Browsing by Type "Thesis Doctoral"

This action research project explores how Aboriginal and Torres Strait Islander participation is addressed in higher education and, in particular, at a regional university campus in Australia. As a non-Indigenous person, I structured the research to involve Aboriginal and Torres Strait Islander people at every stage. This involved engaging Aboriginal and Torres Strait Islander people in the data collection stage, framing the research questions and providing feedback on the data analysis. The research participants also made suggestions and provided the impetus for the action research aspect of the project. My aim was to work with local Indigenous people to develop, implement and evaluate strategies to increase the participation of Aboriginal and Torres Strait Islander people in higher education opportunities at the campus.

This research comprises a portfolio with three pillars: policy, people and place. One overarching research question was developed: What strategies can be effective for enhancing the experience of Aboriginal and Torres Strait Islander students at a regional higher education campus? The policy pillar explored how government policies over the last 50 years have affected individual Aboriginal and Torres Strait Islander people’s involvement and participation in higher education, the practices that resulted from these policies and the effect of the practices on individual Aboriginal and Torres Strait Islander students’ participation and success at the regional university campus. The people pillar focused on the influence of personal and interpersonal aspects of Aboriginal and Torres Strait Islander students’ lives on their learning experiences at the regional university campus. As part of examining students’ learning experiences, the place pillar explored local Aboriginal and Torres Strait Islander people’s sense of belonging at the regional university campus.

This research showed that policy approaches during the 1970s and 1980s effectively created greater participation by Indigenous people and a culturally safe and affirming higher education experience. This thesis discusses what can be learnt from the policy settings at that time to inform contemporary educational practices. Importantly, this research also identified and implemented changes to practices. In keeping with the participatory action research approach, the research participants highlighted opportunities to improve educational practices, implement new strategies and challenge existing university policies. The strategies generated from this research focused on educational pathways recruiting Aboriginal and Torres Strait Islander people into mainstream courses, partnerships with Indigenous organisations to provide educational opportunities for their Aboriginal and Torres Strait Islander employees, developing cultural understandings for university staff and students, incorporating Indigenous knowledge into mainstream curricula, the significance of upholding conciliation values and recognising Indigenous sovereignty and committing to Indigenous decision-making within the university campus. The actions implemented as part of the research positively affected the educational experiences of Indigenous and non-Indigenous students at the regional university campus. This research provides insights for policymakers and educational practitioners into strategies for enhancing Aboriginal and Torres Strait Islander students’ participation in university contexts.

Beneficial and pest invertebrates occur in irrigated cotton crops and in the surrounding landscape. Thus, farming and landscape management are inextricably linked in the challenge to encourage beneficial invertebrate survival and pest suppression. Cotton production has advanced recently in the cultivation of genetically modified cotton, areawide crop management and a reduction in reliance on insecticides. All these strategies contribute to enhancing the number of beneficial invertebrates and reducing the prevalence of pests in cotton crops. Beneficial and pest invertebrates also appear in other common winter crops such as wheat. However, only a small body of research has been conducted on the landscape-wide abundance of beneficial and pest invertebrates, and even less attention has been given to the non-crop habitat near to cotton crops that may play an essential role in beneficial and pest invertebrate abundance in cotton.

This study was undertaken in a cotton-growing area in the Namoi Valley near Boggabri, in northern New South Wales, and an a landscape matrix including riparian river red gum (Eucalyptus camaldulensis) woodland, poplar box (E. populnea) woodland, and native grassland dominated by weeds such as Ammi majus, Aster subulatus, Avena fatua, Bromus catharticus, Cynodon dactylon, Urochloa panicoides and Rapistrum rugosum. Gaining an understanding of beneficial and pest invertebrate abundance and their response to different habitat types requires careful consideration of sampling strategy because of the variety of taxa and different habitats to be studied. With regard to sampling strategy, we compared two sampling methods (beat box and D-vacuum) for sampling key pest and beneficial invertebrates in different habitats. The aim of the first experiment was to evaluate the efficacy of the D-vac and beat box in sampling different invertebrate taxa in different vegetation types. The beat box sampling technique with four beats and six subsamples (the level of sampling effort required at each site in each vegetation type) were sufficient to capture the principal beneficial invertebrate taxa (ants, spiders, blue and red beetles, lady beetles and lacewings) and principal pest invertebrates (leafhoppers, apple dimpling bugs, red-shouldered leaf beetles, peanut scarab beetles, brown flea beetles, cotton seed bugs, flower beetles, mirids, Rutherglen bugs and aphids).

The aim of the second experiment was to examine invertebrate abundance and irrigated cotton yields associated with changing farm management over time. Five years of beatsheet sampling was conducted on three farms near Boggabri NSW, from the beginning to the end of each summer cotton growing season 2009 till 2014. Beneficial invertebrates were significantly more abundant in the 2013/14 season than in the 2009/10 season, while pest invertebrates were significantly more abundant in 2009/10 than 2013/14. In addition, cotton yields were significantly greater in 2013/14 than 2009/10. These changes were associated with avoidance of insecticide use in cotton over the 5 years, which was valuable for increasing beneficial numbers and suppressing pests in cotton and led to greater yield.

The aim of the next experiment was to determine the role of woody native vegetation and weedy native grassland in influencing the abundance of pests and beneficial invertebrates in irrigated cotton crops and the impact of farm management (conventional vs low-insecticide management) on these interactions. Beneficial invertebrates; ants (Hymenopteran), spiders (Araneae), blue and red beetles Tectocoris diophthalmus and lady beetles (Coccinellidae) and pest invertebrates; leafhoppers (Cicadellidae), apple dimpling bugs (Campylomma liebknechti), red-shouldered leaf beetles (Monolepta australis), peanut scarab beetles (Scarabaeidae), brown flea beetles (Chrysomelidae), cotton seed bugs (Oxycarenus hyalinipennis), flower beetles (Coleoptera), mirids (Miridae) and Rutherglen bugs (Lygaeidae) were sampled with beat box on two different types of farm (low-insecticide management vs conventional management) in different habitats (river red gum and poplar box woodland, weedy native grassland, irrigated cotton and refuge crops) in cotton crops stratified by distance to and amount of close by woody native vegetation. Cotton crops with a larger amount of woody native vegetation nearby on low-insecticide managed farms harboured more beneficial invertebrates than on conventionally managed farms. Cotton crops with a larger amount of woody native vegetation nearby on low-insecticide managed farms harboured less pest invertebrates than conventionally managed farms. Woodland harboured more beneficial invertebrates and less pest invertebrates than weedy native grassland, and woody native vegetation on low-insecticide farms harboured more beneficial than pest invertebrates. Cotton crops close to large amounts of native vegetation harboured more beneficials than pests on both types of farm. These results were due to minimal use of insecticides on three farms, which allowed significantly greater pest suppression by beneficial invertebrates.

