Dissertations / Theses on the topic 'Alien planets'

This paper details the process of creating the UNO Graduate thesis film Alien on a Savage Planet. Each major step in the filmmaking process is covered: screenwriting, producing, directing, cinematography, sound, production design, costumes, hair and makeup, workflow, editing, color correction, music and post- sound. A comprehensive assessment of the filmmaking process and the successes and failures of the project are discussed in length.

El estudio se centra detectar los cambios temporales sufridos en la composición florística de las comunidades de malas hierbas de los cultivos de regadío y en descifrar los factores intrínsecos y extrínsecos subyacentes al éxito de las especies exóticas en estos cultivos y a su capacidad de colonizar los hábitats naturales adyacentes. Se ha utilizado una aproximación funcional. Los resultados muestran que a largo plazo, ha habido cambios en la diversidad, la composición y la estructura funcional de las comunidades de malas hierbas y un incremento del protagonismo de las malas hierbas exóticas. En los cultivos frutales, entre los atributos funcionales más beneficiados destacan la vía fotosintética C4, las formas graminoides y perennes y la capacidad de reproducción vegetativa, así como la hidrocoria y las semillas adaptadas a más de un modo de dispersión. Estos atributos se encuentran representados principalmente en las especies exóticas y su selección está determinada fundamentalmente por el sistema de riego por inundación. Por otro lado, el manejo de los cultivos regados por goteo configura una comunidad de malas hierbas caracterizada por una menor prominencia de especies exóticas y una estructura funcional que la hace menos competitiva hacia los árboles frutales. Los atributos favorecidos en los cultivos frutales regados por inundación se relacionan con la capacidad de las malas hierbas exóticas para colonizar los ambientes riparios adyacentes a los cultivos.
L'estudi es centra a detectar els canvis temporals de la composició florística de les comunitats de males herbes dels cultius de regadiu i a desxifrar els factors intrínsecs i extrínsecs subjacents a l’èxit de les espècies exòtiques en aquests cultius i a la seva potencial capacitat de colonitzar els hàbitats naturals dels voltants. S’ha utilitzat una aproximació funcional. Els resultats mostren que a llarg termini, ha hagut canvis en la diversitat, la composició i l’estructura funcional de les comunitats de males herbes a més d’un increment del protagonisme de les males herbes exòtiques. Als fruiters, entre els atributs funcionals més beneficiats destaquen la via fotosintètica C4, les formes graminoides i perennes i la capacitat de reproducció vegetativa, així com la hidrocòria i les llavors adaptades a més d’un mode de dispersió. Aquests atributs es troben representats principalment a les espècies exòtiques i la seva selecció està dirigida fonamentalment pel sistema de regadiu per inundació. Per altra banda, el maneig dels cultius regats per degoteig configura una comunitat de males herbes caracteritzada per una menor prominència d’espècies exòtiques i una estructura funcional que la fa menys competitiva envers els arbres fruiters. Els atributs que es veuen afavorits en els fruiterars irrigats per inundació també es troba relacionat amb la capacitat que tenen les males herbes exòtiques per colonitzar els ambients riparis adjacents als cultius.
This study aims at identifying temporal changes in weed community composition as well as unravelling the intrinsic and extrinsic factors that lay behind the success of alien weeds in irrigated crops and their potential capability to spread and colonize surrounding natural habitats. These main goals were addressed using a trait-based approach. Results showed that at long-term temporal scale, there were changes in diversity, composition and functional structure of weed communities, accompanied by a higher prominence of alien plants within these weed assemblages. In orchards, C4 photosynthesis, graminoid and perennial forms, clonal reproduction, hydrochory and seed dispersed by multiple methods were among the most benefited plant traits, which were mainly found in successful alien weeds. This trait selection was mainly driven by flood irrigation. On the other hand, management in drip-irrigated orchards configures a weed community characterized by a lower prominence of alien species and a functional structure that make it less competitive to the trees.Furthermore, the trait syndrome favoured in flood-irrigated orchards was also linked to the capacity of alien species to overcome ecosystems filtering and colonize surrounding natural riparian habitats.

The introduction of species outside of their native ranges has been extensively studied in ecology. Particular attention has been paid to examining interactions between alien and native plants, and a large proportion of this attention has focused on pollinator-mediated interactions. In order to interact through pollinators, plants must co-occur, coflower, and share pollinators; studies investigating pollinator-mediated interactions between alien and native plants frequently make fundamental assumptions about the definition of these prerequisites to pollinator-mediated interaction. The present analysis examines assumptions about plant co-occurrence and the effects that these assumptions have on study outcomes. In Chapter 2, I present the results of a meta-analysis of 76 studies which overturns previous findings that pollinator-mediated interactions between plants can be predicted on the basis of whether the neighbour is an alien, phylogenetic distance, or floral trait similarity. Moreover, I demonstrate that the spatial definition of the control group (i.e. the distance between the group of focal plants that ‘do not co-occur’ with the alien/alternate neighbour species and the nearest individuals of that neighbour species), and the spatial arrangements of plants within their treatment groups (i.e. the relative placement of the group of focal plants that ‘co-occurr’ with the neighbour species), both have a significant impact on the outcome of pollinator-mediated interactions between alien and native plants. I also emphasize evidence of bias in the selection of study systems and in the process of publication. In Chapter 3, I present the results of a field experiment testing the role of distance between interacting plants in determining patterns of visitation by insects. The results of this analysis are suggestive of visitor functional group-dependent effects but limited by low power. In both Chapter 2 and Chapter 3, I show that heretofore unexamined assumptions about definitions of co-occurrence of plants may be introducing bias into studies of pollinator-mediated interactions between plants, and that facilitation and competition between plants for visitation may be linked across different spatial scales.

Thesis (MSc)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The burgeoning problem of alien plant invasions in South Africa necessitates effective decision-making based on an understanding of the complex processes that govern these invasions. Due to the spatial nature of the problem, this study explored the use of Geographic Information Systems and spatial models for predicting the spread of alien vegetation and assessing the effectiveness of clearing strategies. The Spatially Explicit Individual Based Simulation (SEIBS) model was identified as a potentially useful tool for alien plant management. This thesis documents the further investigation and development that was necessary before recommendations could be made regarding the future use of the model. The landscape version of the SEIBS model was adapted to allow for the convenient input and output of spatial data, making it possible to simulate invasions in different areas. An ArcView extension was developed in order to facilitate the pre- and post-processing of the spatial data required and created by the model. Changes were also made to the fire routine of the model. The new version of the model was called Clear. A series of model tests for Pinus pinaster were conducted to assess the sensitivity of the Clear model to spatial resolution, initial spatial fragmentation and heterogeneity. These tests revealed that the model was sensitive to changes in resolution and needed to be reparameterised when using different resolutions. The initial level of fragmentation was shown to have a major influence on the invasion rate. Although greater levels of spatial heterogeneity with respect to vegetation age did not significantly affect the spread rate, it did increase the effectiveness of clearing strategies based on clearing juvenile or sparse vegetation. Based on these tests, it is concluded that the model can be readily applied to different areas, provided the influence of spatial characteristics is understood and accommodated. The Clear model was shown to be a useful tool for evaluating clearing strategies and for investigating invasion rates. It is recommended that the model be introduced to a wider audience, in order to obtain user feedback and further improve the accessibility of the model.
AFRIKAANSE OPSOMMING: Die toenemende probleem van uitheemse indringerplante in Suid Afrika, noodsaak effektiewe besluitneming wat gebaseer is op 'n begrip van die ingewikkelde prosesse wat indringing beheer. As gevolg van die ruimtelike geaardheid van die probleem, is die gebruik van Geografiese Inligtingstelsels en ruimtelike modelle vir die voorspelling van die verspreiding van indringerplante en die evaluasie van die effektiwiteit van opruimingstrategieë in hierdie studie ondersoek. Die Spatially Explicit Individual Based Simulation (SEIBS) model is as 'n moontlike geskikte hulpmiddel vir die bestuur van uitheemse indringerplante geïdentifiseer, alhoewel verdere ondersoeke en ontwikkeling nodig was voordat aanbevelings vir die gebruik van die model gemaak kon word. Vir hierdie studie is die landskapweergawe van die SEIBS model aangepas om die maklike toevoer en afvoer van ruimtelike data te fasiliteer. 'n ArcView uitbreiding is ontwikkel om met die voor- en naprosessering van ruimtelike data, wat deur die model gebruik en geskep is, te fasiliteer. Veranderinge is ook aan die vuur sub-roetine van die module gemaak. Die nuwe weergawe van die model word Clear genoem. 'n Reeks toetse is vir Pinus pinaster gedoen om die sensitiwiteit van die Clear model te toets teenoor ruimtelike resolusie, aanvanklike vlak van versnippering en vlak van heterogeniteit. Vanuit die toetse het dit geblyk dat die model sensitief was ten opsigte van verandering in resolusie en dat die model se parameters verstel moes word wanneer verskillende resolusies gebruik word. Daar is ook gewys dat die die vlak van aanvanklike versnippering 'n groot impak op die verspreidingstempo het. Alhoewel hoër vlakke van ruimtelike heterogeniteit teenoor plantegroei nie 'n merkbare impak op die verspreidingstempo gehad het nie, het dit wel die effektiwiteit van opruiming-strategieë, gebaseer op die opruiming van jong of yl verspreide plante, verbeter. Die gevolgtrekking wat uit die toetse gemaak kan word is dat die model geredelik op verskillende areas toegepas kan word, op die voorwaarde dat die invloed van ruimtelike eienskappe in ag geneem word en in berekening gebring word. Dit word aanbeveel dat die model wyer bekendgestel word om sodoende gebruikersterugvoer te bekom.

Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Invasive alien plants (IAPs) are known for their detrimental impacts on biodiversity and ecosystem goods and services. A substantial body of research has contributed to our understanding of their impacts on ecology. In comparison the socio-economic aspects of IAPs, are not well understood. Additionally, valuation practises have usually excluded the positive and the non-monetary impacts (benefits and uses) that IAPs hold for local livelihoods. Holistic valuation has been regarded as imperative for decision-making and managerial frameworks. A study was conducted in Elim on the southern Cape coast of the Agulhas Plain, South Africa, which aimed to explore the various impacts of IAPs on the livelihoods of rural land-users. Individual qualitative interviews were conducted face to face with landholders (referred to as farmers) (N = 12) and individuals from the economically marginalized community (referred to as marginalized community) (N = 12). The grounded theory approach to data analysis was used and results of the coding method used were displayed by means of superscripts. Results indicate that farmers were aware of broader uses of IAPs although they themselves did not utilise them as extensively as members of the marginalized communities. Invasive alien and problem plants that held value for both land-users were not perceived as being „invasive‟. Invasive alien plants were believed to have detrimental impacts on biodiversity and ecosystems goods and services which support people‟s livelihoods. Alien clearing programmes such as Working for Water (WfW) and LandCare have done much to alleviate the socio-economic burden of unemployment in this marginalized community. Aside from the social development aims set out by WfW (i.e. employment of low-income communities, poverty alleviation and skills training), knock-on social development benefits (e.g. feelings of pride, responsibility and awareness as well as conflict management skills) were also realised by individuals from the marginalized community that were previously employed by the programme. Farmers regarded alien clearing and management as a process that demands excessive time, energy and financial resources. On single occasions it was found that farmers employed methods other than the conventional clearing and management strategies (e.g. livestock that feed on IAPs and giving refuse IAP biomass from clearing and felling to neighbouring poor communities). No clear consensus was reached about regarding alien clearing and management but more support is desired from government. Working for Water relies on private landholders for alien clearing as it is required by law. This study emphasizes that stronger relationships between government and private landholders as well as more substantial incentives to clear IAPs on private land are prerequisites if required outcomes are to be achieved. Educating society at large about the detrimental impacts of IAPs is fundamental. Additionally, informing landholders on effective alien clearing methods and policies and legislation pertaining to it are key activities for the South African government. Finally, clearing and management programmes need to consider the benefits that local land-users obtain from IAPs when prioritising areas for the management of alien vegetation.
AFRIKAANSE OPSOMMING: Uitheemse indringerplante (UIPe) is bekend vir die nadelige gevolge wat hulle vir biodiversiteit en ekosisteem goedere en dienste inhou. ʼn Aansienlike liggaam van navorsing het bygedra tot ons begrip van die impak daarvan op ekologie. In teendeel, die sosio-ekonomiese aspekte van UIPe word egter nie goed verstaan nie. Daarbenewens, evalueringspraktyke het gewoonlik die positiewe en nie-monetêre impakte (voordele en gebruike) wat UIPe vir plaaslike lewensbestaan hou, uitgesluit. Holistiese evaluering word as noodsaaklik beskou vir besluitneming en bestuursraamwerke. ʼn Studie was uitgevoer in Elim op die Suid-Kaapse kus van die Agulhas-vlakte, Suid-Afrika. Die doel was om die verskillende aspekte van UIP impakte op die lewensbestaan van landelike grondgebruikers aan te spreek. Individuele kwalitatiewe onderhoude is van aangesig tot aangesig gevoer met grondeienaars (na wie verwys word as boere) (N = 12) en individue van die ekonomies gemarginaliseerde gemeenskap (na wie verwys word as gemarginaliseerde gemeenskap) (N = 12). Die gegronde teorie metode tot data analise was gebruik en die resultate van die kodering metode is vertoon deur middel van boskrifte. Resultate dui daarop dat boere bewus was van ʼn wyer reeks van gebruike van UIPe alhoewel hulle dit nie so ekstensief benut het soos die lede van die gemarginaliseerde gemeenskappe nie. Uitheemse en probleem plante wat waarde gehou het vir beide landgebruikers,was nie soseer beskou as „indringers‟ nie. Daar was geglo dat UIPe nadelige impakte het op biodiversiteit en ekosisteme goedere en dienste wat mense se lewensbestaan ondersteun. Programme soos Werk vir Water (WvW) en LandCare wat fokus op die uitroeiing van UIPe, het baie gedoen om die sosio-ekonomiese laste as ʼn gevolg van werkloosheid in hierdie gemarginaliseerde gemeenskap te verlig. Benewens die sosiale ontwikkelings doelwitte uiteengesit deur WvW (o.a. indiensneming van lae-inkomste gemeenskappe, armoedeverligting en vaardigheidsopleiding), is daar ook domino-voordele (bv. gevoelens van trots, verantwoordelikheid en bewustheid sowel as konflik bestuursvaardighede) aangaande sosiale ontwikkeling ervaar deur individue van die gemarginaliseerde gemeenskap wat voorheen in diens van die program was. Boere beskou die uitroeiing en bestuur van UIPe as ʼn proses wat oormatige tyd, energie en finansiële hulpbronne vereis. Op enkele geleenthede was dit gevind dat boere gebruik maak van metodes anders as die konvensionele skoonmaak-en bestuurs strategieë (bv. vee wat voed op UIPe en biomassa wat na afloop van skoonmaak aan die naburige arm gemeenskappe gegee word). Geen duidelike konsensus is bereik met betrekking tot die uitroeiing en bestuur van UIP nie, maar meer ondersteuning van die regering word verlang. Werk vir Water maak staat op private grondeienaars vir die uitroeiing van UIPe. Hierdie studie beklemtoon dat sterker verhoudings tussen die regering en private grondeienaars sowel as meer aansienlike aansporings om UIPe op private grond skoon te maak ʼn voorvereiste is as verwagte uitkomste bereik wil word. Opvoeding van die breër gemeenskap oor die nadelige impakte van UIPe is fundamenteel. Om grondeienaars in te lig oor effektiewe UIP verwyderingsmetodes asook beleide en wetgewing met betrekking daartoe, is belangrikste aktiwiteite vir die Suid-Afrikaanse regering. Ten slotte, skoonmaak- en bestuursprogramme moet oorweging skenk aan die voordele wat plaaslike landgebruikers put uit UIPe wanneer daar geprioritiseer word vir gebiede vir die bestuur van indringerplante.

Degut als impactes ecològics i socioeconòmics causats per les invasions biològiques, la seva gestió s’ha convertit en un repte important i una prioritat pels gestors mediambientals. A Espanya, la informació sobre la gestió de les plantes exòtiques està força dispersa i, en general, no hi ha gaire flux d’informació entre el món acadèmic i el món de la gestió. Per aquests motius, el principal objectiu d’aquesta tesi ha estat aprofundir en les mesures de gestió de plantes exòtiques a Espanya, identificant les seves principals limitacions. Conèixer aquestes limitacions ens ha dut a plantejar‐nos els següents objectius específics: 1) Identificar les principals plantes exòtiques problemàtiques a Espanya i avaluar els criteris utilitzats a l’hora de prioritzar la seva gestió; 2) Identificar i classificar les espècies potencialment invasores per Espanya; 3) A nivell global, quantificar mitjançant un metaanalisi els impactes de les plantes invasores i les conseqüències de la seva eliminació en les comunitats natives; i 4) Com a cas d’estudi, avaluar l’eficàcia de l’eliminació manual de Carpobrotus sp. a la costa d’Andalusia, i la recuperació de la vegetació nativa. Tenint en compte que les mesures de control i eradicació d’espècies exòtiques són extremadament costoses és molt important prevenir l’entrada i l’establiment d’espècies potencialment invasores, així com garantir l'eficàcia de les mesures de gestió aplicades. Aquesta tesi omple una mica el buit d’informació entre el món acadèmic i el de la gestió, proporcionant informació als gestors ambientals per tal de millorar l’eficàcia de les mesures de gestió aplicades. Les principals conclusions són: I. Les invasions biològiques són considerades pels gestors ambientals un problema de prioritat mitjana i un total de 109 plantes exòtiques problemàtiques han estat gestionades. II. La gestió de les plantes exòtiques s'ha centrat principalment en l'aplicació de mesures de control mecànic o químic a escala local i dissenyades, normalment, amb objectius a curt termini. Existeix, per tant, una manca de mesures de prevenció, mesures de seguiment a llarg termini i de pautes per a la priorització de la gestió d’espècies exòtiques. III. Mitjançant l'ús d'esquemes d'avaluació de riscos, s'ha elaborat una llista preliminar de 80 espècies potencialment invasores per Espanya, sent la jardineria la principal via d’entrada d’aquestes espècies. Les espècies amb les puntuacions més altes han resultat ser principalment plantes aquàtiques, i s’hauria de prohibir la seva entrada i comerç. Chromolaena odorata (Asteraceae) és l’espècie amb les puntuacions més altes i, per tant, podria ser considerada l'espècie amb major risc d'esdevenir invasora a Espanya, en cas que s'introduís al medi natural. IV. Aquesta tesi presenta un marc conceptual que compara llocs envaïts, llocs de referència no envaïts i llocs on una determinada espècie invasora ha estat eliminada. Aquestes comparacions permeten quantificar el impacte de l’espècie invasora en qüestió i supervisar la recuperació de les plantes natives després de la seva eliminació. En estudis científics, aquestes comparacions no solen ser utilitzades de manera combinada, i els llocs de referència són poc emprats per avaluar la recuperació d'espècies natives després de l'eliminació. Creiem que l’ús d’aquest enfocament comparatiu hauria de ser més emprat per supervisar l’eficàcia de les mesures de gestió, perquè a més, permet avaluar els possibles efectes secundaris de les tècniques d'eliminació, així com la necessitat de dur a terme mesures de restauració específiques a posteriori. V. La revisió bibliogràfica global demostra que les plantes invasores són responsables d'una disminució local en la riquesa i abundància d'espècies natives. Això, ha estat corroborat pel cas d’estudi sobre l’eliminació de Carpobrotus, on aquesta espècie també redueix significativament la riquesa d'espècies natives en les comunitats que envaeix. VI. En general, després de l'eliminació de les plantes invasores, la vegetació nativa té el potencial de recuperar‐se fins arribar als nivells desitjats previs a la invasió.
Now that the increasing impacts and costs of invasive species are being recognized, management of alien species has become an important challenge and a high priority for environmental managers. However, in Spain, management information on alien plants is quite scattered and, in general, there is a lack of communication between managers and scientists. The general aim of this thesis has been to investigate the management measures on alien plants carried out in Spain and to identify the main limitations of these measures. Once knowing these limitations the following specific objectives have been addressed: 1) To identify the most problematic invasive plant species in Spain and to assess the main criteria used to prioritize their management; 2) To identify and rank potentially invasive species in Spain, not present in the wild yet; 3) To quantify at a global scale, by means of a meta‐analysis, the impacts of invasive plants as well as the consequences of their removal over native communities, and 4) To evaluate, as a case study, the efficacy of the manual removal of Carpobrotus sp. in the coast of Andalucía, and the recovery of the native vegetation after the alien plant removal. Given that management measures are extremely costly in terms of human, technical and economic resources, it is really important to prevent potential invasive species as well as to guarantee management effectiveness in those cases where prevention is no longer a solution. This thesis have provided clear direction for bridging the current gap between the availability in information on alien plant species and the need for environmental managers to successfully prevent and control invasive species. Specifically, the main conclusions are: 1) Biological invasions are considered by Spanish environmental managers a medium priority problem and a total of 109 noxious alien species are being managed. 2) Management of alien plants in Spain has mainly focused, so far, in the application of either mechanical or chemical control measures at a local scale and mostly with short‐term goals in mind. Thus, there is a lack of preventive measures, absence of long‐term monitoring of control actions and few guidelines for prioritization. 3) By using risk assessment schemes, we have identified a preliminary list of 80 potential invasive species, being gardening the most common pathway of introduction. The species with the highest scores, were mainly aquatic plants, and should be prohibited or kept out of trade. Chromolaena odorata (Asteraceae) obtained the highest scores and therefore it might be the species with the highest risk to become invasive in Spain if introduced. 4) We have presented a conceptual framework that compares invaded, non‐invaded and removal sites to quantify invaders’ impacts and to monitor native plant recovery after their removal. In scientific studies, these comparisons are rarely used in concert, and reference sites are scarcely employed to assess native species recovery after removal. Thus, we believe that this comparative approach should be more frequently used to evaluate management effectiveness because it may also be useful to determine possible side‐effects of removal techniques and whether further restoration measures are necessary. 5) Our global literature review has demonstrated that invasion by alien plants is responsible for a local decline in native species richness and abundance. This has been corroborated by monitoring Carpobrotus invaded sites in coastal dunes of Andalucía, where this species has significantly decreased species richness in the communities it invades. 6) Our global literature review has also indicated that, in general, after alien plant removal, the native vegetation has the potential to recover to a pre‐invasion state. The same trend has been found in the case study of Carpobrotus.

