Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2005. / The occurrence of both pre- and postharvest leaf blackening in certain Protea species and cultivars is a problem that severely limits their marketability, vase life and transport options. This research focuses on : (I) The distribution of carbohydrates in inflorescence bearing stems of certain Protea cultivars from harvest, following pulsing with a 10 g.L-1 glucose solution until four weeks postharvest. Stems were held under a variety of postharvest conditions, and (II) The suppression of Protea postharvest leaf blackening with specific focus on the cultivar ‘Sylvia’ (P. eximia x P. susannae).

Thesis (MScAgric)--University of Stellenbosch, 1994 / 127 Leaves printed single pages, preliminary pages i-viii and numberd pages 1-118.Includes bibliography,tables and figures. / Date on t.p.: Dec. 1994. / ENGLISH ABSTRACT: Effects of pH,sucrose, boric acid and temperature on in vitro germination of pollen of Protea repens (L.) L. cv. 'Embers' were investigated in hanging-drop culture to establish optimum conditions for germination. Optimum values were found within ranges pH: 5 - 8, sucroseconcentration:0.4 - 0.7 M, boric acid concentration:50 - 500 mg.e-1 , and incubation temperature: 5 - 30°C. Storage temperature and humidity on pollen viability was studied in four Pro tea clones. Pollen was stored at a range of temperatures and relative humidities for up to one year and tested for ability to germinate in vitro. Pollen of P. repens cv. 'Sneyd', P. eximia cv. 'Fiery Duchess' andP. magnifica clone 'T 84 07 OS', stored in liquid nitrogen (-196°C) and in a freezer (-14° to -18°C), retained a germination percentage as high as that of fresh pollen regardless of humidity. The study showed that long-term storage of protea pollen is not feasible at temperatures above O°C. The correlations between the fluorochromatic reaction (FCR) and germinability were found to be low and nonsignificant. Fifteen month old cryopreserved 'Sneyd' pollen was shown to retain its ability to fertilize and set seed equal to that of fresh pollen. 'Sneyd', 'Fiery Duchess' and 'T 84 07 OS' pollen could be repeatedly thawed and frozen in liquid nitrogen before its germinability in vitro decreased. The morphology and size of Protea pollen was studied, using light and scanning electron microscopy. Polymorphic grains were observed in two interspecific hybrids. Very small differences in pollen grain size were recorded between clones/species. The male fertility of 25 interspecific Pro tea hybrids, based on in vitro pollen germinability, was investigated. The majority of hybrids were found to be sufficiently fertile to be used in a breeding programme. Pistil structure and pollen tube pathways were investigated in 'Sneyd' using light and scanning electron microscopy. The pistil had four distinct regions, consisting of the stigma, the vertebra-shaped upper style, the heart-shaped lower style, and the ovary. The pistil had a stylar canal along its entire length and this canal was also the route by which pollen tubes grew to the ovary. Very low numbers of pollen tubes reached the ovary. The breeding system of 'Sneyd' and 'Fiery Duchess' were determined from pollen tube and seed set data, after controlled hand-pollinations. Both clones were found to be fully selfcompatible. Very low percentages autogamous seed set were recorded. Interspecific crosses had a low success rate. An incompatibility reaction probably occurred on the stigma and/or in the upper style regions.The attainment of maximum stigma receptivity of two Protea cultivars was investigated by means of seed set experiments, pollen tube growth observations and measurement of the degree of opening and closing of the stigmatic groove. Both cultivars were found to be protandrous. The maximum stigmatic groove width of both cultivars never exceeded the pollen grain diameter. It was concluded that Protea spp. must be hand-pollinated two to six days after anthesis in order to obtain maximum seed set; while for the observations of pollen tubes in the ovary, inflorescences must not be harvested before seven days after pollination. / AFRIKAANSE OPSOMMING: Ten einde 'n optimale medium vir die in vitro-ontkieming van Protea-stuifmeel te ontwikkel, is die effek van pH, sukrose, boorsuur, en temperatuur op die in vitro-ontkieming van Protea repens (L.) L. cv. 