South Africa is not well endowed with indigenous forests which are now known to be degraded and declining at unknown rates. This constitutes a direct threat to quality of life of the resource-poor rural households who directly depend on them and to ecological integrity. It is also recognised that the declining tree resources, particularly the high value indigenous tree species, are increasingly threatened by a number of growing subsistence demands. This emphasised the need to cultivate and conserve high-value tree species such as Englerophytum natalense, Ptaeroxylon obliquum and Millettia grandis on-farm in Umzimvubu District. Agroforestry is recognised as a viable option for optimising land productivity, reducing pressure on the indigenous forests, ensuring a sustainable supply of desired tree products and services and improving the quality of life of the resource-poor rural households. This Thesis examines whether agroforestry in Umzimvubu District and similar areas of South Africa has the potential for addressing these needs. It recognises that for successful initiation, implementation and adoption, agroforestry should be considered at two levels, namely, household and institutional. Responses based on structured questionnaires were obtained at these levels. Questionnaires were used to determine whether the households and institutions were aware of, and responding to, the need to intensify and diversify on-farm production, ease pressure on indigenous forest, improve income opportunities and problem solving capacities to address agroforestry related issues. An ecological inventory of E. natalense, P. obliquum and M grandis was carried out to provide a sound basis for integrating high-value species into appropriate agroforestry systems and to facilitate the preparation of future management guidelines for these resources in Mt. Thesiger Forest Reserve. The study: i) confirms that most high value indigenous tree species merit integration into subsistence farming systems through agroforestry, ii) appreciates that some rural households have been unknowingly practising agroforestry, iii) recognises that agroforestry is implied in South Mrica's White Paper on Sustainable Forest Development of 1997, but notes that similar emphasis has not been adopted or incorporated in the National Forestry Action Programme of 1997, and iv) notes that challenges to promoting agroforestry research and development in the South Mrican context of the institutions and resource-poor rural households are many, but can be resolved. The study concludes that agroforestry stands to benefit many resource-poor rural households and enhance environmental resilience in South Africa in the next millennium. / Thesis (M.Sc.) - University of Natal, Pietermaritzburg, 1999.

The patch structure of the grass sward at Kroomie (26°25'38"E 33°48'30"S) in a semi-arid savanna in the Eastern Cape, South Africa, was investigated. The study was conducted on long term grazing trials on five treatments varying in stocking rate (SR; recommended (low) and 1.5 x recommended (high), grazing system (continuous and rotational), and animal type (cattle and sheep). The treatments studied were CR (cattle, rotational stocking, low SR), CC (cattle, continuous stocking, low SR), CH (cattle, rotational stocking, high SR), SC (sheep, continuous stocking, low SR), and SR (sheep, rotational stocking, low SR). Rainfall during the two years of the study (1997/98 and 1998/99) was slightly below the mean average rainfall of the area (66 and 84% of the mean of 519 mm, respectively). Analysis of sward height data using Maximum Likelihood Estimation reflected a bimodal height structure in all treatments. Due to a high overlap of the two distributions in some cases, however, the height at which to separate patches (short grass) from non-patches (tall grass) could not be determined. Canonical Correspondence Analysis (CCA) was used to relate species composition to sward height. It emerged that there are two distinct grass communities at Kroomie, and these are associated with sward height (i.e. patches and non-patches). The interface (in cm) between these two communities, as determined using Two Way Indicator Species Analysis (TWINS PAN) was 6 cm, and this value was subsequently used to discriminate between patches and non-patches. Sward structure was affected by treatments. Animals (cattle and sheep) stocked rotationally at low SR's grazed less than a third of the total area, and this grazing was concentrated primarily in small patches (< 6 m; length is used as a linear indicator of patch size). Animals stocked continuously at low SR's grazed approximately half the area, in small and large (up to 40 m) patches. Animals in the CH treatment grazed approximately two-thirds of the area, in both small and large patches. There was an inverse relation between the size of patches and the size of non-patches, as expected. Nine common grass species were related to sward height. Digiteria eriantha, Eragrostis racemosa, Eustachys paspaloides, and Microchloa caffra were associated with short swards, while Cymbopogon pluronodis, Eragrostis chloromelas, and Sporobolus fimbriatus were associated with tall swards. Themeda triandra (themeda), the most abundant grass at Kroomie, was principally associated with tall swards, but was present at all sward heights. Applying CCA demonstrated a considerable difference between the species composition of patches and of non-patches. There was also a difference in composition between treatments, although these were not as pronounced. Patches reflected a higher species diversity than non-patches. There was a significant (P<0.05) effect of treatment, and of an interaction of treatment by sward structure (i.e. patches and non-patches), on the density of themeda plants. The density of themeda plants was positively correlated with patch size, which suggested that themeda plants that have been grazed may suffer fatal competition from ungrazed neighbours. Anecdotal evidence suggested that patches are stable over the medium term, and that non-patches that are grazed during a drought return to a non-patch structure after rainfall. There was no evidence to support the contention that rotational stocking reduced patch-selective grazing, nor that the species composition of rotationally stocked treatments was better than continuously stocked treatments. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

No abstract available. / Thesis (MBA)-University of KwaZulu-Natal, Westville, 2012.

