Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1994. / Document électronique également accessible en format PDF. CaQCU

Fire is an important disturbance mechanism in big sagebrush (Artemisia tridentata) communities, yet little is known about wildlife population dynamics during post-fire habitat succession. I estimated the abundance of small mammals and birds in relation to fire history in mountain big sagebrush (A.t. spp. vaseyana) communities on the Sheldon National Wildlife Refuge in the northwestern Great Basin, USA. I employed a chronosequence approach that took advantage of multiple wildfires that had occurred in similar plant communities between 7 to 20 years prior to sampling. Belding’s ground squirrel (Spermophilus beldingii) were approximately 10 times as abundant in burned areas relative to adjacent unburned habitat regardless of the number of years since a burn occurred. Deer mouse (Peromyscus maniculatus) was more abundant on more recently burned sites, but not at sites closer to full vegetation recovery. Great basin pocket mouse (Perognathus parvus), sagebrush vole (Lemmiscus curtatus), and least chipmunk (Tamius minimus) abundance did not vary as a function of fire history, but some variance was explained by habitat features such as rocky areas and the canopy characteristics of sagebrush. Bird diversity was higher in unburned habitats irrespective of the number of years of recovery out to 20 years. Nine of the 12 most widely occurring species of birds in the study have population densities influenced by fire or post-fire habitat succession to at least 13 to 20 years following a burn. Sage Sparrow (Amphispiza belli), Black-throated Sparrow (Amphispiza bilineata), and Spotted Towhee (Pipilo maculatus) occurred at relatively low densities and were nearly restricted to unburned habitats. Green-tailed Towhee (Pipilo Chlorurus), Gray Flycatcher (Empidonax wrightii), American Robin (Turdus migratorius), and Brown-headed Cowbird (Molothus ater) occurred at lower densities in burned areas than adjacent unburned areas although the relationship was not strong for the latter two species. The magnitude of the difference in density between burned and unburned sites within a landscape diminished with the number of years of vegetation recovery for Green-tailed Towhee. Brewer’s Sparrow (Spizella brewerii) occurred at lower densities relative to adjacent habitat in the most recent burn, but occurred at higher densities after 20 years of habitat succession, suggesting a positive response with a multiple decade lag period. Horned Lark (Eremophila alpestris) and Vesper Sparrow (Pooecetes gramineus) respond positively to fire, but densities were similar to unburned areas after 20 years of habitat succession. An ordination analysis captured 86% of the variation in 12 bird species with 3 orthogonal axes. My research demonstrates that strong community structure exists for birds associated with mountain big sagebrush habitats, and that fire influences community structure for multiple decades. / Graduation date: 2011 / Access restricted to the OSU Community at author's request from Dec. 22, 2010 - Dec. 22, 2011.

Thesis (DSc)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: No abstract available / AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar

Disturbances, such as herbivory and fire are commonplace in savanna ecosystems. The effects of herbivory and fire on growth and defences of adult trees is a much studied filed in plant ecology. However, there are comparatively few studies that have investigated the effects of herbivory and fire on seedling growth, defences and establishment. African Acacia trees are common and widespread, and are suggested to be keystone species in savanna ecosystems. They have been shown to significantly positively increase soil characteristics, such as soil moisture and infiltration, while also increasing spatial heterogeneity of savannas. These trees are distinguishable by their array of physical and chemical defences. Physical defences are either in the form of spines (physiologically costly to produce, thus considered inducible) or prickles (physiologically cheap to produce, thus considered constitutive), while condensed tannins are the most common form of chemical defences. Adult Acacia trees have been shown on several occasions to be highly resilient to disturbance events, primarily due to their large size. However, the effects of herbivory and fire on Acacia seedlings have been little studied despite their apparent importance for our understanding of African savanna ecosystem functioning. In two separate experiments, this thesis aimed to investigate the individual and combined effects of simulated herbivory and fire on the regrowth, defences, and total non-structural carbohydrates (TNC) of the seedlings of several Acacia species, while also testing the Resource Availability Hypothesis (RAH) (14 Acacia species) and the Expanded Growth-Differentiation Balance Hypothesis (GDBH) (three Acacia species). The RAH (Coley, Bryant & Chapin 1985) and the GDBH (Loomis 1932) both assume that arid-adapted (resource-poor) species are slow growing, with low tissue turnover rates. Contrastingly, humid-adapted (resource-rich) species have fast growth rates and thus a high tissue turnover rate. Therefore, arid-adapted species are predicted to invest more carbohydrate reserves in defence after a disturbance event, in order to defend new photosynthetic material. Conversely, humid-adapted (resource-rich) species are predicted to invest carbohydrate reserves into increased growth after a disturbance event, in order to compensate for tissue loss. The first greenhouse experiment found that, in accordance with the RAH, humid-adapted species displayed elevated growth rates compared to arid-adapted species. Overall, defences significantly increased after herbivory, but significantly decreased after fire. Herbivory was also shown to significantly reduce TNC stores in roots more than fire. We found that arid-adapted species did indeed invest more carbohydrate stores (TNC) into defence, and displaying an increase in spine and prickle abundance, spine and prickle length, and condensed tannin concentration. Humid-adapted species displayed an increase in growth rather than in defence, with the majority of species only increasing one defensive trait. Humid-adapted species also displayed significant trade-offs (negative correlations) between new stem growth and defence traits, while arid-adapted species overall did not display any significant trade-offs between stem growth and increased defences. The majority of arid-adapted species also displayed an allometric effect for spine abundance and length, with an increase in one trait led to an increase in the other. Prickles were found to be inducible, despite the assumption that due to low physiological cost, they are no inducible. Herbivory and fire were shown to not be substitutable in their effects on Acacia seedlings in a controlled experimental setting. The second greenhouse experiment tested the Expanded Growth-Differentiation Balance Hypothesis (GDBH) in the seedlings of A. erioloba, A. karroo, and A. nilotica using five levels of nutrient availability. Overall, spine abundance and spine length displayed a unimodal trend in all three species, with spine abundance and spine length being greatest at a nutrient availability of 800 mg/ ℓ. Spine abundance, spine length and condensed tannins increased significantly after herbivory, but were shown to significantly decrease after fire. We found that with an increase in nutrient availability, the growth of stems and roots, along with the production of TNC in roots and stems of all species significantly increased. Our data provide mixed support for the assumptions and predictions of the expanded GDBH. The regrowth of stems and physical defences were consistent with the GDBH. Chemical defences (i.e. condensed tannins) were however, inconsistent with the predictions of the GDBH. We have shown that Acacia seedlings are highly resilient to disturbance events, while the growth responses of Acacia seedlings are underpinned by TNC stores in roots. Simulated herbivory and fire are often substituted for one another in controlled experiments. However, we have shown that the effects of herbivory and fire have significantly different effects on regrowth patterns of Acacia seedlings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

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.