'Embers'-stuifmeel deur middel van die hangdruppel-metode ondersoek. Die volgende reekse van veranderlikes wat getoets is, is as optimaal gevind; pH: 5 - 8, sukrosekonsentrasie: 0.4 - 0.7 M, boorsuurkonsentrasie: 50 - 500 mg.e-1 en inkubasietemperatuur: 5 - 30°C. Die invloed van bergingstemperatuur en humiditeit op stuifmeel-Iewenskragtigheid is in vier Protea-klone ondersoek. Stuifmeel is gestoor by 'n reeks temperature en relatiewe humiditeite vir tot eenjaar, en vir in vitro-ontkiemingsvermoe getoets.' Stuifmeel van P. repens <?v. 'Sneyd', P. eximia cv. 'Fiery Duchess', en P. magnifica kloon'T 84 07 OS', in vloeibare stikstof (-196°C) en in 'n vrieskas (-14° tot - 18°C) geberg, het 'n ontkiemingspersentasie gelykstaande aan die van vars stuifmeel gehandhaaf, ongeag van die humiditeit. Hierdie studie het verder aangetoon dat langtermynberging van Protea-stuifmeel bokant O°C me die moeite werd is me. Die korrelasie tussen die fluorochromatiese reaksie (FCR) en ontkieming was laag en me betekemsvol me. 'Sneyd' -stuifmeel wat vir 15 maande in vloeibare stikstof gestoor is, het die bevrugtings- en saadsetvermoe gelykstaande aan vars stuifmeel behou. 'Sneyd', 'Fiery Duchess' en 'T 84 07 OS'-stuifmeel kon herhaaldelik in vloeibare stikstof gevries en ontdooi word voordat hul ontkiemingsvermoe afgeneem het. Die morfologie en grootte van Proteastuifmeel is deur middel van lig- en skandeerelektronmikroskopie bestudeer. Polimorfiese stuifmeelkorrels is in twee interspesie-hibriede waargeneem. Baie klein verskille in stuifmeelkorrelgroottes het tussen klone/spesies voorgekom. Die manlike vrugbaarheid van 25 Protea-interspesiehibriede, gebaseer op die in vitro-ontkiembaarheid, is ondersoek. Dit is gevind dat die meerderheid hibriede 'n voldoende graad van vrugbaarheid het om in 'n teelprogram te gebruik. Die stamperstruktuur en stuifmeelbuiswee in P. repens is deur middel van lig- en skandeer-elektronmikroskopie ondersoek. Die stamper bestaan uit vier kenmerkende gebiede, naamlik die stempel, die werwelvormige bo-styl, die hartvormige onderstyl, en die vrugbeginsel. Die stamper het 'n stylkanaal regdeur die totale lengte van die stamper, en hierdie kanaal is ook die weg waarvolgens stuifmeelbuise na die vrugbeginsel gegroei het. Min stuifmeelbuise het die vrugbeginsel bereik. Die teelsisteem van 'Sneyd' en 'Fiery Duchess' is deur middel van stuifmeelbuis- en saadsetdata na gekontroleerde handbestuiwings ondersoek. Beide kIone was ten volle selfverenigbaar. Die persentasie outogame saadset was baie laag. Interspesiekruisings het 'n baie lae sukses gehad. Dit is voorgestel dat die onverenigbaarheidsreaksie in die stempel en/of in die bopunt van die styl plaasvind. Die bereiking van maksimum stempelontvanklikheid van twee Protea-cultivars is deur middel van saadseteksperimente, stuifmeelbuisdata en waarnemings van die oop- en toemaak van die stempelgroef ondersoek. Beide cultivars was protandries. Die maksimum stempelgroefwydte het nooit die stuifmeelkorreldeursnee oorskry nie. Dit is afgelei dat Protea-spesies twee tot ses dae na antese handbestuif moet word vir optimale saadset. Vir die waarneming van stuifmeelbuise in die vrugbeginsel, moet bloeiwyses nie voor sewe dae na bestuiwing geoes word nie.