The aim of the last experiment was to understand the role of woody native vegetation, weedy grassland and spring wheat crops in influencing the abundance of pest and beneficial invertebrates throughout the year in cotton landscapes in northern NSW characterised by two types of farm management: conventional vs low-insecticide management. Beneficial invertebrates (ants, spiders, blue and red beetles and lady beetles) and pest invertebrates (leafhoppers, apple dimpling bugs, peanut scarab beetles, brown flea beetles, flower beetles, mirids, Rutherglen bugs and aphids) were sampled with the beat box on two different types of farm (low-insecticide management vs conventional management) in different habitats (river red gum and poplar box woodland, weedy native grassland, and rotation wheat crops) over the summer and winter growing seasons. Rotation crops (winter growing season) were stratified by distance to and amount of nearby woody native vegetation. Blue and red beetles were absent from grassland, while aphids, Rutherglen bugs, mirids and red-shouldered beetles were abundant but only occurred in grassland. Generally, beneficial invertebrates in total were more abundant on low-insecticide managed farms than on conventionally managed farms, although not always significantly so. In contrast, pest invertebrates in total were less abundant on farms managed with a low-insecticide regime than on farms managed conventionally, although the difference were not always significant. Rotation crops with a higher amount of woody native vegetation nearby on low-insecticide farms harboured less aphids than conventionally managed farms, and this was similar to the pattern in ant abundance. The differences in pest and beneficial invertebrates among farms were related to the amount of woody native vegetation, grassland and reduced reliance on insecticides.

The results in this thesis will encourage researchers and cotton growers to use the beat box sampling technique to sample invertebrate taxa in different habitats (river red gum and poplar box woodland, weedy grassland, irrigated cotton, refuge crops and rotation wheat crops). However, landscape management through conservation and revegetation of woodland habitats e. g. river red gum and poplar box woodland close to cotton fields is also important for supporting beneficial invertebrate abundance in nearby cotton fields. To protect crops, growers can plant local eucalypt species into weedy grassland to restore woodland habitats, as weedy grassland harbours more pests than beneficial invertebrates. Weeds in grassland are a primary food resource for pest invertebrates, some feeding exclusively in weedy grasslands such as Rutherglen bugs and others preferring weeds when crops are absent, such as mirids. We assumed that pest abundance was high in weedy grassland due to the reduced abundance of beneficial invertebrates and lower predation of pests than in woody native vegetation, as well as due to the feeding preferences of pest invertebrates for weeds in grassland. To manage farms, a reduction in the reliance on insecticides to advantage beneficial invertebrate abundance should lead to environmental benefits as well as increased profit in irrigated cotton production.

Soil salinization is a pernicious problem in the coastal areas of Bangladesh that presents substantial challenges to agricultural productivity and difficulties in addressing the sustainable development goals (SDGs). While the biophysical nature of salinity is well understood, dealing with the uncertainties that emerge from the differential nature of its impact on agricultural livelihoods remains unexplored. In order to address the uncertainties in adaptation decisions, this study applied the adaptation tipping points (ATPs) approach to determine the yield loss threshold in a coastal saline environment, and to show the potential signal for tipping points of dry season rice cultivation in the coastal areas. To apply the ATP approach in the agricultural system, this study developed three sequential steps, and showed its potential for an ATP-driven research-extension policy agenda. Using a semi-structured survey, data were collected from 280 farmers (rice farmers; n=109, shrimp farmers; n=107, salt farmers; n=64) who were randomly selected from two coastal sub-districts (Assasuni from Satkhira district (south-west) and Banskhali from Chittagong district (south-east). In a follow-up survey, in-field salinity measurement data were collected from the rice field of the selected farmers (n=36), and how farmers' perceived these salinity level in their rice field were recorded. Then, the literature based salinity classification of these measured salinity data and farmers' perceptions about the same salinity measured data were compared. To complement the semi-structured survey data, key informant interviews and focus group discussions were also conducted.

In the first step (Chapter 2), this study explored the rice farmers' understanding of the salinity problem and their locally practised adaptation strategies to inform the policymakers as to when farmers are concerned about the salinity problem. Rice farmers perceived the reproductive stages of rice plants as being the most vulnerable to salinity. The findings also demonstrated that farmers perceived a field as being affected by high salinity levels when the levels were lower than the scientific literature recommends. In response to the salinity problem, most of the rice farmers undertake early transplanting and apply irrigation to overcome its harmful effects in Boro season rice cultivation. The study demonstrated that farmers' adaptation strategies (e.g. early transplanting) potentially avoid high salinity during the reproductive stages of rice development in Boro season (dry season), indicating that farmers understand the salinity problem and are concerned about the harmful effects of salinity on rice production. Farmers' actions to cope with salinity are pre-emptive of when salinity would have severe effects on rice plant growth and yield.

In the second step (Chapter 3), this study examined differential framing of the salinity problem (i.e. perceptions of diverse types of farmers) in order to understand farmers' perceptions of salinity and the underlying causes, and adaptation preferences. The findings indicated that farmers overall have perceived an increasing salinity trend over the last 20 years. However, salinity perceptions and underlying causes varied among the different types of farmers (i.e. rice, shrimp and salt farmers). The majority of rice farmers (87%) reported increased salinity, while over half of the salt (52%) and shrimp farmers (52%) perceived that salinity has decreased over the past 20 years. The results also indicated that most of the rice farmers (62%) perceived that anthropogenic factors are the main cause of increased salinity, while the majority of the shrimp and salt farmers focused more on natural factors as being responsible for salinity. The results also indicated that while rice farmers perceived severe yield loss due to high salinity, shrimp and salt farmers perceived that they were not disadvantaged and reported higher production from their farming enterprises. According to the study, the rice farmers preferred salinity-tolerant rice varieties that have greater tolerance at the reproductive stages, while shrimp and salt farmers considered that engineering solutions such as strengthening embankments and canal excavation as the preferred adaptation options to cope with salinity. Thus, this study demonstrated that farmers' perceptions of salinity are directly related to the ways in which their livelihoods are being impacted by salinity.

