Dissertations / Theses on the topic 'Fire ecology Australia, Southern'

I used age structure to examine the role of fire disturbance and climate on the population dynamics of the subalpine forest in the southern Sierra Nevada. I cored trees on ten 0.1 ha plots (3300-3400 m elevation) that varied in species composition, from single-species foxtail pine (Pinus balfouriana) or lodgepole pine (Pinus contorta, var. murrayana), to mixed-species stands of both pines. Crossdating was used to produce accurate dates of tree recruitment and fire events. Age structure varied by plot species composition: lodgepole pine recruitment pattern is pulsed, sometimes forming single-cohort patches in response to fire; foxtail pine plots have a more steady pattern of recruitment; mixed-species plots show an intermediate recruitment pattern. Fire may maintain a species composition mosaic in the subalpine forest. Foxtail pine regeneration may increase in areas opened by fire, although not immediately following fire. Low-intensity fire may spread over areas larger than previously reported under certain conditions in the subalpine zone. In addition, unusually frequent, extreme, and/or extended periods of drought may severely limit subalpine tree regeneration. Growing season frost events and grazing before 1900 may also have affected trees establishing in the subalpine zone.

The forests of south-eastern Australia, having evolved in one of the most fire-prone environments in the world, are characterized by many adaptations to recovery following burning. Thus forest ecosystems are characterized by rapid regenerative capacity, from either seed or re-sprouting, and mechanisms to recover nutrients volatilized, including an abundance of N2 fixing plants in natural assemblages. Soil physical, chemical and biological properties are directly altered during fire due to heating and oxidation of soil organic matter, and after fire due to changes in heat, light and moisture inputs. In natural ecosystems, carbon (C) and nitrogen (N) lost from soil due to fires are recovered through photosynthesis and biological N2 fixation (BNF) by regenerating vegetation and soil microbes.
This study investigated post-fire recovery of soil C and N in four structurally different sub-alpine plant communities (grassland, heathland, Snowgum and Alpine ash) of south-eastern Australia which were extensively burnt by landscape-scale fires in 2003. The amount and isotopic concentration of C and N in soils to a depth of 20 cm from Alpine ash forest were assessed five years after fire in 2008 and results were integrated with measurements taken immediately prior to burning (2002) and annually afterwards.
Because the historical data set, comprised of three soil samplings over the years 2002 to 2005, consisted of soil total C and N values which were determined as an adjunct to 13C and 15N isotopic studies, it was necessary to establish the accuracy of these IRMS-derived measurements prior to further analysis of the dataset. Two well-established and robust methods for determining soil C (total C by LECO and oxidizable C by the Walkley-Black method) were compared with the IRMS total C measurement in a one-off sampling to establish equivalence prior to assembling a time-course change in soil C from immediately pre-fire to five years post-fire. The LECO and IRMS dry combustion measurements were essentially the same (r2 >0.99), while soil oxidizable C recovery by the Walkley-Black method (wet digestion) was 68% compared to the LECO/IRMS measurements of total C. Thus the total C measurement derived from the much smaller sample size (approximately 15 mg) combusted during IRMS are equivalent to LECO measurement which require about 150 mg of sample.
Both total C and N in the soil of Alpine ash forests were significantly higher than soils from Snowgum, heathland and grassland communities. The ratio of soil NH4+ to NO3- concentration was greater for Alpine ash forest and Snow gum woodland but both N-fractions were similar for heathland and grassland soils. The abundance of soil 15N and 13C was significantly depleted in Alpine ash but both isotopes were enriched in the heathland compared to the other ecosystems. Abundance of both 15N and 13C increased with soil depth.
The natural abundance of 15N and 13C in the foliage of a subset of non-N2 fixing and N2 fixing plants was measured as a guide to estimate BNF inputs. Foliage N concentration was significantly greater in N2 fixers than non-N2 fixers while C content and 13C abundance were similar in both functional groups. Abundance of 15N was depleted in the N2 fixing species but was not significantly different from the non-N2 fixers to confidently calculate BNF inputs based on the 15N abundance in the leaves.
The total C pool in soil (to 20 cm depth) had not yet returned to the pre-fire levels in 2008 and it was estimated that such levels of C would be reached in another 6-7 years (about 12 years after the fire). The C and N of soil organic matter were significantly enriched in 15N and 13C isotopes after fire and had not returned to the pre-fire levels five years after the fire. It is concluded that the soil organic N pool can recover faster than the total C pool after the fire in the Alpine ash forests.

[Truncated abstract] Mediterranean southwest Australia, a global biodiversity hotspot, has nutrient deficient soils, exacting climatic conditions and is species rich with 7380 native vascular plant species, of which 49% are endemic. The region is expected to experience one of the world's highest degrees of biodiversity loss and change in the coming decades, with introduced species presenting a major threat. Limited knowledge is available on the mechanisms of ecosystem change associated with invasion and fire in this biodiversity hotspot region. Banksia woodland, an iconic complex species-rich natural ecosystem is one of the major vegetation types of the coastal sandplain, extending from 15 to 90 km inland and 400 kms along the west coast. The following hypothesis was tested to explore the ecological impacts of invasion: Is invasion of Banksia woodland by the introduced species Ehrharta calycina and Pelargonium capitatum accompanied by an alteration in ecosystem properties and processes, whereby the degree of change is related to fire frequency and abundance of introduced species? Different vegetation conditions, i.e. Good Condition (GC), Medium Condition (MC), Poor Condition invaded by Ehrharta calycina (PCe) and Poor Condition invaded by Pelargonium capitatum (PCp) were utilized for field assessments. ... In the soil seed bank, species numbers and germinant density decreased significantly for native and seeder (fire sensitive) species between GC sites and invaded sites. Surprisingly 52% of germinants at GC sites were from introduced species, with much of the introduced soil seed bank being persistent. Native species were dominated by perennial shrubs, herbs and sedges, while introduced species were dominated by perennial and annual grasses and herbs. Invasion by introduced species, associated with frequency of fire, altered the ecosystem, thus disadvantaging native species and improving conditions for even greater invasion within the Banksia woodland. Significantly higher soil phosphorus P (total) and P (HCO3) were found at PCe and PCp sites compared to GC sites. Leaf nutrient concentrations of phosphorus were significantly higher, and potassium and copper significantly lower in PCe and PCp sites, with introduced species having significantly greater concentrations than native species (except Manganese). This study demonstrated the key role of phosphorus in the Banksia woodland, in contrast to other research which identified nitrogen as the major nutrient affected by invasion. Higher levels of soil and leaf phosphorus, loss of species diversity and function, changes in fire ecology and canopy cover and a limited native soil seed bank make restoration of a structural and functional Banksia woodland from the soil seed bank alone unlikely. Without management intervention, continuing future fire is likely to result in a transition of vegetation states from GC to MC and MC to PC. The knowledge gained from this study provides a better ecological understanding of the invasive process. This enhanced understanding will enable the development of adaptive management strategies to improve conservation practices within a biodiversity hotspot and reduce the impact of the key threatening process of invasion.

The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park. Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid. The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence. Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire. Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota. Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance. Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.

The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park. Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid. The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence. Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire. Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota. Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance. Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.

Thesis (Ph. D.)--University of California, Riverside, 2008.
Includes abstract. Title from first page of PDF file (viewed Febrary 3, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references. Also issued in print.

Virginia's only montane pine barren, located in the Warm Springs Mountain Nature Preserve in the Allegheny Highlands of western Virginia is likely threatened by successional changes initiated by a history of fire suppression. Dominated by early successional fire adapted species, such as dwarfed Pinus rigida (Mill.) and Quercus ilicifolia (Wangenh.), this shrubland is home to numerous rare plants and invertebrates. We used vegetation analysis and dendrochronology to document establishment and recruitment patterns and to identify successional trends at this site. Tree establishment of the dominant tree species (P. rigida and Quercus rubra L.) peaked following the last known fire event in the early 1930s. Vegetation analysis revealed an absence of P. rigida seedling recruitment as well as a low density of fire adapted species such as Q. ilicifolia. In contrast, Q. rubra is represented in a variety of age classes and shade tolerant trees such as Acer rubrum (L.) and Pinus strobus (L.) are beginning to establish. A dense understory of ericaceous shrubs and a thick litter layer appear to inhibit recruitment of P. rigida and other early successional species pointing to the need for active management in the form of prescribed burns, which have been effective in other pine barrens.
Master of Science

There is growing understanding of the importance of landscape mosaics and heterogeneity for biodiversity outcomes in Western Australia. However, there is limited information on the patchiness (spatial configuration of unburnt and burnt patches which occur at a range of spatial scales) within the perimeter of a single prescribed burn. Of particular concern is the idea that prescribed burning operations, carried out under very restricted weather and environmental conditions, can lead to structural and floristic homogenization of the area within a burn perimeter. This may be evident as reduced post-fire vegetation patchiness. Western Australian Jarrah (Eucalyptus marginata) forests are managed to reduce fuel loads to protect life and property. Additionally, specific biodiversity and fuel reduction programs are completed by means of low intensity controlled burns carried out by the Parks and Wildlife Service, part of the Department of Biodiversity, Conservation and Attractions. The northern Jarrah forest is thus an ideal study site to test whether prescribed burning homogenizes a within-burn area. The objective of this study was to determine the post-fire patchiness of vegetation following prescribed burning to assess the potential for homogenisation of the within-burn area of Jarrah forests. To achieve this, a set of post-burn surveys were created to determine the patchiness of the burnt areas within 18 prescribed burns. The quantitative post-burn assessment designed in this study was evaluated to determine if it is suitable to be used as a possible future management option. A survey was undertaken to obtain data on 29 environmental variables which capture the variability across an individual prescribed burn area to determine the within-burn fire characteristics. A Pearson correlation matrix table was constructed to determine the significant correlations between variables as well as the strength of the relationships (coefficient of determination, r2). The patchiness between seasons autumn and spring was compared. Generalised Linear Modelling (GLM), and the application of Akaike were used to identify which variables were essential and most significant in predicting patchiness, to produce a list of candidate models. The AICc indicated which models were the most parsimonious or plausible candidate models (AICc < 2). Structured Equation Modelling (SEM) was completed to determine which variables in the ‘most parsimonious’ model were the greatest contributors to the model. It was found that the number of vegetation patches decreased with an increase in fire intensity and percentage of area burnt. Autumn and spring burns were not significantly different in terms of overall patchiness and the majority of patches were found to be small, between 1 – 10 m in length. Surface Moisture Content (SMC) was the only pre-fire condition variable that negatively influenced prescribed burn fire intensity and subsequently patchiness, while time since last burn was found to increase the number of vegetation patches and SMC. The post-fire survey data obtained in this study on the 18 post fire sites was also compared to the post-burn assessments completed by Parks and Wildlife Service on the same sites. GLM and AICc showed that the variables Fire Danger Index, ash cover (%), area burnt (%), month of fire and the number of vegetation patches, are the most parsimonious and ‘best’ fit at predictors of patchiness within a prescribed burn area. While SEM showed that area burnt (%) was the most important predictor of patchiness. Within-burn patchiness appeared to be low in the study sites. Results from the prescribed burns in the northern jarrah forests showed that in most prescribed fires, 90 to 100% of the vegetation area was burnt with a limited number of unburned patches (up to 12 km-1) remaining. Although successful for fuel reduction burning, such large scale vegetation loss has been found to lead to structural homogenisation within a burn area, which in turn can result in long-term impacts on biodiversity. This study thus showed that prescribed burns in the northern Jarrah forest can homogenise the within-burn area and the implications of these findings are discussed in the broader context of landscape patchiness. This study also shows that a quantitative post-fire patchiness survey similar to that designed here should be developed as a future management option.

