Thesis (M. Sc. (Botany)) -- University of Limpopo, 2022 / Nature reserves are reservoirs for biodiversity. Their very purpose is to preserve indigenous fauna and flora and thus protect associated ecosystem services. The Schuinsdraai Nature Reserve of rural Sekhukhune District, Limpopo Province, is the focus of this study. Sekhukhune District is predominantly rural, with limited economic opportunities but rich mineral resources, the mining of which negatively impacts biodiversity. The Sekhukhune Centre of floristic endemism falls within this district and the nature reserve is thus an important factor in safeguarding a representative section of this floristic center. The veld type present in the reserve is central sandy bushveld. Although mining is prohibited within the reserve, invasive alien plants or (IAPs) pose as high a threat to biodiversity as does mining. The spread of IAPs in nature reserves is harder to control than mining which is prohibited outright whereas IAP spread is automatic and insidious. The management of IAPs is of concern to the government of South Africa and is an ongoing process. Rural areas and the nature reserves within them, such as the Schuinsdraai Nature Reserve, are often under studied or under managed with regards to IAPs. This study supplements the available but scarce data on IAPs for Schuinsdraai Nature Reserve. The Schuinsdraai Nature Reserve is dominated by the Central Sandy Bushveld vegetation type. Rainfall is on average 470 mm per year and mean annual temperature varies from 24 ˚C in the summer, to 14 ˚C in the winter. The topography includes mountains, hills, plains, and the Flag Boshielo Dam. The aims of the study were to establish the presence and extent of IAPs in the Schuinsdraai Nature Reserve and to determine whether the IAPs present negatively affect the biodiversity. Road-side inspections, road surveys and line transects were used to investigate presence and extent of IAPs. Modified Braun-Blanquet quadrates were used to compare the effect of the most prevalent IAPs on the plant biodiversity in the Schuinsdraai Nature Reserve. Quadrates were positioned in areas heavily infested by species of IAPs and these areas compared with untransformed areas within 10 m of the infested quadrates. Species richness, species evenness and v biodiversity indices were calculated for transformed (control) areas compared with infested areas. Roadside inspections and road surveys indicated the presence of IAPs. They revealed that most IAPs were present on the eastern side of the nature reserve closest to areas most visited by tourists. Roads and the movement of people therefore affect the spread of IAPs within the Schuinsdraai Nature Reserve. The four most prevalent species identified from roadside inspections and road surveys were: Opuntia stricta, Cylindropuntia fulgida, Cereus jamacaru and Boerhavia diffusa. Opuntia stricta had the greatest negative effect and was also the most prevalent IAP on the Schuinsdraai Nature Reserve. The number of IAPs per transect observed in the area where access was unlimited was significantly higher than where access was limited. Opuntia stricta was the IAPs exhibiting the most significant (.00057) impact on species richness and species diversity and, where funds are limited, these should be targeted for eradication rather than other IAPs. From the results obtained, management recommendations were tabled including the most important, which is to clearly demarcate areas where public movement should be restricted, and meticulously patrol areas which are open to the public and remove IAP’s immediately. In conclusion, IAPs are present and do cause deleterious effects on species richness, diversity and evenness within the Schuinsdraai Nature Reserve, however, the strict management of anthropogenic influences should be implemented to control their spread and increase.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 112-121). Also available on the World Wide Web.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Invasive alien plants threaten natural and agricultural pollination systems as they integrate into and disrupt flower visitation networks. Mango (Mangifera indica) production on commercial mango farms in Hoedspruit, South Africa, is an important part of the local economy. Mangoes require pollination for fruiting success, and depend on the native insect community, facilitated by managed bee colonies (Apis mellifera), to pollinate flowers. Managed honeybees and wild insect flower visitors to mango have previously been observed visiting other flowering plants in surrounding natural vegetation, including the alien invasive plant Lantana camara. Lantana camara and mango share similar floral characteristics and co-occur in close proximity, so they may share pollinators/flower visitors. Here, I determined L. camara’s influence on mango flower visitation networks, specifically whether it facilitates visitation, through greater abundance and diversity of insect flower visitors (facilitation), or competes for flower visitors (competition), and whether it supports mango flower visitors when mango trees are not in flower. This study was