Thesis (MSc)--Stellenbosch University, 2008.
ENGLISH ABSTRACT: Alien trees, Pinus spp. and Eucalyptus spp., affect ants negatively in the Cape Floristic Region (CFR), a global biodiversity hotspot in South Africa. They reduce ant abundance and species richness, thus also changing ant assemblage structure. This is alarming, because almost 1300 species of plant species in the CFR are dispersed by certain indigenous ants, and thus there is concern for an indirect effect on indigenous plant assemblages. One of the most impacting ant species on seed dispersal is the invasive Argentine ant (Linepithema humile (Mayr)), which discards seeds outside its nest, where they do not germinate. Ten sites, on Vergelegen Wine Estate, were selected to explore these effects of alien plants. These varied from invaded to non-invaded sites. Each site consisted of six sampling points, which in turn consisted of four pitfall traps left out for seven days, during December 2005, February 2006, May 2006 and September 2006. Forty species of ant were sampled, and various analyses used to illustrate the comparative effects of plant invasion. All analytical methods showed that invasive alien plants had a significant impact on the abundance and richness of the ant species assemblage, by creating a dense canopy cover that changed the abiotic environment of the epigaeic ants’ habitat. Furthermore, increased alien tree invasion correlated significantly with Argentine ant abundances. The Argentine ant displaced Pheidole capensis and Camponotus spp., while it decreased the abundances of commonly-occurring indigenous ants, such as Lepisiota capensis and Plagiolepis spp. Displacement by the Argentine ant may be a result of indirect competition for food resources. The effects of invasive aliens are synergistic in that there is a cascade effects from initial plant invasions to subsequent animal invasion.
AFRIKAANSE OPSOMMING: Indringer bome, Pinus en Eucalyptus, affekteer miere op negatiewe wyse in die Kaap Florsitiese Streek (KFR), ‘n area in Suid Afrika van belang t.o.v. globale biodiversiteit. Hierdie uitheemse indringer bome verminder hulle hoeveelheid en spesies rykheid. Die bogenoemde is kommerwekkend omdat meer as 1300 plant spesies in the KFR versprei word deur miere. Die verandering in hoeveelheid en versameling van inheemse miere kan dus ernstige implikasies hê op die saad verspreiding van inheemse plant spesies. Een van die mees verwoestende effekte op saad verspreiding is veroorsaak deur die indringer Argentynse mier (Linepithema humile (Mayr)), wat sade neer werp buite hulle neste, waar hulle nie suksesvol kan ontkiem nie. Tien monsterings-tereine was geselekteer om die bogenoemde effekte te ondersoek op Vergelegen Landgoed. Hierdie het afgewissel van indringer tot skoon tereine. Elke terrein is op ses versamelings-plekke gemonster, met vier pitvalle, wat oopgelê het vir sewe dae gedurende Desember 2005, Februarie 2006, Mei 2006 en September 2006. 40 spesies van miere was gemonster. Indringer plante het ‚n betekenisvolle impak gehad het op die hoeveelheid en rykheid van die mier gemeenskappe, deur die skepping van ‚n dig baldakyn wat die abiotiese omgewing van die miere se habitat verander het. Die vermeerdering van indringer plante veroorsaak die vermeerdering van Argentyne miere. Kanonieke Mede-Respons Analise illustreer dat die Argentynse mier Pheidole capensis en Camponotus spp. verplaas het, terwyl dit ander inheemse mier getalle verminder het, soos Lepisiota capensis en Plagiolepis spp. Die verplasing deur die Argentynse mier mag die resultaat wees van indirekte wedywering vir hulpbronne. Die effekte van indringer species is dus sinergisties deur dat ‚n kaskade effek ontstaan vanaf plant tot dier indringer spesies.

This study investigates the economic impact of the ARC PPRI Weeds Research Division. The Division researches appropriate methods of biological control for invasive alien plants (IAPs). These plants pose an increasing threat to environmental integrity and ecosystem service provision impacting on economic potential. Since the work of the Division is considered a public good, a predominantly descriptive approach has been adopted for the valuation process. A combination of quantitative cost analysis and a qualitative study of the impacts of research and invasive alien plants is used to deal with the challenges associated with non-market valuation. The study found that investment into the Weeds Division is a valuable activity that supports the long-term growth potential of the South African economy. The role of a well-functioning environment is highlighted as an essential base for the creation of sustained growth opportunities in any society. It was determined that investment into the Division should be increased into the future to support efficient spending of scarce state funds. Biological control research was found to provide strategic future growth potential, creating opportunities for the development of a competitive advantage in the biotechnology and environmental management sectors. The study adds to the increasing move towards a more holistic view of economic valuation, taking factors other than pure finance and econometrics into consideration. This is an important shift in prevailing economic thought, as a realisation is reached that a single, or even triple, bottom line is an outdated and insufficient decision making basis.

Orientador: George John Shepherd
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-07T20:50:25Z (GMT). No. of bitstreams: 1 Morbiolo_SergioRodrigues_M.pdf: 2368807 bytes, checksum: 47541963ceac1776da4ed3c27c6b3085 (MD5) Previous issue date: 2006
Resumo: A taxonomia de Lantana camara tem sido alvo de discussão de estudiosos em todo o mundo. A variabilidade morfológica, ecológica e química da espécie é extremamente grande. Alguns autores consideram que L. camara seja um complexo de espécie ao invés de um táxon monotípico, algumas vezes descrito como composto por até 150 táxons diferentes. Neste trabalho, a variabilidade de L. camara é colocada a prova através de dois métodos: a morfometria geométrica e a modelagem matemática. Os métodos morfométricos são utilizados para analisar a variabilidade morfológica do corpo vegetativo dos indivíduos da espécie no Brasil, país que faz parte da região original de distribuição da espécie, a América tropical. A análise dos dados é feita por métodos multivariados a fim de verificar se existe uma unidade taxonômica nas amostras brasileiras da espécie ou não. É verificado que não existe qualquer ponto confiável em que se possa reconhecer táxons específicos ou subespecíficos em todo o território; apesar da grande discrepância entre os extremos, as medidas formam um contínuo. No segundo capítulo, um algoritmo genético (GARP) é utilizado para traçar um mapa de distribuição potencial da espécie sobre o mundo, baseado em pontos de ocorrência da espécie em áreas nativas da América tropical. Verifica-se uma grande área potencial de distribuição no Novo Mundo e em outros continentes; porém, não houve previsão de ocorrência potencial na Austrália e na África do Sul. Estes dois países estão entre os que mais investem em programas de erradicação da espécie, com populações muito bem estabelecidas em áreas naturais e cultivadas. Como o algoritmo não previu possibilidade de ocupação desses países por L. camara, infere-se, então, que as linhagens ocorrentes nesses países sejam relativamente distantes taxonomicamente da espécie típica, podendo ser oriundas de hibridização e manipulação horticultural. Aparentemente, é necessária uma revisão da espécie em nível mundial
Abstract: The taxonomy of Lantana camara has been the target of discussion by taxonomists all over the world. The morphological, ecological and chemical plasticity observed is very extensive. Some autors consider that L. camara is a species complex instead of a monotypic taxon, composed of up to 150 different taxa. In this sudy, the variability of L. camara is studied using two methods: geometric morphology and mathmatical modelling. Morphological methods are used to analyze the morphological variability of the vegetative parts of brazilian populations. Brazil is within the native distribution for the species, which occurs over a large part of the Neotropics. The data analysis is made using multivariate methods to verify if there is any obvious morphological discontinuity within brazilian samples which would allow specific or insfraspecific taxa to be recognized. It does not appear to be possible to define reliable subdivisions within this taxon; in spite of the huge discrepancy among the more extreme samples, the measures are continuous. In the second chapter, a genetic algorithm (GARP) is used to draw a potential distribution map of the species over the world, based on occurrence points of Lantana camara in areas of the Neotropics where it is native. In spite of having an extremely widespread distribution in the Americas and other continents, no potencial occurrence is predicted for Australia and South Africa, two of the countries with the most active erradication programs for this species. It is inferred that the variants found in these countries may be taxonomically distant from the typical species, possibly resulting from horticultural hybridization and manipulation. A comprehensive review of the species at world level is necessary
Mestrado
Biologia Vegetal
Mestre em Biologia Vegetal

