The conservation of biodiversity and endemism in South Africa’s freshwater aquatic ecosystems is a high priority, particularly in the Cape Floristic Region. However, the perception that South Africa lacks suitable fish species for recreational angling, aquaculture and biological control, led to the widespread introduction and use of alien fish species. As a result, formal stocking programs have seen the introduction of five of the world’s top 100 invasive species into South Africa (Dudgeon et al. 2006). According to Dudgeon et al. (2006) freshwater ecosystems are the most endangered ecosystem in the world. The threats to freshwater biodiversity, according to Dudgeon et al. (2006), can be grouped into five categories that interact with one another: overexploitation, water pollution, flow modifications, destruction of habitat and invasion by exotic species. This PhD study took place in the Amatola region of the Eastern Cape Province, South Africa. The Amatola region is a rural area with no large-scale mining or industrial developments, only localised settlements. These developments are mainly situated around impoundments, because of the resources such as water and food that they provide. Thus the dams within the Amatola region should theoretically have no major industrial stressors on them. The three impoundments studied were Binfield Park, Sandile and Wriggleswade Dams. Binfield Park Dam is a 260ha impoundment. It impounds the Tyume River and is used by both subsistence anglers from the local communities and occasionally by recreational bass anglers. Sandile Dam is a 146ha impoundment and is the smallest of the three dams in this study. It impounds the Wolf and Keiskamma Rivers. Wriggleswade Dam is a 1000ha impoundment used extensively by recreational bass and carp anglers, and impounds the Kubusi River. There is a paucity of information regarding the health of the indigenous and alien fish species from the study region, as well as on the parasite diversity of these various fish species. In order to fill the gaps in the information the following hypothesis was proposed. That the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa. In order to achieve this hypothesis the main aim of this study will be to use the necropsy- and histology- based fish health assessment to determine the health status of the fish species in these impoundments as well as to understand the potential threat of water pollution and fish parasites. Fish were sampled with the aid of gill nets, fyke nets and by angling from each of the three impoundments over three surveys in July 2011, and March and August 2012. Following capture fish were transported to a field laboratory in aerated containers. At the field laboratory the fish were examined and dissected using the methods recommended by Adams et al. (1993) for a necropsy-based fish health assessment. Gills, livers, kidneys and gonads samples were also collected for histological analysis. Macroscopic and histology-based fish health assessment index was used, as well the analysis of muscle tissue of Micropterus salmoides and surface water and sediment from Binfield Park, Sandile and Wriggleswade Dams. It was shown that, according to the macroscopic fish health assessment index, M. salmoides in Wriggleswade Dam had a higher FHAI score compared to those in Binfield Park and Sandile Dam, there were no significant differences between the FHAI scores. However, the cause of the higher FHAI in the Wriggleswade Dam was because of the external skin damage caused by the presence of the alien parasite Lernaea cyprinacea. The histology-based fish health assessment index, however, showed that M. salmoides from Binfield Park had significantly higher histology Fish Index (IFISH) scores compared to those in Sandile and Wriggleswade Dams. The main contributors to the high IFISH score of Binfield Park were the significantly high Liver Index (IL) and Kidney Index (IK). The increased severity of the alterations observed in the liver and kidney tissue of the Binfield Park M. salmoides samples may have been as a result of the high concentration of mercury found in the muscle tissue of M. salmoides. The water quality and metals detected in the water of Binfield Park, Sandile and Wriggleswade Dams were all below the target water quality guideline values, as well as below those of previous research into the nutrients and presence of metals in these impoundments. The sediment metal analysis showed that the levels of Co, Mn and Ni were above the target guideline levels for Binfield Park, Sandile and Wriggleswade Dams, Cu was above target guidelines levels for Sandile Dam, and uranium was above the target guideline concentrations for Wriggleswade Dam. Binfield Park Dam had significantly high levels of mercury in the muscle tissue of M. salmoides, while Sandile Dam had significantly high levels of zinc in the muscle tissue of M. salmoides. It was shown that M. salmoides from each of the three impoundments are in a healthy state according to the parameters assessed. However, the presence of heavy metals, particularly mercury, uranium and zinc, do indicate the presence of human activities. The indigenous parasites of Anguilla mossambica have been well documented including the gastrointestinal nematode Paraquimperia africana, and the stomach nematode Heliconema africanum. Indigenous parasites such as the swimbladder nematode Anguillicola papernai had no effect on the condition factor of infected and uninfected eels. However, the damage caused by the alien parasites were evident, including the first documented effects of the alien gill monogenean Pseudodactylogyrus anguillae on indigenous wild populations of the longin fin eel A. mossambica from the Eastern Cape, South Africa. Histological observations indicated that an alien gill monogenean caused hyperplasia, increase in mucous cells, rupture of pillar cells as well as telangiectasia. This alien parasite has invaded the Keiskamma and Kei River systems in the Eastern Cape, South Africa. According to the macroscopic fish health assessment index, A. mossambica from Binfield Park, Sandile and Wriggleswade Dams are in a healthy state. However, the histology-based health assessment highlighted that the effects on P. anguillae have a severe negative impact on the health of A. mossambica. Using the macroscopic and histology-based fish health assessment, a comprehensive investigation into the fish health status of Mugil cephalus and Myxus capensis from Binfield Park Dam revealed that human effects and parasites are not the only threats to freshwater fish. Nephrocalcinosis is a non-infectious kidney disease which is characterised by abnormal calcium deposition in the kidneys of humans and some fish species. According to the macroscopic and histology-based fish health assessment, the M. cephalus and M. capensis are not in a healthy condition. The macroscopic and histology-based fish assessment indices are not stressor-specific, and therefore the cause of the poor health state of these two fish species could not be determined. A possible suggestion for the poor health of these two species is the age of the species. Because the two mullet species were stocked into Binfield Park Dam, Ellender et al. (2012) could successfully age them accurately to ten years of age, which is the upper limit of the life span for these species. Macroscopic and histology-based fish heath assessments were conducted on Labeo umbratus from Sandile Dam in order to determine the health of this species. Macroscopic and histology-based fish health assessment indicated that its L. umbratus are in a healthy state. The March 2012 survey specimens had a significantly higher macroscopic FHAI score than those from the July 2011 survey. The increased FHAI score was because of parasite infections, as well as discoloured livers and increased total blood plasma protein levels, which are indicators of nutritional state. However, the presence of the anchor worm parasite Lernaea barnimiana in low numbers had no significant impact on the health of L. umbratus. The effect of the alien anchor worm parasite Lernaea cyprinacea was shown on the transloacted small mouth yellowfish Labeobarbus aeneus. It was also shown that L. aeneus are, according the macroscopic FHAI and the histology-based fish health assessment index, in a healthy state. However, the high scores observed in the macroscopic fish health assessment index were primarily as a result of the presence of the alien parasite L. cyprinacea and its associated affects on the fish host. Because of the significant impact of this alien parasite species on the translocated host species, it can be assumed that this alien parasite species will have a negative effect on the health of indigenous fish species in the Great Kei River. It is clear from the results presented in this study that the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa, thus the original hypothesis of this thesis is accepted. Based on work done in this research the gaps in research have been identified. Due to the high levels of mercury indentified in the muscle tissue of M. salmoides from Binfield Park Dam. A human health assessment and edibility should be conducted in order to determine if the fish from Binfield Park Dam is safe for human consumption. In order to conserve South Africa’s Freshwater fish biodiversity, country wide surveys of indigenous fish species must be undertaken so that the health and the parasite diversity can be evaluated. / PhD (Zoology), North-West University, Potchefstroom Campus, 2015