Major transitions between vertebrate and insect pollination systems have occurred many times during the angiosperm radiation and are associated with evolutionary modifications in floral traits. In the large ancestrally bird-pollinated African genus Protea (Proteaceae), an evolutionary shift from bird to insect pollination in the genus is suggested by the fruity diurnal scent of flowers in a recently evolved clade of grassland species. In this study, I confirm that four of these grassland Protea species have mixed mating systems and are indeed insect pollinated, and furthermore demonstrate the functional significance of their floral presentation and scent chemistry for attraction of pollinators, specifically cetoniine beetles. The study species, Protea caffra, Protea dracomontana, Protea simplex and Protea welwitschii, have colourful bowl-shaped inflorescences that produce copious amounts of pollen and dilute, xylose-rich nectar. Cetoniine beetles were found to be the most suitable pollinators due to their abundance, size, relatively pure Protea pollen loads, and their preference for the fruity scent and low growth form of these scented Protea species, as demonstrated by choice experiments in which inflorescences were offered at either end of a y-maze or at various heights above the ground, respectively. Bagging and hand pollinations revealed that these Protea species are self-compatible and capable of autonomous selfing. Self progeny of P. caffra were as vigorous as cross progeny in terms of germinability and survivorship to two months. Vertebrate-excluded and open-pollinated inflorescences yielded similar seed numbers for all species. Supplemental hand-pollinations, however, failed to increase seed set substantially, an indication of resource limitation. Outcrossing rates estimated using polymorphisms at eight allozyme loci in progeny from vertebrate-excluded and open-pollinated treatments of P. caffra were no different (t=0.59), indicating outcrossing by insects and an equal or insubstantial contribution from bird pollinators. The fruity-sweet scents of these species were more complex, with higher whole flower and mass-specific emission rates, than those in eight bird-pollinated congenerics. The overall floral scent is shown to be a blend of emissions from various plant parts, especially nectar. Electroantennography (EAG) revealed that the generalist pollinator Atrichelaphinis tigrina responds to a variety of volatile compounds found in fruity Protea scents. Field trapping confirmed that this cetoniine beetle is strongly attracted to ß-linalool (up to 60% of scent profile) and methyl benzoate. In conclusion, this study demonstrates the evolution of beetle pollination and mixed mating systems in a grassland clade of Protea. Volatile compounds that make up the unique (within Protea) fruity scent of the study species are shown to attract beetles, and the emission of large amounts of these compounds was probably a key step in the transition from bird to insect pollination in Protea. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

A systematic approach to planning, decision-making and management has become best-practice in conservation over the past two of decades. The field of ‘systematic conservation planning’ is concerned with identifying cost-effective places and actions to protect biological diversity. Past research has focused on static assessments. However, given the fact that biological diversity and processes that threaten its persistence vary in space and time, conservation assessments might need to be made in a dynamic context. In addition, we must explicitly account for the trade-offs associated with implementing conservation actions and investing in improved knowledge and learning to reduce uncertainty on where, how and when to act. The aim of this thesis was to develop novel approaches for accounting for both ecosystem dynamics and uncertainty in conservation planning. Ecosystems are generally treated as static in conservation planning despite many being spatially and temporally dynamic. For example, pelagic marine ecosystems are quite dynamic because ecological processes, such as eddies, that produce resources that many species depend on can be erratic. In chapter two we explored the issue of developing a system of fixed protected areas that consider the physical and biological dynamics typical of the pelagic realm. The approach was to maximize the representation of key fisheries species and species of conservation concern due to significant declines in their abundance, within a network of protected areas. We also ensured that protected area design reflected system dynamics and this was achieved by representing key oceanographic process (such as upwellings and eddies), and biological processes (such as the abundance of small pelagic fish) in protected areas. To account for the variability where these processes occur, we used time series data to find both predictable areas and anomalies, assuming that their past location was somewhat reflective of their future locations. Implementing conservation actions that are fixed in space and time are probably not the most effective strategy in ecosystems that are dynamic. This is because of the movements of particular species. For example, many species have distributions and abundances that change seasonally and might only require temporary management in particular areas. In chapter three, we tested the utility of three approaches to implementing fisheries closures to reduce bycatch in the South African Longline Fishery; 1) time closures, 2) permanent spatial closures and 3) episodic spatial closures. In chapter three, we identified these closures using an existing database containing catch and bycatch data from 1998 to 2005. There was variation where and when different species were caught as bycatch, and it was determined seasonal area closures were the best strategy. This was because it achieved the same conservation objectives for bycatch species as the other types of closures, but impacted less on the long-lining industry. While this result is intuitive, it demonstrated quantitatively, how much more effective moveable management can be. Decisions on where conservation actions are implemented are always based on incomplete knowledge about biological diversity. It is generally assumed that gathering more data is a good investment for conservation planning. However, data can take time and incur costs to collect and given habitat loss, there are both costs and benefits associated with different levels of investments in knowledge versus conservation implementation. In chapter four, the aim was to determine the return on investment from spending different amounts on survey data before undertaking a program of implementing new protected areas. We found that, after an investment of only US$100,000, there was little increase in the effectiveness of conservation actions, despite the full species dataset costing at least 25 times that amount. Surveying can take time because of expertise limitations, logistics and funding shortfalls. Biological diversity may be lost while data collection occurs conversely, not collecting enough data can lead to erroneous decisions. Additionally, resources spent on learning may be better spent on other actions. In chapter five, in a series of retrospective simulations, we compared the impact of spending different amounts of time collecting biological data prior to the implementation of new protected areas. The aim was to find the optimal survey period given the trade-off between gaining knowledge to improve conservation decisions while there is concurrent loss of habitat. We discovered that surveying beyond two years rarely increased the effectiveness of conservation decisions, despite a substantial increase in the knowledge of species distributions. Often there are choices between different actions and uncertainty as to which are the most effective. In chapter six, we discuss how the principles of adaptive management might be applied to conservation planning. Improving future management decisions through learning should be viewed as essential in all conservation plans but such learning is often included as a minor step, or is completely ignored. In this chapter we provide a brief overview of an adaptive framework for conservation planning and ideas for future research.