Plant fungal pathogens are a major threat to food security worldwide. The most important method of protecting plants against fungal attack is the use of fungicides, but the development of resistance towards synthetic fungicides is of great concern. Moreover, the health risks associated with the use of chemical fungicides increase the need to search for safe, efficacious and environmentally friendly fungicides. Plants produce antifungal agents by secondary metabolism to protect themselves from fungal attack, and therefore many plant species have substantial antifungal activity. The use of plant extracts could enable the development of inexpensive and environmentally acceptable fungicides based on locally available natural products. This study was undertaken to investigate weedy and invasive plant species for antifungal activity against plant pathogens in order to develop a useful product using a widely available resource. Acetone leaf extracts of seven invasive species (Chromoleana odorata, Ipomoea alba, Tecoma stans, Passiflora suberosa, Passiflora subpeltata, Aristolochia sp, Solanum seaforthianum) were screened against eight plant fungal pathogens viz Rhizoctonia solani, Fusarium oxysporium, Penicillum janthinellum, Penicillum expansum, Aspergillus parasiticus, Aspergillus niger, Pythium ultimum and Phytophthora nicotiana, using microdilution assay and bioautography. The acetone extract of Tecoma stans had reasonable antifungal activity with an average minimal inhibitory concentration (MIC) value against all the fungi of 550 ìg/ml and clear zones on bioautograms indicating inhibition of fungal growth of a compounds with an Rf of 0.082 in BEA against several of the fungal pathogens. Due to the clear compound on bioautography and availability of Tecoma stans, this species was selected for further work. Bioassay-guided fractionation of the leaves of the Tecoma stans dichloromethane (DCM) extract obtained from solvent-solvent fractionation resulted in one major compound, oleanolic acid. The isolated compound had antifungal activity with an average MIC value of 130 ìg/ml against the 10 plant pathogenic fungi and clear bands with an Rf value of 0.082 on bioautograms, indicating fungal growth inhibition. It was surprising that the MIC value of the crude DCM extract was as high as that of the only compound with antifungal activity based on bioautography. These results clearly indicated the possibility of synergisms especially since the average total activity of the extract was nearly 6.5 times higher than that of oleanolic acid with total activity values of 60154 ml for the extract and 9262 ml for oleanolic acid. Cellular cytotoxicity of DCM extract and oleanolic acid was investigated using tetrazoliumbased colorimetric assay (MTT) on Vero monkey kidney cells. The toxicity of the extract and oleanolic acid was determined by LC50 values. The DCM extract and oleanolic acid were toxic with and LC50 of 0.413 mg/ml and 0.129 mg/ml respectively, lower than that of berberine the toxic compound used as control. However therapeutic index which can be defined here as the LC50 in (ìg/ml)/MIC in (ìg/ml), indicated that though the extract and oleanolic acid were toxic, they could be used under controlled conditions against infections of certain of the fungal pathogens. The crude extract had a high therapeutic index value of 21 against microorganisms T. harzianum, R. solani, F. oxysporium and P. expansum; and oleanolic acid had high therapeutic index values of 16 and 64 of against T. harzianum and R.solani respectively. This high therapeutic index value of crude extract and oleanolic acid means that, crude extract and oleanolic acid may be used for treatment of infections by these tested fungi with very little toxicity under controlled conditions. Oleanolic acid had very low antibacterial activity (MIC >250 ìg/ml). against two Grampositive (Staphylococcus aureus, ATCC 29213 and Enterococcus faecalis, ATCC 29212) and two Gram-negative bacteria (Escherichia coli, ATCC 27853 and Pseudomonas aeruginosa, ATCC 25922). Animal pathogenic fungi were more resistant than the plant fungal pathogens. Based on the good activity of the DCM crude extract, the surprising selectivity in activity against different fungi coupled with reasonably good therapeutic indexes and the wide availability of T stans leaves opens up the possibility that a commercial product to protect plants against certain pathogens may be developed from T. stans leaves. Copyright
Dissertation (MSc (Veterinary Science))--University of Pretoria, 2008.
Paraclinical Sciences
unrestricted

Biodiversity is the cornerstone of ecosystem functioning and the realisation that most rural African community livelihoods are directly dependent on ecosystem goods and services warrants its conservation. Invasive alien plants threaten biodiversity and compromise the ecosystem's ability to provide goods and services for rural communities, thereby negatively affecting livelihood strategies. Information on IAPs is lacking in most African countries, thus, the livelihood effects of Invasive Alien Plants (IAPs) are not clearly understood. In Zimbabwe, Cylindropuntia fulgida var. fulgida (Cff) has invaded Gwanda district in the Matabeleland south province compromising local household capital assets that contribute to livelihood strategies and altering the ecosystem. This study exposed the rural worldview of the environment, the effect that Cff has on local livelihood strategies and the effectiveness environmental management institutions in rural Gwanda district. The study followed a post positivist paradigm. The impacts of IAPs on rural communities in Zimbabwe were analysed by looking at the livelihood stresses that arise because of Cff. The research used multi-stage sampling to select a representative sample of respondents. Primary data was collected using semi-structured questionnaires, group discussion and key informant guides. Furthermore, document analysis was conducted to collect secondary data. The data analysis process used Computer packages Microsoft Excel, SPSS and NVIVO. Results showed that livelihood benefits that species in the natural environment provide strongly influence environmental perceptions of rural African communities. Additionally, the study showed that Cff compromises the local ecosystem and reduces its ability to support the dominant livelihoods in the study area. The long-term result of such a situation in the absence of control is increased poverty and the failure to realise sustainable development. However, results indicated that IAPs could also improve the poverty situation of a community before they have reached the threshold points. It is therefore imperative to know the threshold points of an invasive plant in order to ascertain the efficient point to intervene. The study also showed that benefits of invasive plants accrue to different members of a society at different times (private/public). This knowledge allows the adoption of efficient and effective control strategies.

Invasive alien species threaten global biodiversity and can impose severe economic costs. Some invasive alien plants can be strong competitors for pollinators due to a high abundance of attractive flowers, which can disrupt native plant-pollinator interactions and reduce native plant reproductive success. This thesis explores pollinator-mediated competition between native plants and the invasive alien Impatiens glandulifera, Himalayan balsam. Previous studies have found conflicting effects of I. glandulifera on native plant-pollinator interactions. This study aimed, using a combination of direct field observations and controlled experiments, to explore the reasons behind these differences by examining the relationship between impact and the abundance of I. glandulifera at multiple spatial scales, and the responses of a wide range of cooccurring species. Chapters two and three tested the hypothesis that the composition of plant and pollinator communities and bumblebee-flower visitation vary in response to I. glandulifera abundance and spatial scale of invasion. Chapter four tested the hypothesis that I. glandulifera pollen will reduce the reproductive success of the native Lamium album. Chapter five tested the hypothesis that pollinator-mediated competition will alter the genetic quality of pollen received by co-flowering L. album. I found a relationship between the plant and pollinator community composition and the abundance of I. glandulifera, which was generally stronger at a broad scale. Responses to invasion differed according to pollinator taxa and plant traits, which could be useful for identifying and protecting potentially vulnerable native species. Impacts differed according to the mechanism used to examine its effects: bumblebee-flower visitation patterns changed, and L. album experienced reduced seed set and disruption to its mating system; however alien pollen did not prevent L. album from setting seed. In conclusion, the direction and magnitude of pollinator-mediated effects varied with I. glandulifera abundance, spatial scale, and the way in which impact was assessed. A wide range of approaches are necessary to understand the impact of invasive alien plants.

>Magister Scientiae - MSc
Invasive alien plants (IAPs) are often reported to use more water than indigenous plants. Inaddition, IAPs have an ability to adapt to harsh environmental conditions and they tend to spread at rapid rates, thereby threatening the country’s water resources, agricultural land, and biodiversity. Much of South Africa is expected to get drier in future due to climate change and the new climatic conditions are also predicted to accelerate the rate at which alien plants will spread. Approximately 10 million hectares are currently estimated to have been invaded by alien plants in South Africa, with an estimated average annual rate of spread of more than 5%. The first objective of this study was to compare the water use by deep rooted tree species which include invasive alien Prosopis (sp) trees and the co-occurring indigenous A. karroo. These trees are growing in a flood plain of a groundwater dependent catchment in the Northern Cape Province. Both species are dependent on groundwater and thus compete with local communities for this resource. The second objective was to determine the sources of water that the trees were using in order to understand the impacts of each species on groundwater resources. Transpiration was measured using the heat ratio method of the heat pulse velocity sap flow technique while the volumetric soil water content was monitored at several depths down the soil profile using automated capacitance soil water content probes. Weather data was collected using an automatic weather station. Stable isotopes of oxygen and hydrogen from plant, soil and groundwater samples were analysed to determine the sources of water used by the trees. Average tree density was approximately 613 stems per hectare for Prosopis compared to about 100 stems per hectare for A. karroo. Comparative measurements of water use shows that the annual stand level transpiration from Prosopis invasions was approximately 353 mm/year while that from A. karroo was only about 137 mm/year. Differences in stand transpiration were a result of the higher plant density for Prosopis than A. karroo. There were no significant differences in the transpiration rates of the two species for trees with a similar transpiring leaf area. Application of a two compartment linear mixing model for the oxygen isotope ratio during the peak transpiration period in summer showedthat Prosopis derived 23% of its water from the unsaturated zone and 77% from the saturated zone. A. karroo on the other hand derived 53% of its water from the unsaturated zone and47% from the saturated zone. Diurnal fluctuations in groundwater levels were strongly related to the transpiration dynamics of both species. This supports the observation that these deep rooted trees have substantial impacts on groundwater at the study site. Root sap flow patterns of Prosopis showed evidence of hydraulic redistribution wherein the groundwater abstracted by the tap roots was deposited in the shallow soil layers by lateral roots. However, the root sap flow patterns of A. karroo growing adjacent to the Prosopis did not show this phenomenon.