In the third step (Chapter 4), this study applied the adaptation tipping points (ATPs) approach to investigate threshold yield loss from the perspectives of all types farmers affected by salinity, which could signal plausible discontinuation of growing rice in the Boro season (i.e. Dry season). Adaptation tipping points are defined as the points where the current strategies may fail to achieve their objectives. This study considered promoting saline-tolerant rice varieties in the dry season as a management strategy, with a policy objective of coping capacity under a high saline environment. The findings revealed that despite government actions to promote dry season rice cultivation, local farmers have not expanded rice growing in the Boro season, and salinity-induced lower rice yields were found to be the prime reason behind this lack of expansion. This study has shown the existence of a farmer-derived threshold yield loss in the coastal dry season rice farming system that is based on their experience and observations. However, yield loss thresholds varied among the different types of farmers, with rice farmers tolerating a greater rice threshold yield loss (23%) compared to shrimp and salt farmers (at 16% and 14% of threshold yield loss, respectively). Thus, differential perceptions of the salinity affected yield loss thresholds suggest government actions to support and encourage integrated land management for rice, shrimp and salt farming rather than research and extension efforts that are focused on dry season rice expansion alone. These actions could strengthen sustainable livelihood options to ensure food security, and contribute to the achievement of the sustainable development goals for instance, no poverty (SDG-1), zero hunger (SDG-2) and good health and well-being (SDG-3).

Contamination of soil with polycyclic aromatic hydrocarbons (PAHs) by a range of anthropogenic activities causes concern for human and environmental health. Understanding PAH bioavailability provides regulatory decisions for contaminated sites with a realistic assessment of risks associated with the contaminants, and as such a range of approaches have been developed for assessment of contaminant bioavailable fractions. Application of these methods to predict PAH bioaccumulation in terrestrial organisms and plants from historically contaminated (> 50 years) soils has not been broadly studied. The broad aim of this thesis was to understand how a range of well-used in-vitro chemical predictive methods vary in the measurement of PAH bioaccessibility in historically contaminated soils and how effectively the methods can predict PAH bioavailability to different receptors (earthworms and a model plant).

Six in-vitro chemical predictive methods were applied to determine PAH bioaccessible fractions in four historically contaminated manufactured gas plant (MGP) soils. The methods included depletive non-exhaustive extractions (butanol (BuOH), non-buffered and buffered 2-hydroxypropyl-β-cyclodextrin extractions (HPCD, Buf-HPCD), potassium persulfate oxidation (KPS), solid phase extraction using Tenax resin (Tenax)), and a non-depletive method (polyoxymethylene solid-phase extraction (POM)). The chemical extractions were compared with bioassays using different receptors: three representative earthworm ecotypes (Amynthas sp., Eisenia fetida, and Lumbricus terrestris) and ryegrass (Lolium multiflorum) as the model plant.

The PAH bioaccessible fraction measured using different in-vitro methods varied significantly across the methods and also among the soils, with the highest quantity of bioaccessible ∑16 PAHs measured using KPS, and the lowest quantity using POM. Soil properties were generally inconclusive as indicators of bioaccesibility for the historically contaminated soils. Moreover, toxicity values and biodegradation endpoints for the contaminated soils derived using bioaccessibility-biodegradability linear regression models on the PAH extracted using the different methods were highly variable, with significant implications for predicted ecotoxicity or success for bioremediation when applied in risk management.

Earthworm bioaccumulation studies revealed distinct differences between epigeic surface dwelling standard test species, E. fetida, and the relevant epi-endogeic and anecic burrowing species, Amynthas sp. and L. terrestris, with accumulated ∑16 PAH concentration following the order Amynthas sp. > L. terrestris > E. fetida. Results indicated that gut uptake was important for PAH partitioning into earthworm lipids, specifically for burrowing species and the desorption-resistant higher molecular weight (HMW) PAHs in historically contaminated soils. Calculated bioconcentration factors (BCFs) indicated stronger relationships with octanol water partition coefficients (KOW) for the burrowing species than for E. fetida. This together with the results of predicted BSAFs from measured pore water concentrations demonstrated that EqPT does not consider differences in uptake between organisms, nor changing bioavailability through different exposure routes (e.g. gut uptake), and caution is required when using KOW values as a proxy for BCF in EqPT especially for E. fetida

The efficiency of the in-vitro methods for predicting PAH bioaccumulation in the earthworm species was investigated by comparing the method-derived bioaccessibility results with measured bioaccumulation in earthworms directly and using a calculation approach based on EqPT with a combination of different partitioning parameters (KOW values and organic carbon water partition coefficients (K_OC values)) to improve predictions. While Tenax and POM showed the best estimates of bioaccumulation in E. fetida by direct comparison, Buf-HPCD provided the best approximation for Amynthas sp. and L. terrestris. The predictions using the calculation approach depended on the receptor and the partitioning parameters used. Integrating K_OC values derived from historically contaminated soils into calculations improved predictions for E. fetida using all methods (except Tenax), but this was not the case for soil-burrowing species. In general, despite promising results obtained using HPCD-based, Tenax and POM extractions, no one method accurately predicted measured bioaccumulation in MGP soils for the range representative species.

In the last part of this project, PAH bioaccumulation in ryegrass (Lolium multiflorum) roots grown in MGP soils was compared with bioaccessibility outcomes of the in-vitro methods both directly and through the EqPT-based calculation approach using different partitioning parameters and different root components (lipid, carbohydrates, and total) regulating PAH sorption. Accumulation of 16 PAHs in L. multiflorum was estimated within a factor of 5 using direct comparison for all bioaccessibility extraction methods, with Buf-HPCD providing the closest estimate. Outcomes using the calculation approach depended on the K_OC, KOW values and root components used in calculations. Using K_OC values derived from historically contaminated soils improved accuracy of prediction of total root accumulation although precision was poor. Comparative assessment for different root components showed that the combined contribution of PAH in lipid and carbohydrate root components overestimated accumulation and a lipid-based approach using generic partitioning parameters provided more accurate and precise approximation of L. multiflorum bioaccumulation in these soils. Generally, Tenax, Buf-HPCD and POM extractions were promising for the prediction of L. multiflorum root accumulation by different approaches

This work significantly extends current knowledge for integrating simple chemical extractions into ecological risk assessment frameworks. The results demonstrated clearly that predicting bioavailability needs to be adapted to the target receptor, and the success of including sitespecific K_OC values in modelling depended on organism. Generally, Tenax and POM extractions provided the optimum prtedictions for E. fetida and ryegrass; and HPCD-based extractions for Amynthas sp. and L. terrestris. Expanding the work performed in this project to a wider range of historically contaminated soils from different sites by including suggested predictive methods tested against different plant species (including model crop species), and other earthworm species from each ecotype (such as E. andrei from epigeic and Aporrectodea caliginosa from epi-endogeic ecotypes) would advance the modelling and prediction of PAH bioavailability and improve risk assessment for ecological and human exposure.