The conservation of biodiversity and endemism in South Africa’s freshwater aquatic ecosystems is a high priority, particularly in the Cape Floristic Region. However, the perception that South Africa lacks suitable fish species for recreational angling, aquaculture and biological control, led to the widespread introduction and use of alien fish species. As a result, formal stocking programs have seen the introduction of five of the world’s top 100 invasive species into South Africa (Dudgeon et al. 2006). According to Dudgeon et al. (2006) freshwater ecosystems are the most endangered ecosystem in the world. The threats to freshwater biodiversity, according to Dudgeon et al. (2006), can be grouped into five categories that interact with one another: overexploitation, water pollution, flow modifications, destruction of habitat and invasion by exotic species. This PhD study took place in the Amatola region of the Eastern Cape Province, South Africa. The Amatola region is a rural area with no large-scale mining or industrial developments, only localised settlements. These developments are mainly situated around impoundments, because of the resources such as water and food that they provide. Thus the dams within the Amatola region should theoretically have no major industrial stressors on them. The three impoundments studied were Binfield Park, Sandile and Wriggleswade Dams. Binfield Park Dam is a 260ha impoundment. It impounds the Tyume River and is used by both subsistence anglers from the local communities and occasionally by recreational bass anglers. Sandile Dam is a 146ha impoundment and is the smallest of the three dams in this study. It impounds the Wolf and Keiskamma Rivers. Wriggleswade Dam is a 1000ha impoundment used extensively by recreational bass and carp anglers, and impounds the Kubusi River. There is a paucity of information regarding the health of the indigenous and alien fish species from the study region, as well as on the parasite diversity of these various fish species. In order to fill the gaps in the information the following hypothesis was proposed. That the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa. In order to achieve this hypothesis the main aim of this study will be to use the necropsy- and histology- based fish health assessment to determine the health status of the fish species in these impoundments as well as to understand the potential threat of water pollution and fish parasites. Fish were sampled with the aid of gill nets, fyke nets and by angling from each of the three impoundments over three surveys in July 2011, and March and August 2012. Following capture fish were transported to a field laboratory in aerated containers. At the field laboratory the fish were examined and dissected using the methods recommended by Adams et al. (1993) for a necropsy-based fish health assessment. Gills, livers, kidneys and gonads samples were also collected for histological analysis. Macroscopic and histology-based fish health assessment index was used, as well the analysis of muscle tissue of Micropterus salmoides and surface water and sediment from Binfield Park, Sandile and Wriggleswade Dams. It was shown that, according to the macroscopic fish health assessment index, M. salmoides in Wriggleswade Dam had a higher FHAI score compared to those in Binfield Park and Sandile Dam, there were no significant differences between the FHAI scores. However, the cause of the higher FHAI in the Wriggleswade Dam was because of the external skin damage caused by the presence of the alien parasite Lernaea cyprinacea. The histology-based fish health assessment index, however, showed that M. salmoides from Binfield Park had significantly higher histology Fish Index (IFISH) scores compared to those in Sandile and Wriggleswade Dams. The main contributors to the high IFISH score of Binfield Park were the significantly high Liver Index (IL) and Kidney Index (IK). The increased severity of the alterations observed in the liver and kidney tissue of the Binfield Park M. salmoides samples may have been as a result of the high concentration of mercury found in the muscle tissue of M. salmoides. The water quality and metals detected in the water of Binfield Park, Sandile and Wriggleswade Dams were all below the target water quality guideline values, as well as below those of previous research into the nutrients and presence of metals in these impoundments. The sediment metal analysis showed that the levels of Co, Mn and Ni were above the target guideline levels for Binfield Park, Sandile and Wriggleswade Dams, Cu was above target guidelines levels for Sandile Dam, and uranium was above the target guideline concentrations for Wriggleswade Dam. Binfield Park Dam had significantly high levels of mercury in the muscle tissue of M. salmoides, while Sandile Dam had significantly high levels of zinc in the muscle tissue of M. salmoides. It was shown that M. salmoides from each of the three impoundments are in a healthy state according to the parameters assessed. However, the presence of heavy metals, particularly mercury, uranium and zinc, do indicate the presence of human activities. The indigenous parasites of Anguilla mossambica have been well documented including the gastrointestinal nematode Paraquimperia africana, and the stomach nematode Heliconema africanum. Indigenous parasites such as the swimbladder nematode Anguillicola papernai had no effect on the condition factor of infected and uninfected eels. However, the damage caused by the alien parasites were evident, including the first documented effects of the alien gill monogenean Pseudodactylogyrus anguillae on indigenous wild populations of the longin fin eel A. mossambica from the Eastern Cape, South Africa. Histological observations indicated that an alien gill monogenean caused hyperplasia, increase in mucous cells, rupture of pillar cells as well as telangiectasia. This alien parasite has invaded the Keiskamma and Kei River systems in the Eastern Cape, South Africa. According to the macroscopic fish health assessment index, A. mossambica from Binfield Park, Sandile and Wriggleswade Dams are in a healthy state. However, the histology-based health assessment highlighted that the effects on P. anguillae have a severe negative impact on the health of A. mossambica. Using the macroscopic and histology-based fish health assessment, a comprehensive investigation into the fish health status of Mugil cephalus and Myxus capensis from Binfield Park Dam revealed that human effects and parasites are not the only threats to freshwater fish. Nephrocalcinosis is a non-infectious kidney disease which is characterised by abnormal calcium deposition in the kidneys of humans and some fish species. According to the macroscopic and histology-based fish health assessment, the M. cephalus and M. capensis are not in a healthy condition. The macroscopic and histology-based fish assessment indices are not stressor-specific, and therefore the cause of the poor health state of these two fish species could not be determined. A possible suggestion for the poor health of these two species is the age of the species. Because the two mullet species were stocked into Binfield Park Dam, Ellender et al. (2012) could successfully age them accurately to ten years of age, which is the upper limit of the life span for these species. Macroscopic and histology-based fish heath assessments were conducted on Labeo umbratus from Sandile Dam in order to determine the health of this species. Macroscopic and histology-based fish health assessment indicated that its L. umbratus are in a healthy state. The March 2012 survey specimens had a significantly higher macroscopic FHAI score than those from the July 2011 survey. The increased FHAI score was because of parasite infections, as well as discoloured livers and increased total blood plasma protein levels, which are indicators of nutritional state. However, the presence of the anchor worm parasite Lernaea barnimiana in low numbers had no significant impact on the health of L. umbratus. The effect of the alien anchor worm parasite Lernaea cyprinacea was shown on the transloacted small mouth