Invasive predators are major drivers of global biodiversity loss and their impacts may be worsened by other disturbances such as fire. I examined how the fire history of shrublands influences the ecology of feral cats Felis catus, dingoes Canis dingo and their prey species in Western Australia’s northern Wheatbelt region. A review of the literature revealed that feral cats inhabit a diverse range of ecosystems worldwide, but are generally recorded most often in habitat types characterised by a mixture of plant growth forms close to ground level. Cat habitat use is influenced by predation/competition, prey availability, shelter availability and anthropogenic resource subsidies. Relatively few studies were available for review and the strength of evidence contained within them was generally low, which highlighted the need for more rigorous field studies. I examined overlap in resource use between cats and dingoes using remote camera surveys and dietary analysis of scats. Both carnivores were recorded in all four major habitat types: recently burnt shrublands (10 to 14 years since last fire), long unburnt shrublands (34 to ~49 years), very long unburnt shrublands (> 50 years), and woodlands. Dingoes and cats preferred woodlands and very long unburnt shrublands respectively, but spatial overlap between the two species was still common. Mean diurnal activity time for feral cats was two and a half hours later than that of dingoes. The diet of feral cats was more diverse than that of dingoes and dietary overlap between the two carnivores was relatively low. Rabbit remains did occur relatively frequently in both cat and dingo scats, but small mammals, reptiles and birds were also common in cat scats, and macropods in dingo scats. Nine of the 15 prey species studied showed a preference for either recently burnt or long unburnt shrublands. Two small mammals and three reptiles were most abundant in recently burnt areas, while the abundance of one small mammal and three reptiles was highest in long unburnt areas. Using giving up density experiments, I showed that rodents exhibited differential foraging behaviour in the two vegetation fire ages. The rodents foraged for longer in sheltered compared to open microhabitats, but this pattern only occurred in recently burnt, not long unburnt shrublands, probably because the higher density of understorey vegetation in recently burnt areas provided the rodents with extra cover to hide and escape from predators. I also developed a new framework for conceptualising interactions between invasive predators and other ecological disturbances, such as fire, habitat fragmentation, and top -predator decline. The impacts of invasive predators can be classified as either functional (density -independent) or numerical (density -dependent), and they interact with other threats through both habitat -mediated (fire, grazing, land clearing) and community -mediated (top -predator decline, altered prey populations, anthropogenic resource subsidies) interaction pathways. The key findings of this thesis show that both old and young shrublands can be suitable habitat for feral cats; predator -prey dynamics are influenced by successional habitat stages; small mammals show behavioural, as well as population -level responses to fire; and that invasive predator management is likely to benefit from addressing multiple threats in unison.

Bushfire is, in terms of human lives lost, property destroyed, and damage to natural systems, by far the most urgent environmental problem in Australia. This thesis tries to answer a number of questions about bushfire behaviour, history, effects, and management, in the Wungong Catchment of Western Australia. It does so by an overtly cross-disciplinary approach, involving a mixture of the three main streams of human knowledge, namely the humanities, natural science, and social science.First, I offer a literature review of several hundred books and papers drawn from the three main streams of knowledge mentioned above. The review includes some discussion of ‘bushfire epistemology’, a currently vague and neglected matter.The concept of ‘place’ is important to humans, so I then give a straightforward geographical description of Wungong Catchment, with some mention of the history of bushfire. To describe the vegetation, I use inductive statistics, and a method developed by me from the ideas of Delaunay (1929) and Dirichlet (1850). Given that there are hundreds of plant species within the catchment, I use a landscape approach, and only sketch the main tree species, and two iconic plants, the balga and the djiridji, both of which are important to the original custodians of the catchment, the Nyoongar people. There is discussion of other people’s research into the effect of bushfire on seed banks, and the flowering intervals of some plants of the jarrah forest.To see if Western Australia is anomalous, or fits into the worldwide pattern of humans using fire as a landscape management tool, I then examine some records of bushfire in other lands, including Africa, Madagascar, India, and Europe. The thesis then looks at the history of fire in the jarrah forest of Western Australia, based on observations by early European explorers and settlers from 1826 onward, the views of various foresters, and some opinions of current Nyoongar Elders.Using a mixture of natural science, applied mathematics, and archaeology, I give the results of cleaning the stems of those ancient plants called grasstrees, or balga (Xanthorrhoea spp.). These carry the marks of former bushfires, stretching back to 1750. They confirm historical reports of frequent fire in the jarrah forest, at 2-4 year intervals, and a recent decline in fire frequency. This contradicts the view, held by some, that European arrival increased the frequency of fire.As support for the balga findings, I present a simple mathematical model of self-organization in bushfire mosaics. It shows how lengthy bushfire exclusion can lead to disastrous situations, in which large areas of landscape become flammable and unstable. It shows how frequent, patchy burning can maintain a stable bushfire mosaic, with mild, beneficial fires. In the next chapter, I offer mathematical suggestions on how current unstable mosaics can be restabilized, by careful reintroduction of such burning.In dry, south-western Australia, water supply is an important topic, and a better understanding of the hydrological effects of bushfire may help with both bushfire and water management. I draw upon the natural science of forest hydrology, and the effects of fire in catchments. The evidence comes not only from Australia, but also from the United States, and South Africa.Turning to social science, I introduce Professor Peter Checkland’s ‘Soft Systems Methodology’, and suggest how it could be applied in resolving complicated conflict about bushfire management. I finish in legal style, with a summing up, and a verdict on the use of bushfire as a land management tool in Wungong Catchment, and possibly in other flammable landscapes.

La dynamique océanique, notamment dans les régions Australes, se caractérise par d'importantes fluctuations induites par les processus à mésoéchelle (tourbillons, 100-200km) et à sous-mésoéchelle (filaments, <50km). Ces processus sont connus pour stimuler fortement le développement du phytoplancton et avec lui l'ensemble de la chaine trophique. Toutefois les relations entre la distribution des proies et celle des prédateurs sont encore loin d'être bien connues pour la plupart des espèces marines. C'est en particulier le cas pour l'éléphant de mer austral (EDM) dont les proies souvent localisées à grandes profondeurs. Cette thèse s’est intéressée à étudier comment le comportement de plongée et de chasse des EDM est influencé par les variations à fine échelle de l'environnement. Une des originalités de cette thèse a été d’utiliser les mesures à très haute résolution récoltées par les éléphants de mer qui constituent un jeu de données 3-D in-situ unique à sous-mésoéchelle, puis de les combiner aux mesures satellites plus classiques de température et d'altimétrie. Ce travail a montré, pour la première fois à l’aide de données in-situ très haute résolution, l’importance des zones frontales à sous-mésoéchelle dans le comportement alimentaire d’un prédateur supérieur. De plus, elle a permis le développement d’une méthode originale d’identification des zones frontales à fine échelle et confirmé la pertinence de la méthode Quasi-Géostrophique de Surface (SQG) dans l’étude de la dynamique fine échelle, notamment dans les perspectives des futures missions spatiales à hautes résolutions (de type SWOT)
Ocean dynamics, especially in the southern ocean, are caracterized by strong fluctuation due to mesoscale (eddies, 100-200km) and submesoscale (filaments, <50km) processes. Theses processes are known to strongly stimulate primary production and with him the rest of the trophic chain. However, in marine ecosystems, relationship between prey and predator distribution remain challenging to understand. Such complexe link exist within the Southern Elephant Seal (SES) and their deep diving prey.This PhD worked to understand how the SES diving and foraging behaviour is impacted by submesoscale variation of the environment. Two original aspects of this work was first to use the very high resolution measurement from SES as an unique 3-D in-situ submesoscale dataset and then to combine it to, more classic, satellite temperature and altimetry measurement. This work showed, for the first time the in-situ impact of submesoscale frontal regions on one top predator foraging behaviour. Furthermore, during this study, an original method to identify fine scale frontal regions was developped. Finally, this PhD confirm the relevant use of the Surface Quasi-Geostrophic method in the study of fine scale dynamics, especially in the possibility of high resolution spatial missions (such as SWOT)

The establishment of seedling regeneration is a key process in and indicator of ecologically sustainable forest management. The availability of seed and the creation of a suitable seedbed are recognised as important factors limiting seedling recruitment. A silvicultural method commonly used across northern and eastern jarrah forest blocks is shelterwood cutting. The primary objective of treating jarrah forest to shelterwood is to promote seedling regeneration in areas lacking sufficient advanced growth. Despite the widespread and progressive implementation of the shelterwood method, its application in jarrah forest has shown varying degrees of success. This thesis sought to investigate and better understand the roles of seed supply and seedbed condition in promoting successful seedling regeneration in shelterwood-treated jarrah forest. It addressed two questions from an ecological and management perspective. Firstly, could adequate seed supply and favourable seedbed conditions be effectively managed and produced in shelterwood-harvested coupes? Secondly, could adequate seed supply and suitable seedbed conditions be reliably produced to facilitate successful seedling regeneration following disturbance events, in this case post-harvest burning? A major effort was dedicated to developing a more accurate and practical method of assessing seed crops in individual trees. The final model produced a high degree of predictability (R² = 0.85), while still maintaining a high level of practicality for field application, with three easily measured variables being used (stem diameter combined with subjective assessments of capsule clump density and capsule clump distribution). The refined model dramatically improved estimates of crown capsule numbers from the previous model, with the R² value increasing from 0.29 to 0.85. The second major focus of the study was to assess the capacity of prescribed burns, under mild conditions, to produce seedbed conditions suitable for regeneration. Low intensity prescribed burns resulted in the production of suitable conditions for seedling regeneration; that is, leaf litter and understorey vegetation were reduced and ash beds were created. Ash bed production was heterogeneous within sites. This heterogeneity has been attributed to the capacity of low intensity prescribed burns to account for fine-scale variations in fuel quantity, continuity and condition. Patterns of pre-burn aerial seed crop size and seed fall following low intensity prescribed burning were also assessed. Canopy capsule crops showed a high degree of spatial and temporal variability, both in terms of seed quantity and maturation. Such variability has been attributed to individual trees or groups of trees responding differently to localised climatic events and/or interspecific site factors at each stage of the flowering cycle. The main source of this variability was shown to be the numbers and spatial distribution of super trees; that is, trees defined as having a stem diameter >60 cm and >20 000 capsules. The average rate of seed fall increased substantially following prescribed burning under mild conditions. Postharvest burning under the mild conditions of the current survey did not result in en masse seed fall. Rather, peaks in seed fall were observed in the first few weeks post-burn, followed by low level falls throughout the following year. Sites burnt in spring showed a higher and more consistent release of seed in the first few weeks following fire, whereas seed fall after autumn burning was more sporadic. The comparative and interactive roles that seed supply and seedbed conditions play in limiting recruitment of jarrah were also studied. Low seedling densities were recorded across all six burnt study sites. The fact that ample levels of post-burn seed fall produced such low seedling numbers suggested that adequate seed supply did not coincide with seedbed conditions suitable for mass seedling regeneration. Conditions favourable for seedling recruitment were highly variable within sites, since both seed supply and seedbed conditions were spatially heterogeneous. Fine-scale areas burnt to mineral soil showed an additive influence to the overwhelmingly dominant factor of seed supply on seedling recruitment. However, the capacity of low intensity burns to produce these seedbed conditions at a broad scale is limited. Results of this study suggest that successful stocking of shelterwood-treated jarrah forest is not always achievable following a disturbance event, such as post-harvest burning under mild conditions. The chances of a large seed supply coinciding with broad-scale seedbed conditions favourable for mass germination, emergence and establishment appear to be low. Successful stocking of shelterwood-treated jarrah forest is more likely to be a longer term outcome achieved through episodic recruitment, when favourable environmental conditions coincide with optimal seedbed conditions. Such episodic recruitment strategies may be common in resource-limited systems such as jarrah forest and other dry eucalypt forest systems, where conditions controlling the regeneration niche are often variable and unpredictable.