Bush encroachment is a major problem for the savannas supporting livestock in the Eastern Cape. Farmers employ chemical poisoning and mechanical clearing of woody vegetation to improve grass production. This thesis addressed the following questions. 1. Does soil fertility and hence, herbaceous production and/or quality increase beneath or between former bushclumps following woody clearing or poisoning? 2. Are chemical or mechanical control methods effective for all woody species? 3. Does bush density and height decline with increasing competition from the herbaceous layer? 4. Can fire and goats retard or revert woody re-establishment, thereby keeping these savannas open? A trial for assessing different methods of controlling bush was conducted near Kei Road. Initial treatments included chemical poisoning, mechanical clearing and a control, each replicated eight times in 0.36 hectare plots. Follow-up treatments were control, fire, goats, and the combination of fire and goats each replicated twice per primary treatment. Two additional mechanically cleared plots were oversown with Chloris gayana seeds. Herbaceous production, species composition, foliage quality and soil fertility, and mortality, recruitment, height increase and density of woody individuals were monitored for five seasons. Mechanical clearing of the woody vegetation increased soil fertility, except total nitrogen, and that explained the dramatic response in grass production that endured for the first four seasons since clearing. The periphery and ex-bushclump zones were characterised by increased colonization of Panicum maximum while there were no changes in frequencies of other key herbaceous species in all vegetation zones. Acacia karroo and woody "weeds" (Solanum incanum, Berkheya bipinnatifida) established from seed while all other woody species recruited mainly from coppicing. Seedling recruitment and resprouting resulted in high densities of woody stems and individuals by the second season after clearing when compared with the pre-clearing levels. Oversowing cleared areas with pasture grasses did not only increase grass production but also reduced the density of coppicing woody plants and "weeds". Chemical treatments mirrored the controls in terms of grass production, except during a very wet season, and species composition. Although encroaching woody species (e.g. Scutia myrtina, Maytenus heterophylla and Trimeria trinervus) were susceptible to poisoning, woody plant density was not reduced. Multi-stemmed woody individuals were resistant to poisoning. Fire and goats kept most coppicing woody plants short, less than half a metre, after three seasons of browsing and also improved grass production in the dense bushclumps suggesting that these clumps were being opened up. However, high browsing pressure forced goats to graze more hence this effect was masked. This study indicates that chemical and mechanical control of bush are economically unsustainable for beef and mutton production, at least in the medium term. Fire and goats are appropriate as a follow-up strategy for retarding woody regrowth, keeping bushclumps open, improving grass production and economic viability of mechanical clearing. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.

The objective of the study was to assess the farmers’ knowledge and perceptions of P. incana invasion and impacts on rangeland, livestock production and livelihood in four communal grazing areas. Twenty households per village that own livestock were randomly selected to conduct an interview using an open and closed ended questionnaire. In each household, an old and knowledgeable respondent about P. incana invasion was used as a selection criterion. For scientific assessment of range condition, the experiment was conducted in a 270 m x 100 m trial plots that were established in 2014. The area was divided into 3 open and 3 fenced subplots each having an area of 45 m x 100 m established laid down a slope gradient. Each plot was divided into four equal subplots to apply the control treatments. Therefore, the trial layout was a stratified block experiment of four treatments replicated three times. The four control treatments applied to P. incana invasion were chopping and resting (CR), resting without chopping (RWOC), grazing and chopping (GC), grazing without chopping (GWOC). A step point method was applied in each transect to monitor species composition and P. incana cover. On the fenced plots two exclosures of 1mx1m size were randomly distributed to make sure that resting is maintained. Within exclosures 0.25 m2quadrates in each were put randomly to measure biomass. Density of P. incana was determined from 5 m x 5 m quadrates that were placed randomly within each sub-plot. The density and height of individual shrub plant was measured. All rooted live woody plants were recorded and counted in each quadrate. The results revealed that species composition was not affected (P>0.05) by the treatments applied. The herbage height and basal cover had greater values (P<0.05) under rested plus chopping (CR) treatment followed by grazed plus chopping (GC). Grass biomass production and essential nutrients showed a greater concentration (P<0.05) under CR treatment than any treatments applied. The results on perceptions revealed that goats had the highest mean household holding number than any other livestock species across the selected villages in all the villages. Respondents indicated that both goats and cattle had equal or more importance than sheep. Three out of four villages raised cattle primarily for income generation and secondarily for cultural purposes like slaughtering during weddings ceremonies, amazila and also during woman circumcisions (Ntonjane). Similarly, goats and sheep were primarily raised for cash income generation. The results revealed that livestock population decreased over ten to twenty years (one-two decades) and poor rangeland condition is assumed to be the cause of the situation as feed is the key factor for production. The area was dominated by the grasses rather than by browse woody species so the above results are possible as the P. incana is more competitive than grasses. It was concluded that P. incana is detrimental to both rangeland and animal production. Forage and animal performance as well as farmers’ economic status (livelihoods) were negatively affected by P. incana invasion and the scientific assessment reported it to be detrimental to agriculture. Thus chopping and resting (CR) treatment resulted in a greater improvement of the basal cover, biomass production, soil nutrients as well as grass height than the other treatments applied. Therefore it can be concluded that chopping and resting the veld invaded with P. incana can improve the range and consequently animal production.

