Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / The Overberg renosterveld rangelands of the Cape Floristic Region (CFR) has become well associated with commercial and communal agricultural practices, namely crop and livestock production. This Mediterranean region is characterized as being a semi-arid, winter rainfall area with nutrient-limited soils. Livestock farmers rely largely on introduced legume species such as lucerne (Medicago sativa) as high quality forage to sustain their livestock’s diets. Generally, these introduced species are reliant on the accessibility of water and nutrients, due to the specific climatic and edaphic conditions of the region. The availability of high quality forage has always been a major concern to farmers when it comes to managing their livestock, since livestock productivity is determined by the quality of the forage consumed.

Thesis (MScConsEcol)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Rûens Silcrete Renosterveld (RSR) is a critically endangered vegetation type in the Overberg region of the Western Cape Province of South Africa. In the last few centuries about 80% of it has been severely transformed by agriculture. The RSR contains many unique and rare plants species, and has very high conservation value. It is recommended that all remaining areas of this vegetation type should be conserved. However, very few of these areas are formally conserved and most are on farms where they are used for grazing of domestic livestock. The RSR appears to be sensitive to overgrazing and to grazing at a time of the year when it is sensitive to major change. This study examined the effects different grazing regimes had on the RSR vegetation on farms in Buffeljagsrivier, a small farming community in the Eastern Overberg. Different methods were used to compare vegetation structure and composition, of heavily-, medium- and under-grazed areas. Information on the biodiversity in RSR areas was found to be scarce, with almost nothing known of the invertebrates. In this study a comprehensive checklist of plants and vertebrates in the study area was compiled. An insect order/family list and separate species lists of Lepidoptera and Orthoptera were also compiled. The insects were recorded by using different collecting and observation methods. A study was also made of the major plant/animal interactions occurring in the area. For this study, the focus was mainly on interactions with two dominant woody plants, Acacia karroo and Searsia glauca. Other interactions were also noted. Different grazing regimes affected both structure and plant composition in the different grazing camps. Some plant species were found to be more dominant in heavily-grazed areas and some more in under-grazed areas. Heterogeneity in grazing pressure of the camps contributes to make the whole area more diverse and may have enabled the high biodiversity to persist in the area. More than 400 indigenous plant species were recorded in the study area of which more than 30 plant species were found to be of conservation concern. 37 % of the overall species are endemic to the Cape Floristic Region. The study area contained 127 geophyte species. This is 51 % of all the known geophyte species that occur in the Langeberg Centre. A new plant species, Haworthia groenewaldii, was discovered in the study area. Overall, 214 insect families in 23 insect orders were also found in the study area. A total of 103 Lepidoptera species was recorded. About five moth species are possibly new to science and still need to be scientifically described. Some plants and insects were recorded beyond their known geographical ranges. Twelve different frog, 22 reptile, 30 mammal and 122 bird species were found to occur in the study area. Nineteen insect species from 14 insect families in four orders associated with Acacia karroo trees were found in the study area. Thirty-four insect species from 25 families, in six orders, were found to be interacting with Searsia glauca trees. Sixty one bird species were associated with A. karroo and 42 with S. glauca. Other interactions that were observed included caterpillars feeding on host plants. For the Lepidoptera list, the possible plant species on which the juveniles feed was also investigated. This study unequivocally showed that this geographical area has a very high overall biodiversity that needs to be conserved. It also found that grazing can affect the composition distribution and combination of this biodiversity. Much research is still to be done on plant/invertebrate interactions in the RSR. This study provides a baseline for further research on future actions to conserve this unusual and special area in terms of invertebrate biodiversity especially for generations to come. / AFRIKAANSE OPSOMMING: Rûens Silkreet Renosterveld (RSR) is ʼn Kritiek Bedreigde veld soort,in die Overbergstreek van die Wes-Kaap Provinsie van Suid-Afrika. Omtrent 80% van RSR is uitgeroei deur landbouprakteike van die afgelopetwee eeue. RSR bevat baie unieke en skaars plant spesies en het dus ʼn baie hoë bewaringswaarde. Dit word aanbeveel dat alle gebiede wat die tipe plantegroei bevat, bewaar behoort te word. Baie min van die oorblywende RSR word formeel beskerm en die grootste gedeeltes wat nog oor is, kom voor op plase waar dit vir weiding ingespan word. Die veld soort is skynbaarbaie sensitief vir oorbeweiding, asook vir beweiding in die verkeerde seisoen. Hierdie studie het na die uitwerking van verskillende weidingsmetodes op natuurlike veld op aangrensende plase in Buffeljagsrivier, ʼn klein plaasgemeenskap in die Oostlike Overberg, gekyk. Verskillende metodes was gebruik om die plantegroei se samestelling en struktuur van ʼn lae, middelmatige en oorbeweide gebiede met mekaar te vergelyk. Inligting oor die biodiversiteit van RSR, veral oor invertebrate, was moeilik