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 (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.

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 (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (leaves 148-172). Also available via the World Wide Web.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Successful biological invasions take place when species introduced to regions outside their natural dispersal range overcome several barriers and establish, persist, proliferate and spread potentially resulting in major threats to biodiversity. The success of invasive alien plants depends on species-specific traits and characteristics of the introduced environment. In this thesis I explore which species traits are important and which environmental barriers need to be overcome for an invasion to occur using Proteaceae as a test case. Firstly, I assessed the global introduction history and invasion ecology of Proteaceae - a large plant family with many taxa that have been widely disseminated by humans, but with few known invaders. This revealed that at least 402 species (i.e. 24% of 1674 species in this family) are known to have been moved by humans out of their native ranges, 58 species (14%) have become naturalized and 8 species (2%) are invasive. The probability of naturalization was greatest for species with large native range sizes, low susceptibility to Phytophthora root-rot disease, larger seeds, mammal-dispersed seeds and those with the capacity to resprout after fire or other disturbances. The probability of naturalized species becoming invasive was greater for species with larger range sizes, species used as barrier plants, taller species, species with smaller seeds, serotinous species, and those that regenerated mainly through re-seeding. Secondly, I looked at mechanisms underlying naturalization on a regional scale, using species which are not already classified as major invaders. At least 26 non-native Proteaceae species have been introduced to, and are cultivated in, South Africa. Propagule pressure facilitated the naturalization of Hakea salicifolia populations in climatically suitable areas, but in suboptimal climates human-mediated land disturbance and land management activities are important for naturalization. Similar drivers are important for naturalization of other alien Proteaceae: a long residence time, fire regimes, poor land management, and propagule pressure were important mechanisms for naturalization. Thirdly, I determined whether reproduction, which in part drives propagule pressure, serves as a barrier for naturalization. I examined several Australian Proteaceae species introduced to South Africa and observed that all species were heavily utilized by native nectar-feeding birds and insects. The five Banksia species that were assessed are self-compatible but four species have a significantly higher reproductive output when pollinators visit inflorescences. Fruit production in H. salicifolia does not differ between naturally-pollinated and autonomously-fertilized flowers. Moreover, no significant difference in fruit production was observed between the five pollination treatments (i.e. natural, pollen-supplementation, autonomous, hand-selfed and hand-crossed treatments) and naturalized and non-naturalized populations. However, pollen limitation was detected in non-naturalized populations which received fewer pollinator visits than naturalized populations. Thus, reproduction limits but is not a fundamental barrier to invasion for H. salicifolia. I conclude that reproductive success of the studied Proteaceae, which is a key barrier determining invasiveness, is not limited by autonomous seed set or mutualisms in the introduced range. In this thesis I highlight biogeographical characteristics, a set of life-history traits and ecological traits as important determinants of invasiveness. These traits are in turn dependent on the stage of invasion. Characteristics of the recipient environment are also important drivers of invasions. This study provides a better understanding of plant invasions in general, but the patterns and processes of invasions highlighted in this thesis will be particularly useful for the current and future management of alien Proteaceae in South Africa and elsewhere, as well as, other species that are adapted to Mediterranean and nutrient poor ecosystems. For example, combining traits of invasiveness and susceptible environments will help to identify which non-native species pose a high risk of becoming invasive (e.g. species with large home ranges and barrier plants) and which conditions in the target area are likely to facilitate or exacerbate invasions (e.g. strong climate match and high propagule pressure). / AFRIKAANSE OPSOMMING: Suksesvolle biologiese indringing vind plaas wanneer ʼn spesie geïntroduseer word in ʼn area buite sy natuurlike verspreidings area, sekere versperrings oorkom, vestig, bly voortbestaan, vermenigvuldig en versprei en potensieel ʼn groot bedreiging inhou vir biodiversiteit. Die sukses van uitheemse indringer plante hang af van spesifieke kenmerke van die spesie en kenmerke van die omgewing waarin dit geïntroduseer word. In hierdie tesis maak ek gebruik van Proteaceae om te ondersoek watter kenmerke is belangrik en watter omgewing versperrings moet oorkom word vir indringing om plaas te vind. Ten eerste assesseer ek die wêreldwye introduksie geskiedenis en indringers ekologie van Proteaceae – ʼn groot plant familie wat wyd gebruik word deur mense, maar met min indringer spesies. Dit het gewys dat mense ten minste 402 spesies (dus 24% van die 1674 spesies in die familie) uit die inheemse areas verskuif het, 58 spesies (14%) genaturaliseer het en 8 spesies (2%) indringers geword het. Die moontlikheid van naturalisasie was die grootste vir spesies met ʼn groot inheemse streek, lae vatbaarheid vir Phytophthora wortelvrot, groter sade, dier verspreide sade en die met ʼn vermoë om weer uit te spruit na ʼn vuur of ander versteuring. Die moontlikheid van genaturaliseerde spesies om indringers te word, was groter vir spesies met groter streek grootte, spesies wat as versperring plante gebruik word, hoër spesies, spesies met kleiner sade, serotiniese spesies, en die wat hoofsaaklik voortbestaan as saadspruiters. Tweedens, het ek gekyk na onderliggende meganismes op ʼn regionale skaal, deur gebruik te maak van spesies wat nie alreeds as belangrike indringers geklassifiseer is nie. Ten minste 26 nie-inheemse Proteaceae spesies is alreeds geïntroduseer en word gekultiveer in Suid Afrika. Propaguul druk fasiliteer die naturalisering van Hakea salicifolia populasies in areas met geskikte klimaat, terwyl in areas met ʼn sub optimale klimaat, versteurings deur mense en grond bestuurs aktiwiteite belangrik is vir naturalisering. Die selfde drywers is belangrik vir die naturalisering van ander uitheemse Proteaceae: lang verblyftyd, vuur bestel, swak land bestuur en propaguul druk. Derdens het ek bepaal of reproduksie, wat gedeeltelik propaguul druk dryf, ʼn versperring is vir naturalisasie. Ek het gekyk na verskeie Australiese Proteaceae spesies wat geïntroduseer is in Suid Afrika, en het gevind dat al die spesies besoek word deur inheemse nektar etende voëls en insekte. Die vyf Banksia spesies wat geassesseer is, kan self bestuif, maar vier van die spesies het ʼn betekenisvolle hoër reproduksie wanneer bloeiwyses deur bestuiwers besoek word. Vrug produksie verskil nie tussen natuurlik bestuifde en self bestuifde blomme in H. salicifolia nie. Verder was daar geen verskil tussen vrug produksie van die vyf bestuiwings behandelinge (naamlik: natuurlik, stuifmeel bygevoeg, self, hand self en hand kruis) en tussen genaturaliseerde en nie genaturaliseerde populasies. Ewenwel, stuifmeel beperking is gevind in nie-genaturaliseerde populasies wat egter ook minder besoeke ontvang het dan die genaturaliseerde populasies. Dus, reproduksie kan die verspreiding beperk maar is nie ʼn fundamentele versperring vir indringing van H. salicifolia nie. My konklusies is dat die reproduktiewe sukses, wat andersins ʼn sleutel versperring is vir indringing, in die bestudeerde Proteaceae nie beperk word deur outonomiese saad produksie of mutualismes in die geïntroduseerde gebied nie. In hierdie tesis beklemtoon ek die biogeografiese karakters, lewens geskiedenis kenmerke en ekologiese kenmerke as belangrike bepalers van indringing. Hierdie kenmerke is op hulle beurt weer afhanklik van die stadium van indringing. Karakters van die ontvangende omgewing is ook belangrike dryfvere van indringing. Hierdie studie verbeter hoe ons plant indringing in die algemeen verstaan, maar die patrone en prosesse van indringing wat beklemtoon word in hierdie tesis sal besonder bruikbaar wees vir huidige en toekomstige bestuur van uitheemse Proteaceae in Suid Afrika en op ander plekke, asook vir ander spesies wat aangepas is tot Mediterreense en nutriënt arm ekosisteme. Byvoorbeeld, die kombinasie van kenmerke van indringing en vatbare omgewings sal help om te identifiseer watter uitheemse spesies ʼn hoë risiko inhou om ʼn indringer te word (byvoorbeeld spesies met ʼn groot streek grootte en versperring spesies) en watter kondisies in die teiken area die waarskynlikste indringing fasiliteer of vererger (byvoorbeeld sterk klimaat ooreenstemming en hoë propaguul druk).