A systematic approach to planning, decision-making and management has become best-practice in conservation over the past two of decades. The field of ‘systematic conservation planning’ is concerned with identifying cost-effective places and actions to protect biological diversity. Past research has focused on static assessments. However, given the fact that biological diversity and processes that threaten its persistence vary in space and time, conservation assessments might need to be made in a dynamic context. In addition, we must explicitly account for the trade-offs associated with implementing conservation actions and investing in improved knowledge and learning to reduce uncertainty on where, how and when to act. The aim of this thesis was to develop novel approaches for accounting for both ecosystem dynamics and uncertainty in conservation planning. Ecosystems are generally treated as static in conservation planning despite many being spatially and temporally dynamic. For example, pelagic marine ecosystems are quite dynamic because ecological processes, such as eddies, that produce resources that many species depend on can be erratic. In chapter two we explored the issue of developing a system of fixed protected areas that consider the physical and biological dynamics typical of the pelagic realm. The approach was to maximize the representation of key fisheries species and species of conservation concern due to significant declines in their abundance, within a network of protected areas. We also ensured that protected area design reflected system dynamics and this was achieved by representing key oceanographic process (such as upwellings and eddies), and biological processes (such as the abundance of small pelagic fish) in protected areas. To account for the variability where these processes occur, we used time series data to find both predictable areas and anomalies, assuming that their past location was somewhat reflective of their future locations. Implementing conservation actions that are fixed in space and time are probably not the most effective strategy in ecosystems that are dynamic. This is because of the movements of particular species. For example, many species have distributions and abundances that change seasonally and might only require temporary management in particular areas. In chapter three, we tested the utility of three approaches to implementing fisheries closures to reduce bycatch in the South African Longline Fishery; 1) time closures, 2) permanent spatial closures and 3) episodic spatial closures. In chapter three, we identified these closures using an existing database containing catch and bycatch data from 1998 to 2005. There was variation where and when different species were caught as bycatch, and it was determined seasonal area closures were the best strategy. This was because it achieved the same conservation objectives for bycatch species as the other types of closures, but impacted less on the long-lining industry. While this result is intuitive, it demonstrated quantitatively, how much more effective moveable management can be. Decisions on where conservation actions are implemented are always based on incomplete knowledge about biological diversity. It is generally assumed that gathering more data is a good investment for conservation planning. However, data can take time and incur costs to collect and given habitat loss, there are both costs and benefits associated with different levels of investments in knowledge versus conservation implementation. In chapter four, the aim was to determine the return on investment from spending different amounts on survey data before undertaking a program of implementing new protected areas. We found that, after an investment of only US$100,000, there was little increase in the effectiveness of conservation actions, despite the full species dataset costing at least 25 times that amount. Surveying can take time because of expertise limitations, logistics and funding shortfalls. Biological diversity may be lost while data collection occurs conversely, not collecting enough data can lead to erroneous decisions. Additionally, resources spent on learning may be better spent on other actions. In chapter five, in a series of retrospective simulations, we compared the impact of spending different amounts of time collecting biological data prior to the implementation of new protected areas. The aim was to find the optimal survey period given the trade-off between gaining knowledge to improve conservation decisions while there is concurrent loss of habitat. We discovered that surveying beyond two years rarely increased the effectiveness of conservation decisions, despite a substantial increase in the knowledge of species distributions. Often there are choices between different actions and uncertainty as to which are the most effective. In chapter six, we discuss how the principles of adaptive management might be applied to conservation planning. Improving future management decisions through learning should be viewed as essential in all conservation plans but such learning is often included as a minor step, or is completely ignored. In this chapter we provide a brief overview of an adaptive framework for conservation planning and ideas for future research.