[Truncated abstract] Recovery of soil nutrients, microbial populations and carbon (C) and nitrogen (N) cycling processes are critical to the success of rehabilitation following major ecosystem disturbance. Bauxite mining represents a major ecosystem disturbance to the jarrah (Eucalyptus marginata) forest in the south-west of Western Australia. Mining has created a mosaic of mined areas in various stages of succession surrounded by non-mined forest areas. Initial site preparations within rehabilitation areas such as contour ripping alter soil structure (creation of mound and furrows) and over time also influence the distribution of vegetation and litter. Current performance criteria developed by industry, government and other stakeholders have determined that before post-bauxite mined areas of jarrah forest can be integrated back into normal forest management practises they should be functional and demonstrate resilience to normal forest disturbances such as fire. Furthermore, resilience should be of a manner comparable to non-mined analogue forest sites. Currently little is known of the resilience of microbial communities and C and N cycling in rehabilitation sites to normal forest disturbances such as prescription burning. As such, before rehabilitated jarrah forests can be successfully integrated into broad scale forest management regimes, a more thorough knowledge of the potential impacts of burning practises on the soil microbial community and C and N cycling processes in these systems is required. ... While there are similar rates of C and N cycling the underlying microbial community structure was distinctly different; implying a high degree of functional redundancy with respect to C and N cycling. Differences in the C and N cycling and structure of the microbial communities were likely to be due to differences in soil environmental conditions (i.e. soil alkalinity/acidity, soil moisture) and C substrate availability which influence the physiological status of the microbial community and in turn are related to successional age of the forests. Results also suggest that the measurement of CLPP can be a useful approach for assessment of changes in the functional ability of microbial communities. However, the interpretation of how well these rehabilitation forests have recovered heterotrophic abilities was greatly affected by the methodological approach used (e.g. MicroRespTM or Degens and Harris, 1997). Importantly, results from Chapter 4 and 5 suggested that the effects of a moderate prescription fire on C and N processes, CLPP and microbial community structure of 18 year old rehabilitation forests are likely to be short-lived (< 2 years). Furthermore, the effects of the moderate spring prescription fire were not large enough to decouple C and N cycling processes over the short-term (< 1 years) which suggests that by 18 years of age rehabilitation forests demonstrate comparable functional resilience to a moderate prescription burn.

[Truncated abstract] In southern Australian farming systems the replacement of deep-rooted perennial native vegetation with shallow-rooted annual crops and pastures has resulted in rising groundwater tables and an increased incidence of dryland salinity. It has been suggested that to address this issue by restoring hydrological balance, large areas of agricultural land need to be vegetated with perennial plants. One of the most agriculturally productive ways to do this is to introduce perennial pastures, both into upslope groundwater

This thesis investigates the process of habitat fragmentation and the spatial and temporal scales at which it occurs. Fragmentation has become an important topic in biogeography and conservation biology because of the impacts it has upon species??? distributions and biodiversity. Various definitions of fragmentation are available but in this research it is considered to be the disruption of continuity, either natural or human-induced in its origins and operative at multiple spatial scales. Using the distribution of the southern brown bandicoot Isoodon obesulus as a case study, three spatial scales of fragmentation were analysed. At the continental scale, the Australian distribution of the subspecies I. o. obesulus was examined in relation to climate, geology and vegetation cover at the time of European settlement of Australia and two centuries later. Using archived wildlife records and Geographic Information Systems (GIS) analyses, habitat suitability models were created to assess natural and human-induced fragmentation of the distribution of I. obesulus in 1788 and 1988. At the regional scale, a study was made of the distribution of I. obesulus in the south-east of the State of South Australia. Again, natural and human-induced patterns of habitat fragmentation were modelled using GIS with climate, soil and vegetation data for the time of European settlement and at present. At the local scale, the distribution of I. obesulus was the subject of a detailed field survey of 372 sites within 29 remnant patches of native vegetation in south-eastern South Australia in order to understand the variables that cause habitat fragmentation. Geographic information systems were used again but in a different way to carefully stratify the field survey by overlaying maps of topography, vegetation and past fires. The large dataset collected from the surveys was described using six generalized linear models which identified the significant variables that fragment the distribution of I. obesulus at a local scale. From the results of the field surveys, a subset of four remnants was chosen for further GIS spatial modelling of the probability of I. obesulus occurring within remnants in response to fire via a controlled burning programme put in place to reduce accumulating fuel loads. These investigations show that habitat fragmentation can be caused by different factors at different spatial scales. At the continental scale, it was found that climate played a dominant role in influencing the fragmented distribution of I. obesulus but vegetation change during the past two centuries has also had a profound impact on the availability of habitat. Within south-eastern South Australia, the species??? regional scale distribution is constrained by climate and also by soil and vegetation patterns. Dramatic change to its regional distribution occurred in the 20th century as a result of the clearance of native vegetation for planting pastures, crops and pines. Fragmentation at the regional scale has resulted in the remaining habitat being reduced to small, isolated, remnant patches of native vegetation. At the local scale it was found that variables which disrupt the continuity of I. obesulus habitat within remnants include vegetation cover in the 0-1 m stratum, abundance of Xanthorrhoea australis and soil texture. For a subset of sites located in one landsystem of the study area, named Young, the age of vegetation since it was last burnt was also found to be a significant variable, with vegetation 10-14 years old since burning providing the most suitable habitat. Spatial modelling of two scenarios for prescribed burning over 15 years revealed that the use of fire as a habitat enhancement tool will be complicated and require a detailed understanding of the factors that cause natural fragmentation in the distribution of I. obesulus at the local scale. A further conclusion of the study was that ecological relationships between species and their habitats require careful interpretation of multi-scaled datasets and conservation plans for endangered species ought to be made at multiple spatial scales. Future research directions are identified including the linking of multi-scaled habitat fragmentation models to genetic studies of the species throughout its range.

The northern savannas are one of the largest biomes in Australia, extending across northern and north-eastern Australia, and its vegetation has been extensively altered as a result of pastoralism and inappropriate fire regimes following the loss of indigenous fire management (Fraser, 2001; Legge et al., 2019). Small-medium sized mammals and granivorous birds are the most at-risk taxonomic groups (Franklin, 1999; Franklin et al., 2005; Murphy et al., 2010; Woinarski et al., 2010; Woinarski et al., 2013), and this has largely been attributed to unsuitable fire management, predation by feral cats, grazing by introduced herbivores, cane toads and invasive grasses (Fraser, 2001; Legge et al., 2019; Woinarski et al., 2010). The Partridge Pigeon (Geophaps smithii) is a granivorous bird species endemic to the northern savannas of Australia and has faced major declines disappearing from half of its pre-European distribution (Davies et al., 2019; Franklin, 1999; Fraser et al., 2003), largely due to changes in burning regimes, grazing by exotic herbivores and predation by feral cats. As a result, the Partridge Pigeon is an excellent model species for examining savanna management practices (Davies et al., 2019; Fraser et al., 2003). The aims of this study were: 1) to quantify the changes in the distribution of G. s. blaauwi over time; 2) to assess these changes against IUCN criteria to re-evaluate the species’ current conservation status; 3) to determine the land tenure across the species’ current distribution to evaluate the importance of Indigenous owned and managed lands in the protection of this species; 4) to understand habitat selection of G. s. blaauwi and the influence of fire regimes on habitat selection at landscape scales; 5) and lastly to understand the influence of fine-scale variables on G. s. blaauwi habitat selection. Following my analysis of the changes of G. s. blaauwi range over time I determined that it should still be classed as Vulnerable based on IUCN criteria but recommended that more surveys be undertaken to better assess the poorly surveyed areas of their distribution. Analysis of land tenure indicated that this species mostly occurs on Native Title land (93%) and in areas under Indigenous Protected Areas management (49%). I highlight the importance of Indigenous owned and managed lands for protection of G. s. blaauwi and emphasises the critical role IPA and conservation areas may play in the protection of biodiversity and threatened species in Australia. Next, I was able to determine that the most important geological and vegetation structures for G. s. blaauwi are woodland and open woodland areas that occur on alluvium and colluvium. This allowed me to develop a clear conceptual model of what habitats and fire management practices are required to support G. s. blaauwi populations. Lastly, my investigations of fine-scale habitat variables found none of the assessed variables influenced G. s. blaauwi site occupancy.

Termites are considered to be major ecosystem engineers in tropical and sub-tropical environments, and fire in savanna systems is regarded as a major and necessary disturbance for the maintenance of biodiversity. However, most fire ecology studies have focused on vegetation dynamics with little attention given to other taxa, especially invertebrates. This thesis has addressed several aspects of savanna termite ecology. First, based on a review of studies examining the relationship between fire ecology and termites, I found that few broad conclusions can be made based on the published literature. Hence little is known on the interactions between termites and ecological processes such as fire. Leading on from this, several recommendations are provided in the thesis for future research to improve ecological understanding of savannas and the dynamics that structure these systems. Second, savanna termite responses to long-term burning regimes were investigated across four distinct savanna types along a rainfall gradient in South Africa using comprehensive sampling protocols. This was achieved using experimental burning plots which have been in place in the Kruger National Park (KNP) since 1954 as well as sites in Hluhluwe-iMfolozi Park. Termite communities were found to differ significantly between these savannas with higher diversity at Pretoriuskop, a mesic savanna but not the wettest. Termite diversity was lowest at the most arid site (Mopani) but certain feeding groups peaked at Satara, a savanna with intermediate rainfall. Differences between these savannas are attributed to broad underlying changes in net primary productivity, temperature and soil type, with the role of mammalian herbivores also being considered. Seasonality was also examined and it was found that termite activity peaks in the wet and transitional seasons and is significantly lower in the dry season. Considering different fire regimes, termites, in general, were found to be highly resistant to burning, but assemblage composition was affected, this being more pronounced at the mesic savanna where fire has more effect on vegetation. These assemblage changes are linked to changes in vegetation structure caused by fire. Finally, termite ecology is often constrained by sampling difficulties and a lack of sampling protocols in savannas. A comparison of two often used sampling methods, baiting and active searching, was conducted across the savanna types studied. The efficiency of sampling method varied along the rainfall gradient and a single method was not the best for all savanna types. In mesic savannas, active searching (an often neglected sampling method in savannas) was most effective at sampling termite diversity while baiting was more effective in arid savannas, although this method is biased toward wood-feeding termites from feeding group II. Baiting also provides a better measure of termite activity than active searching. I demonstrate that termite communities differ significantly with savanna habitat and their responses to long-term burning regimes differ between these habitat types. Although termite communities were found to be quite resistant to burning, the degree of resistance differed with savanna type and management policies in protected areas and elsewhere need to take this into account when formulating conservation policies. Similarly, sampling methods differ in their efficiency at different sites which needs to be considered when designing sampling protocols in order to accurately reflect the biodiversity present.
Dissertation (MSc)--University of Pretoria, 2010.
Zoology and Entomology
unrestricted

"September 2002" Bibliography: leaves 77-85. Examines the persistence of the yellow-footed antechinus using live trapping in small, remnant patches and strips of forest, to document autecological sata and the investgate occurrence, breeding activity and inter-patch movements. Radio-tracking was conducted to compare home range properties of lactating females in restricted and unrestricted habitat.

The savannas of southern Africa are a highly variable and globally-important biome supporting rapidly-expanding human populations, along with one of the greatest concentrations of wildlife on the continent. Savannas occupy a fifth of the earth's land surface, yet despite their ecological and economic significance, understanding of the complex couplings and feedbacks that drive spatiotemporal patterns of change are lacking. In Chapter 1 of my dissertation, I discuss some of the different theoretical frameworks used to understand complex and dynamic changes in savanna structure and composition. In Chapter 2, I evaluate spatial drivers of water quality declines in the Chobe River using spatiotemporal and geostatistical modeling of time series data collected along a transect spanning a mosaic of protected, urban, and developing urban land use. Chapter 3 explores the complex couplings and feedbacks that drive spatiotemporal patterns of land cover (LC) change across the Chobe District, with a particular focus on climate, fire, herbivory, and anthropogenic disturbance. In Chapter 4, I evaluated the utility of Distance sampling methods to: 1) derive seasonal fecal loading estimates in national park and unprotected land; 2) provide a simple, standardized method to estimate riparian fecal loading for use in distributed hydrological water quality models; 3) answer questions about complex drivers and patterns of water quality variability in a semi-arid southern African river system. Together, these findings have important implications to land use planning and water conservation in southern Africa's dryland savanna ecosystems.
Ph. D.