This dissertation addresses the simultaneous relationship between agency costs, ownership structure and dividend policy in the listed corporate firms in Saudi Arabia - the largest emerging economy in the Middle East. Specifically, the study aims to investigate co-deterministic relations between: (i) agency costs and ownership structure, (ii) agency costs and dividend policy, and (iii) ownership structure and dividend policy. Extant literature generally concludes that both ownership structure and dividend policy can effectively mitigate agency costs in emerging economies; however, these simultaneous relationships have never been researched in the Saudi context, except for a handful of studies examining the relationship between ownership structure and dividend policy. Building on relevant theories and using data from the Saudi Stock Exchange (Tadawul) for the 2010 to 2015 period, this study explores the nature of the simultaneous relationship between agency costs, ownership structure and dividend policy in the Saudi market. Advanced econometric methods (two-stage least squares [2SLS] and system generalised method of moments [GMM]) are applied to analyse the data and produce credible findings from the study.

The 2SLS and system GMM findings on the bi-directional relationship between agency costs, ownership structure and dividend policy reveal a significantly negative simultaneous relationship between agency costs and ownership structure, and between agency costs and dividend policy. However, a simultaneous relationship is not evident between ownership structure and dividend policy, indicating a unidirectional relationship running from ownership structure to dividend policy. In addition, a number of other governance variables demonstrate expected findings with agency costs, dividend policy and ownership structure. These findings of this study from Saudi Arabia have similarities with those reported in previous studies in developed economies, despite the institutional and socio-economic/cultural differences between them. Further, these findings align with the theoretical underpinning in the literature relevant to emerging markets.

The empirical findings of this study provide support for the new corporate governance regime in Saudi Arabia, encouraging good corporate governance practices in Saudi firms to alleviate the level of agency costs for sustained growth. In an emerging market context and as a pioneer of this type of study in Saudi Arabia, the current study extends the existing literature in identifying effective corporate governance mechanisms and their two-way interactions with agency costs, as compatible with developed economies. These findings will be beneficial to policy makers, market authorities, investors and other stakeholders to evaluate, sustain and improve the current corporate governance practices in Saudi listed firms.

The role that children played within the witchcraft trials that erupted over Europe, England and New England between 1450-1750 is a complex phenomenon that differed substantially between each local, temporal and judicial context. Although the witch-hunt episode itself continues to attract significant attention from scholars and other popular writers, the role of children in these trials has been largely undervalued. My research has examined and given insight into the role that children played within key witchcraft trials in England and New England between 1589 and 1692. Relying on primary sources largely in the forms of legal documents, pamphlets and treatises, this thesis demonstrates that the role that children played is not only more complex than originally thought, but it is also a vital part of the witch-hunt phenomena which deserves its own singular attention.

Children are often relegated to the margins of historiography. When they are considered, they are usually done so in relation to other historical events (such as the infamous John Darrell Controversy). In addition to this, some children’s case studies have been written about in the form of microhistories, which are useful, but have had the unintended consequence of rendering a cyclical echo chamber whereby other children’s stories have been forgotten about or ignored. Through a comparative analysis that implements a broad chronological and geographical approach, a total of sixty-one English and New English children are the focus of this thesis’ examination. As liminal beings – not quite infants but not yet adults – children were both loved and feared by their society. They were thought to be both innocent and close to God but also malleable and susceptible to the snares of the Devil. Thus, children held a unique status as agents of the invisible world. Their insight in matters pertaining to the supernatural was frequently used and taken advantage of in witchcraft trials where English and New English children played a variety of roles; they were often accusers, using their spectral sight to be the magistrates of the unseen realm, identifying and denouncing witches, but they could also be accused of witchcraft themselves. My research places children at the forefront of historical knowledge in order to demonstrate both how and why children were pervasive in witchcraft trials on both sides of the Atlantic.

Amid concerns of the looming scarcity of agricultural land and rapidly growing global demand for food and biofuel, cropland abandonment is occurring in many parts of the globe, affecting millions of hectares of cultivated land. Although cropland abandonment trends have been widely reported and studied in European landscapes and other Western countries, this land use change phenomenon is relatively new in developing countries, including Nepal, and knowledge about the drivers and impacts of cropland abandonment is lacking. There is a need for a deeper understanding of why Nepalese farmers are abandoning farming, what are the impacts of cropland abandonment on rural households, and how abandoned croplands can be reutilised for the benefit of the rural community and the environment.

Drawing lessons from global evidence, this PhD work aimed to understand the underlying drivers and implications of agricultural land abandonment, and to explore potential reutilisation pathways to improve the rural economy, food security and sustainable land use in Nepal. To achieve this goal, four research objectives were formulated and investigated using a systematic literature review and quantitative and qualitative data collection from three districts of the hill agroecological region of Nepal, using a mixed methods research approach. Three districts – Kavre, Lamjung and Kaski – were selected considering the diversity of demographic and socioeconomic status of farmers, land use and farming practices, economic opportunities and livelihood systems, and land abandonment trend and prospect for reutilisation. Quantitative data was collected through a household survey and qualitative data were collected through focus group discussions and key informant interviews. In total 374 household surveys, 6 focus group discussions, and 15 key informant interviews were conducted.

The first objective of this study was to conduct a systematic review to understand the drivers and consequences of agricultural land abandonment and pathways for the reutilisation of abandoned agricultural lands reported across the globe (Chapter 2). For the review, 124 relevant articles were retrieved from a systematic search of CAB Abstracts, Scopus and Web of Science, applying exclusion and inclusion criteria in line with standard protocols. The spatial and temporal diversity of the reviewed articles showed that most of the research on the topic of land abandonment is concentrated in European (64 articles) and Asian Countries (44 articles). Although this land use change has received research attention from the early 1990s, about 95% of the articles were published only in the last 15 years. In the case of Asian countries, almost all of the studies took place after 2014.