Sixty one basalt samples from the Drakensberg Subgroup in the Barkly East area were analysed for major elements and fourteen trace elements viz. Sr, Rb, Zr, Y, Nb, Zn, Cu, Ni, Co, V, Cr, La, Ce and Nd . These data confirm the tholeiitic nature of the Drakensberg Subgroup. Geochemical differences in the major element compositions are small within the different units of the Drakensberg Subgroup. Small differences are also evident between these units. The trace element variation between the units and within the Lesotho Formation are more pronounced than the variation of the major elements. The Lesotho Formation samples show a minor vertical increase in value for the top half of the Naudes Nek section in Fe, Ti, P, Zr, Nb, Y, La, Ce and Nd . A decrease in value from the same position in Mg, Ni and Co was observed. These patterns of variation are interpreted as representing low-pressure fractionation of plagioclase, olivine and clinopyroxene. Differences between the units of the Drakensberg Subgroup are examined by using absolute trace element contents and interelement ratios. Ratios of incompatible elements differ for the different units leading to the suggestion that a heterogeneous mantle is the most likely explanation for these differences. A unique unit of flows designated the Omega Formation is examined. The basal massive unit displays an unusual pattern of variation with height which suggests an origin through two different differentiation mechanisms. The data from this thesis are compared with those of Cox and Hornung (1966) on the central Lesotho basalts, Bristow (1976) on the southern Lebombo basalts and Robey (1976) on the Karroo dolerites of the Eastern Cape. The geochemical comparison between the lavas of the Lesotho Formation in the Barkly East area, central Lesotho and the Karroo dolerites show no major differences. However the southern Lebombo basalts show an enrichment in Sr and depletion in Cr.

Aspects of the life history of Myxus capensis which were likely to be most affected by man-induced habitat changes, were studied in the eastern Cape. Myxus capensis was found to be specialized for a catadromous life history. The fry migrate into freshwater reaches of rivers within a few months of being spawned at sea and return to an estuarine or marine environment when maximum size has been attained and large energy reserves necessary for spawning have been accumulated. Myxus capensis penetrates considerable distances up eastern Cape rivers and although present in the upper reaches of some estuaries, is only common in freshwater-dominated systems. Myxus capensis has adapted its life history style in a number of ways to overcome the constraints associated with the spatial separation of the freshwater feeding areas and the marine spawning grounds in a region prone to droughts and erratic river flow. Research on the more estuarine-dependent Mugil cephalus, which is also found in the freshwater reaches of eastern Cape rivers, enabled useful comparisons to be drawn. As the latter species is not dependent on a freshwater phase in its life cycle, it is subject to different selection pressures. This comparative approach gave insights into the adaptive significance of the life history tactics of Myxus capensis. Myxus capensis displays a number of life history tactics characteristic of migratory fish species which are thought to increase population fecundity by increasing the number of large females and hence maximizing egg production. These include a sex ratio in favour of females, faster female growth, females remaining longer in the freshwater feeding areas and reaching a larger ultimate size. Possible adaptations to the periodic isolation of the feeding and spawning areas include: (i) the development of ripe gonads only in estuarine or marine areas when access to the spawning grounds is ensured; (ii) year-round spawning and hence recruitment which enables the erratic floods to be used at any time for downriver spawning migrations and reduces the chances of total recruitment failure due to short-term adverse environmental conditions and (iii) a relatively wide range of size and age at first (and final) sexual maturity (2+ to 5+ years); this tends to ensure successful reproduction and recruitment in spite of a series of poor years, as well as dampen population fluctuations after long periods of isolation in fresh water. The dependence of Myxus capensis on the freshwater reaches of eastern Cape rivers makes this species vulnerable to man-induced habitat changes. The erection of barriers to migration has cut off large stretches of suitable habitat and almost completely eliminated Myxus capensis from certain rivers. This detrimental effect has been largely responsible for the recent inclusion of this species on the Red Data list of endangered fish species in South Africa. This study demonstrated the considerable fisheries potential of both mullet species and this should ensure that their conservation and wise utilization be given high priority. Management proposals include: (i) the netting and lifting of Myxus capensis over barriers to migration; (ii) the construction of fish ladders when feasible and (iii) the artificial propagation of this species to enable large-scale stockings of existing man-made impoundments as well as natural habitats to be carried out. It is predicted that the life history characteristics of Myxus capensis, which evolved in response to an erratic freshwater environment, should ensure that when man-induced habitat changes are rectified, this species will again flourish in eastern Cape rivers.