At Cape Gantheaume, Kangaroo Island (South Australia), adult male, lactating female and juvenile New Zealand (NZ) and Australian fur seals regularly return to the same colony, creating the potential for intra- and inter-specific foraging competition in nearby waters. I hypothesised that these demographic groups would exhibit distinct foraging strategies, which reduce competition and facilitate their coexistence. I analysed the diet of adult male, adult female and juvenile NZ fur seals and adult male Australian fur seals and studied the diving behaviour of adult male and lactating female NZ fur seals and the at-sea movements of juvenile, adult male and lactating female NZ fur seals. Female diet reflected that of a generalist predator, influenced by prey availability and their dependant pups� fasting abilities. In contrast, adult male NZ and Australian fur seals used larger and more energy-rich prey, most likely because they could more efficiently access and handle such prey. Juvenile fur seals primarily utilised small lantern fish, which occur south of the shelf break, in pelagic waters. Juveniles undertook the longest foraging trips and adult males conducted more lengthy trips than lactating females, which perform relatively brief trips in order to regularly nurse their pups. Unlike lactating females, some adult males appeared to rest underwater by performing dives that were characterised by a period of passive drifting through the water column. The large body sizes of adult males and lactating females facilitated the use of both benthic and pelagic habitats, but adult males dived deeper and for longer than lactating females, facilitating vertical separation of their foraging habitats. Spatial overlap in foraging habitats among the age/sex groups was minimal, because lactating females typically utilised continental shelf waters and males used deeper water over the shelf break, beyond female foraging grounds. Furthermore, juveniles used pelagic waters, up to 1000 km south of the regions used by lactating females and adult males. The age and sex groups in this study employed dramatically different strategies to maximise their survival and reproductive success. Their prey and foraging habitats are likely to be shaped by body size differences, which determine their different physiological constraints and metabolic requirements. I suggest that these physiological constraints and the lactation constraints on females are the primary factors that reduce competition, thereby facilitating niche partitioning.

Assemblages of algae are altered by both bottom - up ( e.g. nutrient availability ) and top - down ( e.g. herbivory ) processes. As a result of the increasing human population in coastal areas, massive changes are forecast to benthic habitats in response to increasing coastal nutrient concentrations and a reduction in consumers. To identify the scales over which nutrients may have an effect, abundance of turf - forming algae growing as epiphytes on kelp ( Ecklonia radiata ) were related to water nutrient concentration across temperate Australia. In general, the percentage cover of epiphytes was greatest at sites with the greatest nutrient concentrations. By experimentally elevating mean nitrate concentration from the low 0.064 ± 0.01 µmol L [superscript - 1 ] to 0.121 ± 0.04 µmol L [superscript - 1 ], which was still only ~ 5 % of that measured on a more eutrophic coast, I was able to increase the percentage cover of epiphytes to match those seen on nutrient rich coasts, despite not matching the nutrient concentrations on those coasts. Hence, it appears that the effects of elevated nutrients will be disproportionately large on relatively oligotrophic coasts. Nutrient concentrations were also experimentally elevated to test whether the presence of an algal canopy or molluscan grazers were able to counter the effects of nutrient enrichment on algal assemblages. The loss of canopy - forming algae is likely to be a key precursor to nutrient driven changes of benthic habitats, because nutrients had no direct effect on algal assemblages in the presence of canopy - forming algae. In the absence of canopy - forming algae, space was quickly monopolised by turf - forming algae, but in the presence of elevated nutrients grazers were able to reduce the monopoly of turf - forming algae in favour of foliose algae. This switch in relative abundance of habitat may reflect greater consumption of nutrient rich turf - forming algae by grazers, possibly creating more space for other algae to colonise. Importantly, greater consumption of turf - forming algae in the presence of elevated nutrients may act as a mechanism to absorb the disproportionate effect of nutrients on oligotrophic coasts. In southern Australia, canopy - forming algae have a negative impact on the abundance of turf - forming algae. To assess the mechanisms by which an algal canopy may suppress turf - forming algae, abrasion by the canopy and water flow were experimentally reduced. Abrasion by the canopy reduced the percentage cover and biomass of turf - forming algae. In contrast to predictions, biomass and percentage cover of turf - forming algae were also reduced when water flow was reduced. Light intensity was substantially reduced when there was less water flow ( because of reduced movement in algal canopy ). However, the reduction in available light ( shading ) did not account for all of the observed reduction in biomass and percentage cover of turf - forming algae, suggesting that other factors are modified by water flow and may contribute to the loss of turf - forming algae. Habitat loss and fragmentation are well known to affect the diversity and abundance of fauna in habitat patches. I used experimental habitats to assess how fragmentation of turf habitats affects the diversity and abundance of two taxa of macroinvertebrates with different dispersal abilities. I established that increased isolation of habitats reduced the species richness and abundance of invertebrates with slow rates of dispersal, while the species richness and abundance of invertebrates with fast rates of dispersal were greatest in habitats that were far apart. In summary, this thesis provides an insight into some of the impacts associated with human populations in coastal areas, namely increased nutrient inputs, loss of grazers ( e.g. harvesting ), and loss of canopy algae and fragmentation of habitats. I show that increased nutrient concentrations in coastal waters can alter the relative abundance of algal species, and that some effects of elevated nutrients can be absorbed by the presence of grazers. I also show that elevated nutrients have no effect on algal assemblage in the presence of canopy - forming algae, and that canopies can suppress the colonisation of turf - forming algae. Finally, I show that the fragmentation of turf habitats affects taxa of invertebrates with different dispersal abilities in different ways. Whilst the contemporary ecology of much of the temperate Australian subtidal coast is considered to be relatively unaffected by human activity, this thesis shows that changes to top - down and bottom - up processes could have large consequences for habitats and their inhabitants.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Assemblages of algae are altered by both bottom - up ( e.g. nutrient availability ) and top - down ( e.g. herbivory ) processes. As a result of the increasing human population in coastal areas, massive changes are forecast to benthic habitats in response to increasing coastal nutrient concentrations and a reduction in consumers. To identify the scales over which nutrients may have an effect, abundance of turf - forming algae growing as epiphytes on kelp ( Ecklonia radiata ) were related to water nutrient concentration across temperate Australia. In general, the percentage cover of epiphytes was greatest at sites with the greatest nutrient concentrations. By experimentally elevating mean nitrate concentration from the low 0.064 ± 0.01 µmol L [superscript - 1 ] to 0.121 ± 0.04 µmol L [superscript - 1 ], which was still only ~ 5 % of that measured on a more eutrophic coast, I was able to increase the percentage cover of epiphytes to match those seen on nutrient rich coasts, despite not matching the nutrient concentrations on those coasts. Hence, it appears that the effects of elevated nutrients will be disproportionately large on relatively oligotrophic coasts. Nutrient concentrations were also experimentally elevated to test whether the presence of an algal canopy or molluscan grazers were able to counter the effects of nutrient enrichment on algal assemblages. The loss of canopy - forming algae is likely to be a key precursor to nutrient driven changes of benthic habitats, because nutrients had no direct effect on algal assemblages in the presence of canopy - forming algae. In the absence of canopy - forming algae, space was quickly monopolised by turf - forming algae, but in the presence of elevated nutrients grazers were able to reduce the monopoly of turf - forming algae in favour of foliose algae. This switch in relative abundance of habitat may reflect greater consumption of nutrient rich turf - forming algae by grazers, possibly creating more space for other algae to colonise. Importantly, greater consumption of turf - forming algae in the presence of elevated nutrients may act as a mechanism to absorb the disproportionate effect of nutrients on oligotrophic coasts. In southern Australia, canopy - forming algae have a negative impact on the abundance of turf - forming algae. To assess the mechanisms by which an algal canopy may suppress turf - forming algae, abrasion by the canopy and water flow were experimentally reduced. Abrasion by the canopy reduced the percentage cover and biomass of turf - forming algae. In contrast to predictions, biomass and percentage cover of turf - forming algae were also reduced when water flow was reduced. Light intensity was substantially reduced when there was less water flow ( because of reduced movement in algal canopy ). However, the reduction in available light ( shading ) did not account for all of the observed reduction in biomass and percentage cover of turf - forming algae, suggesting that other factors are modified by water flow and may contribute to the loss of turf - forming algae. Habitat loss and fragmentation are well known to affect the diversity and abundance of fauna in habitat patches. I used experimental habitats to assess how fragmentation of turf habitats affects the diversity and abundance of two taxa of macroinvertebrates with different dispersal abilities. I established that increased isolation of habitats reduced the species richness and abundance of invertebrates with slow rates of dispersal, while the species richness and abundance of invertebrates with fast rates of dispersal were greatest in habitats that were far apart. In summary, this thesis provides an insight into some of the impacts associated with human populations in coastal areas, namely increased nutrient inputs, loss of grazers ( e.g. harvesting ), and loss of canopy algae and fragmentation of habitats. I show that increased nutrient concentrations in coastal waters can alter the relative abundance of algal species, and that some effects of elevated nutrients can be absorbed by the presence of grazers. I also show that elevated nutrients have no effect on algal assemblage in the presence of canopy - forming algae, and that canopies can suppress the colonisation of turf - forming algae. Finally, I show that the fragmentation of turf habitats affects taxa of invertebrates with different dispersal abilities in different ways. Whilst the contemporary ecology of much of the temperate Australian subtidal coast is considered to be relatively unaffected by human activity, this thesis shows that changes to top - down and bottom - up processes could have large consequences for habitats and their inhabitants.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

The disruption of natural fire regimes has threatened animal species in many ecosystems around the world. A combination of prescribed burning and fire suppression is often used to promote successional variation in vegetation (i.e. fire mosaics), with little knowledge of how this will affect animal persistence. Understanding the processes that govern species responses to fire regimes is essential to build a predictive capacity for ecological fire management. I examined life-history, demographic (survival, reproduction and mortality) and dispersal attributes of reptiles to investigate mechanisms of fire responses in reptiles. I studied reptiles in conservation reserves of semi-arid southern Australia dominated by mallee vegetation (multi-stemmed Eucalyptus spp. with a shrubby understory). An introduction describes the ecological and management context of my research (Chapter 1). A community-level framework was used to determine if a generalised model of fire responses could be developed based on traits shared by groups of species (Chapters 2-3). I found a number of fire responses in reptiles that were previously undetected in analyses of smaller, but substantial subsets of the same data (Chapter 2). Nocturnal burrowers tended to be early-successional, while diurnal leaf-litter dwellers tended to be late successional, but a trait-based model of succession had limited power to describe responses among the community. I also documented some observations that suggested non-burrowing reptiles were more vulnerable to mortality during wildfire than burrowers (Chapter 3). A species-level framework was then used to examine variation in demographic and dispersal attributes within species among different post-fire successional stages (Chapters 4-7). These studies focussed on three species with significant and contrasting responses to fire: Amphibolurus norrisi (Agamidae; mid/late successional species), Ctenotus atlas (Scincidae; late successional) and Nephrurus stellatus (Gekkonidae; early/mid successional). Using mark-recapture modelling (Chapter 4), I described changes in abundance of N. stellatus that incorporated detectability, and showed that variation in survival and fecundity are possible drivers of this species strong population response to fire. Microsatellite DNA data were then used to examine gene flow in the three target species and gain insights into the effects of fire on dispersal. Chapter 5 begins this section with a description of the markers I used to generate the genetic data. I then used spatial models of landscape resistance to assess the importance of post-fire succession and other landscape features (e.g. topography) on gene flow in the three species (Chapters 6 and 7). For N. stellatus these analyses were combined with direct observations of movement (Chapter 6). Results showed that long-unburnt vegetation restricts dispersal in N. stellatus, which may result from, or contribute to its decline in population density with increasing time since fire. In Chapter 7 I found that fire affected gene flow in A. norrisi, but not in C. atlas, while genetic diversity in both species was affected by post-fire succession. My thesis demonstrated how examining demographic and dispersal attributes of reptiles can give insights into the mechanisms underlying species responses to fire. I concluded by providing management recommendations and highlighting key points for future research on fire ecology (Chapter 8). -- provided by Candidate.