The review identified seven categories of drivers responsible for cropland abandonment: demographic, household characteristics, farm characteristics, biophysical, economic, regulatory and socio-political. Cropland abandonment had mixed impacts on several abiotic and biotic components of the landscape, with contrasting views about the social and environmental implications. However, negative consequences were most frequently reported compared to positive consequences, particularly in the agricultural landscape, farmland and farm structures, food security, socio-cultural aspects and economic aspects. Positive impacts were observed on carbon sequestration, habitat availability and microbial abundance. Although previous studies often considered land abandonment as a global concern in land use assessment and management, few studies discussed the possible reutilisation pathways of abandoned croplands. Alternative land uses included various farm-forest and afforestation systems, highvalue crop farming and a range of communal land management approaches. Finally, this review chapter provided valuable insights for future research and knowledge about the trade-offs and opportunities associated with land abandonment.

The second objective of the study was to examine the extent, drivers and impacts of cropland abandonment in the hill agroecological region of Nepal (Chapter 3). The study revealed that, depending on the location, between 31% and 48% of croplands were abandoned in the region, with 60% of farming households having abandoned at least one parcel of cropland. Biophysical drivers (distance from homestead to parcel, the slope of the parcel, land fragmentation, land quality and irrigation availability) and socio-demographic drivers (family size, higher education of the household members and out-migration) were commonly responsible for agricultural land abandonment. Negative impacts of land abandonment were reported for rural landscapes, human-made farm structures, socio-economic systems, local food production and food security. In line with global studies, this research suggested that marginal land quality, demographic changes (particularly migration) and rising alternative economic opportunities elsewhere contributed to cropland abandonment.

The third objective of this study was to investigate the dynamics and potential pathways for reutilising abandoned cropland. To address this objective, Chapter 4 examined the potential reutilisation options, farmer preferences, and conditions that create an enabling environment for productive reutilisation of abandoned croplands. Regardless of their abandoned cropland holdings, the majority of the Nepalese hill farmers considered that abandoned croplands should be reutilised. The farmers identified seven options for reutilising abandoned croplands: Cash cropping, Fruit crop farming, Spice and medicinal crop farming, Fodder tree plantation, Cereal cropping, Woodlot plantation and Mixed subsistence farming. Despite the dominance of traditional mixed subsistence farming in the area, the majority of farmers did not consider this system as a viable option for reutilisation. Farmers preferred high value and cash-generating options for reutilisation. This implied that the use of relatively productive croplands for marketoriented farming could help to minimise abandonment and revitalise the Nepalese agricultural sector. The study showed that farmers' preferences and adoption of reutilisation options are influenced by their socio-economic attributes, household needs and availability of resources.

Chapter 4 also showed that the most important conditions that motivate farmers, apart from labour availability, were structural and institutional conditions that require state or commercial intervention to address. However, many aspects of these latter factors are beyond the control of farming households in the region. This highlighted the need for an in-depth understanding of how policies regulate structural, commercial and institutional settings, thereby shaping the reutilisation decisions of farmers at the local level. Chapter 5 addressed this need by analysing the policy constraints for reutilisation of abandoned farmlands and identifying possible policy solutions for the management of abandoned farmlands for productive use.

Chapter 5 found that policy provisions related to land rights, labour, incentives and governance play important roles in shaping decisions on reutilisation of abandoned cropland. Land-related issues rooted in ownership, tenancy rights, access, inheritance law and rising trends of land conversation to non-farm use, have played important roles in shaping the abandonment and reutilisation process. Migration-promoting policies, and agricultural policies that fail to support farming systems innovation or agricultural market development have further limited reutilisation. Similarly, the lack of effective implementation of programs to manage croplands sustainably, weak coordination within and between institutions, and conventional land governance systems are other constraints for reutilisation.

Based on these findings, five potential policy solutions to address these problems have been recommended: (a) provision of land use rights transfer to improve access to land, (b) promoting the consolidation of fragmented land parcels to help ensure economies of scale, (c) improved farm labour management and promotion of farm mechanisation to address labour shortage issues (d) commercially oriented policy priorities to reutilise relatively productive abandoned croplands for high-value, comparative advantage and export potential commodities, and (e) improved administrative and governance capacity of local governments to monitor and manage unauthorised land conversion, fragmentation and abandonment.

From a global policy perspective, abandoned croplands are often viewed as unproductive land, occupying marginal lands. But there is evidence that a significant portion of globally abandoned croplands is still economically viable for recultivation, a view reinforced in this study. Thus, development activities and policies should consider options for reutilising abandoned croplands sustainably to address the growing global socio-economic and environmental challenges associated with land abandonment. Against this backdrop, it is anticipated that the findings of this study will contribute to ongoing national and international discussions about practices, policies and trade-offs of cropland abandonment and its reutilisation pathways.

This thesis examined the efficacy of several alternative feed additives in enhancing performance and enteric health in broilers in the absence of antibiotics. Chapter 1 provides background information, leading to the objectives of conducting the experimental studies. This is followed by a review of literature in Chapter 2, covering the general characteristics of the gastrointestinal tract, gut microflora and the factors affecting gut health. The review also covers enteric diseases, namely necrotic enteritis, factors predisposing birds to necrotic enteritis and methods of controlling it.

Chapter 3 evaluates the efficacy of yeast cell wall extract derived from Saccharomyces cerevisiae as a replacement for zinc bacitracin and the anticoccidial ionophore salinomycin, using an established necrotic enteritis challenge model. The results showed that weight gain, feed intake and livability of challenged birds were lower than for unchallenged birds on d 24 and 35 (P < 0.05). All of the additives had a greater positive impact on weight gain, feed intake and livability in challenged compared to unchallenged birds. Birds given zinc bacitracin, yeast cell wall extract or salinomycin significantly improved in weight gain and livability when compared to control birds given no additives. Challenged birds fed yeast cell wall extract exhibited decreased crypt depth, increased villus height and increased villus to crypt ratio.