om in die hande te kry. Spesies lyste so volledig as moontlik was in die studie vir al die vertebrate en plante opgestel. Lyste is ook opgestel vir alle insek ordes en families, wat in die studiegebied versamel is. Daar is ook aparte lyste opgestel vir alle Lepidoptera en Orthoptera, in die studiegebied. Verskillende metodes was gebruik om insekte te versamel en te monitor. Die interaksies tussen plante en diere, wat voorkom in die studie gebied, is ook bestudeer Twee plantsoorte, Acacia karroo en Searsia glauca, is uitgesonder en so veel moontlik biologiese interaksies is opgeteken. Ander interaksies was ook aangeteken soos hulle in die veld aangetref is. Die studiegebied het meer as 400 plant spesiesbevat. Van die was meer as dertig van bewaringsbelang. Sewe-en-dertig persent van die plante wat aangeteken is, is endemies tot die Kaapse Plant Koningryk. Daar is altesaam 127 bolplant spesies gevind wat net meer as die helfte van alle bolplant species wat vir die Langeberg Kern aangeteken is. Haworthia groenewaldii is ʼn nuwe plant spesies wat in die studie gebied ontdek is. In die studie area is 214 insek families in 23 insek ordes opgeteken. Van die is 103 Lepidoptera species (waarvan vyf moontlike nuwe spesies is) aangeteken in die studiegebied. Negentien insek spesies van 14 insek families in vier ordes het interaksies met A. karroo getoon. Interaksies tussen vier-en-dertig insek spesies van 25 insek families in sesordes het met S. glauca getoon Een-en-sestig voël spesies was geassosieerd met A. karroo en 42 met S. glauca. Ander interaksies watgewaar is, sluit ruspes op voedselplante in. Twaalf verskillende paddas, 22 soorte reptiele, 30 soorte soögdiere en 122 soorte voëls was ook in die studie gebied aangeteken. Uit die huidige studie is dit duidelik dat die gebied ʼn baie hoë biodiversiteit besit wat beskerm moet word. Daar is ook bevind dat weiding die samestelling en struktuur van RSR kan beïnvloed. Verdere studies oor die plant/dier interaksies in RSR behoort gedoen te word en hopelik dien die huidige studie as ʼnbegin vir verdere navorsing oor hoe ons die unieke veld soort vir die nageslag kan bewaar.

Thesis (DSc (Botany and Zoology))—-Stellenbosch University, 2008. / The south-western Cape is a unique region of southern Africa with regards to generally low soil nutrient status, winter rainfall and unusually species-rich temperate vegetation. This region supported a diverse large herbivore (> 20 kg) assemblage at the time of permanent European settlement (1652). The lowlands to the west and east of the Kogelberg supported populations of African elephant, black rhino, hippopotamus, eland, Cape mountain and plain zebra, ostrich, red hartebeest, and grey rhebuck. The eastern lowlands also supported three additional ruminant grazer species - the African buffalo, bontebok, and blue antelope. The fate of these herbivores changed rapidly after European settlement. Today the few remaining species are restricted to a few reserves scattered across the lowlands. This is, however, changing with a rapid growth in the wildlife industry that is accompanied by the reintroduction of wild animals into endangered and fragmented lowland areas. These reintroductions, together with the realisation that we have limited knowledge of the functional role of native large herbivores in the fynbos ecosystem, provided the rationale for this study. Questions on large herbivore ecology were addressed at three different spatial scales. At the biome level, the reason for the absence of three ruminant grazers from the western lowlands was investigated. It was hypothesised that the absence of adequate high quality fodder in the form of C4-grass during the hot and dry summers made it impossible for buffalo, blue antelope, and bontebok to survive on the western lowlands. The results from carbon isotope analysis of late prehistoric, historic and contemporary large herbivore remains were consistent to this Summer Nutritional Stress Hypothesis. I found that eland, elephant, grey rhebuck, ostrich, and red hartebeest (all species that historically occurred in both coastal lowlands) can survive with very little (< 15%) C4 grass in their diet. In contrast, bontebok utilized at least 43% C4 grass biomass in what was considered their natural habitats. At a regional level, I tested the hypothesis that the large herbivores avoid nutrient-poor sandstone, sand, and limestone fynbos shrublands in favour of the more nutrient-rich shale renosterveld habitats. Support for this Renosterveld Preference Hypothesis was found by means of dung count surveys, which showed that both eland and bontebok readily utilize renosterveld, but avoid sandstone and limestone fynbos. In the latter they only utilize grassy microhabitats such as karstic sinkhole depressions. The same hypothesis was addressed in a novel way by using strontium isotope analysis and concluded that the technique needs more refinement for it to produce reliable results. At a landscape level, interactions between fire and grazing by native large herbivores in relation to renosterveld vegetation dynamics were addressed. I conclude that the disappearance of the native herbivores probably had little bearing on the putative structural changes in renosterveld (grassland-shrubland dynamics). Support was found for the notion that a high fire frequency followed by intense grazing by livestock could have converted original renosterveld grasslands to unpalatable shrublands. Herbivory by native grazers/browsers, or the release from it, cannot by itself bring about the vegetation-state (structural) changes in renosterveld patches which had already been altered to herbivoretolerant plant communities. However, in combination with fire, the presence or absence of large herbivores can change the trajectory of the system among the alternative structural states.