Thesis (MScAgric)--Stellenbosch University, 1994. / Some digitised pages may appear illegible due to the condition of the Microfiche / ENGLISH ABSTRACT: Many Proreaceae species indigenous to South Africa have potential as cutflower crops. Commercial production of proteas for expurt, mainly to Europe, must emphasise quality of flowers and time of production. Good export quality flowers have stems longer than 50cm and unblemished flowers. Cut-flower proteas are in greater demand and command better prices during the European winter (September to May, Southern hemisphere), when competition from flowers grown in Europe is less. Both quality and time of harvest can be manipulated by pruning techniques. Protea cv. Carnival (a natural hybrid, possibly between P. neriifolia and P. compacta) produces flowers in late summer, from February through to May. Picking flowers or pruning shoots of Proteo cv. Carnival entails removing the terminal portion of shoots with heading cuts to leave on the plant short stumps, known as bearers. Lateral shoots arising from axillary buds on bearers elongate by successive growth flushes until flowers are initiated terminally. The characteristics of the shoot determine whether or not flower initiation will take place, and will affect the quality of the resulting flower. Plants were pruned to produce bearers of different length and diameter. The characteristics of shoots arising from different bearers were recordea. Thick bearers of length 20-25cm produced the most shoots, and the longest shoots. Plants producing flowers biennially, rather than ann'Jally, produced thicker bearers, which, in turn, lead to production of better quality shoots arising from the bearers in the following season. Changing the time of pruning changed both the flowering cycle and the biomass allocation of Prorea cv. Carnival. Plants of Profea cv. Carnival were pruned on six different dates in 1991. Pruning in March, April or May, 1991, resulted in an annual flowering cycle. Less than 40% of the fresh mass produced in 1993 was reproductive, of which approximately 5% had stems long enough for export. The 1994 annual harvest was of s:milar size and quality as the 1993 annual harvest. Pruning in July, August or September, 1991, resulted in a biennial cycle of flowering. No flowers were produced in 1992, and a large crop was harvested in 1993. In 1993 lip to 70% of the fresh mass produced was reproductive, of which approximately 80% had stems long enough for export. Plants were pruned shortly after flowering in 1993, and the biennial cycle was replaced by an alternate flowering cycle, with a large crop being followed by a smaller crop. The large harvest in 1993 was significantly earlier than normal, but the small crop produced in 1994 was later. The harvest in 1994 from plants with an alternate flowering cycle was similar in size to the 1994 harvest from plants floweting annually, but flower stems were longer. / AFRIKAANSE OPSOMMING: Heelwat inheemse Proteaceae spesies besit die vereiste eienskappe om as snyblomr.-le verhanctci te wod. Indien proteas kommersieel verbou sou word vir uitvoer moet die klem val op gehalte van blomme en die tyd van produksie. Goeie gehalte uitvoer blomme moet steellengte van langer as 50cm en perfek gevormde blomme besit. Daar is 'n groter aanvraag na kommersieel verboude proteas gedurende die Europese winter (September tot Mei, suidelike halfrond) en beter pryse word derhalwe ook dan verkry. Beide gehalte en die oes periode kan gemanipuleer word deur snoeitegnieke. Wanneer blomme gepluk word of lote gesnoei word van Profea cv. Carnival (waarskynlik 'n kruising tussen P. compacta x P. neriifolia) word die terminale gedeelte van die loot teruggesny. Die oorblywende gedeelte bestaan uit kort stompe wat bekend staan as draers. Laterale lote afkomstig van okselknoppe op draers verleng totdat 'n blom terminaal ontwikkel. Die eienskappe van die loot bepaal of 'n blom inisieer sal word of nie, en sal ook die gehalte van die gevormde blom beinvloed. Protea plante was gesnoei om draers van verkillende lengtes en deursnee te produseer. Die eienkappe van lote afkomstig van die verskillende tipe draers was gemeet. Dik ..draers van lengte 20-25cm het die meeste asook die langste lote geproduseer. Plante wat twee-jaarliks, in teenstelling met jaarliks, geblom het, het dikker draers geproduseer en ook gelei tot produksie van beter gehalte lote in die opeenvolgende seisoen. Die verandering in die tyd van snoei het beide die blom siklus en die biomassa verspreiding beinvloed. Plante van Protea cv. Carnival was up 6 verskillende datums in 1991 gesnoei. Snoei in Maart, April of Mei, 1991, het 'n jaarlikse blom siklus veroorsaak. Minder as 40% van die vars massa geproduseer in 1993 was reproduktief, waarvan 5% steellengte lank genoeg vir uitvoer gehad hel. Die 1994 jaarlikse oes was van dieselfde grootte en gehalte as die van 1993. Snoei in Julie, Augustus of September, 1991, het egter 'n twee-jaarlikse blom siklus veroorsaak. Geen blomme was in 1992 geproduseer nie, maar die oes in 1993 was heelwat groter as die jaarlikse oeste. In 1993 was to 70% van die vars massa geproduseer, reproduktief, waarvan 80% steellengte lank genoeg vir uitvoer gehad het. Die twee-jaarlikse blom siklus het 'n vroeer oes in 1993 veroorsaak, maar 'n later oes in 1994. Die twee-jaarlikse oes in 1994 was van dieseifde grootte as die jaarlikse oes in 1994, maar die blomstele was langer.

