A dissertation submitted to the Facult:y of Science, University of the Witwatersrand, Johannesburg, for the degree of Master of Science, Johannesburg 1994 / Rhizosheaths are sandy coatings covering ~ ~ entire length of the roots of many grass species~ .: They consLab of a mass of sand and silica particles en4?eddedin a mucilaginous layer and are matted togethel.· by a meahwozk of prolific epidermal had.ns, A study of the phenomenon of zhd aosheat.ha in South African grasses was undertaken. Aspects which were invest.igated include the occurrence of rhizosheaths amongSouth African grasses and the influence of environmental ccndftions on th.e presenc~ and , extent of rhizosheath development. In addition, information was ~fsll!led on their possible functions in terms of their contribution (s ) to plant vigour, through their influence on (1 nutrient and water uptake, particularly in low nutrient soil~ in '~\ ;'';-''>"\\ arid areas. An extensive surv,sy of herbal:"iul!lspecimens was conducted at the .. National Herbarium in Pretoria. It Wasfound that the presence" of rhizosheaths is a genetically fixed trait, occurring in the majority of gra~s species in south Africa. The extent to which sheaths develop (the thickness of the sheat.h and the degree 'to which the soil particles are bound to the sheath), varies between, and sometimes wi thin;) species. ~< Ii' Seeds of three sheath forming grass spccf.es which occur in South Africa, Anthephora pubescens Nees, Digitaria exientib« Steud and Eragrostis pallens Hade, were gr.ownundez different condi.t.Lona of soil texture and different conditions of water and nutrient (nitrogen (N') and phosphorus: (P) aVailability. Sheath development was found to be more extensive the higher the sand (relative/.: to clay) content in the soil. In addition, rhizoFlheaths developed to a greater extent in sandy soil with high watsr and nutrient availabilityu Therefore, the extent to whi;chsheaths develop is a facultative response directly to sandy soil, rather than toe resulting lower water and nutrient availability in this snil. A:fter \: Jtudying a number of physiological and morphological factors of the indiv~dua.ls in the different water and uutrient treatments it appeared that rhizosheaths compensate",dfor low water availability. In additionq sheaths appeared to «compensate -. I.' for low N availability when this 101;1T availability was a result of low soil water contentc The influence of sheath thickness on immobile nutrient ion uptake was investigated.. 'l'his was achieved by stimulating withinspeoies variation in sheath thiokness and mea.suring the difference in P uptake. The individuals with thick sheaths extracted more p from the. soil, and ~rom a greater volume of soil, than individuals with thin sheaths. This was particularly evident in conditi.ons of low P availabili,;ty i thereby highlighting , the important influence of thick rhizoshea,ths in soils with a low """" p status. The microbial biomass (as indicat;ed by t.he microbial Nand carbon concentrations) in the sheath soil was compared to that in the l?}y_k soil and the rliizosphe:r.e/out.er ,rhizosphere soil of r{ tinsheathed/sheathep, roots. Fromthi~ study it w~s concluded that rhj..zosheaths influence the"mic;:roorganisms in the soil ~djacent, \, to the root surface, since the l.hizosheath I')oil had a sigl,.ificantly higher microbial biomass than the soil .1:romthe other regions. " Fron\.the study it was concluded that the pzeaence of rhj.z6sheaths :maybe a mechanismemployed byce~tain grass species in order to enhance their ability to t.olera,te dry soil, which has J.owNand P availability. This mechanismmaybe a. sUbstitute for increased root production and root branching as well a~ increased mycorrhizal associations in plants in arid, low nutrient status soils~

It is widely believed that Acacia karroo Hayne trees compete with and negatively affect the production of grasses in their immediate surroundings. This perception formed as a result of observations by farmers of their veld as well as some research. The complexity of plant interactions in different conditions required that research be done to better explain the extent of grass and tree interactions. In response to this need, the effect of a range of Acacia karroo densities on grass production was tested in areas of differing rainfall. Results emphasize the complexity of such plant interactions but highlight rainfall as influencing the effect of tree density on grass production and grass quality. Study sites were chosen with significant differences in tree density and rainfall and this was found to be concomitant with significant differences in grass yield and crude protein (p < 0.001). Grass yield (mass produced) was negatively correlated with tree density (p < 0.001) and was affected by rainfall. High tree density reduced grass yield at the lower rainfall sites, but a reduction in yield was only recorded during dry conditions in the higher rainfall areas. By contrast, the crude protein content of grasses was positively correlated to tree density (p < 0.001). However, as with yield, rainfall played an important part in the strength of the correlation. Soil properties