Biodiversity is declining faster than at any other time in the Earth's history, driven mostly by land use change and degradation. Overberg Renosterveld, some of the most species diverse mediterranean type shrublands, are no exception with about 95% of their original extent lost to agriculture. Historically, large herds of indigenous grazing mammals roamed these landscapes. Today the Overberg's agricultural lands are fragmented by land cover change and divided by fences. In the contemporary landscape animals, largely domestic livestock, and plant resources are closely coupled, and overgrazing of remaining renosterveld fragments a significant threat, with potential to cause irreversible damage. The Conservation of Agricultural Resources Act (CARA) (Act 43 of 1983) states that farmers must not exceed the grazing capacity of the veld unless it is protected against deterioration and destruction, and that any land that is degraded or denuded must be effectively restored or reclaimed. Despite this legislation, there is little empirical research on the impacts of livestock grazing on renosterveld, as well as on restoration of overgrazed areas. It was the aim of this thesis to contribute to this gap in understanding. The thesis assessed the role of grazing by different livestock types, namely cattle and sheep, on biodiversity, the soil seed bank, and the restoration potential of renosterveld vegetation from resting the veld. The effect of livestock grazing by sheep and cattle on plant species richness and diversity and growth form diversity was assessed using Modified Whittaker plots and presented in Chapter 3. It was hypothesised that livestock grazing by cattle would have less effect on species richness and diversity and growth form diversity than sheep grazing and that both cattle and sheep grazing would lead to a reduction in species richness and diversity in comparison to renosterveld sites with a treatment of no grazing. Thirty sites where either no grazing has taken place or that have been grazed by cattle or sheep were selected with sites being evenly distributed between Eastern, Central and Western Rûens Shale Renosterveld. At each of the thirty sites, vegetation data were collected from a series of nested subplots of ten 1 m2 , two 10 m2 and one 100 m2 subplots nested within a 1 000 m2 plot. One soil sample was also collected from each 1 000 m2 plot to a depth of 10 cm for nutrient analysis. Findings revealed that sites grazed by sheep had significantly lower plant species richness (median richness = 29 species, mean Shannon-Weiner = 3.39) and diversity when compared to sites with a treatment of no grazing (median richness = 49 species, mean Shannon Weiner = 3.83). Sites with a treatment of no grazing had significantly higher richness of geophyte species (mean = 14.7) than sites grazed by cattle (mean = 7.0) and sheep (mean = 7.1) during the study. The results obtained were in line with the hypothesis that livestock grazing by sheep resulted in a reduction in species richness and diversity and vegetation cover in Overberg Renosterveld in comparison to sites where no grazing has taken place. Sites with a treatment of no grazing showed higher species richness and vegetation cover of non-succulent shrubs, annual forbs and perennial forbs than sites grazed by sheep. It was concluded that livestock grazing of Overberg Renosterveld by sheep needs to be done with care. This can be done by adopting a passive adaptive management approach. Here one set of management protocols can be developed and implemented and through science-based monitoring to inform management, these can be adapted as needed based on the key findings. Chapter 4 investigated ecosystem resilience and the restoration potential of Overberg Renosterveld through an exploration of its soil seed bank as a source for potential recovery. A glasshouse germination experiment investigated the effect of livestock grazing by cattle and by sheep in comparison with a grazing treatment of no grazing on the soil seed bank in Overberg Renosterveld, as well as the similarity between the standing vegetation and the soil seed bank. It was hypothesised that cattle and sheep grazing would reduce species richness, species diversity and growth form diversity in the soil seed bank in comparison with sites with a treatment of no grazing. Soil samples were collected from 30 sites that were also used in Chapter 3. The soil was then spread on top of a 6 cm layer of compost in seed trays, and smoke treated to enhance germination. Seedlings were assigned to growth form categories including forbs, geophytes, annuals, graminoids, succulent shrubs and nonsucculent shrubs and then identified to family, genus or species level. The results of the soil seed bank study were correlated with the vegetation results from Chapter 3 to examine the relationship between the standing vegetation and the soil seed bank. A total of 48% of taxa in the standing vegetation had seed present in the germinable seed bank. However, there were no differences in species richness, species diversity or number of individuals between grazing treatments. The results indicated that livestock grazing has a far less significant impact on the composition, species diversity and growth form diversity of the soil seed bank in Overberg Renosterveld than hypothesised. Instead, the results showed that there was a well-developed seed bank comprising mainly indigenous species with a variety of different growth forms including palatable grasses and shrubs. This indicates that Overberg Renosterveld vegetation has high restoration potential. Chapter 5 showed results on the effects of livestock grazing by cattle and sheep over time on plant species richness, diversity and growth form diversity in comparison with sites protected from grazing. Following collection of a baseline dataset, four years of follow up data were collected. A total of 22 fenced plots across Western, Central and Eastern Rûens Shale Renosterveld had a baseline dataset collected prior to being monitored on an annual basis over four years in grazed/ungrazed paired plots. Results on vegetation recovery from the fenced exclosures showed a significant increase in plant cover over time at sites that were not grazed. Mean species richness increased from 20.6 species to 25.4 species at sites with no grazing. Mean vegetation cover increased from 71% at T0 (the baseline time step) to 120% at T4 (the final time step) at the end of the study. Sites grazed by sheep had a decrease in vegetation cover over time each year from T0 to T4 from 75% to 50%. Results from a linear mixed model revealed that species richness between grazing treatments was significantly different at all time steps in the study. However, the significant differences were primarily due to comparisons between grazed sites and sites with a treatment of no grazing. Therefore, livestock grazing by sheep has a significant effect on renosterveld vegetation over time. Findings from this component of the study indicates that Overberg Renosterveld degraded by continuous heavy grazing has significant passive restoration potential by fencing renosterveld patches to facilitate more effective grazing management. Most of the renosterveld of the Overberg has been lost through habitat transformation for agriculture, and the future of that which remains is uncertain. This thesis affirms concerns around the impact of livestock grazing and shows the importance of improved ecological understanding around grazing management. Grazing by sheep was shown to cause greater impacts on renosterveld than other domestic livestock studied and is therefore a threat to renosterveld. These findings warrant closer attention to management practices around sheep grazing. However, the state of renosterveld soil seed banks offer considerable hope. Findings revealed a diverse indigenous seed bank, showing that renosterveld degraded by overgrazing has high restoration potential. Furthermore, fencing renosterveld to exclude livestock improves species richness and diversity over time. These findings highlight the need for caution when grazing renosterveld. However, where the damage has been done, the potential for recovery is high. Harnessing the soil seed bank in combination with excluding livestock grazing by fencing are effective tools in this critically endangered vegetation for achieving restoration and conservation goals.

