School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe effect of microbial rennet on the quality and proteolysis of cheddar cheese(University of Melbourne, 2008)
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ItemMaize-farmers' attitude towards risk in Mozambique(University of Melbourne, 2008)
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ItemLarger tuber size improves Microseris walteri (Murnong; Yam Daisy) transplant success( 2021)Since European settlement, the vast majority of Natural Temperate Grassland in south-eastern Australia has been destroyed or drastically altered. Microseris walteri, also known as Yam Daisy or Murnong, is one of many grassland species that has experienced considerable losses. M. walteri is known for its small, sweet-tasting tubers that were once a staple food source for many First Nations people. Successfully reintroducing Murnong populations into grasslands has proven very difficult. Here we investigated whether tuber size impacts translocation success. Microseris walteri plants with larger tubers (4.5 - 14.2 g) had significantly higher survival rates relative to medium (2.1 - 3.4 g) and small tubers (0.4 - 1.6 g). Additionally, tuber size was found to be positively correlated with the plants’ total leaf number, as well as the length of the longest leaf. Reintroduction by sowing seed was found to be ineffective. Together these results indicate that future Yam Daisy reintroductions should focus on transplanting plants with a greater tuber mass for a better chance of reintroduction success. Future research is required to better understand how to influence plants to grow larger Murnong tubers in a production system.
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ItemEffects of vegetation structure, fire and habitat amount on microbat functional diversity( 2020)Human modification of land cover and disturbance regimes is occurring at unprecedented rates globally, and often results in significant biodiversity loss. However, it is often unclear how the loss of species affects ecosystem function. The relationship between ecosystem function and biodiversity depends on the functional traits and niches filled by organisms, as these traits respond to and drive ecosystem processes. Functional diversity describes the range, value and distribution of traits and is a better predictor of ecosystem function than species richness. This study investigated the effects of vegetation structure, fire and habitat amount on microbat functional diversity. Using passive acoustic monitoring, we surveyed microbats at 140 sites over two years. Four bat functional traits were used to calculate four functional diversity indices (richness, evenness, divergence and dispersion). The influence of vegetation structural complexity, time since fire and habitat amount on bat functional diversity and species richness was examined using generalised linear models. With the exception of one measure of functional diversity, time since fire did not influence any of the response variables. In contrast, vegetation structural complexity was a much stronger predictor of functional diversity than time since fire, with functional diversity increased in more structurally open environments. Both functional evenness and functional dispersion of bats were both positively associated with habitat amount, indicating that increased habitat amount results in reduced environmental filtering and an increased breadth of functional roles performed by the bat community. Finally, FD responses often depended on the survey year, indicating that responses were influenced by temporal variability in background conditions. These findings suggest that management for biodiversity should be focused on optimising vegetation structure through the use of fire, rather than focusing on fire regime alone. Further, management actions that protect and increase habitat amount should, therefore, increase overall bat functional diversity arising from the increased abundance of foraging and roosting resources available. Lastly, long-term monitoring programs measure species responses across a variety of conditions, thereby providing more representative evidence to develop well informed management decisions.
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ItemWhat factors constrain and enable the integration of blue carbon into the existing locally managed marine area (LMMA) network?( 2018)Blue carbon refers to the carbon stored in coastal ecosystems like mangroves, seagrasses, and tidal salt marshes. The conservation and restoration of these threatened 'blue habitats' is a field that has received increased attention in the international community over the last decade as a means to address climate change mitigation, adaptation, biodiversity protection, and sustainable development agendas. Locally managed marine areas (LMMAs) are community-based marine management schemes where coastal communities are central in the management of their coastal and marine resources for food security, income livelihoods, and coral reef conservation. The LMMA network is a global network of communities, research bodies, civil society organisations (CSOs), government agencies, and private sector partners, that share knowledge, skills, expertise, and best practice approaches to marine natural resource management. The Fiji LMMA network (FLMMA) is the most successful and well recognised national subsidiary. This thesis seeks to identify what factors constrain and enable the integration of blue carbon into the existing LMMA network. This is explored through two chapters written as academic journal papers (intended for publication). Paper one (P1) uses an integrated and adaptive natural resource governance framework, to analyze 16 semi-structured interviews with 'specialists' in the field. Paper two (P2) uses a social-ecological systems (SES) sustainability framework to evaluate key benefits and required trade-offs taken from two focus group discussions (FGDs), interviews, 'mud-mapping', and field observations in one of Fiji's oldest LMMA sites, Navakavu. The thesis finds that there are a range of benefits in terms of the networks’ existing governance structures and sectoral integration in the South Pacific that make this incorporation favourable. However, there are several constraining issues in terms of weak compliance and enforcement systems, high level government corruption, and restrictive bureaucratic processes that threaten its viability. Further, SES outcomes from LMMA implementation have been mixed and some specialists question the efficacy of the approach as local pollution and poaching remain pervasive. Nevertheless, the important role that mangroves and seagrasses play in coastal ecosystems, and the connectivity and co-benefits that they provide from the 'ridge to the reef', makes blue carbon investment in Fiji and across the Pacific ecologically and socially attractive. While delivering carbon finance directly to communities is ill-advised there are several creative options for blue carbon financers to invest into community-based conservation, restoration, and management of blue ecosystems including high level investment into the networks’ capacity to provide ongoing support to its community partners.