Fire ecology encompasses the study of the factors, biotic and abiotic, that influence the occurrence of fire in an area, as well as the effects fire has on the flora and fauna native and non-native to the region (Whelan 1995). Fire has had a major influence on shaping biomes as we see them today. Fire has had an effect on vegetation much before the evolution of Homo on Earth (Keeley and Rundel 2005, Pausas and Keeley 2009, Midgley and Bond 2011). With the evolution and expansion of Homo across Earth, fire has been tamed, and then generated and used over time to yield landscapes that were suitable for their existence (Pyne 1991, Bowman et al. 2009, Archibald et al. 2012). Thus, fire, vegetation and humans were, and still are, inextricably linked in certain biomes on Earth. The best examples are observed in tropical savannas and grasslands, biomes that experience distinct seasonality in climate and are thus prone to frequent fires caused either by lightning or by humans (Keeley and Rundel 2005, Archibald et al. 2012). At the other end of the spectrum of tropical vegetation types are rainforests where the occurrence of fires is constrained by a perpetually moist environment (Meyn et al. 2007, van der Werf et al. 2008), in the absence of manipulation of the forest landscape by humans. Frequent fires have been documented to alter structure and cause a decline in forest diversity in rainforests (Cochrane and Schulze 1999, Cochrane 2003), whereas fire exclusion in mesic savannas leads to increases in biomass and transition to forest ecosystems (Bond et al. 2003, Bond et al. 2005 and references therein). A tropical biome that lies between these two extremes of vegetation types is the Seasonally Dry Tropical Forest (SDTF) where the occurrence of fire is common, but for which there are contrasting views on the effect of fire on this system (Saha and Howe 2003, Otterstrom et al. 2006 as examples). Current forest management policies in SDTF areas, especially in India, actively aim to exclude fire from these forests mostly because of the perception held by forest managers and the general public that fire has negative effects on forests. However, very few scientific studies have explored the ecology of fire in SDTFs. In order to formulate fire management policies, it is necessary to have a more comprehensive understanding of the ecology of fire in this tropical forest type. This thesis addresses two components of fire ecology as applied to SDTFs. The first is how fire is influenced by the environment, and the second, how fires influence the biotic community particular to SDTFs. The study was carried out in an SDTF in southern India where fire is a common occurrence -the forests of Mudumalai – a protected area that exhibits a range of SDTF vegetation types, from moist deciduous to dry thorn forest, corresponding to a rainfall gradient. Fire influenced by the environment: For this section, the influence of fuel load, fuel moisture and ambient weather on area burnt, fire occurrence and fire temperatures were studied in the SDTF vegetation types of Mudumalai. The extent of fire (area burnt) in an ecosystem differs according to the relative contribution of fuel load and fuel moisture available (Meyn et al. 2007). At a global scale, these factors vary along a spatial gradient of climatic conditions and are thus “varying constraints” (Krawchuk and Moritz 2011) on fire activity in natural ecosystems (Meyn et al. 2007, Krawchuk and Moritz 2011). Moist ecosystems such as tropical rainforests are at one end of the spectrum where fire activity is constrained by fuel moisture. At the other end are arid ecosystems, such as deserts, where fire activity is limited by the presence of fuels. The potential for the globally widespread seasonally dry tropical forests (SDTFs) to be placed as a single entity in this framework was examined by analyzing the interacting effects of fuel load and fuel moisture on the extent of fire in Mudumalai. Logistic regression was used to model proportion area burnt in a given year with factors that would influence fuel load and fuel moisture – these were proportion area burnt the previous year, wet season rainfall the previous year and early dry season rainfall. Modelling was conducted at two levels – the overall landscape and within four defined moisture regimes (between 700 and 1700 mm yr-1) – using a dataset of area burnt and seasonal rainfall from 1990 to 2010. The landscape scale model showed that the extent of fire in a given year within this SDTF is dependent on the combined interaction of seasonal rainfall and extent burnt the previous year. However, within individual moisture regimes the relative contribution of these factors to the annual extent burnt varied – early dry season rainfall (i.e. a moderator of fuel moisture) was the predominant factor in the wettest regime, while the previous year’s wet season rainfall (i.e. a proxy for fuel load) had a large influence on fire extent in the driest regime. Thus, the diverse structural vegetation types associated with SDTFs across a wide range of rainfall regimes would have to be examined at finer regional or local scales to understand the specific environmental drivers of fire. While the extent burnt in SDTFs is largely dependent on climatic influences, the probability of ignition has not been characterized for SDTFs. Anthropogenic fires are a regular occurrence during the dry season in SDTFs (Stott et al. 1990). We investigated if the occurrences of anthropogenic fire in Mudumalai were associated with any particular weather conditions during the dry season. Logistic regression between probability of a fire day and weather variables -seasonal rainfall, ambient relative humidity and temperature -was examined during the dry seasons of 20042010 in Mudumalai. Fire incidence data was obtained from the Fire Information for Resource Management System (FIRMS; NASA 2002) and weather data from two automatic weather stations within Mudumalai. The analysis showed that days with high probabilities of fire occurrence were associated with low levels of early dry season rainfall, low daily average relative humidity, and high daily average temperatures. These weather conditions are known to influence moisture levels of fine fuels (Viney 1991, Archibald et al. 2009). In Mudumalai as well as other SDTFs the primary fuels for fires are fine fuels such as litter and dried grass that accumulate on the forest floor during the dry season. Our results suggest that the occurrence of fire is moderated by environmental conditions that reduce or enhance the flammability of fine fuels in the dry tropics. A quantitative framework for assessing risk of a fire day has been proposed as an outcome of this analysis to assist forest managers in anticipating fire occurrences in this SDTF, and possibly for those across south Asia. Of the various components of a fire regime, fire intensity is an important aspect. High fire temperatures (one measure of fire intensity, Keeley 2009) and resulting soil temperatures would have an effect on soil properties as well as plant species demography and community structure (Moreno and Oechel 1991, Neary et al. 1999, Morrison 2002). Fires that occur frequently in a region could vary in their intensity and severity depending upon the amount of fuel available and ambient weather conditions (Stinson and Wright 1969, Stott 1986, Stronach and McNaughton 1989, Ansley et al. 1998, Wotton et al. 2012). However, this relationship has not been examined in a multiple regression framework for SDTFs. Fire temperature was recorded and its relationship with ambient weather and fuel load was studied in two SDTFs of southern India -Mudumalai and Biligiri Rangaswamy Temple (BRT) Wildlife Sanctuary in Karnataka. During “controlled burns” conducted by the forest department staff in these reserves in February and March 2010, temperature indicating lacquers on mica sheets were used to measure fire temperature at several points at ground level and one cm below the ground. Biomass was harvested close to the temperature measurement points to estimate fuel load and fuel moisture. Ambient weather conditions were recorded during the controlled burn when the flame passed over the indicators. Temperatures recorded at ground level ranged from <79oC to 760oC, with the most frequently recorded temperatures between 343-399 oC and 510566 oC. Temperatures measured one cm below the ground ranged from <79oC to 302oC, with a majority of the indicators recording temperatures in the <79oC category. Ground-level temperatures increased with increasing biomass. A linear regression of ground-level temperatures with fuel load and ambient weather conditions of relative humidity and temperature was found to explain most of the variation in the data. Ground-level fire temperatures increased with increasing fuel load, but were also found to be lower at higher relative humidities at a given temperature. In order to reduce the intensity of forest fires that occur accidentally during the dry season, we recommend that fuel loads be reduced in the forest by prescribed burning early in the dry season. This applies especially to areas where there is accumulation of biomass over years, such as that of the tall grass Themeda cymbaria found predominantly in dry deciduous forest types. If prescribed burning is incorporated in fire management policies for these forests, then the season of burning will be important to consider. It is known from ecosystems where prescribed burning is regularly applied that early dry season fires are less intense than late dry season fires (Williams et al. 1998). However, this has not been systematically investigated for SDTFs. Through a burning experiment carried out in private land with vegetation type similar to tropical dry thorn forest, we investigated differences in area burnt, ground-level fire temperatures and soil temperatures one cm below the ground in the early dry season in January, late dry season in April and and early wet season in June. We also examined differences in fuel load, fuel moisture, soil moisture and weather conditions of ambient relative humidity (RH), temperature and wind speed in these phases; these factors could be responsible for observed differences in fire and soil temperatures or area burnt. Although area burnt was not significantly different between the early and late phases of the dry season, fire and soil temperatures were significantly lower in the former. The late dry season was characterized by distinctly higher fuel loads, lower fuel moisture, lower relative humidity, higher ambient temperatures and higher wind speeds compared that measured in the early dry season. Differences in soil temperature between these months may be attributed to the increase in fuel load since there were no significant differences in soil moisture. Fire spread was limited in the experimental plots in the early wet season in June, probably due to significantly higher levels of fuel moisture in this month; the resultant fire and soil temperatures recorded were low. Forest management should, therefore, consider early dry season burns in the month of January for prescribed burns in the sanctuary, although this would have to be tested in other SDTF vegetation types with more variable fuel load, fuel moisture and weather conditions. Fire’s influence on the biotic community: Concerns regarding the regeneration capacity of woody species in SDTFs have been voiced with respect to increasing frequencies of fire (Saha and Howe 2006, Kodandapani et al. 2008). Fire is known to cause high mortality of individuals of small size (Swaine et al. 1990, Suresh et al. 2010). However, mortality has been examined for large size classes, and not for seedlings. It is essential to understand the dynamics of seedlings and their contribution to the regeneration potential of SDTFs. Woody species in SDTFs are known to have traits that help them recover from recurring disturbances, such as sprouting from underground root stocks (Vieira and Scariot 2006). Another trait may relate to growth rates of seedlings. Growth rates of seedlings (defined in this study as established individuals between 10 and 100cm height) after dry season (February-March) fires were compared between adjacent pairs of burnt and unburnt transects established at eight sites in Mudumalai across vegetation types of moist deciduous, dry deciduous and dry thorn forest. The growth of grasses, a possible competitor for resources, was also monitored at each site. Seedling and grass heights were monitored at 3-month intervals between August 2009 and August 2010. A second fire in March 2010 affected transects at two sites in Mudumalai. Seedling and grass heights were monitored for two enumerations till August 2010 subsequent to the second fire at these two sites. A total of 1032 individuals across 58 woody species were enumerated. High seedling survivorship (>95%) was observed in both burnt and unburnt areas. Although seedling heights were significantly different between burnt and unburnt areas at the start of the enumeration in August 2009, heights were comparable within a year and a half of the fire. Comparable seedling heights in such a short time span were because of distinctly higher growth rates of seedlings in burnt areas compared to unburnt areas after the fire event, particularly during the pre-monsoon season. Grass biomass (volume), on the other hand, was significantly different between burnt and unburnt areas at both the first and last enumerations. Grass growth (change in volume) did not differ between burnt and unburnt areas. Rapid growth by seedlings after a fire implies adaptation through the use of stored resources for growth, possibly aided by lower competition from grasses, in order to attain a certain size before the subsequent return of unfavourable factors such as a recurrent fire event. Conclusions: The results from the study point to climatically driven fire regimes in an SDTF in southern India, with daily influences of weather conditions during the dry season on fire occurrences. Fire intensities increase with increasing fuel loads in these forests, moderated by weather conditions such as RH and temperature. Since fires are an anthropogenic phenomenon in these forests, active management with the use of prescribed fires in the early phase of the dry season is a possible option to control late dry season fires that would be higher in intensity. The current woody tree species assemblage in this southern Indian SDTF is resilient to fires at the seedling stage, with established individuals exhibiting high survivorship and rapid growth after a fire. However, the effects of fires of varying intensities on the regenerative capacity of the seedlings are not known. The effect of fire on habitat utilisation by large herbivores, or the impact of fire on the faunal community in general has not been studied for vegetation types that comprise SDTFs. The effect of fire exclusion on the ecology of SDTFs will provide useful information that can feed into management policies for this ecosystem type. These are potential areas of research for the future. Fire, if managed wisely, can be an effective tool for the conservation of SDTFs across south and southeast Asia.

