Thesis (MTech. Nature Conservaion) -- Tshwane University of Technology 2013. / The aim of this study was to determine the current population status of Aloe peglerae in the Magaliesberg Mountain Range.

Climatic oscillation during the Quaternary resulted in fragmentation of once more continuous ancient floras and a series of invasions of different floras into the Pondoland Centre in response to climatic change, with some elements invading more than once. This implies both a temporally complex and a floristically complex origin for the extant flora of the Centre. Data derived from analysis of the melange of extant floristic elements in the Pondoland Centre is presented in support of this hypothesis. A synfloristic comparison of Oribi Gorge (OGNR) and Umtamvuna Nature Reserves (UNR) is the basis for this study. A comparison of the species lists generated for OGNR and UNR reveals that 24% of the 1514 angiosperm species are shared. The familial composition of the reserves is similar, with eight of the ten most diverse families contributing a similar proportion of species to the respective floras, with the exception of Acanthaceae. The ten most diverse families comprise a comparatively small proportion of the respective floras; this is indicative of high diversity over long geological periods, i.e. of refugia. Analysis at the generic level revealed similar consistancy between the two gorge floras. Approximately 4% of the UNR species and 2.3% of OGNR species are Pondoland Centre endemics. Approximately 40% of the endemic species are shared by the gorges. Data reveals that both palaeoendemic (predominantly woody, forest taxa) and neoendemic (predominantly herbaceous or suffrutescent, grassland taxa) species occur. The Pondoland Centre is thus a refugium for species trapped on the Msikaba Group sandstones as a result of climatic oscillation during the Quaternary, and a centre of neoendemism. OGNR and UNR floras include Cape, Afromontane and tropical elements (11.3%, 2.8% and 19.1% respectively for OGNR and 16%,3.4% and 15.3% respectively for UNR). Seventy - two percent of Afromontane species are shared, indicating a relatively recent invasion(s) and lor the relative proximity of the gorges to the Afromontane flora. The lower species overlap in the Cape element (39.2%) of the two gorges implies that the invasion of the element is ancient, with subsequent extinction of many of the taxa from OGNR in response to climatic change. It is also possible that this invasion was initally less successful; fewer species found refuge in OGNR. The tropical element comprises the largest proportion of the flora in both gorges and many (ca. 50%) of the species are shared. The degree of species overlap indicates that the invasive flora was either initially more similar or that it is tess prone to extinction. The level of overlap could also suggest that the invasion was more recent than that of the Cape taxa. The tropical element is larger in OGNR and the Cape element is larger in UNR. This is partly due to the gorges' respective proximities to the tropical and Cape floras. This trend is echoed in the endemic data. iv The conservation status of the endemics and of the Pondoland vegetation types is established and recommendations for further research are made. The data support the establishment of a larger UNR, the maintenance of both Umtamvuna and Oribi Gorge as formal nature reserves and the establishment of a new reserve (or reserves) within the Pondoland Centre. / Thesis (M.Sc.)-University of Natal, Pietermarizburg, 1998.

A new sampling method that decouples spatial and environmental correlations was developed and applied to a temperate forest understory. Data were used to contrast niche theory with neutral theory, and only showed support for niche theory. A spatial and environmental partitioning analysis indicated that the effects of dispersal are primarily important within the spatial extent of environments suitable for a given species. The same sampling data were used to test correlates of non-native species invasion at a species level and as a group. The distributions of non-native plant species are also better explained by the niche model; however, non-native species do not appear to negatively impact native species, nor to be negatively impacted by native species. Together, these results suggest that the forest understory is strongly niche-structured, but likely not saturated. Diversity in this forest appears to be primarily determined by regional processes, and only secondarily by local species interactions.