yellowfish Labeobarbus aeneus. It was also shown that L. aeneus are, according the macroscopic FHAI and the histology-based fish health assessment index, in a healthy state. However, the high scores observed in the macroscopic fish health assessment index were primarily as a result of the presence of the alien parasite L. cyprinacea and its associated affects on the fish host. Because of the significant impact of this alien parasite species on the translocated host species, it can be assumed that this alien parasite species will have a negative effect on the health of indigenous fish species in the Great Kei River. It is clear from the results presented in this study that the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa, thus the original hypothesis of this thesis is accepted. Based on work done in this research the gaps in research have been identified. Due to the high levels of mercury indentified in the muscle tissue of M. salmoides from Binfield Park Dam. A human health assessment and edibility should be conducted in order to determine if the fish from Binfield Park Dam is safe for human consumption. In order to conserve South Africa’s Freshwater fish biodiversity, country wide surveys of indigenous fish species must be undertaken so that the health and the parasite diversity can be evaluated. / PhD (Zoology), North-West University, Potchefstroom Campus, 2015

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Worldwide, invasive alien plants (IAPs) alter aspects of invaded ecosystems including geomorphology, above-ground vegetation, soil seed banks and soil nutrient regimes, thereby affecting the long-term stability of ecosystems. In many cases these invasions call for various management interventions, including restoration. Effects of alien plant invaders on native ecosystems are widely acknowledged, but compared to terrestrial ecosystems, riparian habitats are poorly studied. Riparian habitats are inherently rich in biodiversity, but are particularly prone to invasion by IAPs because of their dynamic nature and because these ecosystems are affected by many anthropogenic activities. This enhances the proliferation of IAPs, especially trees such as Tamarix spp. (e.g. in the southwestern United States), Salix spp. (e.g. in Australia), and Australian Acacia spp. and Eucalyptus camaldulensis (in South Africa). Initiatives such as the Working for Water (WfW) programme in South Africa that are focusing on clearing IAPs, particularly in riparian zones, have reported much success in the short term, but ecosystem recovery remains limited. There is a poor understanding of the nature of the impacts of invasive trees, and of the opportunities that exist for ecosystem restoration. The objective of my thesis was to investigate the effects of the widespread invasions of Eucalyptus camaldulensis in riparian zones. Methodological constraints have been identified as one reason for limited success of restoration projects. Many studies examining the effects of IAPs used a comparative approach of uninvaded (reference) and invaded sites. However, this approach often fails to separate cause from effect. An experimental removal approach has been suggested as an alternative, but it is often inappropriate for large invasive trees owing to time and cost constraints. I used a comparative gradient approach, involving sampling along a continuum from uninvaded sites, and varying E. camaldulensis invasion densities categorised as “lightly”, “moderately” and “heavily” invaded (hereafter the gradient of invasion), each with four replicates (n = 16). This approach enabled me to detect trends that could be reliably attributed to invasion. Furthermore, my study attempted to provide a comprehensive understanding of the effects of IAPs in invaded ecosystems by considering various components of the ecosystem and integrating their feedback relationships to establish the net effects on ecosystem processes. The riparian zone is a unique ecosystem which provides an opportunity for such a multifaceted study examining and integrating the effects of invasive trees on riparian geomorphology, above-ground vegetation, soil seed banks, and soil properties. I studied the effects of E. camaldulensis invasion in riparian zones along the Berg River in the Mediterranean-type climate zone of the Western Cape, South Africa. I asked the questions 1) Are environmental conditions (i.e. the riparian environment created by geomorphological processes) altered by Eucalyptus invasion and if so, are these conditions less suitable for recruitment of indigenous species? 2. Has Eucalyptus invasion altered the composition of indigenous species (potentially limiting post-clearing propagule supply)? 3: How does Eucalyptus invasion change the composition of the riparian soil seed bank; and its potential to re-initiate ecosystem recovery? 4: Do soil properties (physical and chemical) change with Eucalyptus invasion? Data for all four questions were collected in the same sites to enable cross comparisons. For the first question, I employed photogrammetry techniques in a GIS and remote sensing environment to analyse repeated aerial photographs (1938 -2010) to reconstruct the invasion history and riparian geomorphology evolutionary dynamics. For the second and third questions, I compared richness, diversity, evenness and composition of resident above-ground and seed bank vegetation between uninvaded sites and the gradient of invaded sites. For the fourth question, I compared a set of variables describing physico-chemical properties in uninvaded sites to the gradient of invaded sites seasonally. Results of the geomorphology study showed that the riparian zone has been very dynamic over the 70 years, with a 13.5% net decrease in area. There was evidence of channel narrowing, riverbank steepening and river bed incision in areas that were densely invaded. No significant trends were detected in hydrometeorological data. The above-ground vegetation study revealed that species richness, diversity and structural attributes (e.g. height, relative cover and mean basal diameter) of native species decreased consistently along the invasion gradient. Invasion also altered native and alien plant species composition, both of which showed a high preference for lightly invaded sites. The seed bank study revealed that E. camaldulensis invasion had no significant effect on total and native species richness, diversity and evenness, however the effects were bigger on native than alien species. Alien species density was significantly higher than native species density. Invasion also influenced the composition of the native seed bank. However, native seed banks were more diverse than above-ground plant assemblages with some native fynbos species occurring only in the seed bank. In the soil study, I found that soil pH levels were significantly lower in invaded sites than in uninvaded sites in all seasons. Litter cover and thickness increased significantly with invasion intensity. Soil moisture decreased consistently with invasion intensity while temperature increased in winter and spring. Total macro, micro and available nutrients did not vary significantly along the invasion gradient (p > 0.05), but exchangeable cation content was significantly higher in uninvaded than in invaded sites, especially in winter and spring. Narrowing of river channel and steepening of river banks reduces the suitability of the riparian zone to perform certain ecological functions such as soil seed storage and providing space for vegetation to grow. This reduces opportunities for seedling recruitment and consequently reduces species diversity. Conversely, the reduction of species diversity in above-ground vegetation reduces seed input into the soil leading to depauperate soil-stored seed banks. The abundance of seeds of Acacia mearnsii in the soil-stored seed bank poses a threat of secondary invasions post clearing of E. camaldulensis if this is adopted as a management action. The study was successful in addressing the stated objectives. The transition from a native-dominated riparian plant community to a monoculture of E. camaldulensis over c. 50 years has resulted in marked changes to riparian geomorphology and above-ground vegetation, but has yet to radically change the total soil seed bank and soil nutrient concentrations. The findings offer support to the WfW clearing initiatives and show that potential for recovery of native species after removal of the invasive eucalypts still exists. This knowledge not only enhances effectiveness of restoration and long term management of riparian ecosystems, but also advances the field of riparian ecology and restoration. Further experimental work is needed to establish the mechanisms responsible for the changes associated with Eucalyptus invasion. The contribution of agriculture in shaping channel