Thesis (MSc)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: Species’ seasonal behaviour is of paramount importance in understanding community functioning and dynamics. Recently, plant phenology has further gained significance as a reliable indicator of climate change impacts. Despite the importance of understanding plant dynamics, there are relatively few plant phenological records for the sub-Antarctic region, and where records exist they are often not extensive. Sub-Antarctic Marion Island, typical of Southern Ocean Islands, offers a useful setting for addressing these knowledge gaps. This study documented the vegetative and reproductive phenologies (or aggregate phenological patterns) of twelve indigenous and three alien vascular plant species on the island. The phenological differences among the species and distinct seasonal groupings (e.g. early, intermediate and late species) were examined. I also investigated the phenological differences among the indigenous and alien plant species. Furthermore, the onset of selected reproductive phenophases from the current records was compared with historical records for determining the extent of climate change-related alterations in phenology. Phenological data were collected fortnightly on five, 5 m x 5 m permanent plots per species (except for a few species) for a full growing season. Thus the sample size is n = 5 for all plant species except for Crassula moschata (n = 4), Juncus effusus (n=4) and Rumex acetosella (n=1). Sites of the same species were separated by at least 500 m except for the alien plant, Juncus effusus, where all four known populations were selected despite two of these populations being < 500 m apart. This study indicated that Marion Island plants grow throughout the year with no major peaks except in Azorella selago and Acaena magellanica which showed winter dormancy. However, reproduction in most plant species predominately occurred in spring and summer months. Pringlea antiscorbutica and Poa cookii were the first two species to set flower buds in September while most species dispersed their seeds in summer except for Agrostis magellanica and Crassula moschata which dispersed in early autumn. Distinct from most temperate systems, the reproductive seasonality displayed by Marion Island plant species is explained more by daylength than by temperature, perhaps due to the region’s typical thermal aseasonality. Interestingly, many cooccurring species and/or clades across the Falkland, Kerguelen, Macquarie and South Georgia Islands also showed similar flowering onset date to the Marion Island plants, further confirming their daylength sensitivity. However, other external factors seem to come into play at later events of reproduction. Consequently, fruit maturation time of similar species across the sub-Antarctic islands varied substantially despite the plants having flowered in the same month. Although plant species showed similar reproductive seasonality, there were significant differences among species phenologies i.e. phenophase timing, duration and peak occurrence dates. However, using 95% confidence intervals of Generalized Linear Models weighted means, and/or one-way ANOVA (Tukey post hoc test), three homogenous sets of species (early, late, or intermediate onsets) were identified based on flower bud, flowering and seed dispersal phenophase onset dates. The homogenous species groupings observed for flower buds also remained unchanged during flowering onset except for Cotula plumosa and Callitriche antarctica which switched groups. As for the seed dispersal timing, the pattern was not consistent with that of the flower bud and flowering onset homogenous groupings, except for Acaena magellanica and Agrostis magellanica which remained in the early and late groups, respectively. Conversely, in the case of the timing of other phenophases (pollen release, fruit set and fruit ripening), entire phenophase durations, and peak occurrence dates, species overlapped greatly, resulting in an unbroken progression or continuum of phenology among species. Similarly, the three alien plant species investigated here (Cerastium fontanum, Juncus effusus and Rumex acetosella) showed no consistent phenological differences from the rest of the species. However, a widespread alien plant species on Marion Island, C. fontanum, reproduced for most of the year, although its reproduction peak was in summer months as was the case for the rest of the species. This study also indicated that indigenous plant species have altered their reproductive phenologies since 1965. Although the response was species-specific, the majority of plant species significantly delayed the onset of reproductive activities in 2007 by comparison with 1965. However, it is not clear if the observed species response was caused by the now drier and warmer Marion Island climate or by discrepancies in reporting in the earlier studies and/or sampling differences between the recent and historical records. Therefore, these results should be taken with caution. In conclusion, this research provided a detailed phenological dynamics record for vascular plant species on the island. Over time these records may be used as a basis for monitoring and modelling the impact of climate on plant phenology on the island.
AFRIKAANSE OPSOMMING: Spesies se seisoenale gedrag is van die allergrootste belang in die begrip van gemeenskapsfunksionering en dinamika. Meer onlangs het plant fenologie verdere betekenis verwerf as ‘n betroubare indikator vir die impakte van klimaatsverandering. Ondanks die belangrikheid om plant dinamika te verstaan, is daar relatief min plant fenologiese rekords vir die sub-Antarktiese streek en waar rekords wel bestaan is dit dikwels nie omvangryk nie. Sub- Antarktiese Marion Eiland, tipies van Suidelike Oseaan Eilande, bied ‘n nuttige ligging om hierdie kennis gapings aan te spreek. Hierdie studie het die vegetatiewe en voorplantingsfenologieë (of gesamentlike fenologiese patrone) van elf inheemse en drie uitheemse vaatplantspesies op die eiland gedokumenteer. Die fenologiese verskille tussen die spesies en duidelike seisoenale groeperings (bv. vroeë, intermediêre en laat spesies) is ondersoek. Ek het ook die betekenisvolle fenologiese verskille tussen die inheemse en uitheemse plantspesies ondersoek. Voorts, die aanvang van gekose voortplanting feno-fases van huidige rekords is vergelyk met historiese rekords om die mate van klimaatsverandering verbandhoudende veranderings in die fenologie te bepaal. Fenologiese data is twee weekliks ingesamel op vyf, 5 m x 5 m permanente plotte per spesie (behalwe vir ‘n paar spesies) vir ‘n volle groei seisoen. Dus, die insamelings grootte is n = 5 vir al die plantspesies behalwe vir C. moschata (n = 4), Juncus effusus (n=4) en Rumex acetosella (n=1). Persele vir dieselfde spesies is geskei deur ten minste 500 m, behalwe vir die uitheemse plant, Juncus effusus, waar al vier populasies wat bekend is gekies is, ten spyte daarvan dat twee van hierdie populasies < 500 m uitmekaar is. Hierdie studie het aangedui dat Marion Eiland plante regdeur die jaar groei, met geen belangrike spitstye nie, behalwe in Azorella selago en Acaena magellanica wat ‘n winter rusperiode wys. Hoe ookal, voortplanting in meeste van die plantspesies het hoofsaaklik voorgekom tussen die lente en somermaande. Pringlea antiscorbutica en Poa cookii was die eerste twee spesies om blomknoppe uit te stoot in September, terwyl die meeste spesies hulle sade versprei het gedurende die somer, behalwe vir Agrostis magellanica en Crassula moschata wat versprei het in vroeg herfs. Duidelik van meeste gematigde sisteme, word die voortplanting seisoenaliteit, getoon deur die Marion Eiland plantspesies, verduidelik meer deur daglengte as deur temperatuur, moontlik weens die streek se tipiese termiese a-seisoenaliteit. Interessant, baie spesies en/of afstameling-groeperings wat saam aangtref word dwarsoor die Falkland, Kerguelen, Macquarie en Suid Georgia Eilande wys ook soortgelyke bloei aanvangsdatums as die Marion Eiland plante, nog meer bevestigend van hulle dag-lengte sensitieweteit. Hoe ookal, ander eksterne faktore blyk betrokke te raak by latere gebeure van voortplanting. Gevolglik het vrug rypwordingstyd van dieselfde spesies oor die sub-Antarktiek noemenswaardig verskil, ten spyte daarvan dat die plante in dieselfde maand geblom het. Alhoewel plantspesies dieselfde voortplanting seisoenaliteit gewys het, was daar ‘n noemenswaardige veskil tussen spesie fenologieë, m. a. w. feno-fase tydsberekenning, tydsduur en spits voorkomsdatums. Hoe ookal, deur gebruik te maak van 95% betroubaarheid intervalle van Algemene Lineêre Modelle gewigte gemiddelde en/of een rigting ANOVA (Turkey post hoc toets), is drie homogene stelle van spesies (vroeë, laat en intermediêre aanvang) geïdentifiseer gebasseer op blomknop, bloei en saad verspreiding feno-fase aanvangsdatums. Die homogene spesie groeperings waargeneem op blomknoppe het ook onveranderd gebly gedurende bloei aanvang behalwe vir Cotula plumosa en Crassula antarctica wat groepe geruil het. Vir die saadverspreiding tydsberekenning was die patroon nie konstant met die van die blomknop en bloei aanvang homogene groepe nie, behalwe vir Acaena magellanica en Agrostis magellanica wat in die vroeë en laat groepe respektiewelik gebly het. Omgekeerd, in die geval van tydsberekenning van ander feno-fases (stuifmeel vrysetelling, vrugwerp, vrugrypwording), volledige feno-fase tydsduur en spits voorkomsdatums het spesies grootliks oorvleuel, wat ‘n ongebroke vordering of deurlopendheid van fenologie tussen die spesies tot gevolg het. Ooreenkomstig het die drie uitheemse spesies wat hier ondersoek is (Cerastium fontanum, Juncus effusus en Rumex acetosella) geen bestendige fenologiese verskille van die res van die spesies gewys nie. Hoe ookal, ‘n wydverspreide uitheemse spesie op Marion Eiland, Cerastium fontanum, het deur die meeste van die jaar voortgeplant, hoewel met ‘n voorplanting spits in die somer maande soos die res van die spesies. Hierdie studie dui ook aan dat inheemse plantspesies hulle voortplanting fenologieë verander het sedert 1965. Alhoewel die reaksie spesiespesifiek was, het die meerderheid van die plantspesies hulle voortplanting aanvang aansienlik vertraag gedurende 2007 in vergelyking met 1965. Hoe ookal, dis nie duidelik of die waargeneemde spesie reaksie was as gevolg van die nou droër en warmer Marion Eiland klimaat of deur teenstrydighede in verslagewing gedurende die vroëre studies en/of insameling verskille tussen die onlangse en historiese rekords. Daarom moet hierdie resultate met versigtigheid hanteer word. In samevatting, hierdie navorsing voorsien ‘n gedetaileerde fenologiese dinamieka rekord vir vaatplantspesies op die eiland. Oor tyd kan hierdie rekords gebruik word as basis vir monitering en modellering van die impak van klimaat.

Includes bibliographical references.
With the continued spread of invasive alien vegetation in South Africa, there is a growing need and recognition in protecting ecosystem service delivery. While most literature on ecosystem services has focussed on provisioning and supporting services, this study looks at the less addressed cultural ecosystem services, specifically focussing on tourism and recreation. This research explores the relationship between tourism and invasive alien vegetation. This was carried out at firstly a national level, utilising primarily quantitative methods to identify, and map alien vegetation overlaps with key tourist sites in South Africa. This was followed by a more in-depth qualitative analysis, at a case study level, focussed on the Stellenbosch municipality, to determine the understanding and perceptions, tourists, landowners, and tourism operators have regarding invasive alien plants. Moderate to high levels of infestation were found overlapping various key tourism destinations across the country. The most heavily impacted provinces include the Western Cape, Eastern Cape, and KwaZulu-Natal. In certain areas, invasion levels at key tourist destinations raise concerns regarding the management of these sites. The findings of this research signify a close link and definite relationship between tourism, and invasive alien vegetation. Looking specifically at tourism as a cultural ecosystem service, and the relationship this service has with invasive alien vegetation, future studies need to recognise the significance of this association, while the broader tourism industry needs to recognise the potential threats invasive alien vegetation poses to their operations. Furthermore, this research identifies the value in combining qualitative, human dimensions, with quantitative data and mapping approaches in ecosystem services research.