Thesis (MA.)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: There are many reasons to conserve fynbos. Not only does fynbos form part of the Cape floral kingdom, one of the richest floral kingdoms in the world, but the contribution that it makes to the regional economy through utilisation, education, recreation and tourist opportunities is immeasurable. Fire plays an integral role in fynbos ecosystems. According to Van Wilgen, Richardson & Seydack (1994: 322) " ... managing fynbos equates to managing fire". Therefore managers need accurate fire information about a fynbos area to manage it properly. This is where satellite remote sensing can provide the manager with useful information about the fire regime. In other words, satellite remote sensing can help a manager establish where and when an area has burnt. Using readily available satellite data, this study attempts to establish (through comparison) what techniques would be most suitable and affordable to compile a fire information database. Landsat Thematic Mapper data from 1990 - 1996 of the southwestern Cape was used and compared with existing fire records of the area. The results show that techniques such as supervised and unsupervised classification are reliable in identifying burnt areas, but a major drawback of these techniques is that they require a large amount of user input and knowledge. They are thus not regarded as simple or easily repeatable. - The' more simple techniques like image differencing and image ratioing were also found to be reliable in identifying burnt areas. These techniques require less user input and in some instances less data (image bands) to produce similar (or better) results than supervised and unsupervised classification techniques. The results show that differencing temporally different Images, obtained from applying principle components analysis, produces reliable results with very little confusion and little user input. Using such a technique could enable users to procure only two bands of Landsat data and still produce reliable fire information for managing a fynbos ecosystem. / AFRIKAANSE OPSOMMING: Daar is verskeie redes waarom fynbos bewaar moet word. Nie net vorm dit deel van een van die rykste blommeryke in die wereld nie, maar die bydrae wat dit tot die streeksekonomie maak, deur die benutting van veldblomme en die geleenthede wat dit bied vir toerisme en ontspanning, is enorm. Vuur speel 'n belangrike rol in die bestuur van fynbos ekosisteme. Soos beklemtoon deur Van Wilgen, Richardson & Seydack (1994: 322) se stelling: " ... managing fynbos equates to managing fire". Om hierdie rede is dit belangrik dat 'n bestuurder akkurate inligting oor die verspreiding van veldbrande moet he. Satellietafstandwaarneming kan hier 'n belangrike rol speel deur sulke inligting te verskaf Deur gebruik te maak van maklik bekombare satellietdata, poog hierdie studie om te bepaal (d.m.v. vergelyking) watter tegnieke die mees geskikte is in terme van bekostigbaarheid en gebruikersvriendelikheid. Landsat Thematic Mapper data van 1990 tot 1996 van die suidwes-Kaap is gebruik en vergelyk met bestaande branddata van die studiegebied. Daar is gevind dat tegnieke soos gerigte en nie-gerigte klassifikasie in staat is om gebrande dele betroubaar uit te ken. Hierdie tegnieke verg egter baie insette en kennis van die gebruiker en is ook nie maklik om jaar na jaar te herhaal nie. Daarom word hierdie tegnieke nie aanbeveel nie. Daar is gevind dat die eenvoudiger tegnieke soos veranderingsanalise ook gebrande dele betroubaar kon uitken. Hierdie tegnieke het die voordeel dat die gebruiker nie baie' kennis van die gebied hoef te he nie en ook nie so baie insette hoef te lewer nie. Hierdie tegnieke word bo gerigte en nie-gerigte klassifikasie aanbeveel. - Die resultate dui daarop dat betroubare resultate verkry kan word deur tempo reel verskillende beeIde, verkry deur hoofkomponentanalise, van mekaar af te trek. Hierdie tegniek vereis relatief min gebruikersinsette en daar kan selfs met slegs twee Landsat bande gewerk word. So 'n tegniek kan beslis 'n bekostigbare en effektiewe manier wees om nodige inligting vir die bestuur van 'n fynbos ekosisteem te bekom.

Thesis (MSc (Geography and Environmental Studies))--University of Stellenbosch, 2007. / The Agulhas Plain, an area rich in fynbos, was monitored within six months after the February 2006 fire. The potential of using medium resolution imagery, specifically from the Moderate Resolution Imaging Spectroradiometer (MODIS) in determining the re-growth rates of indigenous and alien vegetation types after fire was explored. Pixels representing dense areas of each vegetation type were selected. There was a significant difference in the pixels selected for each vegetation type. A time series of Normalized Difference Vegetation Index (NDVI) data was derived and fitted to functions, such as Double Logistics and Asymmetric Gaussian as implemented in the TIMESAT software. The results show that alien vegetation grows faster after a fire occurrence than in its absence. Within the specified months of monitoring, it was observed that fynbos grew faster than the alien vegetation. Also, the re-growth rates of vegetation on the coastal soils were higher than those of vegetation on the inland soils. The determination of the re-growth rate was necessary to assist resource managers determine the appropriate time for follow-up of clearing invaded sites after fire.