Thesis (MSc (Conservation Ecology and Entomology))--Stellenbosch University, 2009. / ENGLISH ABSTRACT: An understanding of the interactions of herbivores, plant nutrients and soil properties is crucial for grazing management. Of particular interest are plant palatability and herbivore grazing preferences. These aspects, the focus of this thesis, were studied in a Swartland Shale Renosterveld and Swartland Alluvium Fynbos mosaic in the Western Cape of South Africa. This vegetation is classified as critically endangered due to the transformation of its landscape in favour of agricultural production and urban settlement. Pre-colonial herbivore vertebrates were hunted out by 1700, leading to a sparse knowledge of the early dynamics of the vegetation. However, currently game farmers and landowners are re-introducing selected species into the area. Thus, managers require knowledge on how to implement practical guidelines for best-practice grazing management. This study investigates, firstly, the relationship between plants and animals. This included seasonal assessment of seed germination from dung of bontebok and eland; the effect of stocking rates on plant palatability (crude protein, crude fibre, crude fat, moisture, tannin and mineral) of herbage was studied with the aim to understand how palatability influences herbivore forage decisions. Secondly, this study looked at how stocking rates influence soil nutrients (nitrogen, phosphorus), and others soil properties such as pH and soil moisture. The distribution of alien grasses was facilitated by grazers. About 58 % of grasses germinated from the dung of eland and Bontebok were alien species. Additionally, there was significant variation in palatability related to grazing pressure and plant maturity between sites and over seasons. Grasses on the high grazing site had higher carbohydrate (3%-5% higher) and protein content (1%-5% higher) than at the least grazed site. Mature grasses contained less water (10%-20%), but no obvious variation in tannin concentration than immature grasses. However, species such as Ficinia sp. showed variations with grazing pressure and maturity. Ficinia sp. on the high grazing site had higher tannin concentration (5mg/ml-22mg/ml) and crude protein (4%-9%) than at the least grazed site. When the plant ages, tannin concentration increase (ranging from 15% to19% higher). Two types of plant were recoreded according to their chemical response following grazing pressure. These types are 1) plants that are grazing tolerant and which produce more carbohydrate when grazed and 2) plants that are grazing intolerant under high grazing pressure and which produce chemical defence compounds such as tannin to deter herbivores attacks. The results indicate that in fynbos and renosterveld, the relationship between preference and plant chemical compounds is not consistent since no IV patterns emerged to explain what compounds drive preference. A combination of chemical compounds may be the reason for the selection by the grazers; alternatively, other compounds not included in the study may influence the forage selection by an herbivore. The second part of the study showed that stocking rates appeared to have a significant effect on soil properties investigated. Soil moisture was significantly affected by the stocking rate in autumn. The high grazing intensity site had the lowest soil moisture especially in autumn (10% lower than the control site), likely due to heavy trampling and soil compaction. pH was the lowest at the high grazing intensity site in all seasons compared to the control site. Likely reasons were the high deposition of nitrogen through dung and urine deposition, high removal of basic cations and animal exportation through hunting activities. Lastly, grazing maintains inorganic nitrogen at stable levels regardless of seasonal changes and increases the concentration of phosphorus especially under high grazing pressure compare to less grazed sites. The grazing dynamics of Swartland Shale Renosterveld - Swartland Alluvium Fynbos mosaic system are complex and multifaceted. Farmers need to pay attention to the nutritional status of plant species grazed to know whether they meet the nutritional requirements of the game in the area. Overstocking should be avoided in this system as it triggers the production of tanniferous compounds that could decrease the survivorship of herbivores. Moderate grazing 0.09 LAU/ha pressure provides the best stocking rates for effective grazing management. / AFRIKAANSE OPSOMMING: Vir suksesvolle weidingsbestuur is dit noodsaaklik om die interaksie tussen herbivore, plantvoedingstowwe en