morphology also needs to be investigated. / AFRIKAANSE OPSOMMING: Die langtermyn stabiliteit van ekosisteme wêreldwyd word bedreig deur uitheemse indringer plante (UIPs) wat, onder andere, die geomorfologie, bo-grondse plantegroei, onder-grondse saadbanke en voedingstofstatus van ekosisteme kan verander. In baie gevalle word bestuursoperasies vir indringer plante vereis, en sluit onder andere herstel (restorasie) in. Die invloed van UIPs op inheemse ekosisteme word wyd erken, maar kennis oor oewerbank-habitatte, in vergeleke met ander terrestriële ekosisteme, skiet steeds tekort. Oewerbank-habitatte is inherent ryk aan biodiversiteit maar uiters sensitief vir indringing deur UIPs. Dit is weens die dinamiese aard van hierdie ekosisteme asook vele menslike aktiwiteite in hierdie tipe habitat. Dit dra by tot die vermeerdering van UIPs, veral bome wat byvoorbeeld insluit Tamarix (tamariske) (bv. in die suid-wes van die Verenigde State van Amerika), Salix (wilger) (in bv. Australië) en die Australiese Acacia (wattel) en Eucalyptus spesies (bloekom) in Suid Afrika. Inisiatiewe soos die Werk vir Water (WvW) program in Suid Afrika fokus juis daarop om UIPs vanuit oewerbank areas te verwyder, en alhoewel groot sukses in die kort termyn behaal is, is die herstel van ekosisteme steeds beperk. Daar is dus min inligting beskikbaar oor die impak van indringer bome en gevolglik ook oor geleenthede vir die herstel van hierdie ekosisteme. My tesis ondersoek die impak van die wydverspreide voorkoms van die indringer, Eucalyptus camaldulensis, in oewerbank-omgewings. Beperkte metodes is tans beskikbaar om die impak van indringer plante te ondersoek, en dit is geïdentifiseer as een van die oorsake vir die beperkte sukses van herstelprojekte. Baie studies ondersoek die effekte van UIPs deur natuurlike areas sonder enige indringer plante te vergelyk met areas waar UIPs voorkom. Hierdie tipe benadering kan ongelukkig, in meeste gevalle, nie onderskei tussen die oorsaak en die impak nie. ʼn Alternatiewe voorstel is om UIPs eksperimenteel te verwyder, maar is ongelukkig nie van toepassing op groot bome nie weens die tyd en kostes verbonde hieraan. Ek het gebruik gemaak van ʼn vergelykende-gradiënt benadering wat steekproefnemings langs ʼn geleidelike kontinuum van natuurlike areas sonder enige indringer plante na areas wat effens gematig, en erg ingedring is (hiernaas bekend as die indringer-gradiënt) deur die indringer, E. camaldulensis. Die steekproefnemings van elke kategorie van indringing (geen, effens, gematig en erg) is vier keer herhaal (n = 16). Hierdie benadering het my toegelaat om neigings te identifiseer wat met sekerheid toegeskryf kan word aan die teenwoordigheid van indringers. My studie het ook verder gemik om ʼn omvattende beskrywing van die impak van UIPs in ekosisteme met indringers te verskaf deur verskeie komponente van die ekosisteem, sowel as hul terugvoer-verhoudinge, in ag te neem, en sodoende die totale effek op ekosisteem prosesse te bepaal. ʼn Oewerbank is ʼn unieke ekosisteem wat ʼn geleentheid bied vir ʼn veelsydige studie wat die impakte van indringer bome op oewerbank-geomorfologie, bo-grond plantegroei, grond saadbanke en grondeienskappe, kan bestudeer en integreer. Ek het die impak van die teenwoordigheid van die indringer, E. camaldulensis in oewerbank areas langs die Bergrivier, wat ʼn Meditereense-tipe klimaat het, in die Wes Kaap, Suid Afrika, bestudeer. My studie het die volgende vrae gevra: 1) Is omgewings-omstandighede (bv. die oewerbank-omgewing geskep deur geomorfologiese prosesse) verander deur die teenwoordigheid van die Eucalyptus indringing, en indien wel, is hierdie omstandighede minder geskik vir inheemse spesies?; 2) Het die indringing van Eucalyptus gelei tot ʼn verandering in die samestelling van inheemse spesie gemeenskappe (moontlik beperkte plant voorplantings materiaal nadat die indringer verwyder is)?; 3) Hoe verander die indringing van Eucalyptus die samestelling van saad teenwoordig in die grond (saad bank) van die oewerbank en het dit die potensiaal om ekosisteem-herstel weer aan die gang te sit?; 4) Verander indringer Eucalyptus grond eienskappe (fisies en chemies)? Data vir al vier vrae is by dieselfde plek versamel om vergelykings te kan tref. Vir die eerste vraag het ek fotogrammetrie-tegnieke in ʼn Geografiese Inligting Stelsel (GIS) en afstandwaarnemings-omgewing toegepas om herhaalde lugfotos (1938-2010) te analiseer om die indringings geskiedenis sowel as die oewerbank se geomorfologiese evolusionêre dinamika saam te stel. Vir die tweede en derde vraag, het ek die aantal, diversiteit, gelykheid en samestelling van die bo-grond en saad bank plantegroei tussen natuurlike (geen indringers) en die gradiënt met indringers vergelyk. Vir die vierde en laaste vraag, het ek ʼn stel veranderlikes wat die fisies-chemiese eienskappe van die natuurlike omgewing sonder indringers beskryf, vergelyk met die eienskappe van die indringers gradiënt op ʼn seisoenale basis. Die resultate van die geomorfologiese studie wys dat die oewerbank omgewing baie dinamies was oor die afgelope 70 jaar met ʼn totale afname van 13.5% in rivieroewer-area in die gebied wat bestudeer is. Daar is ook bewyse vir ʼn vernouing van die kanaal, toename in die steilte van die rivierbank sowel as insnyding in die rivierbedding in areas wat ernstige indringing ervaar. Daar was geen beduidende neigings in die hidro-meteorologiese data nie. Die studie van die bo-grondse plantegroei het gewys dat die aantal plantspesies, diversiteit en strukturele kenmerke (bv. hoogte, dekking en gemiddelde basale diameter) van inheemse spesies afneem soos wat die indringings gradiënt toeneem. Indringing verander ook die inheemse sowel as uitheemse plant spesies samestelling. Beide inheemse en uitheemse spesies het areas wat slegs effense indringing wys, verkies. ʼn Studie van die saad bank (aantal sade in die grond) het gewys dat die indringer, E. camaldulensis geen merkwaardige invloed op die aantal, diversiteit en gelykheid van die totale en inheemse spesies teenwoordig gehad het nie. Die aantal uitheemse spesies was merkwaardig meer as die aantal inheemse spesies. Alhoewel indringing ook die samestelling van die inheemse saadbank beïnvloed het, was die inheemse saad bank, waarvan sommige spesies slegs daar voorgekom het, meer divers as die bo-grond plant samestellings. ʼn Studie van die grond het gewys dat die pH vlakke, afgesien van die seisoen, aansienlik laer is in die areas met indringers in vergeleke met areas sonder die indringers. Die hoeveelheid en dikte van plantmateriaal op die grond neem ook toe met ʼn toename in indringers. Die waterinhoud van die grond het afgeneem met ʼn toename in indringers en temperatuur het verhoog in beide winter en lente. Die totale makro- en mikrovoedingstowwe het nie merkwaardig gewissel saam met die indringingsgradiënt nie (p > 0.05), maar die uitruilbare katioon inhoud was aansienlik hoër, veral in die winter en lente-maande, in die areas sonder indringers in vergelyking met die areas met indringers. Vernouing van rivierkanaal en versteiling van rivieroewers verminder die geskiktheid van die oewersone om sekere ekologiese funksies te verrig soos grond-saadstoring en die verskaffing van ruimte vir plante om te groei. Dit verminder geleenthede vir werwing van saailinge en verminder gevolglik spesiediversiteit. Aan die ander kant, die vermindering van die spesiediversiteit in die bogrondse plantegroei verminder saadinsette in die grond en dit lei tot verarming van grondgestoorde saadbanke. Die oorvloed van sade van Acacia mearnsii in die grondgestoorde saadbank hou die bedreiging van sekondêre indringing in na die skoonmaak van E. camaldulensis indien dit wel as 'n bestuursaksie aangeneem word. Hierdie studie het die uiteengesette doelwitte suksesvol aangespreek. Die oorgang van ʼn oewerbank-gemeenskap wat hoofsaaklik uit inheemse plante bestaan na ʼn gemeenskap wat slegs uit E. camaldulensis bestaan, oor ʼn periode van ongeveer 50 jaar, het duidelike veranderinge tot gevolg gehad. Hierdie veranderinge is veral opmerklik in die oewerbank-geomorfologie en bo-grondse plantegroei, maar tot op hede is dit nog nie so opmerklik in die saadbank en grond-voedingstowwe konsentrasies nie. Hierdie bevindinge bied ondersteuning aan die WvW verwyderings-ondernemings en wys dat daar wel moontlike herstel van inheemse spesies kan wees na die verwydering van die indringer Eucalyptus. Hierdie kennis dra nie net by tot verhoogde effektiwiteit van herstelwerk en langtermyn-bestuursplanne nie, maar ook tot die navorsingsveld van oewerbankekologie en-herstel. Verdere eksperimentele navorsing word benodig om die moontlike meganismes wat verantwoordelik is vir die waargeneemde veranderinge, geassosieerd met Eucalyptus indringing, te verduidelik. Die bydrae van landbou tot die vorming van kanaal morfologie moet ook verder bestudeer word.