No - till systems have been widely adopted by farmers in Australia over the past decade to reduce soil erosion, improve soil physical and chemical properties, conserve soil moisture and save on fuel costs. These changes in tillage practices can have a major influence on the ecology and management of weeds. Studies were undertaken on the seed biology of six important Australian weed species to provide underpinning knowledge of their response to tillage. Field studies were also undertaken to investigate the effect of no - till on weed seedling emergence, seed bank persistence and herbicide behaviour. Seed germination of threehorn bedstraw and wild turnip, the latter only at sub - optimal temperatures, was inhibited by light. In contrast, seed germination of common sowthistle and Indian hedge mustard was stimulated by light. Seed germination of small - flowered mallow was not influenced by the light conditions. Seedling emergence of threehorn bedstraw, wild turnip, small - flowered mallow and annual ryegrass was low on the soil surface but increased with shallow burial, which suggests that farming practices that achieve shallow burial of seeds are likely to promote greater seedling emergence of these weed species. In contrast, seedling emergence of common sowthistle and Indian hedge mustard was greatest for the seeds present on the soil surface and emergence decreased with increased burial depth. In field experiments, low soil disturbance tillage systems left more seeds on the soil surface after crop sowing, whereas high soil disturbance systems buried most of the seeds. Seedling emergence of annual ryegrass, threehorn bedstraw and wild radish was greater under minimum tillage than no - till system. In contrast, seedling emergence of Indian hedge mustard, common sowthistle, silvergrass, small - flowered mallow and turnipweed was greater under the no - till system. Seedling emergence of wild oat and wild turnip was not influenced by the tillage system. Even though seedling emergence of annual ryegrass was much lower under no - till, the persistence of residual viable seeds of annual ryegrass from one season to the next was similar between the tillage systems. This was because of much greater seed decay under no - till ( 48 to 60 % ) than that recorded under minimum tillage ( 12 to 39 % ). All dinitroaniline herbicides ( trifluralin, pendimethalin and oryzalin ) were more effective in reducing the number of plants, spikes, dry matter and seed production of annual ryegrass when incorporated at sowing with tines than with the discs. At Minlaton in 2004 and 2005, bioavailable trifluralin was greater under tillage systems with greater levels of soil disturbance than under lower soil disturbance systems. In the absence of the herbicide, annual ryegrass was less competitive with wheat under the disc - sown systems. The response of grain yield to herbicides was greater under the tine - sown systems than the disc - sown systems. The performance of S - metolachlor on annual ryegrass control was investigated under no - till. The control of annual ryegrass was greater than 80 % when S - metolachlor was applied at sowing ( incorporated by sowing or post - sowing pre - emergence ). However, application of the herbicide at sowing resulted in phytotoxic effects on crop emergence and grain yield of wheat. Application of S - metolachlor at 20 or 23 days before sowing not only provided effective control ( 74 to 83 % ) of annual ryegrass, it was also safe on wheat. Application of this herbicide at 40 or 46 days before sowing was relatively ineffective in controlling annual ryegrass ( 33 to 49 % weed kill ) but safe on wheat. In conclusion, soil disturbance caused by tillage was found to have a major influence on the behaviour of the seed bank of different species including seedling emergence and decay rates of weed seeds. However, the response to tillage tended to be species - specific and was related to their seed biology. Tillage systems also had a major influence on the efficacy and bioavailability of trifluralin, which is prone to volatilisation losses. The findings of this research program are expected to contribute to the improvement in weed management under no - till systems.
Thesis (Ph.D.)--School of Agriculture, Food and Wine, 2006.

Includes copies of author's previously published works
Guano deposits in caves form a rich food resource supporting diverse arthropod communities. Guano piles consist of distinct micro - habitats, fresh, moist, highly basic guano and older, dry, slightly acidic guano. Micro - habitat variation is strongly controlled by seasonal guano deposition that, in turn, effects the structure of arthropod communities. The maternity chamber of Bat Cave, Naracoorte, South Australia, contains extensive guano deposits supporting 38 species from three classes and 12 orders. This community was studied to determine spatial and temporal variation of arthropod communities, and biogeographic relationships between different regions in Australia. Species richness forms a positive linear relationship with pH, in situ moisture content and guano deposition. Many species show strong associations with fresh guano and hence are strongly seasonal, although some species are present throughout the year. Arthropod community structure in winter was found to be more closely related to prior summer arthropod structure than to subsequent seasons. Starlight Cave near Warrnambool, western Victoria, the only other maternity site for Miniopterus schreibersii bassanii, contained 43 species from 39 families and 14 orders. Seven species are common to both caves. The community structure of Starlight Cave was found to be more homogeneous than Bat Cave with samples clustering by season rather than sample year as was the case at Bat Cave. Different cave morphology was found to significantly alter the micro - habitat conditions and, hence, community structure in Starlight Cave compared with Bat Cave. Migration of guano associated arthropods at local, regional and continental scales was assessed using mtDNA and allozyme electrophoresis the pseudoscorpion genus Protochelifer as a model organism. Phylogenetic tree reconstruction revealed a wide geographic distribution of cavernicolous species across southern Australia. Cave colonisation is believed to have occurred only once, followed by dispersal to the Nullarbor Plain and other caves in south - eastern Australia. Dispersal was possibly phoretic on cave bats or occurred prior to aridification of surface environments that currently restricts migration. The distribution of guano - associated arthropods from arid, semi - arid and monsoonal karst areas in Australia are compared with temperate south - eastern Australia. Different climatic areas show large biogeographical differences in community structure, although similar families ( Urodinychidae, Reduviidae, Anobiidae, Carabidae and Tineidae ) are present in many Australian guano communities. Several potential mechanisms of dispersal are discussed including phoresy, colonisation from soil, terrestrial migration and interstitial cavities. Endemism to specific caves cannot be definitely assigned to any species, although 13 species show restricted distribution.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, 2006.

Includes copies of author's previously published works
Guano deposits in caves form a rich food resource supporting diverse arthropod communities. Guano piles consist of distinct micro - habitats, fresh, moist, highly basic guano and older, dry, slightly acidic guano. Micro - habitat variation is strongly controlled by seasonal guano deposition that, in turn, effects the structure of arthropod communities. The maternity chamber of Bat Cave, Naracoorte, South Australia, contains extensive guano deposits supporting 38 species from three classes and 12 orders. This community was studied to determine spatial and temporal variation of arthropod communities, and biogeographic relationships between different regions in Australia. Species richness forms a positive linear relationship with pH, in situ moisture content and guano deposition. Many species show strong associations with fresh guano and hence are strongly seasonal, although some species are present throughout the year. Arthropod community structure in winter was found to be more closely related to prior summer arthropod structure than to subsequent seasons. Starlight Cave near Warrnambool, western Victoria, the only other maternity site for Miniopterus schreibersii bassanii, contained 43 species from 39 families and 14 orders. Seven species are common to both caves. The community structure of Starlight Cave was found to be more homogeneous than Bat Cave with samples clustering by season rather than sample year as was the case at Bat Cave. Different cave morphology was found to significantly alter the micro - habitat conditions and, hence, community structure in Starlight Cave compared with Bat Cave. Migration of guano associated arthropods at local, regional and continental scales was assessed using mtDNA and allozyme electrophoresis the pseudoscorpion genus Protochelifer as a model organism. Phylogenetic tree reconstruction revealed a wide geographic distribution of cavernicolous species across southern Australia. Cave colonisation is believed to have occurred only once, followed by dispersal to the Nullarbor Plain and other caves in south - eastern Australia. Dispersal was possibly phoretic on cave bats or occurred prior to aridification of surface environments that currently restricts migration. The distribution of guano - associated arthropods from arid, semi - arid and monsoonal karst areas in Australia are compared with temperate south - eastern Australia. Different climatic areas show large biogeographical differences in community structure, although similar families ( Urodinychidae, Reduviidae, Anobiidae, Carabidae and Tineidae ) are present in many Australian guano communities. Several potential mechanisms of dispersal are discussed including phoresy, colonisation from soil, terrestrial migration and interstitial cavities. Endemism to specific caves cannot be definitely assigned to any species, although 13 species show restricted distribution.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2006.

"July 2003"
Bibliography: leaves 108-121.
iv, 133 leaves : ill. ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
This study focused on the the use of resources by the small nocturnal species Ningaui yvonneae, with particular reference to diet and habitat.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2003

"July 2003"
Bibliography: leaves 108-121.
iv, 133 leaves : ill. ; 30 cm.
This study focused on the the use of resources by the small nocturnal species Ningaui yvonneae, with particular reference to diet and habitat.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2003