Chapter 4 investigates whether acetylated high amylose maize starch or butyralated high amylose maize starch play a positive role in digestion in broiler chickens and particularly in ameliorating the severity of necrotic enteritis in broilers under experimental disease challenge. The results showed that on d 24 and 35, all challenged birds had lower (P < 0.001) livability, weight gain and feed intake compared to unchallenged birds. Birds fed acetylated high amylose maize starch and butyralated high amylose maize starch diets had higher (P < 0.001) weight gain and feed intake compared with those fed the control diet. Birds fed acetylated or butyralated high amylose maize starch diets had poorer (P < 0.002) feed conversion ratio at d 35. Butyralated high amylose maize starch increased jejunal villus to crypt ratios, ileal and caecal butyrate levels and decreased caecal pH. Acetylated high amylose maize starch significantly improved ileal acetate content and decreased caecal pH.

Chapter 5 determines the efficacy of acylated starches on performance, heat production and energy efficiency of broiler chickens during an induced outbreak of necrotic enteritis. The data demonstrate that Eimeria sp. and Clostridium perfringens challenge reduces growth performance, heat production, respiratory quotient, heat increment, metabolisable energy and metabolisable energy intake of birds fed the control, acetylated or butyralated high amylose maize starch. However, birds fed antibiotics exhibited nearly total resistance to the challenge with necrotic enteritis.

Chapter 6 describes the effect of encapsulated sodium butyrate on growth performance and gut health in broilers fed wheat or corn based diets, at normal or high protein levels and normal or low energy levels. The inclusion of encapsulated sodium butyrate at 1 g/kg had no effect on growth performance, ileal and caecal pH and levels of SCFAs, but increasing the inclusion rate to 2 g/kg improved bird performance.

Chapter 7 discusses the major findings on the effects of some feed additives, namely microencapsulated sodium butyrate, yeast cell wall extract and acylated starches, on broiler chickens production and gut health, and the role of yeast cell wall extract and acylated starches in ameliorating the severity of necrotic enteritis in broilers under experimental disease challenge. In conclusion, necrotic enteritis is characterized by necrosis and inflammation of the gastrointestinal tract with a significant decline in growth performance. However, yeast cell wall extract and acylated starches can be used as tools for reducing the severity of necrotic enteritis outbreaks.

The series of experiments reported in this thesis suggests that the yeast cell wall extract consists mainly of mannano-oligosaccharides, butyralated starch and acylated starch products are able to partially ameliorate the impact of necrotic enteritis in broiler chickens by improving gut health, but are unable to replace antibiotics in terms of effectiveness against severe challenges. Further studies are required to investigate the modes of action of these feed additives in improving gut health and reducing the severity of necrotic enteritis.

Five industry-relevant animal experiments were completed to investigate amino acid supplementation in reduced protein diets and the impacts on meat-chicken performance, metabolism, and physiology. Specifically, the role of the non-essential amino acid glycine in reduced protein wheat-based diets was investigated. This work was developed in response of increasing expenses and environmental impacts associated with current dietary crude protein levels in broiler diets, however, reducing the crude protein and supplementing all assumed essential nutrients typically results in impaired performance. The work completed in this thesis contributes to our understanding of broiler amino acid requirements in reduced protein wheatbased diets.

The first experiment investigated the role of the non-essential amino acid, glycine, in broiler performance when fed reduced protein wheat-based diets. An industry-standard protein diet and three reduced protein diets with and without glycine supplementation were fed to Ross 308 cockerels. Glycine was supplemented to equal that in the standard protein diet at 0.712 and 0.648% in grower and finisher diets respectively. Performance, water intake, and amino acid digestibility were measured. Reducing crude protein reduced body weight gain by up to 18% and reduced water intake by 28%. However, supplementing glycine in reduced protein diets restored the impaired performance and increased water intake. Supplementing crystalline amino acids in reduced protein diets increased their respective apparent ileal digestibility, with the greatest difference in threonine digestibility increasing by up to 8.3 percentage points. When feeding reduced protein wheat-based diets, supplementing crystalline amino acids, including glycine, can maintain performance like that observed in standard protein diets.

A second experiment was completed to determine if supplementing glycine precursors have the same effect on performance as glycine in reduced protein diets. Ross 308 cockerels were fed one of two protein levels; an industry-standard protein diet with meat and bone meal or a plant-based diet approximately 3% lower in crude protein. In the reduced protein diet, glycine, serine, and threonine were assigned a glycine equivalence and supplemented to match the glycine in the standard protein diet at 1.558 and 1.390% in grower and finisher diets respectively. Reducing the dietary protein by 3% reduced feed efficiency by 10-points, however, the supplementation of glycine or serine did not restore performance. Threonine supplementation further reduced body weight gain in reduced protein diets by 6.8%. Therefore, glycine did not appear to be limiting in the reduced protein diet investigated, however, using threonine to supplement glycine requirements exacerbated the performance reducing effects of reduced protein diets.

A third experiment explored the effects of different crude protein diets and the supplementation of glycine precursors on the in vivo synthesis of glycine. To investigate this, a second glycine equivalence level was added to the reduced protein treatments described above at 1.8% giving a total of eight treatments. Using these treatments, the effects of reduced protein diets on glycine and uric acid metabolism was investigated. The in vivo conversion of serine and threonine to glycine was evident in the blood plasma, however, reducing dietary protein reduced blood serum uric acid. The expression of hepatic genes for enzymes associated with threonine degradation to glycine, glycine degradation, and uric acid-synthesis were downregulated in reduced protein diets. No effect of crude protein or supplementing different glycine precursors at differing levels was observed on the expression of the enzyme associated with the interconversion of glycine and serine. The supplementation of excess essential amino acids and non-specific nitrogen may not fulfil the non-essential amino acid requirements for efficient growth as the in vivo synthesis of non-essential amino acids is altered in reduced protein diets.

A fourth experiment investigated the differences in performance when increasing both the essential and non-essential amino acid densities by 15% in reduced protein diets. Ross 308 cockerels were fed one of three protein levels; standard, reduced, or low protein, with one of three amino acid profiles using AMINOChick®2.0 (Evonik Animal Nutrition, 2016) software recommendations; 100% amino acids (100% AA), 115% essential amino acids (115% EAA), or 115% amino acids (115% AA). In this experiment, glycine was considered an essential amino acid and formulated to 1.6% glycine equivalence. Performance, nitrogen digestibility, and blood parameters were measured. No significant difference was observed between feeding 100% AA and 115% EAA treatments at each protein level in body weight gain. However, feeding 115% AA increased body weight gain in standard and low protein diets by up to 18.7%. Blood parameters indicated reduced uric acid synthesis in low crude protein diets, despite glycine supplementation. Feeding 115% AA in the standard and low protein treatments increased nitrogen digestibility compared to the other amino acid profiles. The results from this study indicate that non-essential amino acids play key roles in growth and development that cannot be overcome with extra essential amino acid supplementation.