Thesis (MScConEcol)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Soil respiration (Rs) is a major component of CO2 emissions and the global carbon balance. In the context of global change it of interest to understand seasonal patterns of RS in fynbos riparian ecosystems, particularly in invaded-riparian ecotones of these Mediterranean type ecosystems (MTE's) in the Western Cape, South Africa. Riparian ecotones are three dimensional transitional zones that provide multiple ecosystem services and functions and they act as the linkage between terrestrial and aquatic ecosystems where key ecological and geomorphological processes occur. Riparian ecotones are highly prone to disturbance, and because of this reason are also vulnerable to invasion by invasive alien plants (IAPs), notably Acacia species. Invasion by IAPs is considered one of the major threats to global change and biodiversity causing extensive ecological, economical, and social impacts. In south-western Cape, more than two thirds of the riparian environment is invaded to some extent, IAPs replacing the well adapted native species along river systems. In particular, impact of IAPs on soil respiration (Rs) may be relevant, with consequences for ecosystem function and services. Clearing of invaded riparian zones initiated by the Working for Water program has been a successful in eradicating alien plants within riparian areas even though recovery after alien clearing is lagging at many sites, and knowledge on repair of ecosystem function is lacking. Various studies have generated knowledge on carbon cycling and Rs in forests, savanna, grasslands, tundra and Mediterranean shrublands, but little is known about Rs in riparian zones, and even less about soil CO2 efflux in invaded riparian fynbos riparian ecotones. The objective of this study was to contribute to a better understanding and quantifying the effect and impact of IAPs on carbon cycling between and across riparian ecotones with different invasion status: natural, invaded, and cleared. The study areas were located in the south-western Cape and measurements of Rs, soil temperature, soil moisture, root mass, litter mass, and soil properties were carried out in riparian soils of the mountain and transitional stream longitudinal river sections, and uplands fynbos areas of six different perennial river systems. In each site, four to five transects were laid out with one sampling site of each landscape position (wet bank, dry bank, and terrestrial areas) giving a total of 12 to 15 samples per site. Soil respiration measurements were taken over a period of two years, and were done seasonally. Results from this study showed that Rs was different among seasons with highest soil respiration rates in summer. Soil CO2 efflux increased in response to warm and dry conditions during summer, while seasonal soil CO2 efflux declined in autumn and winter in response to wet and cold soil conditions. The large increase in soil CO2 efflux response to warm and dry periods when temperature was 25 to 30 °C over all riparian sites and was highest in invaded sites compared to the natural and cleared sites. A significant difference was found between sites with different statuses with invaded sites leading seasonal Rs rates. Natural and cleared sites did not differ significantly in their CO2 efflux rates, suggesting that clearing of IAPs may put invaded ecosystems on a trajectory of restoration. There were also differences in terms of landscape positions; dry banks zones of the invaded sites had higher rates compared to wet banks and the uplands areas. Our results further suggest that roots are the most important component of overall Rs rates, rather than microbial respiration. When we incubated soils minus roots, little difference was evident, either when viewing the results by invasion status or by landscape position, which suggest that inherent soil differences in terms of microbial respiration were not different. We also use a trenching approach to further investigate this, and though we found Rs to decline significantly, trends later suggest that decomposition of fine and course roots likely obscured the decline in overall Rs due to root respiration. Overall, our results showed that clearing of invaded riparian zones will likely lead to successful restoration of soil functioning in terms of C cycling. Clearing of Acacia-invaded riparian ecotones will likely lead to a decline in root density, and which removes a major component of overall Rs. These results make the investigation of the C balance of invaded riparian ecotones and terrestrial areas critical in order to assess their contribution to regional C cycles. / AFRIKAANSE OPSOMMING: Grondrespirasie (Rs) is 'n belangrike komponent van CO2 uitstroming en die globale koolstofbalans. Binne die konteks van globale verandering is dit van groot belang om die seisoenale patrone van Rs in fynbos oewer ekosisteme, veral in indringer-oewer ekotone, in die Meditereense tipe ekosisteme (MTE's) in die Wes- Kaap, Suid- Afrika te verstaan. Oewerekotone is drie-dimensioneel oorgangssones wat veelvuldige ekosisteem dienste en funksies verskaf. Hulle dien as die verbinding tussen terrestriële en water-ekosisteme waar kern ekologiese en geomorfologiese prosesse plaasvind. Oewerekotone is hoogs vatbaar vir versteuringe, en as gevolg van hierdie rede, is hul ook kwesbaar vir indringing deur indringer plante (IAPs), veral Acacia spesies. Indringing deur IAPs word beskou as een van die groot bedreigings tot en met globale verandering en biodiversiteit, wat ekstensiewe ekologiese, ekonomiese, en sosiale impakte veroorsaak. In die suid- westelike Kaap word meer as twee derdes van die oeweromgewing tot 'n mate binnegedring. IAPs vervang die goed aangepaste inheemse spesies langs riviersisteme. Die impak van IAPs, spesifiek op grondrespirasie mag substansieël wees, met gevolge vir ekosisteem funksies en dienste. Opruiming van hierdie spesifieke oewer sones, geinisieer deur die Working for Water program, was suksesvol in die uitroeing van indringer plante binne oewer areas. Alhoewel herstel na indringer opruiming op baie terreine agter is, is kennis oor die herstel van ekosisteemfunksies gebrekkig. Verskeie studies het kennis ontwikkel oor koolstofsiklisering en Rs in woude, savanna, graslande, tundra en Meditereense struiklande, maar daar is minimale informasie oor oewersones,en nog minder oor grond CO2 uitstroming in indringer oewer fynbos en oewer ekotone. Die doel van hierdie studie is om 'n bydrae te lewer koolstofsiklisering beter te verstaan, en die impak van IAPs op koolstofsiklisering te kwantifiseer tussen en oor oewerekotone met verkillende indringer statusse: natuurlik, binnegedring en skoongemaak. Die studie areas was geleë in die suid- westelike Kaap, en maatstawe van Rs, grond temperature, grondvogtigheid, wortelmassa, plantafvalmassa, en grondeienskappe is uitgevoer in oewergrond van die berg en transisionele stroom longitudinale rivier seksies, asook terrestriële fynbos areas van ses verskillende standhoudende riviersisteme. In elke area is vier tot vyf transekte uitgelê met een monsternemingsarea van elke landskapsposisie (nat bank, droë bank en terrestriële areas) met 'n totaal van 12 tot 15 monsters per area. Grondrespirasie maatstawe is geneem oor 'n periode van twee jaar, en is seisoenaal uitgevoer. Resultate van die studie het getoon dat Rs verkil het tussen seisoene, met die hoogste grondrespirasietempo in die somer. Grond CO2 uitstroming het toegeneem in reaksie op warm en droë kondisies gedurende somer, terwyl seisoenale grond CO2 uitstroming afgeneem het in herfs en winter in reaksie op nat en koue grond kondisies. Die grootste toename in grond CO2 uitstroming was in reaksie op warm en droë periodes wanneer temperature gewissel het tussen 25 tot 30˚C oor alle oewersones, en was die hoogste in binnegedringde sones, vergeleke met die natuurlike en skoongemaakte terreine. 'n Beduidende verskil is gevind tussen terreine met verskillende statusse in CO2 uitstromingskoerse‚ 'n aanduiding dat opruiming van IAPs binnegedringde ekosisteme op 'n trajek van restorasie plaas. Daar was ook verskille in terme van landskapsposisies; droë bank sones van die binnegedringde terreine het hoër tempos gehad, vergeleke met die nat bank en die hoogland areas. Ons resultate dui verder aan dat wortels, eerder as mikrobiologiese respirasie, die mees belangrike komponente van Rs koerse uitmaak. Toe ons grond minus wortels inkubeer, is min verskille opgemerk, as gekyk word na die resultate deur indringer status of landskapsposisie, wat toon dit dat inherente grondveskille in terme van mikrobiologiese respirasie nie verskillend is nie. Ons het verder ook 'n sloot-benadering gebruik om verdere ondersoek hierop in te stel, en alhoewel ons bevind dat Rs aansienlik afgeneem het, dui neigings later aan dat afbraak van fyn en growwe wortels die afname in gehele Rs as gevolg van wortel respirasie waarskynlik verdoesel. Ons resultate dui daarop dat opruiming van binngedringde oewers klaarblyklik sal lei tot suksesvolle restorasie van grondfunksionering in terme van C siklisering. Opruiming van Acacia- binnegedringde oewer ekotone sal vermoedelik lei tot 'n afname in worteldigtheid, en wat 'n belangrike komponent van die gehele Rs kan verwyder. Hierdie resultate maak die ondersoek van die C balans van binngedringde oewer ekotone en terrestriële areas krities, om sodoende hulle bydrae tot streeksgewyse C siklusse te asseseer.