The work presented in this thesis aimed to do the following : 1. investigate the cause of decline of the three Melithreptus species of the Mt Lofty Ranges, with a particular emphasis on M. gularis due to its critical status in the ranges ; 2. investigate the ecology and behaviour of sympatric M. brevirostris and M. lunatus populations in the Mt Lofty Ranges ; and 3. suggest management options for the three species. Further, it became clear through the course of the project that an understanding of the decline in Melithreptus required : 1. comparisons with other honeyeater species, particularly widespread and abundant honeyeater species. Three species of Melithreptus occur in the Mt Lofty Ranges : Brown - headed Honeyeater Melithreptus brevirostris ; White - naped Honeyeater Melithreptus lunatus ; and Black - chinned Honeyeater Melithreptus gularis. Since at least the 1970 ' s all three species have been in decline within the ranges. One species has been reduced in both abundance and distribution within the region ( M. gularis ), while the other two are now recognised as having reduced in abundance. Melithreptus species in the Mt Lofty Ranges are sympatric with strikingly similar ecology. Melithreptus gularis is the largest of the three, while M. brevirostris and M. lunatus are almost identical in weight, feeding behaviour and morphology. Despite their similarities no studies have closely examined their ecology in sympatry and no studies have examined possible causes of their decline. Interspecific competition is thought to be important in the organisation of honeyeater communities. Studies of nectarivore communities suggest a number of ways in which competition causes the component species to partition resources : size ; beak length ; habitat ; and behaviour, which includes a mix of social and feeding strategies. Due to its role in honeyeater community organisation, changed level of interspecific competition has been highlighted as a possible cause of decline in some honeyeater species in the woodlands of southern Australia. Both interference competition and exploitative competition have been highlighted in various situations ( Ford et al. 2001 ). Given the hypothesised role of interspecific competition in the decline of honeyeater species and the declining status of all the Melithreptus in the Mt Lofty Ranges the genus appeared to provide a good basis for examining the hypothesis that interspecific competition is contributing to the decline of some honeyeater species through exclusion from resources and / or reduction in resources available. ( Ford et al. 2001 ) give the following as potential tests for their interspecific competition hypothesis : 1. examine community structure for ' forbidden combinations ' ( pairs of species that rarely occur together ) ; 2. compare time spent in interspecific competition ( interference ), and foraging in fragmented and continuous habitat ; 3. measure seasonal and spatial patterns of resource abundance and depletion ; and 4. remove competitors and observe response in abundance and behaviour of other species. These suggestions form the basis for much of the work presented in this thesis. An initial survey examined not only community structure for forbidden combinations, but also investigated other possible causes of decline, based on literature for both declining woodland birds and Melithreptus. Besides interspecific competition, other possible causes included insufficient preferred habitat, insufficient food resources and landscape fragmentation. Repeated counts of honeyeaters at 90 sites of one hectare in the Mt Lofty Ranges were undertaken over a one year period. Melithreptus lunatus was found to be more abundant where certain eucalypt species occurred ( particularly E. viminalis ), although this was postulated to be a reflection of productive soils. Melithreptus brevirostris was found to be more abundant where Phylidonyris novaehollandiae ( New Holland Honeyeater ) was most abundant, despite P. novaehollandiae also being the most widespread and abundant honeyeater in the Mt Lofty Ranges. Thus, the survey work did not find forbidden combinations of honeyeaters. However , the scale at which the survey work was undertaken ( sites of 1ha ) may have masked any competition between species due to spatial heterogeneity. At the scale of one hectare there is likely to be areas of resource not used by other honeyeaters, allowing Melithreptus to avoid feeding territories of aggressive honeyeaters. Therefore, in order to more thoroughly investigate competition between P. novaehollandiae and Melithreptus, a removal experiment with finer resolution than 1ha was carried out. This demonstrated that P. novaehollandiae do prevent M. lunatus from using certain areas of the landscape. A final examination of interactions between Melithreptus and widespread and abundant honeyeaters was carried out in the form of a survey in which individual trees were watched and visits by honeyeater species timed. Based on observations of Melithreptus, it appeared that generally M. brevirostris groups used a swamping strategy to access defended resources, whereas M. lunatus moved quietly, often as individuals or pairs. Thus the two species were hypothesised to use two different behavioural strategies to access defended resources, termed stealth ( the use of secretive behaviour to access resources that are being protected ) and swamping ( the use of a combined direct approach by a number of individuals to access resources that are being protected ). Based on estimations of the standardised protection of resources for individual trees, M. lunatus were able to access defended resources for longer, while M. brevirostris were able to access better defended resources but for a shorter time. These results were consistent with the hypothesis of two different behavioural strategies for accessing defended resources. Both species may employ both strategies, but M. brevirostris more often use swamping, and M. lunatus more often use stealth. Investigating the morphology of the small honeyeaters of the Mt Lofty Ranges confirmed that size and beak length were important in discriminating between most species. However, these did not provide any basis for separating the Melithreptus. Closer examination of morphology between M. brevirostris and the M. lunatus sexes revealed further similarities to those previously documented. The average values for many morphological attributes of M. brevirostris fell between the average value for the M. lunatus sexes, suggesting that ecologically the three species / sexes formed a continuum. The M. lunatus sexes and M. brevirostris were then referred to as the small Melithreptus guild ( it was not possible to sex M. brevirostris based on the range of attributes measured ). The greatest differences between the small Melithreptus guild were found in wing length and leg morphology. The direction of the differences suggested that M. brevirostris would be more similar to female M. lunatus in movements and more similar to male M. lunatus in foraging behaviour. These two aspects of Melithreptus ecology were the subject of the last and most extensive phase of the project. Movements were investigated for Melithreptus at four sites in the Mt Lofty Ranges using radio - telemetry techniques. Melithreptus were found to use large areas of the landscape and to have large core areas of activity within their home range. Using the same methods confirmed that Melithreptus had larger home ranges ( mean 100 % minimum convex polygon 23 hectares ) than P. novaehollandiae ( mean 100 % MCP 5 hectares ), and larger home ranges than those reported in the literature for other honeyeater species. Data on a single M. gularis ( 100 % MCP 140 hectares ) suggest that this species has even larger home range requirements. Information from colour - banded birds suggests that most M. brevirostris and male M. lunatus had stable core areas of activity over the period of this study, while female M. lunatus were less likely to have stable core areas of activity, particularly during the non - breeding season. A trend in home range and movement data was consistent with the hypothesis that M. brevirostris was more similar to female M. lunatus than to male M. lunatus. Behaviour of Melithreptus and P. novaehollandiae were investigated using time budget techniques. Melithreptus were found to spend most of their day foraging ( up to 84 % ), very little time resting ( as little as 1.8 % ) and very little time in aggression ( as little as 0.6 % ). These values are each within the outer range of results published on other honeyeaters. Melithreptus gularis behaviour was very similar to both M. brevirostris and M. lunatus. Melithreptus appear to forage predominantly from poor quality resources, requiring a large proportion of their time allocated to foraging. The small proportion of time spent resting is probably a result of the time spent foraging. The small proportion of time spent in aggression is partly the result of a lack of aggression by Melithreptus, but is also potentially due to their knowledge of aggression levels within their home range and their use of stealth and swamping. Melithreptus are likely to avoid the most highly protected ( and therefore the most productive ) areas within their home ranges. A trend in behavioural data was consistent with the hypothesis that M. brevirostris was more similar to male M. lunatus than to female M. lunatus. Based on the data collected in this study, Melithreptus in the Mt Lofty Ranges are characterised by : relatively large home range size with core areas that are used over extended periods of time ; similar foraging behaviour and morphology ; lack of aggression ; and ( probably ( complex social behaviour. Their decline in the Mt Lofty Ranges can be attributed to the preferential clearance of their preferred habitat, their requirement for a large home range and their predominant use of poor quality resources, particularly in comparison to other, locally successful honeyeaters. The final aim of this work on Melithreptus honeyeaters in the Mt Lofty Ranges was to provide options for managing remaining Melithreptus populations, in particular M. gularis which according to informed observers is now critically endangered in the region. Due to the extent of habitat clearance in the Mt Lofty Ranges, the decline of Melithreptus will only be addressed in the long term through large scale revegetation projects. Melithreptus requirements in any large scale revegetation are most likely to be met by providing a range of eucalypt species. In the short to medium term, management actions may be needed to prevent the loss of M. gularis from the region. Given the findings of this study, there are few such options available. The management of woody weeds in known Melithreptus home ranges is suggested as one possible management strategy. Melithreptus rarely use a shrub layer for foraging, shelter or nesting, whereas P. novaehollandiae use a shrub layer for each of these activities. Thus, where grassy woodlands have been invaded by woody weeds, P. novaehollandiae potentially have an increased year round presence.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

The work presented in this thesis aimed to do the following : 1. investigate the cause of decline of the three Melithreptus species of the Mt Lofty Ranges, with a particular emphasis on M. gularis due to its critical status in the ranges ; 2. investigate the ecology and behaviour of sympatric M. brevirostris and M. lunatus populations in the Mt Lofty Ranges ; and 3. suggest management options for the three species. Further, it became clear through the course of the project that an understanding of the decline in Melithreptus required : 1. comparisons with other honeyeater species, particularly widespread and abundant honeyeater species. Three species of Melithreptus occur in the Mt Lofty Ranges : Brown - headed Honeyeater Melithreptus brevirostris ; White - naped Honeyeater Melithreptus lunatus ; and Black - chinned Honeyeater Melithreptus gularis. Since at least the 1970 ' s all three species have been in decline within the ranges. One species has been reduced in both abundance and distribution within the region ( M. gularis ), while the other two are now recognised as having reduced in abundance. Melithreptus species in the Mt Lofty Ranges are sympatric with strikingly similar ecology. Melithreptus gularis is the largest of the three, while M. brevirostris and M. lunatus are almost identical in weight, feeding behaviour and morphology. Despite their similarities no studies have closely examined their ecology in sympatry and no studies have examined possible causes of their decline. Interspecific competition is thought to be important in the organisation of honeyeater communities. Studies of nectarivore communities suggest a number of ways in which competition causes the component species to partition resources : size ; beak length ; habitat ; and behaviour, which includes a mix of social and feeding strategies. Due to its role in honeyeater community organisation, changed level of interspecific competition has been highlighted as a possible cause of decline in some honeyeater species in the woodlands of southern Australia. Both interference competition and exploitative competition have been highlighted in various situations ( Ford et al. 2001 ). Given the hypothesised role of interspecific competition in the decline of honeyeater species and the declining status of all the Melithreptus in the Mt Lofty Ranges the genus appeared to provide a good basis for examining the hypothesis that interspecific competition is contributing to the decline of some honeyeater species through exclusion from resources and / or reduction in resources available. ( Ford et al. 2001 ) give the following as potential tests for their interspecific competition hypothesis : 1. examine community structure for ' forbidden combinations ' ( pairs of species that rarely occur together ) ; 2. compare time spent in interspecific competition ( interference ), and foraging in fragmented and continuous habitat ; 3. measure seasonal and spatial patterns of resource abundance and depletion ; and 4. remove competitors and observe response in abundance and behaviour of other species. These suggestions form the basis for much of the work presented in this thesis. An initial survey examined not only community structure for forbidden combinations, but also investigated other possible causes of decline, based on literature for both declining woodland birds and Melithreptus. Besides interspecific competition, other possible causes included insufficient preferred habitat, insufficient food resources and landscape fragmentation. Repeated counts of honeyeaters at 90 sites of one hectare in the Mt Lofty Ranges were undertaken over a one year period. Melithreptus lunatus was found to be more abundant where certain eucalypt species occurred ( particularly E. viminalis ), although this was postulated to be a reflection of productive soils. Melithreptus brevirostris was found to be more abundant where Phylidonyris novaehollandiae ( New Holland Honeyeater ) was most abundant, despite P. novaehollandiae also being the most widespread and abundant honeyeater in the Mt Lofty Ranges. Thus, the survey work did not find forbidden combinations of honeyeaters. However , the scale at which the survey work was undertaken ( sites of 1ha ) may have masked any competition between species due to spatial heterogeneity. At the scale of one hectare there is likely to be areas of resource not used by other honeyeaters, allowing Melithreptus to avoid feeding territories of aggressive honeyeaters. Therefore, in order to more thoroughly investigate competition between P. novaehollandiae and Melithreptus, a removal experiment with finer resolution than 1ha was carried out. This demonstrated that P. novaehollandiae do prevent M. lunatus from using certain areas of the landscape. A final examination of interactions between Melithreptus and widespread and abundant honeyeaters was carried out in the form of a survey in which individual trees were watched and visits by honeyeater species timed. Based on observations of Melithreptus, it appeared that generally M. brevirostris groups used a swamping strategy to access defended resources, whereas M. lunatus moved quietly, often as individuals or pairs. Thus the two species were hypothesised to use two different behavioural strategies to access defended resources, termed stealth ( the use of secretive behaviour to access resources that are being protected ) and swamping ( the use of a combined direct approach by a number of individuals to access resources that are being protected ). Based on estimations of the standardised protection of resources for individual trees, M. lunatus were able to access defended resources for longer, while M. brevirostris were able to access better defended resources but for a shorter time. These results were consistent with the hypothesis of two different behavioural strategies for accessing defended resources. Both species may employ both strategies, but M. brevirostris more often use swamping, and M. lunatus more often use stealth. Investigating the morphology of the small honeyeaters of the Mt Lofty Ranges confirmed that size and beak length were important in discriminating between most species. However, these did not provide any basis for separating the Melithreptus. Closer examination of morphology between M. brevirostris and the M. lunatus sexes revealed further similarities to those previously documented. The average values for many morphological attributes of M. brevirostris fell between the average value for the M. lunatus sexes, suggesting that ecologically the three species / sexes formed a continuum. The M. lunatus sexes and M. brevirostris were then referred to as the small Melithreptus guild ( it was not possible to sex M. brevirostris based on the range of attributes measured ). The greatest differences between the small Melithreptus guild were found in wing length and leg morphology. The direction of the differences suggested that M. brevirostris would be more similar to female M. lunatus in movements and more similar to male M. lunatus in foraging behaviour. These two aspects of Melithreptus ecology were the subject of the last and most extensive phase of the project. Movements were investigated for Melithreptus at four sites in the Mt Lofty Ranges using radio - telemetry techniques. Melithreptus were found to use large areas of the landscape and to have large core areas of activity within their home range. Using the same methods confirmed that Melithreptus had larger home ranges ( mean 100 % minimum convex polygon 23 hectares ) than P. novaehollandiae ( mean 100 % MCP 5 hectares ), and larger home ranges than those reported in the literature for other honeyeater species. Data on a single M. gularis ( 100 % MCP 140 hectares ) suggest that this species has even larger home range requirements. Information from colour - banded birds suggests that most M. brevirostris and male M. lunatus had stable core areas of activity over the period of this study, while female M. lunatus were less likely to have stable core areas of activity, particularly during the non - breeding season. A trend in home range and movement data was consistent with the hypothesis that M. brevirostris was more similar to female M. lunatus than to male M. lunatus. Behaviour of Melithreptus and P. novaehollandiae were investigated using time budget techniques. Melithreptus were found to spend most of their day foraging ( up to 84 % ), very little time resting ( as little as 1.8 % ) and very little time in aggression ( as little as 0.6 % ). These values are each within the outer range of results published on other honeyeaters. Melithreptus gularis behaviour was very similar to both M. brevirostris and M. lunatus. Melithreptus appear to forage predominantly from poor quality resources, requiring a large proportion of their time allocated to foraging. The small proportion of time spent resting is probably a result of the time spent foraging. The small proportion of time spent in aggression is partly the result of a lack of aggression by Melithreptus, but is also potentially due to their knowledge of aggression levels within their home range and their use of stealth and swamping. Melithreptus are likely to avoid the most highly protected ( and therefore the most productive ) areas within their home ranges. A trend in behavioural data was consistent with the hypothesis that M. brevirostris was more similar to male M. lunatus than to female M. lunatus. Based on the data collected in this study, Melithreptus in the Mt Lofty Ranges are characterised by : relatively large home range size with core areas that are used over extended periods of time ; similar foraging behaviour and morphology ; lack of aggression ; and ( probably ( complex social behaviour. Their decline in the Mt Lofty Ranges can be attributed to the preferential clearance of their preferred habitat, their requirement for a large home range and their predominant use of poor quality resources, particularly in comparison to other, locally successful honeyeaters. The final aim of this work on Melithreptus honeyeaters in the Mt Lofty Ranges was to provide options for managing remaining Melithreptus populations, in particular M. gularis which according to informed observers is now critically endangered in the region. Due to the extent of habitat clearance in the Mt Lofty Ranges, the decline of Melithreptus will only be addressed in the long term through large scale revegetation projects. Melithreptus requirements in any large scale revegetation are most likely to be met by providing a range of eucalypt species. In the short to medium term, management actions may be needed to prevent the loss of M. gularis from the region. Given the findings of this study, there are few such options available. The management of woody weeds in known Melithreptus home ranges is suggested as one possible management strategy. Melithreptus rarely use a shrub layer for foraging, shelter or nesting, whereas P. novaehollandiae use a shrub layer for each of these activities. Thus, where grassy woodlands have been invaded by woody weeds, P. novaehollandiae potentially have an increased year round presence.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