such as temperature (-) (p = 0.011), phosphorus content (+) (p = 0.006), calcium concentration (+) (p = 0.005), acid saturation (-) (p = 0.018), and soil pH (+) (p = 0.008) were also significantly correlated to tree density. Tree density enriched the soil, subsequently benefitting grass quality. The study sites investigated, had different plant communities and environmental conditions with Cradock, Kubusi Drift and Kei Mouth having unique communities and conditions while Adelaide and Cathcart could not be separated in either. Cradock was the driest site and the vegetation was dominated by both grasses and karroid shrubs, differing in pattern and process from the other sites. The Kubusi Drift site had high tree densities, to the extent that the trees altered the grass species composition. The effects of rainfall on grass yield and quality exceeded that of community composition differences.

This study was designed to provide the means for implementing formal scientific vegetation management 1n the succulent valley bushveld of the eastern Cape, South Africa. Nowhere in the world has a detailed, effective and practical veld management system being developed entirely from research, and even the most successful management systems rely heavily on the intuition of people. A process, formally called 'adaptive management', combines this intuition with scientific testing and the overall objective of this study was to provide a framework for formalized adaptive management in succulent valley bushveld. On analyzing the process of adaptive management, the following knowledge 'tools' were identified: (i) a management system for immediate implementation; (ii) a technique for vegetation assessment; (iii) a technique for monitoring vegetation change; (iv) a technique for monitoring forage use and recovery; (v) a list of key forage species; (vi) a model to set initial stocking rates; (vii) a method of recording essential information; and (viii) a database of ecological principles. Providing these 'tools' became the goals of this study. These topics covered almost all facets of rangeland science, and the approach was to address these in a 'top down' manner, rather than sub-optimize by specializing on anyone component. Most of the 'tools' were achieved to a greater or lesser extent and are presented as a series of publications. However, a central tool, that for monitoring vegetation change, remains outstanding despite comprehensive testing of a range of traditional botanical methods. Indeed, critical review revealed that this 'missing tool' is a problem which is common in all vegetation communities in South Africa - despite the impression created by vegetation researchers that adequate techniques are indeed available. This is serious because land managers are not able to evaluate the impact of their efforts and the government is unable to monitor the effectiveness of their research and extension services, costing millions of public monies annually. The implication also, is that vegetation cannot be managed scientifically (management implies monitoring). Either formal adaptive management is not practicable, or researchers are operating from an inappropriate paradigm; specifically that of providing techniques for their research projects and claiming that these (or derivatives of these) are adequate for farm or regional scale monitoring. More generally, research has often become an end in it's self, with research quality being judged by criteria which are of little significance to the real world and which damage efficiency. Perhaps, the real value of vegetation research lies in the experiential learning which the researcher gains not the inevitably parochial results. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science. / This work describes the coastal grasslands of Mkambati Game Reserve and their suitability for the present large herbivore complement. The initial description makes use of both field survey and quantitative sampling and multivariate analysis which facilitated the production of soil and vegetation maps at tre scale of 1: 10 000. Suitability of these grasslands for herbivores is assessed in terms of both quantity and quality of food available and the present herbivore impact. Local variation in soil type was considerable. Eight standard soil forms were distinguished as well as severaI others previously undescribed. Most of the soils were dystrophic although nutrient 'hot-spots' were common. This determined floristic composition of the various communities to some extent. Three grassland communities and four subcommunities were recognized which contributed 81, 5% to the total area of the reserve. The remaining area comprised forest. wetlands. exposed rock and accommodation camps. Each grassland community was associated with particular ranges of the measured environmental variables. The standing crop of the three communities was high relative to other areas of Southern Africa. Absolute amounts varied seasonally being highest in summer and lowest in winter Partitioning between the phytomass, necromass and litter components also varied seasonally. Total standing crop increased with increasing interval since the last