Thesis (PhD (Botany and Zoology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Although the impacts of biological invasions are widely appreciated, a bias exists in research effort to post‐dispersal processes because of the difficulties of measuring propagule pressure and the detecting of newly established species. Here the Antarctic is used as a model system in which to quantify the initial dispersal of alien species and investigate the factors that contribute to the establishment and range dynamics of alien species once they have arrived in the region. Human movements are known to transport alien species into the Antarctic, some of which have successfully established and had wide ranging consequences in recipient ecosystems. Considering terrestrial flora, this research found that over 700 seeds from 99 taxa, including some species known to be invasive, are transported into the Antarctic each year in association with South African National Antarctic Programme (SANAP) passenger luggage and cargo. The first ever assessment of propagule drop‐off indicated that 30‐50% of these propagules will enter the recipient environment. Further results suggested that the construction of the British Antarctic Survey Halley VI station will facilitate the transport of over 5000 seeds from 34 taxa into the region, making this a significant pathway for introductions. Propagule pressure due to SANAP logistics is also considerable for marine species. Fouling assemblages on the external hull surfaces of the SANAP resupply vessel, the SA Agulhas, form only once the vessel’s anti‐fouling paint has been damaged by travel through sea ice and are characterised by low diversity. Ice scour prevents fouling assemblages from being transported to the Antarctic continent, but assemblages remain largely intact when travelling to sub‐Antarctic Islands. In the sea‐chests of the vessel populations of a known invasive, Mytilus galloprovincialis, were found with some individuals having survived transportation to the Antarctic region on multiple occasions. Once species have overcome initial dispersal barriers, they face further ecological and physiological challenges in order to establish in the recipient region. The parasitoid wasp Aphidius matricariae was first recorded on Marion Island in 2001. Surveys around the island show that adult abundance and the frequency of aphid parasitism are highest adjacent to a common anchor point of the SA Agulhas and decline away from this region. Genetic diversity was low, suggesting that the population was established from a single introduction. This highlights that high propagule pressure is not necessary for successful establishment of introduced invertebrates. Another species that has overcome the dispersal barrier is the terrestrial slug Deroceras panormitanum, which was introduced to Marion Island in the 1970’s and has since spread throughout much of the coastal habitat of the island. For this species range limits are set by intolerance of low temperature and salinity, and abundance structure is characterized by patches and gaps which are associated with this species inability to tolerate dry conditions. To prevent further alien introductions in the region, targeted management of high risk pathways is required. In addition, increased vigilance is needed to detect and manage newly established aliens before their ranges expand. / AFRIKAANSE OPSOMMING: Alhoewel die impak van biologiese indringings in die breë waardeer word, bestaan daar vooroordeel in navorsingspogings ten opsigte van na‐verspreidingsprosesse, weens die moeilikhede om verspreidingseenheid druk te meet en in die opsporing van nuut gevestigde spesies. Hier word die Antarktiese streek as ‘n model sisteem gebruik waarin die aanvanklike verspreiding van uitheemse spesies gekwantifiseer kan word en om die faktore wat bydrae tot die vestiging en grens dinamika van uitheemse spesies te ondersoek, wanneer hulle in ’n streek aangekom het. Menslike bewegings is bekend daarvoor om uitheemse spesies na die Antarktiek te vervoer, sommige waarvan suksesvol gevestig het en omvattende gevolge in die ontvanger ekosisteme gehad het. Aangaande terrestriële flora het hierdie navorsing gevind dat oor die 700 sade van 99 taxa, insluitende sommige spesies wat bekend is om indringend te wees, jaarliks na die Antarktiek vervoer word in assosiasie met die Suid Afrikaanse Nasionale Antarktiese Program (SANAP) se bagasie en vrag. Die eerste waardebepaling van verspreidingseenheid afgooi het aangedui dat 30‐50% van hierdie verspreidingseenhede die ontvanger omgewing sal binnedring. Verdere resultate het voorgestel dat die konstruksie van die Britse Antarktiese Opname Halley VI stasie die vervoer van 5000 sade van 34 taxa sal fasiliteer die streek in, wat dit ’n betekenisvolle weg maak vir indringings. Verspreidingseenheid druk is ook, as gevolg van die SANAP logistiek, aanmerklik vir mariene spesies. Vuilgoed versamelings op die eksterne omhullende oppervlaktes van die SANAP her‐voorsieningsvaartuig, die SA Agulhas, vorm wanneer die vaartuig se anti‐vuilgoed verf beskadig is met reis deur see‐ys en word gekenmerk deur lae diversiteit. Ys skuring voorkom dat vuilgoed versamelings vervoer word na die Antarktiese kontinent, maar versamelings bly grootliks vasgeheg wanneer na sub‐Antarktiese eilande gereis word. Populasies van ’n welbekende indringer, Mytilus galloprovincialis, is gevind in die see‐storingsarea van die vaartuig, met sommige individue wat die vervoering na die Antarktiese streek oorleef het op verskeie geleenthede. Wanneer spesies die aanvanklike verspreidingshindernisse oorkom het, staar hulle verdere ekologies en fisiologiese uitdagings in die gesig ten einde in die ontvanger streek te vestig. Die parasitiese wespe Aphidius matricariae is vir die eerste keer op Marion aangeteken in 2001. Opnames om die eiland toon dat volwasse oorvloed en die frekwensie van plantluis parasitisme die hoogste is aangrensend die algemene ankerpunt van die SA Agulhas en afneem weg van die omgewing af. Genetiese diversiteit was laag, wat voorstel dat die populasie gevestig het van ’n enkele bekendstelling. Dit lig uit dat hoë verspreidingseenheid druk nie nodig is vir die suksesvolle vestiging van bekendgestelde invertebrata nie. ‘n Ander spesie wat die verspreidingshindernisse oorkom het is die landslak Deroceras panormitanum wat in die 1970’s op Marion Eiland bekendgestel is en wat sedertdien versprei het oor meeste van die kushabitat van die eiland. Vir hierdie spesie word grens limiete vasgestel deur onverdraagsaamheid vir lae temperature en saliniteit en die oorvloedstruktuur word gekenmerk deur laslappe en gapings wat geassosieer word met die spesie se onvermoë om droë kondisies te hanteer. Om verdere uitheemse bekendstellings in die streek te voorkom, word geteikende bestuur van hoë risiko weë vereis. Toenemende waaksamheid is bykomend nodig vir die opsporing en bestuur van nuutgevestigde uitheemse spesies voordat hulle grense verbreed.

Invasive non-native species are believed to be one of the biggest threats to biodiversity. Until now biological invasions have been mainly studied from a biological perspective and much research has been undertaken to investigate species’ ecology and potential options for management. Comparatively little attention has been devoted to questions regarding the social construction of the issue. This is despite invasion biologists increasingly acknowledging the fundamental importance of human perceptions, beliefs, attitudes and values inherent in debates about invasive non-native species. This thesis employs a mix of methods from the social sciences to investigate the social construction of biological invasions. Research conducted here is based on the theory of social representations. Thus, taking a social scientific perspective, the thesis contributes to both the development of the theory and an identification of beliefs inherent in the debate on biological invasions and their relationship to people’s attitudes towards species and their management. Those species attributes that predominantly shape the debate – but yet appear to be under-researched – are identified. Based on the findings in this thesis I argue that invasion biology would benefit from a more explicit and transparent use of its concepts and terminology. This will have implications also for the communication with policy makers, conservation managers and the general public. Recommendations for future research are discussed along with limitations of the thesis.

Story of an alien who inhabits the body of middle-aged man George. Mission for Alien George is to convince a fertile, intelligent, attractive woman to move back with him to their planet to create a hybrid species. The major benefit for the woman is having the alien's elixir for her to live for thousands of years. George begins to feel human emotions for Connie, the young woman he initially picks. However, Connie is a lost drug addict who has no signs of a future. This does not appease George's alien guide. George must weigh his new human emotions with his almost eternal life with creating a new species. George is supposed to develop Connie's love to get back to his planet. But does love remain an idea aliens have studied or does George begin to feel what love feels like?