conducted on the margins of three mango farms and bordering natural vegetation. Firstly, L. camara’s effect on mango flower visitation was investigated by comparing flower visitation to mango in plots with and without L. camara nearby. The presence of L. camara was associated with greater mango flower visitation, with increases in both flower visitor species abundance and richness. Secondly, the composition of flower visitor communities of mango orchard boundaries and bordering natural vegetation were evaluated. Although some flower visitors were shared between mango and naturally occurring plants, flower visitor community assemblages were significantly different between natural vegetation and mango orchard boundaries. In natural vegetation, flies, butterflies, wasps, wild bees and ants played a primary role in the visitation networks, whereas honeybees, wild bees and flies were the main visitors in mango orchards. The presence of L. camara significantly influenced community structure in both natural vegetation and orchards. Natural vegetation with L. camara had a more diverse flower visitor community than natural vegetation without L. camara. Lantana camara seems to facilitate mango flower visitation during mango flowering, attracting a larger visitor abundance and species richness where it occurs in bordering natural vegetation and nearby mango orchard boundaries. However, L. camara was seen to be visited by few species known to visit mango outside of mango flowering, suggesting that L. camara may benefit more from facilitation than mango. Given its extreme invasive nature and threat to local plants which sustain native pollinators, L. camara should be removed from mango orchards and bordering natural vegetation. Furthermore, farm managers are encouraged to plant and maintain indigenous flowering plants, especially plants with a facilitative value to mango, in land surrounding mango orchards to sustain native wild pollinators beneficial to mango pollination. / AFRIKAANSE OPSOMMING: Indringerplante bedreig natuurlike- en landboubestuiwingsisteme deur blombesoekingsnetwerke binne te dring en te ontwrig. Mango (Mangifera indica) produksie op kommersiële plase in Hoedspruit, Suid-Afrika, speel 'n belangrike rol in die plaaslike ekonomie. Suksesvolle mangovrugproduksie is afhanklik van bestuiwing deur inheemse insekte, gefasiliteer deur bestuurde heuningbykolonies (Apis mellifera). Dit is vantevore waargeneem dat hierdie heuningbye en inheemse insekblombesoekers ook ander blomme besoek in die omliggende natuurlike plantegroei, veral Lantana camara wat in hierdie areas ook voorkom. Lantana camara en mango deel soortgelyke blomeienskappe en groei baie na aan mekaar op die buitenste rande van mango boorde. In hierdie studie bepaal ek L. camara se invloed op mangoblominsekbesoekers, en kyk spesifiek of dit mangoblombesoeking fasiliteer, deur om die aantal blombesoekers en blombesoekerspesies te verhoog (fasilitering), of mee kompeteer vir blombesoekers (kompetisie), en of dit mangoblombesoekers onderhou wanneer mango bome nie blom nie. Hierdie studie is uitgevoer op die grensgebied tussen die mangoboorde en natuurlike plantegroei van drie mangoplase. Eerstens is L. camara se effek op mango ondersoek deur mangoblombesoeking te vergelyk tussen plotte met en sonder L. camara. Daar is gevind dat L. camara mangoblombesoeking fasiliteer deur om die aantal blombesoekers en besoekerspesies te verhoog. Tweedens is die gemeenskapsamestelling van blombesoekers in mangoboordrande en aangrensende plantegroei geëvalueer. Alhoewel sommige blombesoekers by mango én ander plante gevind word, is hul gemeenskapsamestelling aansienlik verskillend tussen die mangoboordrande en aangrensende plantegroei. Vlieë, skoenlappers, wespe, bye en miere speel 'n primêre rol in die blombesoekingsnetwerke van natuurlike plantegroei, waar hierdie rol in mangoboord-besoekingsnetwerke vervul word deur heuningbye, wilde bye en vlieë. Die teenwoordigheid van L. camara het die gemeenskapstruktuur in beide gebiede beduidend beïnvloed. Die aangrensende natuurlike plantegroei, waar L. camara voorkom, het ‘n meer diverse blombesoekersgemeenskap as dié sonder L. camara. Mangoboorde wat grens aan plantegroei, wat L. camara insluit, het soortgelyk 'n groter blombesoekerspesierykheid en aantal blombesoekers gehad. Dit blyk dat, waar hierdie plant voorkom, Lantana camara mangoblombesoeking fasiliteer tydens mangoblomtyd sowel as om 'n groter aantal blombesoekersinsekte met ‘n groter spesierykheid te lok in beide die mangoboorde en aangrensende natuurlike plantegroei. Daar is egter geen bewyse gevind wat voorstel dat L. camara mangoblombesoekers ondersteun buite mangoblomtyd nie, wat aandui dat L. camara voordeel trek uit die fasiliterende verband met mango. Gegewe L. camara se uiterse indringende geaardheid en bedreiging aan die plaaslike inheemse plantgemeenskap wat inheemse bestuiwers onderhou, word L. camara se verwydering vanuit die aangrensende plantegroei aanbeveel. Dit word aanbeveel om L. camara se fasiliterende rol te vervang deur inheemse blomplante in dié areas aan te plant en natuurlike blomplantegroei te bewaar en te onderhou.