fire. Litter breakdown rates differed between communities and species. Forage quality was poor being lowest in autumn and winter and declining with age. This was probably a result of the dystrophic soils. Crude protein and phosphorus were limiting for several months of the year. Total forage quantity was in excess of the present herbivore needs although availability declined with age and during the non-growing season. However, the poor quality reduced the amount available such that present herbivore impact was low, at all times being less than 9%.. Removal by herbivores was highest several months after a fire when absolute amounts of various nutrients were at a maxinum per unit area. Thereafter it declined to less than 1% with aging of the sward. The implications of the results for management are discussed and future research needs identified. / AC 2018

A detailed investigation into the harvesting of the standing grass crop within camps by cattle showed the following: 1. Cattle have a definite order of preference for the components of the Dohne Sourveld grass sward. The most palatable species in order of preference (based on Corrected Species Importance rating) are Themeda triandra, Tristachya hispida, Andropogon appendiculatus, Alloteropsis semialata and Heteropogon contortus. The least preferred species is Elionurus argenteus. 2. The key species, which is defined as the most abundant and productive palatable species, has been identified as Themeda triandra. 3. In harvesting the grass crop, cattle not only have a set preference for species, but also have a set grazing sequence pattern. This can be divided into three main phases. On entering the camp the animals first select the species of their choice, "creaming" these plants (grazed less than 50%) to obtain the most nutritious feed. In their daily search for food they spread their grazing over an increasingly wider area and over a wider range of species. When they can no longer obtain their daily requirements from this "creaming" operation of the more preferred species they return to the most preferred species , which are then heavily grazed (more than 50%) producing the common pattern of area grazing within a camp. These areas increase in size as the cattle graze down the species of their choice, moving to less preferred species as soon as they can no longer obtain their daily intake requirements from the more preferred species. Finally when they have no alternative they graze the least preferred species. 4. Increasing the stocking density does not alter the grazing sequence pattern or change the order of preference for the component species in the sward. It only increases the rate of utilization of the more preferred species and the various phases in the grazing sequence pattern are reached more rapidly. 5. At higher stocking densities the palatable species are more evenly utilized than at lower stocking densities. 6. Cattle graze a greater variety of species when the sward is young and actively growing. As the maturity of the sward increases the cattle concentrate on the more preferred species and are more selective in their grazing. However, their order of preference remains the same. Species that are highly preferred early in the season retain their ranking when the sward is mature. The only exception to this rule is Alloteropsis semialata. Early in the growing season this species is high on the preference list, but as it matures less is taken until when fully mature, it is rejected by cattle. 7. Elionurus argenteus is the least preferred of all the species in the Dohne Sourveld. Cattle will graze this plant as a last resort when grazing a camp early in the season, but reject the plant when it is fully mature. 8. To retain vigour and production of the Dohne Sourveld results of this investigation support the view that grazing management should be based on the principle of controlled selective grazing. Having shown that the more preferred species are over-utilized when attempting to utilize the least preferred species any grazing management that calls for total utilization of all standing vegetation should be rejected. 9. The results of this investigation supports a multicamp system for the Dohne Sourveld where high stocking densities are employed. This will result in the rapid and even utilization of the more preferred species. Management should be based on short period of stay and long period of absence. Cattle should be moved as soon as the key species have been well utilized, but not overgrazed. Cattle should only be returned to the camp when key species have made adequate regrowth following grazing. 10. A method, that is simple to use, is proposed for determining utilization of the veld and key species at different times of the year using the relationship between percentage of ungrazed plants and utilization of the sward and of Themeda triandra, the key grazing species in the sward. 11. Results show that when rested camps are grazed after May, the number of Themeda triandra inflorescences are drastically reduced. Veld that is specifically rested for the production of Themeda triandra seed should be rested from March of the year preceding expected seeding.