Food webs consist of a combination of bottom-up (resource-driven) and top-down (predator-driven) effects. The strength of these effects depends on the context in which they occur. I investigated food web (trophic) relationships between wolf (Canis lupus) predation, elk (Cervus elaphus) herbivory, aspen (Populus tremuloides Michaux) recruitment, and fire. The study setting, in the central portion of the Crown of the Continent Ecosystem, spans the US/Canada border and encompasses Glacier National Park (GNP), Montana and Waterton Lakes National Park (WLNP), Alberta. I stratified my observations across three spatially distinct areas, the North Fork Valley, in the western portion of GNP; the Waterton Valley, in the eastern portion of WLNP; and the Saint Mary Valley, in the eastern portion of GNP. All valleys are elk winter range (low-lying grasslands with patches of aspen). The valleys have three different observed wolf population levels (Saint Mary: low; Waterton: moderate; North Fork: high), which represent three levels of long-term predation risk (the probability of an elk encountering a wolf). Ecological characteristics (e.g., climate, soils, elevation, plant associations) are comparable among valleys. Fire has occurred in 90% of the North Fork. My objective was to examine the relative influence of bottom-up (fire) and top-down (predation risk) factors and the context-dependence of these relationships via data gathered during a three-year time span. I found complex elk responses to bottom-up and top-down factors that could influence habitat use by elk. Pellet transect data demonstrated that elk exhibited the same risk reduction behavior at all wolf population levels, even at very low levels. Predation risk variables that provided impediments to detecting or escaping wolves had a similar and negative influence on occurrence of elk (pellet piles), regardless of wolf population density. Fire had a negative effect on elk density and a positive effect on wolf density (per scat piles) in aspen communities where a high wolf population existed. Aspen cover, which may be riskier than open grassland, also had a negative effect on elk density, except at very high wolf levels without fire. The risk of wolf predation alone did not drive elk behavior. Conversely, focal animal (elk vigilance behavior) data suggested a positive relationship between wolf population and elk vigilance. However, when I deconstructed vigilance, elk demonstrated complex, context-dependent adaptive behavior in response to the long-term risk of predation by wolves. Commonly identified drivers of elk vigilance (group size, impediments to wolf detection and escape) appeared to be important drivers at an intermediate level of long-term predation risk (e.g., Waterton). These drivers ceased to function in this manner when the long-term predation risk level increased (The North Fork). At high levels of long-term predation risk, vigilance was high, but not driven by these common factors. In some cases, the relationship between vigilance and risk factors was reversed (e.g., group size). And at a low level of long-term predation risk (Saint Mary), elk did not respond to these drivers of vigilance. When I measured aspen demography (browse, recruitment), browse was lower in the North Fork, where there was a high wolf population, suggesting a top-down effect. However, I found low aspen recruitment in the absence of fire in all valleys, which indicates a bottom-up effect in that aspen is highly fire-dependent. Top-down predictors of aspen recruitment (e.g., plot position and stand size, which are related to predation risk) had no effect on browse levels regardless of wolf population level. In sum, the risk of wolf predation alone did not drive the food web relationships I observed. Bottom-up and top-down forces worked together in valleys that contained well-established wolf populations, and to a lesser degree in a valley with a low wolf population. Commonly used measures of predation risk responses (e.g., vigilance) reversed their relationship as the wolf population increased. Low aspen recruitment in the absence of fire demonstrates the importance of bottom-up effects. Bottom-up and top-down effects may be important joint engineers of aspen communities. My findings invite deeper inquiry into the interaction between bottom-up and top-down effects in large mammal systems. / Graduation date: 2012