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.

O medo é sinônimo da incerteza, da ignorância frente ao desconhecido. E, assim como argumentado por Bauman (2008), a escuridão não é a causa do perigo, mas é o habitat natural da incerteza - e, portanto, do medo. Na sociedade há inseguranças em praticamente todas as instâncias da vida e o sujeito vivencia o medo constante. Como reflexo dessa sociedade globalizada, baseada na privatização e desregulamentação, a cultura da mídia por vezes figurativiza, representa o tema do medo (de desastres naturais, doenças, desemprego, terrorismo) à imagem de monstros fantásticos, ou contrafactuais. São seres que confrontam nossa identidade e ameaçam a estabilidade social. Ao misturar a fantasia a elementos reais (promovidos pela ciência) o gênero da ficção científica utiliza um cenário futuro para levantar questionamentos sobre a sociedade atual e as relações entre o eu e o outro. A partir dessa discussão, neste estudo utilizamos o universo ficcional de dois filmes que fazem sucesso há mais de quatro décadas unindo terror e ficção científica, para, a partir deles, agrupar teorias e referenciais que possibilitem problematizar a alteridade no gênero da ficção científica e compreender como ela reflete os medos e as ansiedades. Os filmes O planeta dos macacos (1968) e Alien - o oitavo passageiro (1979) foram analisados pela perspectiva de autoras e autores dos Estudos Culturais, como Fredric Jameson, Douglas Kellner e Stuart Hall, além da metodologia de análise fílmica e da semiótica greimasiana. Observamos como conclusão que os seres alienígenas têm mais em comum com a espécie humana do que pensamos num primeiro momento; eles são capazes de aflorar os sentimentos mais obscuros, como a ganância e o ódio; geram insegurança e ameaçam a vida e o bem-estar
Fear is synonymous with uncertainty, with the ignorance in the face of the unknown. And, as argued by Bauman (2008), darkness is not the cause of danger, but it is the natural habitat of uncertainty - and therefore, fear. In society, there are insecurities in virtually every instance of life and people experiences constant fear. As a reflection of this globalized society, based on privatization and deregulation, media culture is sometimes figurative, representing the theme of fear (natural disasters, illness, unemployment, terrorism) as fantastic or counterfactual monsters. They are beings who confront our identity and threaten social stability. By blending fantasy with real elements (promoted by science), the genre of science fiction uses a future scenario to raise questions about current society and the relationship between self and other. From this discussion, in this study we used the fictional universe of two films that have been successful for more than four decades, uniting terror and science fiction, and, from them, group theories and references that make it possible to problematize the otherness in the genre of science fiction and to understand as it reflects fears and anxieties. The films The Planet of the Apes (1968) and Alien (1979) were analyzed from the perspective of authors of Cultural Studies, such as Fredric Jameson, Douglas Kellner and Stuart Hall, as well as the methodology of film analysis and Greimasian semiotics. We have observed that the alien creatures in the film have more in common with the human species than we might think at first; they are able to surface the most obscure feelings, such as greed and hatred; they can generate insecurity and threaten life and welfare

In this thesis, I have assessed and modelled invasion of alien plant species in the forest of the southeastern United States. There are over 380 recognized invasive plants in southeastern forests and grasslands with 53 ranked as high-to-medium risk to natural communities. I have focused on ten of these: Chinese lespedeza, tall fescue, Japanese honeysuckle, Chinese privet, autumn olive, princesstree, silktree, chinaberry, tree of heaven, tallowtree. Assessing them at differing scales, locally (Chapter 2 and 3), eco-regionally (Chapter 4 and 5) and regionally (Chapters 6 and 7), using field based measurements integrated with remotely sensed and digital datasets, and applying both parametric and non-parametric modelling approaches. Data from field based measurements as well as digitally available sources was evaluated, bringing together freely available data with time consuming, intensively collected data. Once models were developed application to assessing long term impacts was done by integrating potential climate change scenarios. At the local level Chinese lespedeza and Japanese Honeysuckle were the most prevalent, with models at the local level dominated by remotely sensed variables. At an eco-regional level Japanese honeysuckle was the most prevalent with models primarily dominated by environmental variables. At a regional level, where only trees were assessed, potential distributions of the invasive species ranged from 12 to 33 percent of the southeastern forests under current conditions with this dramatically increasing for chinaberry and tallowtree under most climate change scenarios, up as high as 66 percent of southeastern forest sites. In this thesis information on anthropogenic factors added some value to the models, however it was rarely dominant. Roads and land use (proportion of forest or distance to forest) were the most useful anthropogenic variables. In all models evaluated, only six times did any one anthropogenic variable represent more than 25 percent of the models, four of these were at the local scale. At the regional and eco-regional level, roads had a greater than 25 percent contribution to the silktree models, at a local level, distance to forest and distance roads contributed more than 25 percent to three of the species evaluated, sawtooth oak, Japanese honeysuckle and privet. Human activities have the most influence on invasion progression through dispersal (movement and introduction rate) and disturbance of the landscape (increased resource availability). Anthropogenic variables such as roads are likely to be a mechanism of spread, thus the more a model is driven by anthropogenic variables, the more likely the invasive plant is to be in the early stages of invasion process. Thus our results suggest that many of these species have moved through the first stages of invasion. Environmental characteristics play an important role in determining a site’s vulnerability to invasion. At an eco-region and regional scale, environmental characteristics dominated (>50%) all but one model (silktree at the regional scale). At the eco-region level elevation was the dominant variable, and at a regional level minimum temperature was the dominant variable. These have some correlation, with higher elevation often relating to lower temperatures, particularly at a smaller scale. This confirms the validity of matching the climate ranges of native species with the range of potential invasion, and the approach of integrating elevation, latitude and longitude to estimate potential distribution. It also suggests that climate change will influence the distribution and that variation in climate should be integrated into models. Two different modelling approaches, logistic regression and maximum entropy, were used throughout my thesis, and applied to the same data. Agreement between different modelling types adds strength to conclusions, while disagreement can assist in asking further questions. The inclusion in the models of similar variables with the same direction of relationships gives confidence to any inference about the importance of these variables. The geographical agreement between models adds confidence to the probability of occurrence in the area. Alternatively using the same model but different datasets can give you similar information. Overall for all models created by both logistic regression and MaxEnt, the logistic regression had slightly better omission rates and the MaxEnt model had better AUC’s. Logistic regression models also often predicted larger geographical areas of occurrences when the threshold of maximum sensitivity plus specificity was used, thus the lower omission rates is related to the less stringent model that predicts a larger area. The selection of appropriate data to answer the question was shown to be fundamental in Chapter 7. When data were used outside of the area of interest it generalized the models and increased the potential for invasion significantly. There was more value in the intensive surveyed data but this was less dramatic than in using the defined areas of interest to select the data for models.

Biological invasions are reportedly one of the major contributory factors to biodiversity loss worldwide. The impacts of invasive alien plant (IAP) species on native communities are widely documented in the scientific literature, however, there is still a lack of detailed information on their impacts within the most vulnerable habitats. Riparian habitats are highly dynamic systems and naturally disturbed, making them particularly vulnerable to invasion. Climate change, directly or indirectly, is also predicted to adversely impact river systems, which may subsequently alter invasion rates and the impacts of IAPs. However, the interactions between climate and IAPs and their combined effects on vegetation have rarely been examined. To address these knowledge gaps, this thesis investigates: (1) the role of environmental variables, such as sediment loading or climate-related changes to river flow regime, on the abundance of IAPs within riparian zones; (2) how variation in IAP abundance impacts native vegetation, relative to the effects of native dominant plant species and (3) some of the mechanisms underlying the effects of IAPs in riparian habitats. Historic and recent field survey data were used to investigate changes in riparian vegetation on British rivers during the last 20 years. Analyses indicate that IAPs had a negative but small effect on native plant diversity. Overall, changes in land use and differences in flow regime between recording periods were the most important predictors of plant community change. Specifically, IAPs had a greater probability of being present along lowland rivers that experienced increased frequency of high flow events. On a local scale across rivers in Scotland, the abundance of IAPs was constrained by greater soil moisture in summer, whilst greater abundance was associated with tree-lined banks. Both native dominant species and IAPs negatively affected subordinate species abundance to a greater extent than species richness, although this effect varied spatially with bank elevation. Artificial turf mats were used to quantify viable propagules within riverine sediment deposited over-winter along invaded riverbanks. The data indicate that there is a legacy effect of IAP abundance, with the most invaded sites being associated with higher sediment loading the following year, though, contrary to the general pattern, 12 sediment associated propagules were scarcer at invaded sites. Moreover, lower above-ground native diversity was associated with sites which had been previously invaded. Plant species composition in the propagule bank and above-ground vegetation were highly dissimilar, particularly closest to the water’s edge at highly invaded sites. This suggests that mono-specific stands of IAPs proliferate best under less disturbed environmental conditions, although fluvial disturbance events may be required to create opportunities for initial establishment. The propagule bank contributed very little to the above-ground vegetation, nor did it limit invasion, suggesting that above-ground plant composition is largely dictated by competitive interactions. The findings presented in this thesis suggest that invasion by IAPs is an additional stressor for native vegetation within riparian habitats, modifying above-ground plant communities via competition and suppressing recruitment from the propagule bank. However, native dominant species common in riparian habitats also negatively impact, subordinate species via competition, in some cases equalling the effect of IAPs. Native dominant and IAP species are differently affected by environmental factors operating in the riparian zone, which may provide future opportunities for reducing and managing invasions.

The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.