In fire-prone ecosystems, plant species exhibit a range of traits which allow them to persist under certain fire regimes. Two critical traits are resprouting and regeneration from seed. Resprouters and seeders can coexist within plant communities, but their relative proportion varies. This research investigated variation in patterns of community composition, in terms of fire response traits, across a mountainous region of south-eastern Australia. The relative importance of fire regimes, habitat, vegetation cover and resource gradients in influencing these patterns was tested. Associations between leaf traits and fire response types were also explored to investigate whether traits related to fire persistence can be considered as part of a broader spectrum of plant ecological strategies, and assist in explaining landscape patterns. In January 2003 unplanned fires burned through the region, creating the opportunity to investigate the responses of locally occurring plants. An initial study of observed field data demonstrated that some species varied in their response between sites. Furthermore, observed responses often differed from those reported in a fire response trait database. As such, the decision was taken to use observed site-specific data on fire response traits where possible to analyse community composition across the region. Data were subsequently collated from five post-fire surveys conducted across 284 sites in the study area. Resprouting was a dominant response of species in the region. However, woody obligate seeders, although infrequent, were often structurally important. Within-species variation was identified, with variability in post-fire seed regeneration particularly evident in trees. The results unexpectedly identified 'dataset' as the factor most strongly associated with the observed patterns, raising important questions about the use of data collated from different sources. Obligate resprouters were favoured at sites burned with no short intervals between fires, whereas several woody obligate seeding types were in higher proportions at sites burned with one or two short intervals. This suggests that some degree of fire is required for obligate seeder persistence. However, the possibility that woody obligate seeders had already been eliminated from the region prior to this study, due to short inter-fire intervals, could not be discounted. Significant differences between habitats were identified, with woody obligate seeders found in high proportions on rock outcrops and in wet grasslands. However, trends in the proportions of fire response types across habitats could not be reconciled with trends in habitat characteristics such as canopy height and understorey cover. Understorey cover was negatively associated with seeders and facultative resprouters, suggesting an important influence of competition post-fire. Leaf trait comparisons showed that facultative resprouters differed from obligate seeders and obligate resprouters, indicating that this strategy requires an investment into rapid acquisition of resources and fast growth to compete. Differences in leaf traits in species with a canopy seed bank were also identified, raising some important considerations regarding approaches to classifying species by fire response traits. This research illustrates the value of considering the relative importance of fire in relation to other factors for developing a thorough understanding of the processes governing community composition in fire-prone ecosystems. Importantly, the approaches taken in this thesis also revealed a range of issues regarding the application of trait data, which are discussed in relation to trait-based ecological research and management.

This study assessed the distribution of coral assemblages on coral reefs fringing continental islands between 20°5 and 23°5 on the Great Barrier Reef, Australia. Two questions were investigated. What is the composition and distribution of the coral assemblages and how are they influenced by ambient environmental conditions and episodic disturbance events, both natural and anthropogenic? The study was conducted at four island groups; the Whitsunday (20°00'S), Cumberland (20°30'S), Northumberland (21°00'S), and the Keppel Islands (23°00'S). Sixteen coral assemblages which recurred largely as a function of habitat and regional conditions were identified. Direct gradient analysis of 102 taxa and eight environmental gradients indicated that variation in coral composition was correlated with depth, exposure, tidal amplitude, distance from the mainland and the presence of seasonal macrophytes. There was a lack of fringing reef development in the vicinity of 21°S and a restricted range of coral growth forms and species. Reef decline was not constrained by latitude, as fringing reefs were prolific at 23°S, but significantly correlated with extreme tidal fluctuations (10m); which induce high turbidity and reduce the euphotic zone. Major framework builders, massive and branching corals, dominated reefs north of 21°S but significantly declined at 21°S. Fast-growing, plate-like, encrusting and columnar forms dominated reefs at 21°S, suggesting coral growth rates and reef accretion are not directly related. High turbidity appears to have influenced coral composition and coral morphology to such a degree that poor reef development has occurred through the Holocene period. Biological assemblages are also a product of episodic disturbances. Two case studies examined effects of disturbance; a major flood and the discharge of secondary sewage. The prolonged reduction in salinity, associated with the 1991 Queensland floods (cyclone Joy), caused a considerable decline in live coral biomass in the Keppel Islands. The dominant coral genus Acropora was most affected. Shallow corals in the Whitsunday Islands suffered minimal mortality, however many deep water pocilloporids (eg. Seriatopora hystrix) were killed. Low light levels associated with the monsoonal conditions may have caused the mortality. Acropora spp. and pocilloporid corals appear most vulnerable to physico-chemical stress. Mild disturbance events (as in the Whitsunday Islands) tend to eliminate monospecific stands of these opportunistic corals. Suppressing space monopolisation by periodic exclusion may be essential in maintaining regional diversity over long time scales. Large disturbances (Keppel Islands) tend to reduce regional diversity. Effects of sewage on the coral assemblages at Hayman Island were investigated. Results suggest an impact 20-40 m from the outlet. Elevated nutrient levels reduced coral cover, suppressed colonization and induced community instability. It is important to understand the scale of impact from such influences as the inshore environment is most susceptible to anthropogenic interference.

Brome grass species Bromus rigidus (rigid brome) and B. diandrus (great brome) are winter annual grasses that have proliferated in recent years to become serious weeds of crops and pastures in southern Australia. Until recently there had been few studies on the population ecology of B. rigidus and B. diandrus and the research that had been done tended to focus on populations that had naturalised in Western Australia. Increased knowledge of the behaviour of B. rigidus and B. diandrus under current farming systems in southern Australia and the impact of management strategies on population ecology and seedbank dynamics would facilitate development of more effective weed control programs. A field survey was undertaken in 2003 on the Yorke and Eyre Peninsulas of South Australia to determine relative distribution of these two brome grass species. Bromus rigidus was found more frequently and at higher densities in South Australian crops than B. diandrus. Field populations of both spp. were shown to possess much longer seed dormancy than what had been previously reported in Australian literature. Germination of dormant seeds of B. rigidus and B. diandrus was overcome with the addition of gibberellic acid (0.001 M GA₃) rather than upon removal of the husk (i.e. lemma and palea) protecting the seed; indicating that dormancy is most likely under hormonal control within the embryo. Dormant populations of B. diandrus from cropping fields were highly responsive to cold stratification (i.e. chilling), a process which has been shown to increase GA synthesis within the seed. Populations of B. diandrus from cropping fields also showed much longer seed dormancy than those collected from adjacent fence-lines. The large differences in germination pattern between these cropping and adjacent fence-line populations provide some evidence to suggest that management practices being used by growers in crop production are selecting for increased dormancy in B. diandrus. In cropping fields, there could be considerable adaptive value of dormancy mechanisms (i.e. cold stratification requirement, light inhibition) that delay germination and seedling emergence until after pre-sowing weed control tactics have been used. Dormant populations of both B. rigidus and B. diandrus also showed strong inhibition of seed germination when exposed to light. This is the first Australian study to report the inhibitory effect of light on seed germination of Bromus spp. and provides a possible explanation for their increasing prevalence in southern Australia since the adoption of no-till farming. Selection of greater dormancy in Bromus spp. is likely to contribute to the development of a more persistent seedbank. A 3-year field experiment undertaken at Lock on the Eyre Peninsula of South Australia from 2003 to 2005 showed that about 20% of B. rigidus seedbank can persist from one season to the next. In this field study, management strategies that combined effective herbicides (ACCase-inhibitors and imidazolinone Clearfieldtechnology) and crop competition over consecutive years provided effective control of B. rigidus population and depleted its seedbank to low levels (from 1748 to <5 seeds m⁻²) within 3 years. In field studies, metribuzin, and metribuzin plus pendimethalin incorporated by sowing provided safe and effective control of B. rigidus (>75%) in barley. Post-emergent applications of imidazolinone herbicides, imazapyr, imazapyr plus imazapic and imazapyr plus imazamox, to imidazolinone-tolerant wheat (Clearfield™) also provided consistent and high levels of B. rigidus control (≥87%). Effective management of Bromus spp. will require a major change in cropping systems used by growers in southern Australia and will involve combining effective herbicide technologies (i.e. Clearfield™) with more competitive crops and more diverse rotations, where possible.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2013

"August 2003."
Includes bibliographical references (leaves 294-333)
2 v. (xxxi, 333 leaves) ; ill. (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005