[Truncated abstract] Weeds which invade native communities can have major impacts on biodiversity and ecosystem processes. However, these impacts are rarely quantified, and the mechanisms behind these impacts are rarely investigated. Asparagus asparagoides (L.) Druce (Asparagaceae; common name: bridal creeper), a plant native to southern Africa, is a significant environmental weed in southern Australia. Bridal creeper can invade both disturbed and undisturbed native ecosystems and then dominate native communities. As is the case for many environmental weeds, there has been little work conducted on the impacts of this plant. This lack of knowledge has hampered restoration efforts of invaded areas because very little is known about the potential for invaded communities to recover prior to undertaking weed management. There is a need to improve our understanding of how to manage ecosystem recovery during and after weed control. This can be achieved by (i) determining the impacts caused by the weed; (ii) assessing the condition of invaded communities; and (iii) predicting the impacts that weed management itself will have on the native communities. These three prerequisites to environmental weed control have been determined across sites invaded by bridal creeper in southern Australia. The impacts of this invasive geophyte have been determined through multi-site comparisons, weed removal experiments and controlled glasshouse and laboratory experiments. ... Without additional restoration, we will see those species that readily germinate and those that respond positively to increased soil fertility, replacing bridal creeper after control. This will be dominated by other weeds as the invaded sites have large exotic seed banks that will readily germinate. The tuberous mats of older bridal creeper plants will also leave a legacy as they will remain many years after control and still impact on vegetation, even if control has killed the plant. These impacts will be highest at sites where bridal creeper has dominated over the longer term. Environmental weeds, such as bridal creeper, that are capable of altering ecosystem functions can lead to substantial declines in biodiversity. Therefore, it was fortunate that bridal creeper became a target for biocontrol in Australia even though the impacts of the weed were not quantified when this decision was made. There are areas in southern Australia that are still free of bridal creeper or have sparse populations, and it is highly likely that this biological control programme has lead to the protection of these areas. This protection would not have been possible if other control measures were chosen over biological control, given that biocontrol agents can self-disperse and are able to give continuous control. This means that biological control of weeds in conservation areas can be very effective and is the only economically viable option for the control of widespread environmental weeds such as bridal creeper.

[Truncated abstract] Fire ephemerals are pioneer species that germinate in large numbers after fire and generally live for between six months and four years. Seeds produced during the short life span of these plants persist in the soil seedbank until a subsequent fire. This study examined the dormancy characteristics and germination requirements of ten Australian fire ephemeral species from five families. Seeds of four species germinated at one or more incubation temperatures in the laboratory, indicating that a proportion of their seedlots were non-dormant at the time of testing. Austrostipa compressa and Austrostipa macalpinei (Poaceae) produced >80% germination at 10?C and Alyogyne hakeifolia and Alyogyne huegelii (Malvaceae) produced 30-40% and 35-50% germination respectively at 10 to 25°C. In each of the Alyogyne species approximately 50% of seeds were impermeable to water, but scarification did not enable germination of all viable seeds suggesting that seeds which did not germinate, may have possessed physiological dormancy as well as physical dormancy. Remaining species had water permeable seeds. ... Germination of both Alyogyne species declined after six months of winter burial but was enhanced by heat treatments after a further six months of summer burial. Actinotus leucocephalus and Tersonia cyathiflora seeds exhibited annual dormancy cycling over two years of burial. Dormancy was alleviated over summer, allowing seeds of both species to germinate in smoke water when seeds were exhumed in autumn, and reimposed over winter, suppressing germination in spring. In Actinotus leucocephalus these dormancy changes were induced in the laboratory by warm (≥15°C) and cold (5°C) temperatures, alleviating and re-imposing dormancy, respectively. Wetting and drying seeds stored at 37°C further accelerated the rate of dormancy release. This dormancy cycling would increase the likelihood of seeds germinating when moisture availability in south-western Australia is greatest for seedling survival. It also explains the variation in germination response to smoke water observed in many species. Thus under natural conditions dormancy levels of fire ephemerals were altered during soil storage which enabled them to respond to fire-related cues such as heat and smoke water, and germinate in autumn. This information will assist in the use of these species in land rehabilitation and ornamental horticulture, and in the conservation of rare or endangered fire ephemerals.