Finally, a fifth experiment assessed the efficacy of low protein diets and increasing amino acid densities by 15% on mitigating the effects of sub-clinical necrotic enteritis. To investigate this, the standard and low protein treatments and the 100% AA, 115% EAA, and 115% AA profiles of the previous experiment were used in birds either challenged or not with sub-clinical necrotic enteritis. Ross 308 cockerels were fed one of six dietary treatments across 12 replicates. Six replicates per treatment were challenged with sub-clinical necrotic enteritis using Eimeria spp. and Clostridium perfringens. Differences in bird performance between those fed the standard and low protein diets were not apparent in challenged birds. Feeding diets with 115% AA increased body weight gain after the challenge by 10.5%. As evident from the finisher body weight gain, regardless of amino acid profile, low protein diets delayed recovery. However, in standard protein diets, feeding 115% AA increased body weight gain by 16.7%. These results suggest reducing crude protein may not mitigate the effects of sub-clinical necrotic enteritis, however, increasing both essential and non-essential amino acids will assist with recovery.

The work completed has been highly industry-relevant and has highlighted the complex relationships between amino acids and the effects they have on meat-chicken performance, metabolism, and physiology. The Australian chicken meat industry now has a dataset of Australian diets for assessment to consider implementing reduced protein diets to improve industry sustainability and access potential diet cost savings .

Purpose

The purpose of this study was to develop a framework for the analysis, description, and comparison of the administrative arrangements used by school systems for making decisions about the selection of teachers for appointment to positions in schools. Administrative arrangements are defined in terms of the administrative units of which they are composed, the functions performed by these units, and the relations that exist between them. The term 'appointment' refers to any kind of appointment and specifically includes first appointments, transfers, promotions, and appointments made on a permanent, temporary, or casual basis.

The purpose was to be accomplished through the analysis, Gescription, and comparison of the administrative arrangements used by the state education departments of New South Wales and Queensland. The study had three specific objectives: 1) the development of an analytic framework; 2) the description of the arrangements used by the two state education departments; and 3) the identification of significant distinguishing features.

Procedures

The concurrent, parallel case study approach was adopted for the examination of the selected appointment systems. In this approach the same research procedures are used in the investigation of each case, and each phase of the investigation is carried out in respect of each case before proceeding to the next phase.

Data were collected in the sequential mode, i.e., analysis proceeds concurrently with collection and influences subsequent data collection. The major technique of data collection was the research interview. In these interviews the focus was provided by the researcher, the detailed structure and content by the informant. Twenty-five major interviews were conducted, fourteen in New South Wales and eleven in Queensland. A preliminary analysis of each interview was made as soon as possible after the interview. This analysis converted the raw data of the interviews into items of information which provided the basis for further analytic procedures. Supplementary information was obtained by a large number of less formal interviews.

The interviews were preceded by an analysis of the formal framework of each appointment system based on official documents. The information obtained through the interviews was used to develop this framework and to contribute to the evolving description of each system. The descriptions of the systems were compared in terms of the framework.

Findings

There was a great variation in the character of the administrative units identified by the study. They ranged from those whose membership and functions are prescribed in some detail by law or regulation to those which have no formal constitution and are identified largely by the function they perform. Three major orientations that one unit may have to another were identified: 1) sequential; 2) parallel; and 3) hierarchical. The orientation that exists between any two units circumscribes the questions to be asked about the detail of the relations between them.

Type of tenure and level of position were identified as the key appointment type variables. The values of each of these variables fell into two categories. Full and restricted in the case of tenure, base and higher in the case of position. The combination of these variables result in four appointment types: 1) higher-level positions, full tenure; 2) base—level positions, full tenure; 3) higher-level positions, restricted tenure; and 4) base-level positions, restricted tenure.

Three decision areas were identified: 1) teacher assessment; 2) teacher listing; and 3) teacher placement. They were found to apply to each of the appointment types, thus the basic analytic framework consisted of twelve cells, four appointment types each divided into three decision areas.

The comparison of the descriptions of the administrative arrangements used by each system revealed important similarities and significant differences. They shared: 1) an interdependence between various decision areas; 2) an interdependence between various appointment types and subtypes; 3) a concentration of formal power near the top; 4) a notable concern for teacher welfare; 5) varying degrees of formality in different parts of the system; and 6) being in a state of constant change.

Many differences were identified. Particularly significant differences related to: 1) promotions lists; 2) handling teacher preferences; 3) inter-regional transfers; and 4) staffing less popular schools.

Conclusions and Recommendations

The major conclusion was that the framework developed in the course of the study was suited to the purpose for which it was designed. Other conclusions were: 1) the information available in official documents is insufficient for an. accurate description; 2) the research interview as used in this study was a particularly appropriate means of obtaining the data required; 3) the use of the sequential mode of data collection is clearly indicated for research of this kind; 4) the distribution of information among informants makes the systematic collection of multiple viewpoints essential rather than merely desirable; and 5) the study of any component of an appointment system must take into account the influence of other parts of the system on that component.

The major recommendation is that the framework developed in this study be applied to the analysis, description, and comparison of other systems of teacher appointment. To this end the study includes a recommended approach to such studies. Other recommendations for further research are: 1) further analysis of administrative arrangements and in particular the development of a taxonomy of administrative units; 2) investigation of the consequences of using particular administrative arrangements; and 3) the application of the methods used in this study to the investigation of the arrangements used for making decisions about other important matters (such as curriculum).

The present research analysed the expansion of urbanization and land cover changes and the associated environmental impacts in five Saudi Arabian cities: Riyadh, Jeddah, Makkah, AlTaif and Eastern Area using Landsat data. It first started by reviewing the related literature that have utlized the use of remote sensing (RS) data and techniques to quantify land use and land cover (LULC) changes and urban expansion. It was divided into three sections. First, it investigated the most used techniques to detect the LULC changes in the previous studies. Both pixel-based image analysis (PBIA) and object-based image analysis (OBIA) have been reviewed. An evaluation of the strengths, weaknesses and the acurracy of these techniques has been discussed. The second section focused on the spatial and statsitical techniques used to model the future LULC changes. The final section reviewed and discussed the previous studies that used RS data and techniques in Saudi Arabia.