grondeienskappe te verstaan. Van besondere belang is plantsmaaklikheid en herbivore se weidingsvoorkeure. Hierdie aspekte, wat die fokus van hierdie tesis is, is bestudeer in ‘n Swartland Shale Renosterveld en Swartland Alluvium Fynbos-mosaïek in die Wes-Kaap Provinsie van Suid-Afrika. Hierdie plantegroei word as kritiek bedreigd geklassifiseer weens die transformering van sy landskap ten gunste van landbou-aktiwiteite en stedelike vestiging. Pre-koloniale herbivoor vertebrata is teen 1700 deur jagters uitgeroei, wat gelei het tot min kennis oor die vroeë dinamiek van die plantegroei. Wildsboere en grondeienaars is egter besig om geselekteerde spesies in die area te hervestig. Bestuurders moet dus weet hoe om praktiese riglyne vir beste-praktyk weidingsbestuur te implementeer. Hierdie studie ondersoek eerstens die verhouding tussen plante en diere. Dit sluit seisoenale evaluering van saadontkieming uit die mis van bontebokke en elande in; die effek van veegetalle op plantsmaaklikheid (ruproteïen, ruvesel, ru-vet, vogpeil, tannien en minerale) van die weiveld is bestudeer om vas te stel hoe plantsmaaklikheid herbivore se weidingsbesluite beïnvloed. Tweedens het die studie die invloed van veegetalle op grondvoedingstowwe (stikstof, fosfor) ondersoek, asook ander grondeienskappe soos pH en grondvogpeile. Die verspreiding van uitheemse grasse is deur weidende diere gefassiliteer. Ongeveer 58% van alle grasse wat uit die mis van elande en bontebokke ontkiem het, was uitheemse spesies. Verder was daar beduidende variasie in plantsmaaklikheid verwant aan beweidingsdruk en plantvolwassenheid tussen verskillende persele en oor seisoene. Grasse op die hoogs beweide persele het 3%-5% hoër koolhidraatinhoude en 1%-5% hoër proteïeninhoude gehad as die minder beweide persele. Volwasse grasse het 10%-20% minder water bevat as onvolwasse grasse, maar het nie in terme van tannienkonsentrasie van die onvolwasse grasse verskil nie. Spesies soos Ficinia sp. het variasies getoon met beweidingsdruk en volwassenheid. Ficinia sp. het op die hoog-beweide perseel ‘n hoër tannienkonsentrasie (5mg/ml-22mg/ml) en meer ruproteïen (4%-9%) gehad as op die minste beweide perseel. Wanneer die plant verouder, verhoog die toename in tannienkonsentrasie (met tussen 15% en 19%). Twee tipes plante is aangeteken volgens hul chemiese response ná beweidingsdruk. Hierdie tipes is 1) plante wat beweidingstolerant is en wat meer koolhidrate produseer wanneer hulle as weiding dien en 2) plante wat onder hoë beweidingsdruk beweidingsintolerant is en wat chemiese verbindings VI soos tannien produseer om herbivooraanvalle af te weer. Die resultate dui aan dat die verhouding tussen voorkeur en plante se chemiese verbindings nie konstant bly in fynbos en renosterveld nie, aangesien geen patrone na vore getree het wat kon verklaar watter verbindings bepalend is vir voorkeur nie. ‘n Kombinasie van chemiese verbindings mag die rede wees waarom die herbivore sekere plante verkies; alternatiewelik mag ‘n herbivoor se plantseleksie beïnvloed word deur chemiese verbindings anders as dié wat in hierdie studie ondersoek is. Die tweede deel van die studie het aangetoon dat veegetalle blyk ‘n beduidende invloed te hê op die grondeienskappe wat ondersoek is. Grondvogpeile is in die herfs beduidend beïnvloed deur die veegetalle. Die perseel met die hoë beweidingsintensiteit het die laagste grondvogpeil gehad, veral in die winter (10% laer as dié van die kontrole-perseel), waarskynlik weens erge getrappel en grondkompaktering. Vergeleke met die kontrole-perseel was pH die laagste op die perseel met die hoë beweidingsintensiteit, in alle seisoene. Waarskynlike redes hiervoor is die hoë neeerslag van stikstof deur mis- en uriene-neerslae, hoë verwydering van basiese katione en dierevervoer wat deur jagaktiwiteite teweeg gebring word. Laatstens behou weiding anorganiese stikstof teen stabiele vlakke ongeag van seisoenale veranderinge en toenames in die konsentrasie van fosfor, veral onder hoë beweidingsdruk vergeleke met minder beweide persele. Die weidingsdinamiek van die Swartland Shale Renosterveld - Swartland Alluvium Fynbosmosaïeksisteem is kompleks en veelvlakkig. Boere behoort aandag te skenk aan die voedingstofstatus van die plantspesies wat as weiding dien, sodat hulle kan weet of die voedingsbehoeftes van die wild in die omgewing bevredig word. Die aanhou van te veel vee in hierdie sisteem behoort vermy te word aangesien dit as sneller dien vir die produksie van tannienbevattende verbindings wat die oorlewingsvermoë van herbivore kan verlaag. Matige beweidingsdruk (0.09 LAU/ha) bied vir effektiewe weidingsbestuur die beste veegetalle.