Cycads first appeared about 300 million years ago and historical data indicates that they survived fluctuations of global temperature and carbon dioxide concentrations and reached peak abundance during periods where temperature and carbon dioxide concentrations were much higher than the present conditions as well as the predicted increased levels. With Africa being one of the most vulnerable regions to climate change and in the absence of an evaluation of predicted impacts of climate change on cycads, this study aims to contribute to our understanding of responses of Encephalartos longifolius to increased temperature. Encephalartos longifolius (Jacq.) Lehm is an Eastern Cape endemic and like most cycads has been around for millions of years with very little change to its basic structure. Photosynthetic rates showed E.longifolius seedlings have C3 photosynthesis and even under stress they do not switch over to CAM photosynthesis. The photosynthetic rates of seedlings showed a typical C3 -plant type response under elevated carbon dioxide levels. Increased temperatures could be detrimental to the species but coupled with elevated carbon dioxide levels the growth of Encephalartos longifolius are postulated to outweigh the negative impacts of increased temperatures. Whilst climatic conditions in the Eastern Cape might not impact the abundance of Encephalartos longifolius, the species however is declining rapidly to the present near-threatened status. Demographic studies revealed a high percentage of juvenile numbers in the wild; however juvenile plants are impacted on by animals thereby jeopardizing their survival. Adult plants are heavily impacted on by animals; this reduces the probability of new offspring being produced. Cycads are also very slow - growing which is the primary cause of their ruin in the wild. Encephalartos longifolius grows at just over approximately 1 cm per year with growth being more rapid in the juvenile plants. Once juvenile plants reach approximately 60 cm they stop growing in diameter but only get taller. Seed germination is also a very slow process with an optimum temperature of 28°C and a growth medium of at least 50 percent moisture. Regardless of the Eastern Cape predicted to become the hottest province in South Africa as a result of climate change, cycads will be able to adapt to the changing environment and conservation plans should focus on animal and human impacts that are the major force causing decreasing abundance of Encephalartos longifolius in the wild.

The study was conducted in Eastern Cape Province to 1) investigate local people’s knowledge and perceptions on Euryops floribundus and 2) landscape distribution and effect of Euryops floribundus on herbaceous vegetation and soil. A total of 90 households who own livestock were randomly selected from the three communal areas, namely; Tsengiwe, Upper Mnxe and Manzimdaka for household surveys and group discussions. For landscape study, a total of about 5 ha of land were selected at Upper Mnxe communal area. Selection criteria included the presence of E. floribundus and different landscape gradients. A total of four 50mx50 plots were marked along the landscape gradients: Bottom, Middle, and Upper Slope and upland positions. To study the effect of E. floribundus invasion on the herbaceous vegetation and soil, a total of 4 ha communal land was selected in an accessible area which had a largely flat terrain. The area was selected to have adjacent sites with no invasion (< 5% shrub cover), light (5-15% shrub cover), moderate (>15-35) and heavy invasions (>35% shrub cover) of E. floribundus. The average household size in the study area was 6.8± 0.7. All people in the three communal areas unanimously ranked sheep as the most important species for their livelihood, but the ranking of cattle and goat varied among the communal areas. All elder groups agreed that Europs floribundus decreases both the quantity and quality of herbaceous forage as well as livestock production. Moreover, invaded patches create more bare areas which are responsible for the loss of top fertile soils and the formation of rills and gullies. The result showed that the total density of E. floribundus significantly increased from the topland (2301 plants ha-1) moving to the bottomland (4888 plants ha-1). Canopy cover was significantly lowest in the topland (17.9%), but the remaining gradients had similar cover. Grass dry matter yield was higher in the bottomlands and sloppy gradients than the toplands. Soil organic carbon was significantly higher (P<0.05) in the flat than the sloppy terrain. Soils from higher elevations (toplands and upper sloppy) had significantly higher N than the lower elevations (bottomlands and Middle sloppy). The lowest dry matter was observed at low invasion and non-invaded sites. Soil chemical properties were generally different from all density levels. In conclusion, E. floribundus encroachment was found to be major cause of decline in the peoples’ livelihood because as this reduces the vegetation diversity and livestock production, both of which are the major of their livelihoods.