Looking at the use of plants as food reflects how humankind has fashioned nature. There has been a significant change in production patterns from hunter-gathering through subsistence agriculture to technologically advanced commercial agriculture with a subsequent reduction in the diversity of plants used as food. A parallel trend in consumption patterns has occurred, from home-based food processing for subsistence through small- scale production to large-scale industrial processing and the commodification of food. The overall result of such trends is a narrowing of the food resource base and an increasing reliance on processed foods at the expense of traditional diets, accompanied by increasing diet-related health risks. This research is an ethnographic case study on the use of indigenous food plants by the community of Tuku A village in the Eastern Cape using interviews and observations as the main data collecting strategies. A nutritional analysis of some wild food plants was also carried out. An inventory of more than 70 food plant species was compiled, with the knowledge of such plants found among both the elderly and the youth. The incorporation of this knowledge into education systems is recommended. Of the wild food plants documented, some were non-indigenous indicating the dynamic nature of indigenous knowledge. Some wild spinach were left to grow amongst cultivated food plants, hinting at some form of ‘domestication’ in process. This observation together with the observation that wild fruit trees were selectively conserved highlights the possibility of the continued use of wild food contributing to conservation of botanical diversity. Community use of indigenous food was found to be diminishing. Stigmatisation of indigenous food plants, urbanisation, formal education, changes in lifestyle, and media were some of the factors possibly influencing this dietary shift. The community made links between diet and health, which correspond to modern scientific knowledge, with modern diet being lamented for ill health. The nutritional analysis revealed that wild food plants do contain essential dietary nutrients, an area recommended for further research.

Analysis of the flora of the Pondoland Centre of Endemism (PCE) recorded 2253 species in the combined checklist of four sites (Port St. Johns, Mkambati, Umtamvuna and Oribi Gorge). Of these 1 % species are endemic to Pondoland, representing 8.7% of the Species, 15% of the genera and 26% of the families of the combined flora. Forty-four percent ofthe combined flora was only recorded from one locality (between 17% and 26% of each flora) and only 12% of the flora was present in all four localities. Of the endemics only sixteen (8%) occurred in all four sites thus each site had its own complement of unique endemics and 21 % endemics were not recorded from any of the four sites. At species level the floras of Mkambati and Umtamvuna were the most similar, followed by that of Umtamvuna and Oribi Gorge. Port St Johns had the least in common with any of the othersites, but more in common with non-neighbours Umtamvuna and Oribi Gorge than with its nearest neighbour Mkambati. Mkambati and Umtamvuna had the largest proportion of PCE endemics and Port St Johns had the lowest. The four sites are quite similar at family level, sharing thirteen families in the top ten family list between them, but much less similar at generic level.

MSCAGR / Department of Plant Production

Abstract in English / The number of studies focused on the digital preservation of indigenous knowledge has been growing steadily over the years. Despite the growth in this area of research, there is still a lack of information technology tools that preserve and disseminate indigenous knowledge. Indigenous knowledge has been highlighted as an area that can advance sustainable development, and its preservation is therefore of the utmost importance. Indigenous knowledge is mostly present within older generations, and if it is not preserved, this knowledge will die with its custodians. African communities rely heavily on indigenous medicine. A digital platform needs to be explored that can preserve practices relating to these medicines for future generations. Since indigenous knowledge is dynamic and is constantly evolving, there is a need to explore a digital tool that can highlight this dynamic nature. Current methods of preserving indigenous knowledge of medicinal plants were found to be less than effective and marred by constraints such as space and time. The main objective of this study was therefore to develop a model that could be used to guide the design of a new e-learning system aimed at facilitating the preservation of indigenous knowledge of Namibia’s medicinal plants. In this study, e-learning technology was used to determine the requirements for presenting indigenous knowledge of Namibia’s medicinal plants in such a way as to ensure that individuals can internalise and preserve this knowledge. An interpretivist qualitative approach was followed. Data was collected by conducting a literature review and carrying out a survey. A prototype e-learning system was developed and evaluated based on the collected data. It was found that preserving indigenous knowledge of medicinal plants through e-learning would require, among other things, engagement with the relevant knowledge custodians, leveraging multimedia, and offering content in indigenous languages. / School of Computing / M.Sc. (Computing)