<p>This&nbsp / thesis&nbsp / examines&nbsp / the&nbsp / changes&nbsp / that&nbsp / have&nbsp / occurred&nbsp / within&nbsp / West-Coast Renosterveld within&nbsp / the&nbsp / last 350 years, and assesses&nbsp / the viability of&nbsp / the&nbsp / remaining fragments.</p>

<p>This&nbsp / thesis&nbsp / examines&nbsp / the&nbsp / changes&nbsp / that&nbsp / have&nbsp / occurred&nbsp / within&nbsp / West-Coast Renosterveld within&nbsp / the&nbsp / last 350 years, and assesses&nbsp / the viability of&nbsp / the&nbsp / remaining fragments.</p>

Philosophiae Doctor - PhD / South Africa

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: This study investigated the composition of Themeda triandra Renosterveld in part of the Grootvadersbosch Conservancy and the effects of selected environmental and management variables to provide guidelines for promoting the presence of Themeda triandra in the veld. The Zürich-Montpellier phytosociological method was used to determine the composition of the Renosterveld communities. The point quadrat method was used to determine the cover of Themeda triandra at three grass dominated sites and compare cover from one site with past cover measurements at the specific site. Ordination was used to examine the effects of the environmental and management variables on the plant communities. Two community groups, five communities and five subcommunities were identified and described. The Themeda triandra – Stoebe phyllostachys Grassland Community Group consists of two communities of which one has two subcommunities. The Themeda triandra – Elytropappus rhinocerotis Shrubland Community Group consists of three communities of which one has three subcommunities. The vegetation units described in this study have not been described previously in the literature. One community belongs to Silcrete Fynbos while another subcommunity is transitional between Renosterveld and thicket and gallery forest. The rest of the plant communities fit the definition for Renosterveld (the local Renosterveld type is Eastern Rûens Shale Renosterveld). Cover of Themeda triandra did not differ significantly either between sites or between years. The comparison of Themeda triandra cover between years was done at a site that had been burnt between the last two sampling times yet the cover was not significantly different. This indicates that fire and other management practices did not have a negative impact on Themeda triandra at the site. Unconstrained ordination of the dataset in which cover/abundance values were included, grouped the relevés by moisture and disturbance but the presence/absence dataset indicates that the two community groups have a slight transitional overlap. Constrained ordination of both datasets with a) soil variables and b) management variables, both showed a tendency to separate the relevés into community groups, that did not happen with topographic and vegetation variables. Ordination did not separate the community groups into their subdivisions. The soil variables (both nutrients and texture) influence the vegetation structure and the community distribution. Under the existing grazing management regime, fire at three to five year intervals promoted the dominance of Themeda triandra by affecting the structure of the plant communities, the abundance of species other than Themeda triandra, and influencing which plant community is present. The use of fire as a management tool was regulated by the importance of the natural veld pastures to the farmers. The natural veld pastures are not suitable for dairy cattle in milk. Thus dairy farmers are less likely to burn the natural veld (no planned burns only chance fires) than those who farm with mutton or beef (planned burns on a three to five year interval). / AFRIKAANSE OPSOMMING: Die studie het die samestelling van Themeda triandra Renosterveld in ’n deel van die Grootvadersbosch-Bewaria en die uitwerking van geselekteerde omgewings- en bestuursveranderlikes ondersoek om riglyne vir die bevordering van Themeda triandra in die veld daar te stel. Die Zürich-Montpellier fitososiologiese metode is gebruik om die samestelling van die Renosterveldgemeenskappe te bepaal. Die puntkwadraat-metode is gebruik om ’n skatting van die dekking van Themeda triandra by drie gras-gedomineerde persele te bepaal en om ’n vergelyking te maak tussen die huidige en vorige dekking van ’n enkele perseel. Ordinasie is gebruik om die invloed van omgewings- en bestuursveranderlikes op die plantgemeenskappe te bepaal. Twee gemeenskapsgroepe, vyf gemeenskappe en vyf subgemeenskappe is geïdentifiseer en gedefinieer. Die Themeda triandra – Stoebe phyllostachys Grasland-gemeenskapsgroep bestaan uit twee gemeenskappe waarvan een in twee subgemeenskappe onderverdeel is. Die Themeda triandra – Elytropappus rhinocerotis Struik-gemeenskapsgroep bestaan uit drie gemeenskappe waarvan een in drie subgemeenskappe onderverdeel is. Die plantegroei-eenhede wat in die studie beskryf is, is nie voorheen in die literatuur beskryf nie. Een gemeenskap behoort aan Silkreet-fynbos en ’n ander subgemeenskap is ’n oorgangsfase tussen Renosterveld en struikbosveld of woud, terwyl die res van die plantgemeenskappe binne die definisie van Renosterveld val (die plaaslike Renosterveld tipe staan bekend as Oostelike Rûens Skalierenosterveld). Die bedekking van Themeda