Protea cynaroides L. (King Protea) is a well known cutflower. Seeds and stem cuttings are commonly used to propagate P. cynaroides. However, the success rate and rooting rate of seeds and cuttings, are inconsistent and slow. The potential of in vitro propagation as an alternative method to produce P. cynaroides plantlets was investigated. In vitro studies consisted of in vitro germination of mature zygotic embryos, micrografting and direct somatic embryogenesis of zygotic embryos and excised cotyledons. In the germination study, temperature was the most important factor in obtaining a high germination percentage. Alternating temperatures of 21±2ºC/12±2ºC (light/dark) was suitable for germination and over 90% of embryos germinated, while the germination percentage of embryos at 25±2ºC was poor. Plantlets were successfully established in ex vitro conditions when planted in a peat/coir/sand mixture. Micrografting of P. cynaroides was done by grafting microshoots (microscion), which was taken from in-vitro-established nodal explants, onto roots of decapitated in-vitro-germinated seedlings. After the graft union formed, buds on the microscion sprouted. A protocol to induce direct somatic embryogenesis was developed. Direct somatic embryogenesis was achieved on both P. cynaroides mature zygotic embryos and excised cotyledons. The addition of auxins such as NAA and 2,4-D singly or in combination with TDZ, BAP or kinetin suppressed the formation of somatic embryos. Formation of somatic embryos was observed in medium lacking growth regulators. Germination of somatic embryos was highest in medium containing GA3. The roles of starch and phenolic compounds in the rooting of P. cynaroides cuttings were also studied. Starch and total soluble phenol analyses results revealed a positive correlation between high root formation and increased starch and phenolic content. NMR and MS analyses identified high amounts of 3,4-dihydroxybenzoic acid in stems of P. cynaroides. In vitro bioassay showed that 3,4-dihydroxybenzoic acid stimulated and inhibited root growth of P. cynaroides explants, depending on the concentration. A link was made between the endogenous concentration levels of 3,4-dihydroxybenzoic acid and rooting of P. cynaroides stem cuttings. Findings of this study contribute towards a better understanding of the roles starch and phenolic compounds play in the rooting of P. cynaroides. / Thesis (PhD (Horticulture))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

This study was undertaken to determine the effect of vegetation structure (the ratio of re-seeding to re-sprouting plants) on post-fire catchment water yield. Plant communities are the only components of mountain catchments which can be manipulated to augment water supplies on any practical scale. Burning, which is one of the options available to catchment managers, reduces plant biomass and increases water yield by reducing transpiration and interception losses. Communities dominated by re-seeding species tend to recover more slowly after fires than when sprouters predominate. The rate of vegetation recovery will determine the rate at which streamflow returns to pre-fire levels. Sprouters may use more water than seeders in the early post-fire period by virtue of their greater leaf area, which both increases interception and transpiration losses. Leaf area development could be used as a simple determinant of post-fire water yield if transpiration losses per unit leaf area are similar in seedlings and sprouters. In this study, a comparison was made of the transpiration rates of seedlings and sprouters of Protea nitida after a fire in Swartboskloof (Cape Province) in 1987. Plant water potentials were determined (index of the degree of stress) and leaf stomatal conductances were measured. Results indicate that transpiration rates are similar throughout the year except during the short summer drought period when the seedlings have comparatively low transpiration rates (< 1 mmo1 m-2 s-1 compared to 2-3 mmo1 m-2 s-1 of the sprouter), and i immediately after the first winter rains where the seedlings have comparatively high rates (approxi.mately 4 mmol m-2 s-1 compared to 2 mmol m-2s-1.) The 1ow summer rates are thought to be the result of drought stress induced by limited water supply and the shallow root systems of the seedlings. The higher winter rates suggest that the shallow surface roots of the seedlings respond quickly to increased surface moisture. Differences in root structure (Le. shallow seedling roots and well-developed deep sprouter roots) rather than regeneration mode appear to be responsible for the marginal differences observed in transpiration rates. These differences are expected to disappear as seedling roots develop and occupy the profile. Leaf area could therefore, be used as a determinant of catchment water yield. / Thesis (M.Sc.)-University of Natal, 1990

Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: With growing concerns about current environmental issues, such as climate change, that affect ecosystems around the world, understanding ecosystem function is becoming increasingly important. In this study, I investigate the plant – seed disperser mutualism between an endemic scatter-hoarding mouse Acomys subspinosus and its Proteaceae plant counterpart Leucadendron sessile in the biodiversity hotspot of the Cape Floristic Region, South Africa. The main objective of this thesis is to investigate the seed selection and caching behaviour of A. subspinosus. First, I determined the seed selection strategy for dispersal and burial by A. subspinosus. Acomys subspinosus may exert stabilizing selection pressure onto L. sessile seeds by dispersing and burying medium seeds with medium hull-thicknesses. Small seeds were eaten in situ and large seeds left at depots. I concluded that the buried L. sessile seeds may have a competitive advantage when it comes to seedling establishment in a post-fire environment, since seeds dispersed by rodents in the fynbos, such as L. sessile, are much larger in size and therefore have more stored nutrients and rapid growth capabilities than seeds dispersed by other vectors. Secondly, I documented rodent dispersal behaviour over a full years’ time. Acomys subspinosus dispersal behaviour changed significantly over the seasons, which I attributed to a change in food availability as the year progressed. Acomys subspinosus buried seeds in autumn after mass seed drop but began to recover caches and consume seeds during winter and spring. The rodent switched to an insectivorous diet in spring. I propose that the A. subspinosus – L. sessile relationship is mutualistic during the year, but the relationship does shift in the favour of the rodent during winter and spring. Lastly, I address the scatter-hoarding behaviour of A. subspinosus and cache recovery ability of its assumed closest food competitor Rhabdomys pumilio. I found that cache size has a profound influence on pilferage rates of L. sessile seeds. Acomys subspinosus scatter-hoarded the majority of seeds singly in the field and R. pumilio had difficulties finding those single-cached seeds in dry substrate under controlled experimental conditions, serving as evidence that scatter-hoarding is an effective method of pilferage mitigation by A. subspinosus during the dry summer months. Relatively little was known about this plant – disperser mutualism and how it functions before this thesis were conducted. I have provided insights into the influence of rodent disperser behaviour on seed morphology development, seed fate and seed persistence in the field and suspect that the plant –disperser relationship may have a larger influence on ecosystem dynamics than previously anticipated. Further research on this system is of importance, especially with today’s emerging environmental instability and human interference that threaten the robustness of highly interconnected ecosystems like the fynbos. / AFRIKAANSE OPSOMMING: Met die huidige omgewingskwessies, soos die klimaatsverandering, wat ekosisteme wêreldwyd affekteer, word die begrip van ekosisteemfunksionering toenemend belangrik. In hierdie studie ondersoek ek die dier – saadverspreidingsmutualisme tussen die endemiese verstrooiings-storing muis Acomys subspinosus en sy Proteaceae plant eweknie Leucadendron sessile in die biodiversiteit 'hotspot’ van die Kaapse Floristiese Ryk, Suid-Afrika. Die hoof doelwit van die tesis is om die saadseleksie en storingsgedrag van A. subspinosus te ondersoek. Eerstens het ek die saadseleksie strategie vir die verspreiding en begrawing deur A. subspinosus bepaal. Acomys subspinosus het direksionele druk uitgeoefen op L. sessile sade deur mediumgrootte sade met medium saadhuiddiktes te versprei en te begrawe. Klein sade was in situ geëet en groot sade was gelaat by afgesette plekke. Ek het die gevolgtrekking gemaak dat die L. sessile sade wat begrawe is ‘n kompeterende voordeel mag hê wanneer dit kom by die vestiging van saailinge in ‘n afgebrande omgewing, aangesien sade wat in die fynbos deur knaagdiere versprei word, soos L. sessile, baie groter is en dus meer gestoorde voedingstowwe en spoedige groeivermoëns het, as sade wat deur ander vektore versprei word. Tweedens het ek die knaagdier verspreidingsgedrag oor die tydperk van ‘n jaar gedokumenteer. Acomys subspinosus se verspreidingsgedrag het beduidend verander deur die verloop van die jaar, wat ek toegeskryf het aan die verandering in voedselbesbikbaarheid soos wat die jaar gevorder het. Acomys subspinosus het sade begrawe in die herfs na grootskaalse vrylating en val van die sade, maar het gestoorde sade begin terug kry en sade begin eet gedurende die winter en lente. Die knaagdier het na ‘n insekvretende dieët omgeskakel in die lente. Ek stel voor dat die A. Supspinosus – L. sessile verhouding nie die hele jaar mutualisties is nie, maar eerder antagonisties, in die knaagdier se guns, gedurende die winter en lente. In die laaste hoofstuk spreek ek die verstrooiings-storingsgedrag van A. subspinosus en storingsverkrygingvermoeë van sy naaste voedselmededinger en deponeringsdief Rhabdomys pumilio aan. Ek het gevind dat die storingsgrootte ‘n beduidende invloed het op die koers van diefstal van L. sessile sade. Acomys subspinosus het die meerderheid van die sade gestoor in die veld en R. pumilio het die enkel-gestoorde sade in droeë substraat onder gekontroleerde eksperimentele kondisies moeiliker gevind. Dit is ondersteunende bewyse dat verstrooings-storingsgedrag ‘n effektiewe metode is om diefstal te verminder in die droë somer in die fynbos. Relatief min was bekend oor hierdie dier – saad verspreidingsmutualisme en hoe dit funksioneer voordat die studie uitgevoer was. Ek het insig verskaf oor die invloed van knaagdier verspreidingsgedrag op saadmorfologie ontwikkeling, die lot van sade en die tydperk wat dit begrawe is in die veld. Ek vermoed dat die mutualisme ‘n hoeksteenproses is in die fynbos en die invloed daarvan op ekosisteemdinamieka mag dalk groter wees as wat voorheen verwag was. Verdere navorsing oor hierdie sisteem is belangrik, veral met vandag se opkomende omgewingsonstabiliteit en menslike inmenging wat die robuustheid van hoogs verbonde-netwerk ekosisteme soos die fynbos bedreig.