The dynamics and complexities of climate-soil-vegetation relations in the Kruger National Park are poorly known. Although primary production and composition of the grass layer are very important components of the Park's ecosystem, equally little is known about the determinants of these parameters. A better understanding of these processes and relations will be of value to the management of this Park, as well as providing a better insight into these complex dynamics. A study was consequently undertaken covering a 14-year period to identify the most important determinants of above-ground grass production and composition. At the core of the study is the soil water balance. The use of evapotranspiration data in a study of this nature is however not absolutely essential, provided a variety of rainfall parameters are used, though it has the important advantage of providing a much more detailed and more complete insight into the relations of the grass sward with its environment. Stepwise and tree regression procedures were used to identify the important factors. It is concluded that rainfall in its various forms is the primary determinant of grass production, standing crop, and composition, the latter either as perennials or Decreasers. Secondary determinants, in varying degrees of importance, are the thickness and base status of the A horizon, distance to permanent drinking water, and competition by woody plants. Herbivore utilization is insignificant or at most, plays a relatively minor role. Herbivores appear to exert a negative influence on Decreaser abundance only when soil moisture stress exceeds a threshold level. When this is exceeded, relatively low herbivore densities are apparently sufficient to reduce Decreaser abundance. The definitions of Decreasers and Increasers consequently require revision to take into account the overriding influence of environmental factors, particularly those of soil moisture stress. The calibration of the disc pasture meter was re-evaluated. The relation between mean disc height and standing crop is non-linear. Up to a mean disc pasture meter height of 260 mm, the correlation between this parameter and above-ground standing crop is very strong (r2 = 0.95; P<0.0005). Beyond this height, the correlation is very poor (r2 =0.09; P<0.0005), apparently being strongly influenced by the structure of the grass plant, with tall grasses, or grasses with highly lignified culms resulting in a weaker correlation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Fire, natural or of anthropologic origin is a recurrent phenomenon in South African mesic grasslands. The species composition of these grasslands is sensitive to fire frequency and there exists a permanent fire-species relationship syndrome. The shift follows a general trend where, in the absence of fire for longer periods, the native grass species, possibly the most economically important grass species, give space to relatively less desirable and invasive species accompanied by significant decline in basal cover. Though much is known as to how the floristic composition of the grassland changes in response to fire, the underlying mechanisms responsible for changes in plant vigour and species composition are not fully understood. There exists limited information on germination requirements of the local flora and how recruitment of the species is influenced by fire, fire-related factors and the interaction of these factors among themselves is virtually unknown. Since the discovery by DE LANGE and BOUCHER (1990), plant-derived smoke is being widely studied as an important germination cue and the theme has been the subject of intense experimental research and theoretical work. Germination studies conducted on South African Fynbos, Californian Chaparral, and Australian species have illustrated the widespread ability of plant-derived smoke in promoting germination of species from both fire and non-fire prone habitats. Studies have also showed that plant-derived smoke plays a significant role in vegetative growth of many plants including horticultural and agricultural crops, though mechanisms of smoke action in enhancing germination and promoting plant growth are still under active research. This study sought to gain insight into the role of fire and fire-related cues and other related factors on germination and seedling growth of key grass species from fire-prone grassland in South Africa. In this study, various investigations were conducted on different aspects related to smoke-induced seed germination. Furthermore, in