hoe interaksies tussen versteurings en indringing plantegroei prosesse dryf, deur gebruik te maak van die merkwaardige indringing van C. equisetifolia op die vulkaniese eiland van Reunion. Indringer populasies van C. equisetifolia het aansienlik vermeerder in die afgelope 40 jaar. Lava vloei het die verspreiding van C. equisetifolia gefasiliteer en indringing van hierdie spesie het plantegroei prosesse radikaal verander, deur die tempo van opvolging sewevoudig te verhoog. Hierdie studie weerspieël werk wat op Morella faya en Falcataria moluccana in Hawa’ii gedoen is en toon tot watter mate indringer spesies ekosisteem funksies kan verander en voordeel kan trek uit natuurlike versteurings wat gegenereer word deur vulkansiese lava vloei. Die voortgesette verspreiding van C. equisetifolia hou ‘n groot bedreiging in vir oorblywende inheemse laeveld reënwoude op Reunion wat tans < 2% van hul oorspronlike area dek. Die studies in hierdie tesis het patrone, prosesse en indringer risikos vir indringer bome ontdek wat nie goed in die literatuur verteenwoodig word nie. Sommige insigte wat deur goed bestudeerde boom genera, soos Acacia en Pinus, ontdek is, blyk om redelik goed van toepassing te wees op boom indringers in geheel. Alhoewel, sekere ekologiese funksies van Casuarina spesies en die manier wat hulle deur mense gebruik word, vra vir unieke oorwegings aangaande hul wêreldwye verspreiding en effektiewe beheer.

La lutte biologique est souvent présentée comme une méthode de lutte contre les ravageurs respectueuse de l'environnement, même si la lutte par acclimatation (introduction d'une espèce exotique) peut être à l'origine d'invasion biologique. La coccinelle asiatique Harmonia axyridis Pallas (Coleoptera : Coccinellidae) a été utilisée comme agent de lutte biologique introduit en Amérique et en Europe pour lutter contre les pucerons. Actuellement, cette espèce est considérée comme envahissante, et a des impacts négatifs sur l'environnement. L'objectif principal de cette thèse est d'améliorer notre connaissance des processus évolutifs pouvant accompagner l'élevage en captivité, ainsi que ceux qui sont liés aux invasions biologiques. J'ai pour cela utilisé une approche expérimentale au travers d'études permettant de caractériser les différences de traits d'histoire de vie entre les trois compartiments populationnels d'H. axyridis (populations natives, envahissantes et de lutte biologique). Les résultats obtenus montrent que les changements évolutifs les plus importants concernent le compartiment de lutte biologique par rapport aux compartiments sauvages (natifs et envahissants). Ce compartiment a subi des changements phénotypiques remarquables en réponse aux conditions d'élevage en laboratoire. Les changements évolutifs les plus spectaculaires concernent différents traits liés à la reproduction. Par exemple, les femelles de lutte biologique se reproduisent plus tôt, ont une fécondité journalière plus élevée, ainsi qu'une longévité et une durée de vie reproductive plus courte. Nous avons également mis en évidence des changements évolutifs entre des populations sauvages natives et envahissantes. Les adaptations aux conditions d'élevage peuvent parfois être désavantageuses dans l'environnement naturel. Par exemple, la résistance au froid et aux pathogènes est moins importante que celle des populations sauvages. Nos résultats montrent aussi que, même si la souche de lutte biologique européenne est incapable de s'implanter dans la nature, l'hybridation avec les populations envahissantes américaines pourrait avoir jouer un rôle positif au cours de l'invasion en Europe. / Biological control is generally considered as an environmentally low-impact solution for pest control. However, the use of foreign control agents may ultimately lead to undesired biological invasions. The Asian harlequin ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae) was originally used as a biological control agent of aphids in North America and Europe. This species is now considered as invasive, and can have harmful effects on the environment. The main objective of this thesis is to better understand the impact of mass rearing on life-history traits, with a focus on traits that may be associated with invasion success. To do so, experimental approaches were carried out to monitor changes in life-history traits for three types of populations (biocontrol, native or invasive). The corresponding results indicate that the most important evolutionary changes occur in the biocontrol populations (by contrast with the invasive and native populations). Mass rearing appears to induce significant phenotypic changes in the biocontrol populations, with the most spectacular changes being related to reproductive life-history traits. For instance, biocontrol females reproduce significantly earlier, have a higher daily fecundity, but also exhibit lower life expectancy and lower reproductive lifespan. We also evidence other differences between the native and invasive populations. Cold tolerance and pathogen resistance are also lower in biocontrol populations than in wild populations. Altogether, our findings indicate that adaptations to mass rearing conditions may affect the fitness of H. axyridis populations in natural environments. This suggests that, even if the European biocontrol strain is unable to successfully colonize a natural environment, it may nonetheless impact the invasion dynamics of the species in Europe thanks to the admixture with the invasive American population