Thesis (MSc) -- University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The fires, which occurred during January 2000 on the Southern Cape Peninsula, Cape Province, South Africa, focused attention on the importance of sound, informed management of exotic plant invaders in fynbos, especially at the urban interface. The fires also highlighted the relative lack of knowledge about the combined impacts of fire, exotic plants and the exotic-clearing programme on soil seed banks and regeneration. This study examines soil borne seed banks, regeneration, soil chemistry and micro biota in different postfire environments, focusing on three components of exotic plant management: The post-fire effects of standing invasive exotic plants; stacks of slashed exotic plant material which were deliberately burnt and stacks reduced to heat scars by a wildfire. The primary hypothesis addressed is that post-fire vegetation regeneration patterns, seed bank diversity and seed bank abundance are linked to pre-fire vegetation characteristics and, in particular, to the treatment of exotic plant species. It is also hypothesised that soil microbe population sizes are linked to pre-fire vegetation and soil chemical composition. Differences in soil seed banks, soil micro biota and vegetation regeneration patterns occur in different post-fire environments. High volumes of (live or dead) woody exotic biomass negatively impact upon postfire indigenous species diversity and abundance, both above and below-ground. Soil seed banks and above-ground regeneration decline with increasing fire intensity, wildfire burnt stack treatments showing the largest declines followed by wildfire burnt standing exotics, control burnt stacks, wildfire burnt cleared areas and wildfire burnt Mountain Fynbos treatments. Persistent indigenous seed banks are found under some exotic dominated stands. Heat damage, associated with high woody exotic biomass, affects seeds of all species into deep soil layers. Depth of burial is a more important determinant of seed survival during fires than seed size. Soil microbial populations are variably affected by exotic plants, their management and increases in fire intensity. The most drastic microbial population changes are in post-fire treatments of high exotic plant biomass. Soil chemistry affects microbial population sizes as does seasonal climatic changes. In this thesis vegetation, seed bank and microbial responses to various exotic plant management practices are shown and management recommendations are made. Keywords: exotic plants, fire, Fynbos Siome, microbes, post-fire succession, soil seed banks. / AFRIKAANSE OPSOMMING: Die Januarie 2000 vure op die Suid Kaapse Skiereiland het fokus gerig op die belangrikheid van goeie, ingeligte bestuur van uitheemse indringerplante in fynbos, veral naby stedelike gebiede. Die vure het ook 'n relatiewe .gebrek aan kennis aangaande die gekombineerde impakte van vuur, uitheemse plantegroei en indringer plant beheer programme op grond saadbanke en die hergroei van plante na 'n vuur aan die lig gebring. Hierdie projek bestudeer die invloed van vuur op grond saadbanke, hergroei van plante, grond chemie en mikro-organismes. Die klem lê op drie komponente van uitheemse plant bestuur: waar staande uitheemse plante voorkom; waar skoongekapte uitheemse plante in hope gestapel is en gekontraleerd gebrand is en waar soortgelyke hope in 'n onbeplande weghol vuur gebrand is. Die primêre hipotese is dat plant herstelpatrone, saadbank diversiteit en grootte gekoppel is aan veldtoestande voordat daar gebrand is, en veral aan die bestuur van uitheemse plantspesies. Nog 'n sentrale hipotese is dat die grootte van grond mikrobiale populasies gekoppel is aan veld toestande voor die brand en aan grond chemiese samestelling. Hierdie studie dui verskille aan in grond saadbanke, mikro-organismes en plant hergroeipatrone onder verskeie toestande na vuur. Die brand van hoë volumes (lewende of dooie) houtagtige uitheemse plant biomassa benadeel inheemse plant spesie diversiteit en getalle (bo en onder die grond oppervlak). Grond saadbanke neem af met vehogings in vuur intensiteit. Die grootste afnames is in wegholvuur gebrande gestapelde uitheemse plantmateriaal gevolg deur wegholvuur gebrande staande uitheemse plante, opsetlik gebrande hope uitheemse plante, gebrande skoongekapte areas en wegholvuur gebrande Berg Fynbos. Ou inheemse saadbanke is gevind onder sommige areas wat voor die vuur oorheers was deur uitheemse plantegroei. Hitteskade, geassosieer met hoë volumes houtagtige uitheemse biomassa, affekteer sade van alle spesies tot diep in die grond. Saad oorlewing tydens brande is meer geaffekteer deur diepte van begrawing in die grond as deur saad grootte. Grond mikro-organisme populasies is geaffekteer deur uitheemse indringer plante, die bestuur van uitheemse plante en vuur intensiteit. Die grootste veranderinge is waar die biomassa van uitheemse plantegroei baie hoog is. Grond chemiese samestelling en seisoenale veranderinge in weerspatrone affekteer die grootte van mikrobiale bevolkings. In hierdie tesis word verskille in plantegroei, saad store en grond mikrobes, soos geaffekteer deur uitheemse plant beheer programme uitgewys en voorstelle vir toekomstige bestuur gemaak. Sleutelwoorde: Fynbos Bioom, grond saad stoor, mikrobes, plant hergroei, uitheemse plante, vuur.

Abstract not available