Thesis (MScConEcol)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The role of mites as primary vectors of various fungi within Protea infructescences was recently confirmed and raised questions about their general diversity and their role within this unique niche. Although mites evidently form an integral part of Fynbos ecosystems and probably play a significant role in Protea population dynamics, there is a general void in our knowledge of mite diversity within the Cape Floristic Region. These organisms do not only affect ecological processes within the CFR, but also the economic value of Protea exports. This study sets out to describe mite communities within the infructescences of a variety Protea species. In the process, the role of various environmental variables and differences in host characteristics affecting these communities are also explored. A total of 24281 mite individuals, comprising of 36 morphospecies in 23 families, were collected from 16 surveyed Protea spp. Mite community structure and composition were significantly influenced by plant taxonomy, phenology and infructescence architecture in different Protea spp. At a temporal scale, infructescence age and season were influential factors on mite community structure. Collection locality significantly influenced mite communities within the infructescences of a single Protea sp. Host architecture had no influence on mite communities within a single host species. Geographic distance had no significant influence on mite community structure within Protea infructescences. This implies that factors particular to particular host species determine mite communities. These include factors such as the mode of pollination of the host plant, level of serotiny and plant life form. Numerous newly recorded mite species collected from Protea infructescences are also described in this study. An identification key to the Tydeidoidae of South Africa is provided here for the first time. This study forms a baseline dataset for future studies on the biodiversity of mites in this extremely diverse eco-region. / AFRIKAANSE OPSOMMING: Die rol van myte as primêre vektore van verskeie funguses binne Protea vrugtekoppe is onlangs bevestig, en het vrae laat ontstaan oor hulle algemene diversiteit en rol binne hierdie unieke nis. Alhoewel myte duidelik ‘n integrale deel vorm van Fynbos ekosisteme en waarskynlik ‘n belangrike rol speel in Protea populasie-dinamika, is daar ‘n algemene leemte in ons kennis van mytdiversiteit binne die Kaapse Floristiese Ryk (KFR). Hierdie organismes affekteer nie slegs ekologiese prosesse binne die KFR nie, maar ook die ekonomiese waarde van Protea-uitvoere. Hierdie studie mik as vertrekpunt om die verkillende myt-gemeenskappe binne die vrugtekoppe van verskeie Protea spesies te beskryf. In die proses is die rol van verskillende omgewingsveranderlikes en verskille in gasheer kenmerke wat hierdie gemeenskappe affekteer, ook ondersoek. ‘n Totaal van 24281 myt individue, saamgestel uit 36 morfspesies in 23 families, mytgemeenskappe is beduidende beinvloed deur die taksonomie van die plant, die fenologie en die vrugtekop-argitektuur van verskillende Protea spesies. Op ‘n temporale skaal is gevind dat vrugtekop-ouderdom en seisoen beduidende faktore is in die samestelling van mytgemeenskapstruktuur. Versamel-lokaliteit het verder mytgemeenskappe binne die vrugtekoppe mytgemeenskappe binne ‘n enkele gasheerspesie getoon nie. Geografiese afstand het geen beduidende invloed op mytgemeenskapstruktuur binne Protea vrugtekoppe getoon nie. Dit faktore in soos die metode van bestuiwing van die gasheer plant, die vlak van saadhoudendheid van die Protea koppe en plant-lewensvorm. Verskeie nuwe myt spesies wat uit Protea vrugtekoppe versamel is, word ook in hierdie studie beskryf. ‘n Identifikasie-sleutel vir die Tydeidoidae van Suid-Afrika word verder vir die eerste keer hier verskaf. Hierdie studie vorm die basis datastel vir toekomstige studies van die biodiversiteit van myte in hierdie besonder diverse eko-omgewing.