triandra het nie betekenisvol gevarieer tussen óf die verskillende lokaliteite óf die verskillende jare nie. Die vergelyking van Themeda triandra-bedekking oor tyd is onderneem in ’n gebied wat tussen opnames gebrand is. Die bedekking het nie betekenisvol verskil nie. Dit dui aan dat vuur en ander bestuurspraktyke nie ’n negatiewe invloed op Themeda triandra in hierdie gebied het nie. Onbeperkte ordinasie van die datastel met die vergelyking van bedekking/volopheidwaardes, groepeer die relevés volgens vogtigheid en versteuring, terwyl die datastel ten opsigte van teenwoordigheid/ afwesigheid aandui dat die twee gemeenskapsgroepe ’n effense oorgangs-oorvleueling het. Beperkte ordinasie van beide datastelle met a) grondveranderlikes en b) bestuursveranderlikes, toon albei ’n neiging om die gemeenskapsgroepe te skei, wat nie gebeur het met die topografiese- en plantegroeiveranderlikes nie. Ordinasie het nie die gemeenskapsgroepe onderverdeel in gemeenskappe of subgemeenskappe nie. Die grondveranderlikes (beide voedingstowwe en tekstuur) beïnvloed die struktuur en die verspreiding van die plantegroei. Met die bestaande weidingsbestuur bevorder brande met ’n interval van tussen drie tot vyf jaar die oorheersing van Themeda triandra deur die struktuur van die teenwoordige plantgemeenskap te beïnvloed, deur die getal van die verskillende plantsoorte te beïnvloed en selfs deur die plantgemeenskap se voorkoms te beïnvloed. Die waarde wat die boer aan die natuurlike veld as weiveld heg bepaal die mate waartoe hulle veldbrand gebruik as ’n deel van bestuur. Die natuurlike veld is nie geskik vir melkkoeie wat in die melkproduksiestadium is nie. Die melkboere is dus minder geneig om die natuurlike veld te brand (geen beplande brande nie net kans brande) as die boere wat met vleisbeeste of skape boer (beplande brande elke drie tot vyf jaar).

Dissertation presented for the degree of Doctor of Philosophy (PhD) at Stellenbosch University. / Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The South African Cape lowlands have been severely transformed and reduced to fragments embedded in matrices of various activities. With the need to prioritise conservation efforts, information on the conservation worthiness and management of these fragments is required. This study aimed to better understand how fragmentation affects the Cape lowland vegetation patterns and dynamics and more specifically, to determine if, and if so to what extent these fragments contribute to regional plant diversity and more importantly their functionality. The novel approach adopted focused on plant functional traits, which are better predictors of ecosystem response to global change than individual species. Species were sampled at four scales in four sites of decreasing sizes, including: a mainland and three fragments of three Cape lowland vegetation types i.e. Atlantis Sand Fynbos (ASF), Swartland Shale Renosterveld (SSR) and Langebaan Dune Strandveld (LDS). Traits such as dispersal, pollination, breeding mode and longevity were selected based on relevance to species’ and plantfunctional types’ (PFTs) responses to fragmentation. The findings revealed different effects on species richness and PFTs. The effect of reduced patch size on species richness was more evident in ASF where fragments below 600 ha had significantly fewer species than the mainland. This effect was not unequivocal in SSR and LDS due to several confounding factors (notably the grazing history of the sites). The SSR fragment grazed by indigenous herbivores had significantly more species than the ungrazed sites. Also, the largest LDS fragment grazed by livestock had significantly more species than the ungrazed mainland, indicating that grazing rather than fragment size influences species richness, although the smallest fragments of these two vegetation types had significantly fewer species than the larger fragments. Species turnover and complementarity were high for all three vegetation types, reflecting the degree of habitat heterogeneity and high contribution of beta diversity to overall gama diversity. The effect of reduced patch size was higher on PFT diversity than on PFT richness, with Langebaan Dune Strandveld where habitat fragmentation was more recent being the least affected of the three vegetation types. This indicates a degree of functional redundancy in the Cape lowlands, which is important for ecosystem resistance and resilience. The ASF mainland and the largest fragment had higher PFT diversity than the medium-sized and the smallest fragments; the mainland had also higher PFT diversity than all the fragments combined. Similarly, the smallest SSR fragment had significantly lower PFT diversity and richness than the other sites. The grazed SSR fragment had higher PFT richness and diversity than the ungrazed mainland and smallest fragment, indicating the role of grazing in maintaining renosterveld vegetation. The PFTs absent from the different sites were mostly short-distance dispersed dioecious and non-dioecious species, and some with highly specialised pollination systems. This suggests that dispersal and pollination are vital functional attributes for the persistence of the studied fragmented ecosystems. Habitat fragmentation effects plant community composition and ecological functions in the Cape lowlands, a conclusion supported