published_or_final_version / abstract / Ecology and Biodiversity / Master / Master of Philosophy

3 pp. / Tips for Arizona's Rural Landowners Series -- Plants Unit / The Tips for Arizona's Rural Landowners Fact Sheet Series is intended to educate homeowners who have recently purchased small acreages in Arizona. The purpose of the series is to give homeowners information about living in rural settings. The Plant Unit includes fact sheets on Arizona's native plant law, small-scale gardening, pasture establishment, invasive plants, and assessing plant damage.

Understanding why some introduced alien plant species become invasive whilst others fail is a fundamental question in ecology, not least because of the considerable ecological and economic damage caused by invasive plants globally. Identifying factors that drive alien plant invasions can inform efforts to predict the nsk of invasion by an introduced plant species. This would allow prevention of introduction of high risk aliens, as well as targeted management of species already introduced that pose the latest threats to the ecolocal integrity of host ecosystems. However, generalisations among the findings of comparative plant invasion studies have been limited by a lack of control of confounding variables such as propagule pressure, time since introduction and phylogeny, a lack of knowledge of introduced species that failed to establish, and inconsistent use of terminology defining the invasion process. This thesis used Amani Botanical Garden (ABG) in the East Usambara Mountains of Tanzania, as a comparative case study system to assess the relative ability of multiple factors to explain invasion success of species introduced to a tropical forest ecosystem.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 73-81). Also available on the World Wide Web.

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

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.

Point Pelee National Park in Ontario, Canada has been affected by a long history of human activity. This activity has encouraged the establishment of approximately 276 exotic invasive plant species. These plants decrease biodiversity and effective function of ecosystems within the Park. A 5 Year Exotic Plant Species Management Plan for the Park was written in 1990. Since that time inventories have been done on some of the species but a monitoring of all the high priority exotic invasive plants has not. As part of this study an inventory of the high priority exotic invasive plants and their spatial extent in the Park, was created. From May to September, 2011 a comprehensive inventory took place within a 5.5km stretch in the terrestrial area at the southern end of the Park. Systematic belt transects were performed, on foot, from west to east at 100 m intervals. Within the quadrats percent cover of each plant species was determined. The data collected in the field were compiled using geographic information systems (GIS), resulting in maps of the extent of the most abundant species studied. Analysis as part of this study included using the data to determine which plants and areas are higher priorities for management within the Park. Quadrats were analysed for diversity using the Simpson Index and, since the data was non-parametric, comparisons were made across diversity and native richness using the Kruskal Wallis test. Alliaria officinalis is the only non-native species that is widespread within the study area. Other non-native species with a high potential for invasiveness were observed but only consisted of a few individuals along roads and paths. Some non-native species were present along or near roads and paths in denser patches (17-100% plot coverage). Recommendations include removal of some non-native species deemed to be a potential threat to native richness and diversity, followed by re-vegetation with native species, and continued monitoring. Future restoration efforts are best directed at the area around DeLaurier, along west beach and at the Tip. These areas have the lowest diversity and native richness and therefore need the most improvement.