depth examinations were conducted on the effects of fire-related factors such as smoke, heat, soil and nutrients on seed germination and seedling growth of representative key mesic grassland species from South Africa. Laboratory-based germination and vigour experiments were conducted using smoke solutions. The aim was to examine if the strong fire-species relationship syndrome we encounter in post-fire mesic grassland in South Africa is related to the effect of plant-derived smoke on germination and seedling growth. In addition, the interaction of plant-derived smoke solutions with temperature was examined by incubating seeds at a range of temperatures. Treating seeds with smoke-water and butenolide, the germination rate (GR) and final germination percentage (FGP) were greater in 3 of the 6 species. Themeda triandra Forssk. and Tristachya leucothrix Trin. ex Nees showed the greatest response, with final germination increased from 43% to 67% and 35% to 63% respectively. These smoke solutions have also significantly enhanced germination in Eragrostis tef (Zucc.) Trotter from 62% to 80%. The degree of responsiveness varied from species to species and across different temperatures. Findings from this study suggested that plant-derived smoke and its interaction with temperature significantly influence the germination and seedling growth of the South African mesic grassland species, which can further impact on the grassland composition. To characterise the role of plant-derived smoke on certain economically important seed traits, the effect of smoke-water and a smoke-isolated butenolide on seed germination and seedling growth of Eragrostis tef (grass species which has moderately good tolerance to east African drought) was investigated at a range of temperatures, light conditions and osmotic potentials. Smoke-water (1:500 v/v) and butenolide (10ˉ⁸ M) treatment of the seeds increased percentage germination, seedling vigour and imbibition from high to low osmotic potential. These results suggested that smoke solutions have characteristics with overriding effects toppling stresses exerted from high temperature and low osmotic potential, thereby widening the temperature and moisture zone over which germination can occur. Furthermore, these findings suggested that the mode of smoke action in promoting seed germination is likely to be linked to the role of smoke in facilitating water uptake by seeds (imbibition). A simple and rapid bioassay was implemented to detect the germination activity of extracts from soils in pre/post-burn status. Soil samples taken from burnt, unburnt and adjacent plots at depths of 0-2, 2-4, 4-6 and 6-8 cm before and after burning mesic grassland in South Africa were analysed for germination activity over an eight-week period. Soil samples were extracted using dichloromethane and bioassayed using Grand Rapids lettuce (Lactuca sativa L.) achenes. The Grand Rapids lettuce seeds exhibited several-fold greater germination percentages when treated with extracts from burnt soil compared to the other plots. The magnitude of such an activity declined through time since burn. The Grand Rapids lettuce seeds also showed significantly greater germination percentage when treated with unburnt soil extracts compared to the control (distilled water) which indicates the existence of other factors controlling germination in unburnt soil. Germination percentage was negatively influenced in the adjacent plots which reflected the inhibitory role of smoke on adjacent plots neighbouring the burn. Findings from this study suggested that the germination activity of a burning plant-material (smoke) indeed diffuses into the soil and its persistence declines with time. Furthermore, the findings implied that fire and smoke may significantly influence the germination of the soil seed bank of mesic grassland in South Africa. The effect of smoke solutions of various concentrations and their interaction with soil macronutrients NPK in influencing seedling growth of three selected grass species namely, Eragrostis curvula, Panicum maximum and Themeda triandra was investigated. These grass species were selected on the basis of the contrasting response they previously showed to smoke treatments. Results showed that the interaction between species, treatment and nutrients for seedling vigour index was highly significant (P < 0.001). In the absence of NPK elements, the smoke solutions generally enhanced seedling growth in Themeda triandra, while suppressing seedling vigour indices of Eragrostis curvula and Panicum maximum. It