Invasive plant species threaten native plant communities and inhibit efforts to restore disturbed landscapes. Surface coal mines in the Appalachian Mountains are some of the most disturbed landscapes in North America. Moreover, there is not a comprehensive understanding of the land cover characteristics of post- mined lands in Appalachia. Better information on mined lands' vegetative cover and ecosystem recovery status is necessary for implementation of effective environmental management practices. The invasive autumn olive (Elaeagnus umbellata) is abundant on former coal surface mines, often outcompeting native trees due to its faster growth rate. The frequent revisit time and spatial and spectral resolution of Landsat satellites make Landsat imagery well suited for mapping and characterizing land cover and forest recovery on former coal surface mines. I performed a multitemporal classification using a random forest analysis to map autumn olive on former and current surface coal mines in southwest Virginia. Imagery from the Operational Land Imager on Landsat 8 were used as input data for the study. Calibration and validation data for use in model development were obtained using high-resolution aerial imagery. Results indicate that autumn olive cover is sufficiently dense to enable detection using Landsat imagery on approximately 12.6% of the current and former surface coal mines located in the study area that have been mined since the early 1980s. The classified map produced here had a user's and producer's accuracy of 85.3% and 78.6% respectively for the autumn olive coverage class. Overall accuracy in reference to an independent validation dataset was 96.8%. These results indicate that autumn olive growing on reclaimed coal mines in Virginia and elsewhere in the Appalachian coalfields can be mapped using Landsat imagery. Additionally, autumn olive occurrence is a significant landscape feature on former surface coal mines in the Virginia coalfields.
Master of Science

Thesis (MSc)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: With only 1.76% conserved West Coast Renosterveld remaining it is crucial to prioritize the conservation and management of this fragile vegetation type. Because of its occurrence on fertile soils, renosterveld has been cleared for cultivation and other agricultural use and is thus fragmented to a critical point. These remaining fragments are subject to extensive edge effects and the exact parameters of a viable fragment must still be determined. The extent of alien grass species invasion into remnant renosterveld patches was determined using data collected using the line-intercept method. Sampling included three different management treatment areas adjacent to old lands: 1) a recently burned area, 2) a grazed area and 3) an unburnedlungrazed area providing a control sample. Additionally all small-scale soil disturbances along the lines were recorded. Results showed that Briza spp., Bromus spp. and Avena fatua were the most significant invading alien grass species. There was a significantly high variation between alien grass cover in each treatment, with the grazed area containing the highest overal! level of alien grass invasion. The control area, with the exclusion of fire and animal activity, showed minimum alien grass invasion. Edge effects were apparent in all treatments, but were lowest in the control area, where percentage alien grass cover significantly decreased after a distance of fifteen meters into the remnant patch. A weak positive correlation between the occurrence of alien grass and indigenous grass was found, as well as evidence of a weak association between alien grass cover and shrub cover. The possibility that small-scale soil disturbances could be an important contributing factor to alien grass invasion was supported by the positive correlation between disturbances and percentage alien grass cover. A positive correlation was found between the occurrence of indigenous grass and small-scale soil disturbances, while shrub cover tended to be less associated with animal activity. It is concluded that the correct management regime could effectively control the excessive invasion of alien grass species into the remnant renosterveld patches. Grazing (including all animal activity and small-scale soil disturbances) was the main facilitator of alien grass establishment - even dominating the prominent consequences of edge effects by facilitating alien grass establishment much deeper into the remnant patches. It could be assumed that a precise balance of low-pressure grazing and fire management should be established to enable the effective control of alien grass species while maintaining optimum biodiversity. Keywords: renosterveld, alien grass, grazing, fire, management, small-scale soil disturbances
AFRIKAANSE OPSOMMING: Met slegs 1.76% oorblywende Weskus Renosterveld wat bewaar word, is die beskerming en effektiewe bestuur van hierdie bedreigde plantegroei 'n prioriteit. Die vrugbare grond waarop renosterveld voorkom, het veroorsaak dat dit uitgeroei word om eerder die kultivering van ekonomies produktiewe landbou gewasse moontlik te maak. Dus het renosterveld verminder en gefragmenteer tot 'n kritieke punt. Hierdie ooblywende klein areas bedek met renosterveld, is blootgestel aan ekstensiewe invloede van die omliggende areas en die presiese afmetings vir 'n effektiewe grate renosterveld fragment vir bewarings doeleindes, moel nog vasgestel word. Die male van uitheemse gras spesie indringing in hierdie renosterveld fragmente is ondersoek deur die versameling van data deur die lyn-onderskep metode. Drie verskillende bestuursstelsels vir renosterveld is ondersoek om vas te stel wat die ergste graad van uitheemse gras indringing voorkom. Die studie het 'n 1) onlangs gebrande area, 2) 'n beweide area en 3) 'n kontrole area (wat nie gebrand of bewei is nie) ondersoek. Alle kleinskaalse grond-versteurings langs die lyne is ook aangeteken. Die resultate het aangetoon dat Briza spp., Bromus spp. en Avena fatua, as uitheemse grasse, die belangrikste indringers was en dus die grootste bedreiging inhou. Daar was 'n beduidende hoë variasie tussen die mate van uitheemse gras bedekking aangeteken in elk van die bestuurs-stelsels. Die beweide area het die hoogste graad van uitheemse gras indringing getoon, terwyl die kontrole area (in die afwesigheid van vuur en weidings aktiwiteite) die meeste weerstand teen uitheemse gras indringing getoon het. Die invloed van die omliggende omgewing was ook duidelik sigbaar in al drie die bestuurs-stelsels, maar was duidelik minder in die kontrole area waar die persentasie uitheemse gras indringing aansienlik verminder het na 'n afstand van vyftien meter in die renosterveld fragment in. 'n Swak positiewe korrelasie tussen die voorkoms van uitheemse grasse en inheemse gras spesies was aangeteken, asook bewyse van 'n swak negatiewe assosiasie tussen die uitheemse gras spesies en die inheemse bosse. Soos verwag, is daar bewyse gevind vir die teorie dat kleinskaalse grond-versteurings 'n belangrike fasiliterende faktor is vir uitheemse gras vestiging. Daar was 'n duidelike positiewe korrelasie tussen hierdie grond-versteurings en die persentasie uitheemse gras grondbedekking. Dieselfde positiewe assosiasie was gevind tussen die inheemse gras en hierdie kleinskaalse grond-versteurings, terwyl die inheemse bossie duidelik minder verbind was met die verskynsel. Die gevolgtrekking is gemaak dat 'n korrekte bestuurs-plan die indringing van uitheemse grasse effektief sal kan beheer. Dier aktiwiteite (insluitende beweiding, grawe van gate, mier en termiet neste ens.), en dus kleinskaalse grond-versteurings. was die grootste fasiliteerders van uitheemse gras indringing en vestiging binne hierdie renosterveld stukke. Dit oorheers selfs die aansienlike effek wat invloede van die omringende omgewing op hierdie areas het, deur die uitheemse gras indringing selfs dieper in die fragmente in aan te help. Daar kan dus aangeneem word dat 'n presiese balans tussen lae-intensiteit beweiding (en dus fauna aktiwiteit) en veld brande vasgestel moet word vir die effektiewe beheer van uitheemse gras spesies terwyl die optimum bio-diversiteit terselfde tyd gehandhaafword. Sleutelwoorde: renosterveld, uitheemse grasse, beweiding, vuur, veldbestuur, kleinskaalse grond-versteurings