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2007. / Thesis documentation sheet inserted. Appendix reproduces five papers and manuscripts, two co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

Alien plant invasions and human-induced land transformations are the two most important factors contributing to loss of biodiversity, and Chromolaena odorata (C. odorata) is one of the world’s worst invader plants. It impacts negatively on biodiversity conservation, forestry and agriculture due to its rapid rate of spread, fast growth and hence an ability to transform habitats. It was introduced into KwaZulu-Natal, South Africa in the mid-1940s, and has spread north and southwards along the coastline and adjacent interior. In 1961 it was observed in Hluhluwe Game Reserve, and has invaded and transformed large parts. In this thesis I use C. odorata distribution maps from 1978 to 2001 to investigate invasion pathways, and whether these are related to species or habitat characteristics. Invasion in the twelve vegetation types identified in the Reserve showed two patterns. In some vegetation types invasion expanded linearly, while in others there were three phases of invasion, driven by interactions between habitat suitability, habitat fragmentation and propagule pressure. Expansion of existing invasions (phalanx or wave invasion) through short distance seed dispersal was the primary mode of spread, rather than the formation of new infestations (guerrilla or diffuse invasion). Known distribution of dense stands was used to develop a spectral signature and run a supervised classification of satellite images. I utilized the dense stands and other GIS data sets of climate, altitude, solar radiation, distance from roads, distance from rivers and normalized differential vegetation index from 1973 and 2001 to determine a probability model, and assess the impact of the invasion on biodiversity conservation. The supervised classification underestimated the extent of the invasion, as C. odorata is a cryptic understory species in some habitats. Supplementation by using multiple regression to develop a probability model, and combining these into one map provided a realistic result. I used this map and GIS data sets of vegetation types and protected areas to assess the impact of the invasion on biodiversity conservation. This showed that C. odorata was preferentially impacting sensitive areas, and the conservation of threatened vegetation types is not guaranteed by including them in protected areas. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.

Thesis (M. Sc.)--University of Stellenbosch, 2008. / Includes bibliographical references. Also available via the Internet.