is ecologically significant that not only smoke but also its interaction with soil macronutrients appears to be important in structuring the post-fire regeneration and colonisation processes. To examine the effect of fire-associated cues of smoke and high temperature on germination and seedling emergence from the mesic grassland soil seed bank in South Africa, and disentangle responsible factors, the effect of heat and smoke-water on seedling emergence and the resultant effect on biomass production was examined in a greenhouse tray experiment over 90 days. Soil seed bank samples obtained from 0-5 cm top soil were treated with smoke-water solution (SW 1:500 v/v), heat (H = 100 °C for 15 min) and heat + smoke-water (H = 100 °C for 15 min + SW = 1:500 v/v) combined. Significantly, the highest number of seedlings emerged from soil seed bank samples treated with heat + smoke-water combined followed by smoke-water alone. Heat + smoke-water treatment of soil seed bank samples also significantly enhanced the rate of seedling emergence and total dry biomass production. Heat treatment by itself was not statistically different from the control in many respects. Generally, these results suggest that both heat and smoke are important germination cues and play a curial role on germination and seedling emergence from the mesic grassland soil seed bank. A greater number of fire-loving Themeda triandra seedlings emerged from soils treated with smoke, though this was not statistically significant. Seedling emergence indicators showed that seedling emergence was favoured more by smoke and smoke + heat treatments compared to the control. Seedling growth indicators also showed that soil samples treated with smoke or smoke + heat combined produced significantly higher biomass than untreated samples. In general, findings from this comprehensive study suggest that plant-derived smoke and its interaction with temperature (heat) and soil nutrients significantly influences seed germination and seedling growth of South African mesic grassland species differently, this can further influence the grassland composition. The association of certain fire-climax species with the re-occurrence of fire can partly be explained due to the association of such species with fire-induced changes in the habitat. Post-fire conditions of low nutrient (NPK) availability, presence of high heat and smoke cues in the habitat may favour the competitive ability of native short and smoke-responsive species such as Themeda triandra and Tristachya leucothrix over those characteristic species of fertile habitats such as Eragrostis curvula and other non-smoke-responsive species. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.

MRDV / Institute of Rural Development / See the attached abstract below

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: With only 1.76% conserved West Coast Renosterveld remaining it is crucial to prioritize the conservation and management of this fragile vegetation type. Because of its occurrence on fertile soils, renosterveld has been cleared for cultivation and other agricultural use and is thus fragmented to a critical point. These remaining fragments are subject to extensive edge effects and the exact parameters of a viable fragment must still be determined. The extent of alien grass species invasion into remnant renosterveld patches was determined using data collected using the line-intercept method. Sampling included three different management treatment areas adjacent to old lands: 1) a recently burned area, 2) a grazed area and 3) an unburnedlungrazed area providing a control sample. Additionally all small-scale soil disturbances along the lines were recorded. Results showed that Briza spp., Bromus spp. and Avena fatua were the most significant invading alien grass species. There was a significantly high variation between alien grass cover in each treatment, with the grazed area containing the highest overal! level of alien grass invasion. The control area, with the exclusion of fire and animal activity, showed minimum alien grass invasion. Edge effects were apparent in all treatments, but were lowest in the control area, where percentage alien grass cover significantly decreased after a distance of fifteen meters into the remnant patch. A weak positive correlation between the occurrence of alien grass and indigenous grass was found, as well as evidence of a weak association between alien grass cover and shrub cover. The possibility that small-scale soil disturbances could be an important contributing