Student Number : 9907276D - MSc Dissertation - School of Animal, Plant and Environmental Sciences - Faculty of Science / The broad aim of this study was to measure the ecosystem repair of the Sabie River (which traverses through both the grassland and savanna biomes) riparian environment in Mpumalanga, South Africa, in response to the clearing of alien plants by the Working for Water (WfW) alien plant clearing programme. This was done in order to assess the effectiveness of the WfW clearing on the Sabie River riparian plant community composition and associated environmental factors. Although “effectiveness” can be assessed in various ways, in this study it included determining whether there was a reduction in the invasion intensity (defined as the percentage aerial cover of woody alien plants) after clearing. This broad aim was achieved by studying the impacts of the WfW alien plant clearing programme, as well as the invasion of alien plants, on the plant species composition, diversity and vegetation structure of riparian ecosystems on the Sabie River. Hence, in 2005 40 modified Whittaker nested plots were sampled. The impacts on the Sabie River riparian environment were also assessed by measuring various environmental variables that are likely to change as a result of clearing, such as the ground cover (percentages of exposed soil, rock, litter, herbaceous vegetation and grass), as well as various soil chemical and physical properties. Twenty plots were surveyed along the Sabie River in the Hazeyview region (savanna biome), ten in the Sabie region (grassland biome) and ten in the Graskop region (grassland biome). The response of the Sabie River riparian community to invasive alien plant clearing by WfW (and the alien plant invasion itself) was also assessed over time, by comparing the 2005 study with one done in 1996, which used the same plots. In 2005, a cumulative total of 282 species were found, 222 (79%) of which were indigenous and 60 (21%) alien. The grassland sites had a higher cumulative total of 222 species compared with the 171 species in the savanna sites. A total of 112 (39%) species were common between the biomes, 86 (30%) of which were indigenous and 26 (9%) alien. At the 1000 m2 scale, the indigenous species richness (32.4 ± 1.4 (S.E.)) was significantly higher than the alien species richness (12.0 ± 0.5) (P < 0.001). Of the 60 alien species, 17 (28%) were shrubs and 15 (25%) trees. The grassland sites were more species rich at the 1000 m2 scale (48.8 ± 1.8) and diverse at the 100 m2 scale (Simpson’s index of alpha diversity of 0.90 ± 0.01) than the savanna sites (species richness of 40.0 ± 2.1 and alpha diversity of 0.85 ± 0.02; P = 0.003 for species richness and P = 0.04 for alpha diversity). The Sabie sites were more species rich at the 1000 m2 scale (52.6 ± 2.8) than the Graskop sites (45.0 ± 1.4) (P = 0.12). The higher species richness in the Sabie region contributed to the higher total species richness in the grasslands relative to the savanna sites. At the 1000 m2 scale, the overall beta diversity (Sorenson’s coefficient of community) between the biomes was 0.57, and the species complementarity (the Marczewski-Steinhaus distance) between the biomes was 0.60, indicating that the biomes were not that similar in terms of species composition. Even though the grassland was more rich and diverse in terms of species than the savanna, the overall relative abundances of plant species in each biome was very similar (species evenness (Simpson’s measure of evenness), at the 100 m2 scale, of 0.52 ± 0.03 in the grassland and 0.51 ± 0.03 in the savanna; P = 0.74). The savanna tended to have a higher degree of invasion intensity (aerial cover of woody alien plants of 34.4 ± 4.6% compared to 29.4 ± 4.5% in the grassland; P = 0.44), possibly due to its position lower in the catchment, and hence a sink for upstream alien plant propagules. It was hypothesized that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions, in both the grassland and savanna biomes. In the Sabie (grassland) region, there was a negative correlation between the indigenous and alien species richness, thus indicating that the Sabie region plant community may have been more resistant to the invasion of alien plants than the other two regions. Therefore, the hypothesis was not rejected for the Sabie region. On the other hand, in the Graskop (grassland) and Hazeyview (savanna) regions, there were positive correlations between the indigenous and alien species richness, thus indicating that these plant communities may not have been as resistant to the invasion of alien plants. Therefore, the hypothesis was rejected for both the Graskop and Hazeyview regions. When considering the biome scale, the hypothesis was not rejected as the increase in total species richness with increasing invasion intensity in the grassland (which was more diverse than the savanna) indicated that it may have been more resistant to the invasion of alien plants than the savanna, which had a total species richness that decreased with increasing invasion intensity. In 2005, exposed soil, litter and grass covers tended to be slightly higher in the savanna (14.4 ± 1.6%; 43.5 ± 3.0%; 21.8 ± 1.7% respectively) than in the grassland (12.1 ± 2.5%; 43.2 ± 4.2%; 20.1 ± 2.3% respectively) (P = 0.43, 0.96 and 0.56 respectively). Rock and herbaceous covers were higher in the grassland (4.3 ± 1.6% and 20.3 ± 1.7% respectively) than in the savanna (0.8 ± 0.2% and 19.5 ± 2.2% respectively), but only rock cover was significantly different (P = 0.04) (P = 0.76 for herbaceous cover). These patterns in ground cover may have been a response to the slightly higher invasion intensity in the savanna. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, which may result in reduced cover of exposed soil and litter, in both the grassland and savanna biomes, was not rejected as the grassland tended to have a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. The biomes (in 2005) did not differ significantly in soil pH (grassland pH: 4.6 ± 0.1; savanna pH: 4.8 ± 0.1; P = 0.34). However, the grassland soils were generally more fertile than the savanna soils, i.e. higher organic matter (4.5 ± 0.2% versus 3.3 ± 0.4%; P = 0.01) and total nitrogen (0.3 ± 0.02% versus 0.2 ± 0.02%; P = 0.03). The concentrations (mg/l) of most of the nutrients were also higher in the grassland. The lower fertility of the savanna soils may have been related to the higher litter cover of the savanna immobilizing a larger amount of available nutrients than the grassland; another possibility may have been slower rates of soil organic matter decomposition in the slightly cooler (higher altitude) grassland regions. The soils of the grassland sites tended to be more compacted (0.8 ± 0.1 kg/cm2) (but not significantly) than those of the savanna sites (0.7 ± 0.1 kg/cm2) (P = 0.43), and the savanna plots were on significantly steeper ground (12.8 ± 1.7º) than the grassland plots (4.8 ± 1.1º) (P < 0.001), which may have also contributed to lower fertility through greater leaching and erosion losses. From the detrended correspondence analysis (DCA) of the species by plot data, there were no distinct plant communities separating out between the biomes and regions. This is probably because the Sabie River riparian environment essentially supports a riparian forest/woodland, rather than reflecting the species typically found in the adjoining (more upland) grasslands and savannas. Hence, the species composition of the riparian environment was fairly uniform throughout the study area. The canonical correspondence analysis (CCA), which also incorporates the environmental variables, showed that altitude, exposed soil cover, soil pH, organic carbon content and slope steepness were the variables that most closely (and significantly) correlated with the species composition, and two of these variables relate directly to soil fertility, and the other three are indirectly related to soil fertility. Of the original “treatments” of the 1996/1997 study, namely (A) biome (grassland versus savanna), (B) invasion intensity (high (> 50%) versus low (< 50%)), and (C) clearing (cleared versus uncleared), the legacy of the latter two did not persist over time, as there was little or no clear overall relationship between the 1996 and 2005 data when analysed by ANCOVA. The cumulative total species richness sampled in the 40 plots increased from 163 species in 1996, to 282 in 2005 (42% increase). Mean species richness (at the 1000 m2 scale) was 24.1 ± 1.0 in 1996 and 44.4 ± 1.5 in 2005 (P < 0.001). Trees increased from 28 species in 1996 to 46 in 2005 (39% increase), shrubs from 44 to 82 (46%), herbaceous plants from 71 to 121 (41%), and grasses from 20 to 33 (39%). However, even though the species richness of each growth form increased over time, the proportion of each growth form remained approximately the same, i.e. in 1996, 17% of the species were trees, 27% shrubs, 44% herbaceous and 12% grasses; whereas in 2005, 16% were trees, 29% shrubs, 43% herbaceous and 12% grasses. The greatest increase over time was for category 1, 2 and 3 weed species, namely 25 in 1996 to 50 in 2005, a 50% increase. Although mean alpha diversity was higher in 2005 (0.9 ± 0.01 compared to only 0.3 ± 0.03 in 1996 (at the 