also by the revealed significant trait-convergence and divergence assembly patterns. These communities result from various fragmentation filters that operate at different spatial-temporal scales and selecting species with suitable responses. All three vegetation types are susceptible to fragmentation, albeit at varying degree. The fragmentation effect was confounded by the sampling and temporal scales, the nature of disturbance regime, and the traitmediated differences in species’ response. The role of the surrounding matrix on fragment connectivity and gene flow appears to be of crucial importance, hence mitigation measures focusing on improving connectivity between patches, monitoring threatened taxa, and promoting dispersal and pollination have been recommended. / AFRIKAANSE OPSOMMING: Suid-Afrika se Kaapse laagland het dramaties verander en weggekwyn tot fragmente wat in matrikse van verskeie bedrywighede veranker is. Gedagtig aan die voorkeuraandag wat bewaringspogings tans geniet, is inligting oor die bewaringswaardigheid en bestuur van hierdie fragmente nodig. Hierdie studie stel dit ten doel om beter begrip te vorm van hoe fragmentasie die plantegroeipatrone en -dinamiek in die Kaapse laagland raak, en meer bepaald om vas te stel óf, en indien wel, in watter mate, hierdie fragmente tot streeksplantdiversiteit en -funksionaliteit bydra. Die ongewone studiebenadering konsentreer op funksionele kenmerke van plante, wat beter aanwyser van ekosisteemreaksie op wêreldwye verandering is as individuele spesies. Spesiemonsters is op vier skale by vier terreine van wisselende grootte ingesamel, wat insluit moederstrook en drie fragmente van elk van drie plantegroeisoorte in die Kaapse laagland, naamlik Atlantis-sandfynbos (ASF), Swartland-skalierenosterveld (SSR) en Langebaan-duinestrandveld (LDS). Kenmerke soos verspreiding, bestuiwing, voortplantingsmetode en lewensduur is gekies op grond van die tersaaklikheid daarvan vir spesies en plantfunksionele tipes (PFT’s) se reaksie op fragmentasie. Die studie bring verskillende uitwerkings op spesie-oorvloed en PFT’s aan die lig. Wat spesie-oorvloed betref, was die uitwerking van kleiner strookgrootte (“patch size”)duideliker te sien by ASF, waar fragmente kleiner as 600 ha beduidend minder spesies as die moederstrook bevat het. Hierdie uitwerking kon nie so duidelik by SSR en LDS waargeneem word nie weens verskeie strengelingsfaktore, veral die weidingsgeskiedenis van die terreine. Die SSR-fragment waarop inheemse herbivore gewei het, het beduidend meer spesies as die onbeweide terreine bevat. Voorts het die grootste LDS-fragment waarop vee gewei het heelwat meer spesies as die onbeweide moederstrook gehad, wat daarop dui dat weiding eerder as fragmentgrootte spesie-oorvloed beïnvloed, hoewel die kleinste fragmente van hierdie twee plantsoorte steeds aansienlik minder spesies as die groter fragmente bevat het. Spesie-omset en -aanvullendheid was hoog vir ál drie plantsoorte, wat aanwyser is van die mate van habitat-heterogeniteit en die groot bydrae wat betadiversiteit tot algehele gammadiversiteit lewer. Die uitwerking van kleiner strookgrootte was duideliker te bespeur op PFT-diversiteit as PFT-oorvloed – in dié verband het LDS, waar habitatfragmentasie mees onlangs plaasgevind het, die ligste van die drie plantsoorte afgekom. Dít dui op mate van funksionele oorbodigheid in die Kaapse laagland wat belangrik is vir ekosisteemweerstandigheid en -gehardheid. Die ASF-moederstrook en die grootste ASF-fragment het hoër PFT-diversiteit getoon as die medium- en kleinste fragmente; die moederstrook het in werklikheid oor hoër PFT-diversiteit as ál die fragmente saam beskik. Insgelyks het die kleinste SSR-fragment beduidend minder PFT-diversiteit en -oorvloed as die ander terreine getoon. Die beweide SSR-fragment was hoër in PFT-oorvloed én -diversiteit as die onbeweide moederstrook en die kleinste fragment, wat die rol van weiding in die instandhouding van renosterveldplantegroei beklemtoon. Die PFT’s wat nié op die verskillende terreine voorgekom het nie, was meestal tweehuisige en nietweehuisige spesies wat oor kort afstande versprei, en sommige spesies met hoogs gespesialiseerde bestuiwingstelsels. Dít dui daarop dat verspreiding en bestuiwing noodsaaklike funksionele kenmerke vir die voortbestaan van die bestudeerde gefragmenteerde ekosisteme is. Habitatfragmentasie raak die samestelling en ekologiese funksies van plantgemeenskappe in die Kaapse laagland. Dié gevolgtrekking word ook gerugsteun deur die bewese patrone van beduidende kenmerkkonvergensie (“trait convergence”) en divergensiesamekoms (“divergence assembly”). Hierdie plantgemeenskappe spruit uit verskeie fragmentasiefilters wat op verskillende ruimte-tydskale funksioneer, en wat spesies met geskikte reaksies kies. Ál drie plantsoorte is ontvanklik vir fragmentasie, hoewel in wisselende mate. Die fragmentasie-uitwerking is beïnvloed deur monsterinsameling- en tydskale, die soort versteuringsbedeling, en die kenmerkbemiddelde (“traitmediated”) verskille in spesiereaksie. Die rol van die omringende matriks op fragmentverbondenheid en geenvloei blyk van die allergrootste belang te wees, en dus word temperingsmaatreëls aanbeveel wat daarop gemik is om verbondenheid tussen stroke te verbeter, bedreigde taksa te moniteer, en verspreiding en bestuiwing aan te help.