factor to alien grass invasion was supported by the positive correlation between disturbances and percentage alien grass cover. A positive correlation was found between the occurrence of indigenous grass and small-scale soil disturbances, while shrub cover tended to be less associated with animal activity. It is concluded that the correct management regime could effectively control the excessive invasion of alien grass species into the remnant renosterveld patches. Grazing (including all animal activity and small-scale soil disturbances) was the main facilitator of alien grass establishment - even dominating the prominent consequences of edge effects by facilitating alien grass establishment much deeper into the remnant patches. It could be assumed that a precise balance of low-pressure grazing and fire management should be established to enable the effective control of alien grass species while maintaining optimum biodiversity. Keywords: renosterveld, alien grass, grazing, fire, management, small-scale soil disturbances / AFRIKAANSE OPSOMMING: Met slegs 1.76% oorblywende Weskus Renosterveld wat bewaar word, is die beskerming en effektiewe bestuur van hierdie bedreigde plantegroei 'n prioriteit. Die vrugbare grond waarop renosterveld voorkom, het veroorsaak dat dit uitgeroei word om eerder die kultivering van ekonomies produktiewe landbou gewasse moontlik te maak. Dus het renosterveld verminder en gefragmenteer tot 'n kritieke punt. Hierdie ooblywende klein areas bedek met renosterveld, is blootgestel aan ekstensiewe invloede van die omliggende areas en die presiese afmetings vir 'n effektiewe grate renosterveld fragment vir bewarings doeleindes, moel nog vasgestel word. Die male van uitheemse gras spesie indringing in hierdie renosterveld fragmente is ondersoek deur die versameling van data deur die lyn-onderskep metode. Drie verskillende bestuursstelsels vir renosterveld is ondersoek om vas te stel wat die ergste graad van uitheemse gras indringing voorkom. Die studie het 'n 1) onlangs gebrande area, 2) 'n beweide area en 3) 'n kontrole area (wat nie gebrand of bewei is nie) ondersoek. Alle kleinskaalse grond-versteurings langs die lyne is ook aangeteken. Die resultate het aangetoon dat Briza spp., Bromus spp. en Avena fatua, as uitheemse grasse, die belangrikste indringers was en dus die grootste bedreiging inhou. Daar was 'n beduidende hoë variasie tussen die mate van uitheemse gras bedekking aangeteken in elk van die bestuurs-stelsels. Die beweide area het die hoogste graad van uitheemse gras indringing getoon, terwyl die kontrole area (in die afwesigheid van vuur en weidings aktiwiteite) die meeste weerstand teen uitheemse gras indringing getoon het. Die invloed van die omliggende omgewing was ook duidelik sigbaar in al drie die bestuurs-stelsels, maar was duidelik minder in die kontrole area waar die persentasie uitheemse gras indringing aansienlik verminder het na 'n afstand van vyftien meter in die renosterveld fragment in. 'n Swak positiewe korrelasie tussen die voorkoms van uitheemse grasse en inheemse gras spesies was aangeteken, asook bewyse van 'n swak negatiewe assosiasie tussen die uitheemse gras spesies en die inheemse bosse. Soos verwag, is daar bewyse gevind vir die teorie dat kleinskaalse grond-versteurings 'n belangrike fasiliterende faktor is vir uitheemse gras vestiging. Daar was 'n duidelike positiewe korrelasie tussen hierdie grond-versteurings en die persentasie uitheemse gras grondbedekking. Dieselfde positiewe assosiasie was gevind tussen die inheemse gras en hierdie kleinskaalse grond-versteurings, terwyl die inheemse bossie duidelik minder verbind was met die verskynsel. Die gevolgtrekking is gemaak dat 'n korrekte bestuurs-plan die indringing van uitheemse grasse effektief sal kan beheer. Dier aktiwiteite (insluitende beweiding, grawe van gate, mier en termiet neste ens.), en dus kleinskaalse grond-versteurings. was die grootste fasiliteerders van uitheemse gras indringing en vestiging binne hierdie renosterveld stukke. Dit oorheers selfs die aansienlike effek wat invloede van die omringende omgewing op hierdie areas het, deur die uitheemse gras indringing selfs dieper in die fragmente in aan te help. Daar kan dus aangeneem word dat 'n presiese balans tussen lae-intensiteit beweiding (en dus fauna aktiwiteit) en veld brande vasgestel moet word vir die effektiewe beheer van uitheemse gras spesies terwyl die optimum bio-diversiteit terselfde tyd gehandhaafword. Sleutelwoorde: renosterveld, uitheemse grasse, beweiding, vuur, veldbestuur, kleinskaalse grond-versteurings