100 m2 scale); P < 0.001), overall beta diversity over time (a change from 1996 to 2005) was relatively low, indicating a small change in overall species composition, despite the increase in species richness. The invasion intensity (percentage aerial cover of woody alien plants) was similar between the years, i.e. 30.0 ± 4.6% in 1996 and 31.9 ± 3.2% in 2005 (P = 0.73). When comparing the invasion intensity between the three original treatments over time, the invasion intensity of the 1996 grassland and savanna plots remained unchanged. The invasion intensity of the 1996 high invaded plots also remained unchanged over time, however the low invaded plots had a significantly higher invasion intensity in 2005 (P = 0.004). The invasion intensity of the 1996 uncleared plots remained unchanged over time, whereas the cleared plots had a significantly higher invasion intensity in 2005 (P = 0.03). These results clearly show that the legacy of the original invasion intensity and clearing treatments measured in the 1996/1997 study did not persist over time, whereas the inherent differences between the biomes did. The hypothesis that higher plant species richness and/or diversity should enhance community resistance to alien plant invasions was rejected, as both the 1996 and 2005 plant communities were not that resistant to the invasion of alien plants, even though there was a significantly higher species richness and diversity in 2005 than in 1996. It is concluded that because of both the similar growth form composition and invasion intensity over time, the WfW clearing efforts are not succeeding in the primary aim of controlling aliens, particularly woody alien species. However, there was a considerable decrease in the aerial cover of large alien plants, namely (a) alien plants > 5 m decreased from 15.8 ± 4.1% in 1996 to 5.8 ± 1.2% in 2005 (P = 0.02), and (b) those between 2 – 5 m tended to decrease from 13.3 ± 2.8% in 1996 to 11.1 ± 2.4% in 2005 (P = 0.55). However, these decreases were balanced by a considerable increase in the aerial cover of alien plants < 2 m in height, which increased from 3.9 ± 1.0% in 1996 to 15.0 ± 2.1% in 2005 (P < 0.001). This therefore showed that the WfW clearing programme is succeeding, to some extent, in removing most of the larger alien plants but not in controlling the regenerating plants, which recover through post-clearing resprouting and/or newly established seedlings. Exposed soil, rock and litter covers were higher in 2005 (13.3 ± 1.5%; 2.5 ± 0.8%; 43.3 ± 2.5% respectively) than in 1996 (2.1 ± 0.5%; 0.9 ± 0.3%; 16.4 ± 2.7% respectively) (P < 0.001 for soil and litter covers, and 0.07 for rock cover). Herbaceous and grass covers were significantly higher in 1996 (47.8 ± 2.8% and 32.8 ± 2.6% respectively) than in 2005 (20.0 ± 1.4% and 20.9 ± 1.4% respectively) (P < 0.001 for herbaceous and grass covers). These differences in the ground covers between the years may have partially been a response to the major February 2000 flood event, which cleared a large proportion of the vegetation, resulting in much greater rates of erosion and deposition of soils. The WfW clearing operations also removed a significant proportion of the vegetation, and disturbed much that remained, thus modifying the environment. The increase in litter cover may have also been due to the slightly higher invasion intensity in 2005 than in 1996. Soil pH remained unchanged over time (both years had a pH of 4.7 ± 0.1; P = 0.99), indicating that pH was unaffected by the invasion and subsequent clearing of alien plants, as well as the 2000 flood event which moved a tremendous amount of sediment. The hypothesis that the lower the degree of alien plant invasion, the higher the understorey vegetation cover, in both 1996 and 2005, was not rejected as the plots in 1996 had a lower degree of alien invasion (although not significant), a higher cover of herbaceous vegetation, and corresponding lower covers of exposed soil and litter. Along the Sabie River, the alien tree and shrub species with the greatest densities were Rubus cuneifolius (American bramble) (1828 plants/ha), Lantana camara (Lantana) (1760), Solanum mauritianum (Bugweed) (838), Indigofera macrophylla (640), Eucalyptus grandis (Saligna gum) (560), Caesalpinia decapetala (Mauritius thorn) (403), Agrimonia odorata (Agrimonia) (220), Lilium formosanum (St. Joseph’s lily) (218), and Populus x canescens (Grey popular) (125). Focusing the clearing efforts on these species will help to reduce the frequency of re-invasions, reduce costs, and increase ease of clearing. The primary aim of the WfW programme is to increase water supplies by controlling woody alien plants. Therefore, it is concluded that the WfW clearing along the Sabie River has been partially successful, as there has been a significant decrease in the invasion intensity of large (> 5 m) alien trees (which tend to have the highest transpiration rates) over time from 1996 to 2005. In 1996, these large alien trees were represented mainly by Eucalyptus spp. However, the WfW programme was not effective in terms of ecosystem repair, as the invasion intensity increased slightly from 1996 to 2005, largely as a result of the significant increase in the aerial cover of smaller alien shrubs (< 2 m). If left unchecked, these will probably in time result in even higher levels of invasion intensity when the individual plants increase in size and cover. Furthermore, the growth form composition remained relatively unchanged over time, and more than half of the alien species found in 2005 were tree and shrub species. Therefore, little or no ecosystem repair has occurred along the Sabie River. In order to improve the effectiveness of the WfW programme, various detailed recommendations are included, which largely revolve around improvements in follow-up treatments.

Lao Man-hoi. / Thesis submitted in: December 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 52-54). / Abstracts in English and Chinese. / Abstract (English) --- p.i / Abstract (Chinese) --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Objectives of the Thesis --- p.1 / Chapter 1.2 --- Organization of the Thesis --- p.5 / Chapter 2 --- Literature Review --- p.6 / Chapter 3 --- A Model with Perfect Competition --- p.18 / Chapter 3.1 --- Introduction --- p.18 / Chapter 3.2 --- The Model --- p.19 / Chapter 3.3 --- Income Distribution --- p.23 / Chapter 3.3.1 --- Changes in the Relative Price --- p.23 / Chapter 3.3.2 --- Income Distribution --- p.24 / Chapter 3.4 --- WelfareAnalysis --- p.26 / Chapter 4 --- A Model with Imperfect Competition --- p.28 / Chapter 4.1 --- Introduction --- p.28 / Chapter 4.2 --- The Model --- p.29 / Chapter 4.3 --- Outputs and Income Distribution --- p.33 / Chapter 4.3.1 --- Short-Run Capital Specificity --- p.35 / Chapter 4.3.2 --- Long-Run Capital Mobility --- p.38 / Chapter 4.4 --- Welfare Analysis --- p.42 / Chapter 4.4.1 --- Short-Run Capital Specificity --- p.43 / Chapter 4.4.2 --- Long-Run Capital Mobility --- p.44 / Chapter 5 --- Summary and Concluding Remarks --- p.47 / Appendices --- p.50 / Bibliography --- p.52

Conversations concerning the missional posture of 1 Peter have been dictated largely by the now (in)famous debate between David Balch’s assimilationist position over and against John Elliott’s more sectarian position. More recent work has sought to bridge the gap between Balch and Elliott with a variety of more nuanced positions such as Miroslav Volf’s “Soft Difference”. Most of the discussion revolves around the practicalities of cultural engagement and what it might mean for church members to interact with the world as “Christians” in an increasingly hostile environment. The present thesis takes a step back from the coal face of missional engagement to focus on how that mission is shaped. More particularly, I am concerned with how 1 Peter utilises the language of divine calling (καλέω) that appears in five specific instances (1:13–21; 2:4–10; 2:18–25; 3:8–17; 5:6–14), alongside central events and motifs from the Old Testament, to cultivate a narrative that forges a distinct Christian identity and mission, that has its basis in Israel’s history and the life of Christ. Our concern with narrative and cultural interaction leads us to consider the relevant Petrine texts, through the dual lenses of Social Identity and Narrative Transportation theories which reveal how various groups interact, and how narratives shape actions and beliefs respectively. I argue that through the language of calling, and with the assistance of key OT motifs, 1 Peter seeks to develop a Christian identity that might be best described as “elect sojourners”; that believers are those who are elect of God and yet rejected by the world. This identity manifests itself in a life of “resident-alien-ness”—in the world, yet no longer of the world—that consequently leads to various forms of suffering. Amid such suffering, 1 Peter calls the church to a priestly ministry—representing God to the people, and the people to God—through a life geared towards blessing, even when such a life leads to suffering. This is the life to which the Anatolian believers have been called: a life of holiness as a priestly community, committed to the gracious endurance of suffering, and of blessing those who would oppose them.