Tesis por compendio / [ES] La sequía y la salinidad son los factores ambientales que más afectan a las plantas, aunque en general, las plantas mediterráneas están bien adaptadas a las condiciones adversas. Las previsiones estiman que debido al calentamiento global las condiciones ambientales se volverán más estresantes, especialmente en las zonas semi-áridas y áridas como muchas áreas de la Península Ibérica. Estas condiciones pueden afectar a la presencia de muchas especies silvestres, en especial, de las que ya de por si están amenazadas, son raras o endémicas. Tanto la sequía como el estrés salino provocan la activación de una serie de mecanismos de defensa o respuesta de las plantas, que incluyen entre otros, el control del transporte iónico, la acumulación de solutos compatibles u osmolitos, y la activación de sistemas antioxidantes. Para contribuir a la conservación y/o reintroducción de las especies de interés en hábitats prioritarios se ha realizado un estudio multidisciplinar abarcando los parámetros que pueden afectar sus poblaciones, como el clima, el suelo, y la vegetación acompañante, junto a estudios comparativos sobre las respuestas a la sequía y a la salinidad. Para entender mejor los mecanismos de tolerancia se han incluido en el estudio además de los taxones de interés conservacionista, especies relacionadas genéticamente con diferentes niveles de tolerancia. El estudio presenta dos objetivos principales: i) establecer la tolerancia relativa al estrés hídrico y salino de las especies en base a su distribución en la naturaleza y en los análisis realizados en campo y, en función de la inhibición relativa de su crecimiento bajo condiciones provocadas de estrés; y, ii) evaluar los cambios bioquímicos inducidos por el estrés analizando diferentes mecanismos de respuesta (inhibición de la fotosíntesis, transporte iónico, acumulación de osmolitos, mecanismos antioxidantes). / [CA] La sequera i la salinitat són els factors ambientals que més afecten les plantes, encara que en general, les plantes mediterrànies estan ben adaptades a les condicions adverses. Les previsions estimen que a causa del calfament global les condicions ambientals es tornaran més estressants, especialment en les zones semi-àrides i àrides com moltes àrees de la Península Ibèrica. Aquestes condicions poden afectar la presència de moltes espècies silvestres, especialment, de les que ja de per si estan amenaçades, són rares o endèmiques. Tant la sequera com l'estrès salí provoquen l'activació d'una sèrie de mecanismes de defensa o resposta de les plantes, que inclouen entre altres, el control del transport iònic, l'acumulació de soluts compatibles u osmolits, i l'activació de sistemes antioxidants. Per a contribuir a la conservació i/o reintroducció de les espècies d'interès en hàbitats prioritaris s'ha realitzat un estudi multidisciplinari abastant els paràmetres que poden afectar les seues poblacions, com el clima, el sòl, i la vegetació acompanyant, al costat d'estudis comparatius sobre les respostes a la sequera i a la salinitat. Per a entendre millor els mecanismes de tolerància s'han inclòs en l'estudi a més dels tàxons d'interès conservacionista, espècies relacionades genèticament amb diferents nivells de tolerància. L'estudi presenta dos objectius principals: i) establir la tolerància relativa a l'estrès hídric i salí de les espècies sobre la base de la seua distribució en la naturalesa i en les anàlisis realitzades en camp i, en funció de la inhibició relativa del seu creixement sota condicions provocades d'estrès; i, ii) avaluar els canvis bioquímics induïts per l'estrès analitzant diferents mecanismes de resposta (inhibició de la fotosíntesi, transport iònic, acumulació de osmolits, mecanismes antioxidants). / [EN] Drought and salinity are the environmental factors that most affect plants, although in general Mediterranean plants are well adapted to adverse conditions. Predictions estimate that, due to global warming, environmental conditions will become more stressful, especially in semi-arid and arid areas, such as many areas of the Iberian Peninsula. These conditions may affect the presence of many wild species, especially those that are already threatened, rare or endemic. Both drought and salt stress cause the activation of a series of defence or response mechanisms in plants, which include, among others, the control of ionic transport, the accumulation of compatible solutes or osmolytes, and the activation of antioxidant systems. To contribute to the conservation and/or reintroduction of species of interest in priority habitats, a multidisciplinary study has been carried out covering parameters that may affect their populations, such as climate, soil and accompanying vegetation, together with comparative studies on responses to drought and salinity. To better understand tolerance mechanisms, genetically related species with different levels of tolerance have been included in the study, in addition to taxa of conservation interest. The study has two main objectives: i) to establish the relative tolerance to water and salt stress of the species according to their distribution in nature and based on field analyses and, according to the relative inhibition of their growth under stress-induced conditions; and, ii) to evaluate stress-induced biochemical changes by analysing different mechanisms (inhibition of photosynthesis, ionic transport, osmolyte accumulation, antioxidant mechanisms). / This research was partially funded by Project AICO/2017/039 from the Generalitat Valenciana. / González Orenga, S. (2021). Mecanismos de tolerancia a estrés salino e hídrico en plantas endémicas, raras o amenazadas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/168443 / TESIS / Compendio