Thesis (MSc)--Stellenbosch University, 2008.
ENGLISH ABSTRACT: Macroecological relationships have rarely been studied at wide spatial scales and across geographic ranges of species in the field in the sub-Antarctic. In this thesis I examined the occupancy, distribution and abundance, and the relationships thereof, of indigenous plants and alien species at broad (island-wide) and fine scales across sub-Antarctic Marion Island. The impacts of alien species and their interactions with indigenous plants were also investigated. I examined the nature of the abundance structure of a cushion-forming, vascular plant, Azorella selago, at the island-wide scale. Moreover, the hypothesis that species reach their highest abundances at the centre of their geographic range and decline in abundance towards the range edges was tested. Azorella selago cushions were counted in 8 m x 8 m quadrats, placed regularly at 1 minute latitude and longitude intervals across Marion Island. Using spatially non-explicit and explicit methods, this study showed that the abundance structure of A. selago had a more complex pattern of high abundance patches and low abundance gaps in its island-wide distribution. Subsequently, the hypothesis of an abundant centre distribution was not supported for A. selago across Marion Island. Rather, there were sharp discontinuities at both the coastal and altitudinal (667 m a.s.l.) limits for the species, between which little pattern in altitudinal abundance structure existed. Mice (Mus musculus) have recently been found to cause extensive structural damage to A. selago. The structural influence of mice on vegetation structure at the landscape scale has largely been overlooked on many sub-Antarctic islands. I mapped the distribution of evidence of mouse damage within the cushions of A. selago across the island using systematic (at 1 minute latitude and longitude intervals) and opportunistic sampling. Approximately 40 % of the systematically sampled sites had evidence of mouse damage to A. selago. Furthermore, a third of cushions in opportunistically sampled sites was damaged. Mouse damage was high in sites of low A. selago abundance, emphasizing that impacts of mice may be greater in low cushion abundance areas. This damage sometimes led to the disintegration of entire cushions. Given that A. selago acts as a nurse plant and supports high abundances of indigenous invertebrates, the impacts of mice on this keystone species may have significant ecological implications. Studies on interactions between alien and indigenous plants are limited within the sub-Antarctic. I examined the fine-scale distributions and co-occurrences of alien plants, Agrostis stolonifera and Sagina procumbens, and the indigenous Acaena magellanica (in 2 m x 2 m plots, subdivided into 0.25 m x 0.25 m quadrats) along rivers on Marion Island. Environmental variables were important for the occurrence of these species. In particular, 42.95 % and 24.82 % of the deviance in the occurrence of A. stolonifera and S. procumbens, respectively, was explained by environmental variables, compared to 17.35 % for A. magellanica. Furthermore, the co-occurrence of A. magellanica with A. stolonifera was significantly influenced by environmental variables. Significant positive spatial associations between A. magellanica and A. stolonifera were found, while the interactions of either species with S. procumbens were either spatially dissociated or random. Therefore, this study highlighted that alien species are responding to different environmental variables and conditions on Marion Island. Sagina procumbens seems to be less sensitive to the island’s environmental conditions and may thus be affecting biodiversity at broader ranges. This thesis provides unparalleled data on the distributions and interactions of indigenous plants and alien species for Marion Island. Alien species are undoubtedly posing significant threats to indigenous plants on the island and this thesis presents insight into interactions of species, specifically plants, an approach underrepresented in the sub-Antarctic to date.
AFRIKAANSE OPSOMMING: Makro-ekologiese verhoudings is selde bestudeer op wye ruimtelike skale en oor geografiese gebiede van spesies in die veld in die sub-Antarktiek. In hierdie tesis het ek die digtheid, bewoning, verspreiding en die verhoudings daarvan, van inheemse plante en uitheemse spesies ondersoek op breë (eiland-wyd) en smal skale oor sub-Antarktiese Marion Eiland. Die impakte van uitheemse spesies en hul interaksies met inheems plante is ook ondersoek. Ek het die aard van die digtheidstruktuur ondersoek van 'n kussing-vormende, vaatplant, Azorella selago, op die eiland-wydte skaal. Bowenal is die hipotese dat spesies hul hoogste digtheid bereik in die sentrum van hul geografies gebied en afneem in digtheid na die grense van die gebied getoets. Azorella selago kussings is getel in 8 m x 8 m kwadrante, wat eweredig geplaas is op 1 minuut breedte- en lengtegraad intervalle oor Marion Eiland. Deur gebruik te maak van ruimtelik nie-eksplisiete en eksplisiete metodes, het hierdie studie getoon dat die digtheidstruktuur van A. selago ‘n meer komplekse patroon van hoë digtheidslaslappe en lae digtheidsgapings in sy eiland-wyd verspreiding het. Vervolgens is die hipotese van 'n digte sentrum verspreiding nie gesteun vir A. selago oor Marion Eiland nie. Daar was eerder skerp diskontinuïteite by beide die kus- en hoërliggende (667 m bo seespieël) grense vir die spesie, waartussen daar ’n oneweredige patroon in digtheidstruktuur bestaan het. Onlangs is bevind dat muise (Mus musculus) uitgebreide struktuele skade aan A. selago veroorsaak. Die struktuele invloed van muise op plantegroei struktuur op landskapskaal is grootliks oor die hoof gesien op baie sub-Antarktiese eilande. Ek het die verspreiding van die bewyse van muisskade binne die kussings van A. selago oor die eiland gekarteer deur gebruik te maak van sistematiese (tot 1 minuut breedte- en lengtegraad intervalle) en opportunistiese opnames. Ongeveer 40 % van die sistematiese opname kwadrante het bewyse van muis skade aan A. selago vertoon. Verder, ‘n derde van die kussings in die opportunistiese opname kwadrante was beskadig. Muisskade was hoog in plotte met lae A. selago volopheid, wat beklemtoon dat impakte van muise groter mag wees in lae kussing digtheid gebiede. Hierdie skade het partykeer gelei tot die verbrokkeling van hele kussings. Gegewe dat A. selago as 'n verpleegsterplant optree en ’n hoë digtheid van inheemse invertebrata ondersteun, mag die impakte van muise op hierdie hoeksteen spesie beduidende ekologiese implikasies tot gevolg hê. Studies oor interaksies tussen uitheemse- en inheemse plante is beperk in die sub-Antarktiese gebied. Ek het die smal-skaal verspreidings ondersoek en medevoorkoms van uitheemse plante, Agrostis stolonifera en Sagina procumbens, en die inheems Acaena magellanica (in 2 m x 2 m kwadrante, subverdeel in 0. 25 m x 0. 25 m kwadrante) langs riviere op Marion Eiland. Omgewingsveranderlikes was belangrik vir die voorkoms van hierdie spesies. In besonder, 42.95 % en 24.82 % van die afwykings in die voorkoms van A. stolonifera en S. procumbens, onderskeidelik, is verduidelik deur omgewingsveranderlikes, vergeleke met 17.35 % vir A. magellanica. Verder, die medevoorkoms van A. magellanica saam met A. stolonifera is beduidend beinvloed deur omgewingsveranderlikes. Beduidende positiewe ruimtelike assosiasies tussen A. magellanica en A. stolonifera is gevind, terwyl die interaksies van beide spesies met S. procumbens was of ruimtelik nie-geassosieerd of lukraak. Daarom het hierdie studie uitgelig dat uitheemse spesies reageer op verskillende omgewingsveranderlikes op Marion Eiland. Sagina procumbens blyk minder sensitief te wees tot die eiland se omgewingsomstandighede en mag dus moontlik biodiversiteit op breër vlakke beïnvloed. Hierdie tesis voorsien onge-ewenaarde data oor die verspreiding en interaksies van inheems plante en uitheemse spesies vir Marion Eiland. Uitheemse spesies hou ongetwyfeld ’n beduidende bedreiging in vir inheems plante op die eiland, en hierdie tesis bied insig in die interaksies van spesies, spesifiek plante – ’n benadering wat swak verteenwoordig was in die sub-Antarktiese gebied tot op hede.

It is well known that invasive alien plants (IAPs) pose a significant threat to natural biodiversity and human well-being. Through various pressures exerted on natural ecosystems, IAPs decrease and alter natural processes that provide important ecosystems services and livelihoods to human communities. These plants also displace and out-compete natural plant communities in the areas in which they invade. Management of IAPs is a complex issue with social, environmental and financial challenges. The long-term sustainable management of IAPs requires a management approach that monitors and measures the outcomes of current management practices, and considers the lessons learnt in future decision making. Adaptive management is such an approach and is characterised by monitoring, assessment, reflection and adaptation. In this dissertation I explore IAP management within the South African National Parks (SANParks) organisation. I focus on the quality of the available IAP clearing data for monitoring and environmental decision-making and explore how strategic adaptive management (SAM) is being applied to IAP management. Strategic adaptive management is a form of adaptive management that SANParks adopted to deal with the inherent unpredictability of the social ecological systems they manage, and is primarily a learning-by-doing approach. In chapter one I describe the various impacts that IAPs have on natural environments. I also discuss management of IAPs, the national Working for Water (WfW) programme and how SANParks control IAPs in partnership with WfW. Clearing of IAPs within the borders of SANParks is funded by the Department of Environmental Affairs‘ (DEA) Natural Resource Management programmes and carried out through the Working for Water programme, under SANParks‘ Biodiversity Social Projects programme and is done on a contract basis. Contract data are stored in the Working for Water Information Management System (WIMS) database. Although IAP clearing is well established, the efficiency of overall clearing operations within the parks, and quality and reliability of the data available in the WIMS, needs to be examined. In Chapter two, I (i) assess the status of IAP clearing and the direct clearing costs in each of the five national parks (costs are inflated to 2012 equivalents using the consumer price index), (ii) assess the accuracy of workload estimations for WfW IAP clearing, and (iii) discuss the utility of WIMS as a system to collate and store accurate data for monitoring purposes, focusing on the integrity and reliability of the data, the accuracy of density estimations and whether it can inform sound decision making. The planning of future clearing contracts lacks efficiency due to inaccuracies and unreliability of input data, specifically estimates of invasive alien plant density. The accuracy of density estimation and cost of clearing varies greatly between parks and does not appear to reflect the reality on the ground. In Chapter 3, through an interview process with IAP managers, I 1) unpack the steps in the SAM ‗cycle‘ and investigate the effectiveness of implementation of each step according to respondents; 2) assess the barriers that are currently keeping managers from implementing effective IAP management; 3) discuss whether learning and adaptation is taking place, and 4) discuss how the SAM process can be modified to promote its effectiveness.

Alien invasive species pose a great threat to ecosystems and human communities (Richardson & van Wilgen 2004; Hobbs & Humphries 1995). On private lands, there is a need to find institutional, administrative and scientific responses to the alien plant problem that operate beyond the scale imposed by property boundaries (Slocombe 1998; Grumbine 1994). One such response is the development and support of institutions, such as the St Francis Conservancy, that foster cross-boundary management of landscapes (Hurley et al. 2002). This study seeks to promote collective decision-making and collaborative management by private landowners through the development of a resource allocation system for the control of alien invasive plants on the St Francis Conservancy. The conservancy is located in the south-eastern lowlands of the Cape Floristic Region, between the villages of Cape St Francis and Oyster Bay, and is comprised of the properties of multiple landowners. Mutliple Criteria Decision Analysis (MCDA) and Geographical Information Systems (GIS) techniques were integrated to provide a spatially explicit resource allocation system that considered environmental, social and economic concerns. The MCDA technique selected for use was the Analytical Hierarchy Process (AHP). This technique has a record of providing robust, defensible decisions and enabled the resource allocation decision-problem to be decomposed into a hierarchy of objectives, criteria and indicators. Stakeholders participated in the development of the resource allocation system, especially through providing input into the determination of the relative importance of criteria and indicators through the assignment of weights. Various weighting scenarios were presented and these were interpreted into an ii implementation plan. The costs and effort required to clear alien plants were estimated, and obstacles facing the implementation of the plan were identified.

[Truncated abstract] Annual grasses have colonised a diverse range of environments in southern Australia. The “Silvergrasses” of the genus Vulpia are excellent examples being widely distributed, are prevalent weeds of agriculture and have had a long history to naturalise on the continent. Research was undertaken on Vulpia populations to identify if naturalising species have reproductive traits that provide propagules with the best chances of success. Furthermore, research aimed at investigating if these traits vary between species and their populations and how this variability related to the environment. A herbarium and field study was undertaken to establish what Vulpia species occur in SW Australia and to investigate environmental factors affecting their distribution. 169 herbaria specimens was examined and a botanical field survey of 189 sites was carried out in September 1998. Four species occur in the region: V. fasciculata, V. muralis, V. bromoides and two variants of V. myuros (V. myuros var. megalura and V. myuros var. myuros). V. bromoides and V. myuros were introduced early into the region while V. fasciculata and V. muralis more recently. It is plausible that Vulpia invaded the region via early seaport settlements and was spread by agricultural expansion. 96% of field sites contained V. myuros var. myuros, 79% V. myuros var. megalura, 50% V. bromoides, 6% V. fasciculata and 6% contained V. muralis. 90% of sites contained a mix of species and 9% of sites contained pure species stands. V. myuros var. myuros is the most widespread species and dominant form of V. myuros. It is found from high rainfall regions through to arid locations occurring on mostly light textured low fertility soils. V. muralis and V. fasciculata occur infrequently with the former widely dispersed and the later occurring predominantly on sands. V. bromoides occurs extensively in high rainfall regions but rarely extends to locations receiving less than 400-450mm annual rainfall and northward above 30°00’ latitude. It is predominantly on light to loamy textured soils that are fertile and acid. The most common species V. myuros and V. bromoides often coexist within sites but the dominance of one over the other is strongly correlated with growing season length and false break frequency. V. bromoides is positively correlated to growing season length and V. myuros is negatively related. The distribution of Vulpia species is strongly influenced by climate and soils. Variability in distribution is a reflection of the ecological differentiation between species to colonise different environments