The second research used two sets of Landsat images of 1985 and 2014 to map and monitor the spatial distribution of the urban extent among the five cities. A decision tree classifier was applied using object-based image analysis (OBIA) to analyse urban land cover in the five cities. The accuracy assessment of the urban change detection maps indicated a high overall accuracy and kappa coefficient. The results of this research show a high rate of urbanization and complex dynamics across the five cities. The significant changes were the result of a rapid increase in land development, exhibiting complex patterns in the urbanization process across the five cities. The government’s policy and increased oil revenues significantly contributed to increasing the urban cover in the five selected cities.

The third research investigated the effect of four driving forces, including elevation, slope, distance to drainage and distance to major roads, on urban expansion in the selected five cities. The prediction of urban probabilities in the selected cities based on the four driving forces was generated using a logistic regression model for two time periods of urban change in 1985 and 2014. The validation of the model was tested using two approaches. The first approach was a quantitative analysis by using the Relative Operating Characteristic (ROC) method. The second approach was a qualitative analysis in which the probable urban growth maps based on urban changes in 1985 was used to test the performance of the model to predict the probable urban growth after 2014 by comparing the probable maps of 1985 and the actual urban growth of 2014. The results indicate that the prediction model of 2014 provides a reliable and consistent prediction based on the performance of 1985 model. The analysis of driving forces shows variable effects over time. Variables such as elevation, slope and road distance had significant effects on the selected cities. However, distance to major roads was the factor with the most impact to determine the urban form in all five cites in both 1985 and 2014.

The fourth research quantified LULC changes and the effect of urban expansion in the five cities using Landsat images of 1985, 2000 and 2014. A total of 72 images including Multispectral Scanner (MSS) and Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) were acquired during winter (December to February), spring (March to May), summer (June to August) and autumn (September to November). The seasonal change of vegetation cover was conducted using Normalized Difference Vegetation Index (NDVI). OBIA was used to classify the LULC changes. The overall accuracies of the classified maps ranged from 82% to 96% which indicated sufficiently robust results. Urban area was the most changed land cover, and most of the converted land to urban was from bare soil. The seasonal analysis showed that the change of vegetation cover was not constant due to climatic conditions in these areas. The agricultural lands were significantly decreased between 1985 and 2014, and most of these lands were changed to bare soil. Dwindling groundwater resources has significantly led to a reduction in the agricultural practices, especially in Riyadh.

The fifth research analysed the expansion of urban growth and land cover changes in the five Saudi Arabian cities using Landsat TM, ETM+ and OLI images for the 1985, 1990, 2000, 2007 and 2014 time periods. The classification was carried out using OBIA to create land cover maps. The classified images were used to predict the land cover changes and urban growth for 2024 and 2034. The simulation model integrated the Markov Chain (MC) and Cellular Automata (CA) modelling methods and the simulated maps were compared and validated with the reference maps. The simulation results indicated high accuracy of the MC– CA integrated models. The total agreement between the simulated and the reference maps was > 92% for all the simulation years. The results indicated that all five cities showed a massive urban growth between 1985 and 2014 and the predicted results showed that urban expansion is likely to continue for 2024 and 2034 periods. The transition probabilities of land cover, such as vegetation and water, are most likely to be urban areas, first through conversion to bare soil and then to urban land use. Integrating of time-series satellite images and the MC–CA models provides a better understanding of the past, current and future patterns of land cover changes and urban growth in this region. Simulation of urban growth will help planners to develop sustainable expansion policies that may reduce future environmental impacts.

This thesis explores methods for estimating genotype by environment (G×E) interactions in livestock and plants. Genotype by environment interactions occur when the genetic architecture of a trait changes depending on the environment it exists in. They are particularly interesting as a source of genetic variation that could be utilised in breeding programs to select genotypes who have genetic merit that is more robust to environmental variation. This thesis aims to estimate genotype by environment interactions in livestock and plant populations using different methods and improve our understanding of how these interactions could be used in breeding programs to increase the robustness of agricultural populations to environmental variation.

The first experiment of this thesis investigated genotype by environment interactions in the bodyweight of Australian sheep using reaction norm and multi-trait models in combination with genomic data. It found significant variation in the slope of the reaction norm model that could be used to increase robustness of sheep, and that this variation was highly polygenic. It highlighted that both heterogenous genetic variance (scale-type G×E) and heterogenous genetic correlations (rank-type G×E) contributed to the variation in the reaction norm slope and found it could be important to separate these sources to better understand the genetic variation in robustness.

The second experiment of this thesis utilised a multi-environment trial of a Barley population to examine the effectiveness of two methods to partition the different types of G×E interactions when estimating the robustness of genotypes in reaction norm models. It found that genetic regression, which made breeding values for the slope independent of the intercept, was very effective in removing the impact of G×E interactions due to scale and isolating the variability across environments due to heterogenous genetic correlations. This enables the change in genetic architecture of traits across environments to be studied more clearly in reaction norm models. We also showed that factor analytic models, which are an alternative to reaction norms, are better equipped to capture complex G×E interactions because of their flexibility.

The third experiment of this thesis examined the use of factor analytic models to capture genotype by environment interactions in a multi-environment trial of sheep. The factor analytic models were able to approximate the unstructured genetic co(variance) matrix between 31 discrete environments using 85% fewer parameters than what would have been required with a multi-trait model. The model enabled the flock-years to be clustered by their similarity and showed that G×E interactions were large both between flocks and across years within flocks. It was unclear whether factor analytic models were preferrable to reaction norms based on the goodness-of-fit tests, and the estimates of heritability, genetic variance and genetic correlations between environments were inconsistent between the models.

The final experimental chapter assessed the capacity of reaction norm models to predict the robustness of a sire’s progeny performance across different growth environments. Using data collected in a research flock, the reaction norm models were predictive of the ability of a sire’s progeny to reliably gain weight across different growth environments at an accuracy that was consistent with the power of the data. It then found that these breeding values for robustness were consistent with breeding values estimated using data from the wider industry population recorded by commercial stud breeders. Selection based on reaction norm breeding values could be used to increase the robustness of body weight gain in Australian sheep to variation in growth environments.