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ItemDirect seeding onto green roof substrate supports species rich, high cover novel grassland( 2016)The vegetation of green roofs is central to their functioning and ability to provide ecosystem services. When vegetation performs well, green roofs contribute to storm water mitigation, thermally buffer buildings, improve biodiversity and provide aesthetic and recreational relief in the grey city landscape. However, poor vegetation performance is common, with a decline in both species richness and cover over time. This decline can in part be attributed to design, failing to consider community assemblage mechanisms that lead to quality vegetation performance. Direct seeding of grassland species could offer a randomness in distribution and abundance of seedlings that supports early community self-organization and co-existence. Comparatively, adult plant establishment does not provide this early opportunity. This thesis determines, the ability of a scoria based green roof substrate to support the germination and establishment of a species rich, high cover, novel grassland community, and the direct seeding sowing methods to achieve this. Additionally, species richness, and abundance were investigated as potential drivers of cover. A grassland forb only species seed mix was applied in two experiments. Experiment One (n=7), in glasshouse conditions, investigated application of seed with and without a sand bed, and depth of sowing; six treatments. Experiment Two (n=10) in green roof module conditions outside under irrigation, investigated depth of sowing and rate; four treatments. Main results showed a species rich and abundant germination on scoria based green roof substrate. Results indicated that both depth of sowing at greater than 10 mm and application in a sand bed, reduced species richness and abundance. In green roof module conditions, surface sowing indicated a slight species richness advantage and an abundance disadvantage, in comparison to sowing between 0 to 10 mm depth. Sowing rate approaching that of on ground grassland restoration rates, were shown to be as effective as a doubled sowing rate in producing a species rich, high cover. This study found; no support for species richness as a key driver of cover, however abundance is indicated as an early key driver of cover, and may not act in isolation during rapid cover development. These findings are relevant to management practices. Quality vegetation performance, achieved at sowing rates approximating on ground restoration, suggest that further investigation into lowering rate and species richness and cover response, is warranted. Long term studies investigating community dynamics, would give insight into this novel community’s ability to continue co-existence as a functional resilient system, as a predictor of ecosystem service potential.
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ItemWhat the flux? High eddy covariance NEP in a dry sclerophyll eucalypt forest is validated using inventory and growth models( 2016)Globally forests contribute to climate change mitigation by sequestering about a quarter of anthropogenic fossil fuel CO2 emissions. Understanding their contribution to the global carbon budget is therefore critical. Recent measurements of carbon uptake in temperate eucalypt forests using eddy covariance indicated un-usually high carbon sequestration of these forests. This abnormality could alter our understanding of their carbon uptake. Due to a range of uncertainties in the eddy covariance method and potential for violating flux tower assumptions, validating carbon sequestration is necessary. I validated Net Ecosystem Productivity (NEP) measurements of an eddy covariance flux tower site at a dry sclerophyll eucalypt forest in South Eastern Australia for a three year period (2013 – 2015). A novel approach combining inventory and growth models was used for retrospective prediction. Inventory Net Primary Productivity (NPP) was calculated and a source area adjusted NPP also calculated to account for the wind source area contribution to tower flux measurements. Inventory NPP was 3.19 Mg C ha-1 yr-1 (95% CI: 2.48, 3.88) in 2013, 7.85 Mg C ha-1 yr-1 (95% CI: 6.82, 8.88) in 2014 and 9.48 Mg C ha-1 yr-1 (95% CI: 8.33, 10.6) in 2015. The source area adjusted NPP was 2.90 Mg C ha-1 yr-1 (95% CI: 2.73, 3.06) in 2013, 7.27 Mg C ha-1 yr-1 (95% CI: 6.81, 7.72) in 2014, and 8.91 Mg C ha-1 yr-1 (95% CI: 8.38, 9.45) in 2015, indicating that eddy covariance consistently overestimated carbon flux by 27 – 45%. In the year of low carbon uptake (2013) rates of carbon sequestration were comparable to temperate forests globally, but in years of high uptake (2014 – 2015) sequestration in this forest was comparatively greater. These results demonstrate the importance of validating flux tower measurements and confirm high sequestration rates in this forest type.
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ItemImpacts of urbanisation on autumn-breeding amphibians in the greater Melbourne region( 2016-06-17)Modification of environments by urban development is a significant threat to global amphibian populations. Of all vertebrate classes, amphibians are facing the greatest risk of extinction – with 25% of species in Australia threatened with extinction. Urbanisation can result in habitat loss and degradation, changes to water availability, and introduction of exotic competitors and predators, which all have the potential to impact on amphibian populations. Past studies have focused on the effects of urbanisation on aquatic breeding amphibian species, but few have investigated how terrestrial breeding species may be responding to these threats considering they depend on habitat availability for reproduction. In the rapidly expanding urban centre of Melbourne, Australia, there are three terrestrial breeding species that call throughout the autumn months, the Victorian smooth froglet (Geocrinia victoriana), the southern toadlet (Pseudophryne semimarmorata), and Bibron’s toadlet (Pseudophryne bibronii). This project investigated how G. victoriana and two associated frog species, the common eastern froglet (Crinia signifera) and the southern brown tree frog (Litoria ewingii), are responding to urbanisation in the greater Melbourne region. To investigate this question I visited 45 water bodies in the greater Melbourne region in the Austral autumn. At each site I completed visual and acoustic amphibian surveys, vegetation surveys for terrestrial and aquatic vegetation cover, and recorded abiotic measurements. The level of urbanisation at each site was represented by the ratio of total area within a surrounding sub-catchment covered by impervious surfaces. I utilised Bayesian regression modelling to estimate the effect of variables such as impervious surface cover and aquatic vegetation cover on the probability of detecting G. victoriana, C. signifera, and L. ewingii. The results revealed a strong negative association between impervious surface cover and the probability of detecting G. victoriana, although, there was less evidence to suggest the same relationship for C. signifera or L. ewingii. Environmental factors such as aquatic vegetation cover had a positive effect on the probability of occurrence of G. victoriana and C. signifera, however, this was not found for L. ewingii. The data presented in this study support the conclusion that G. victoriana is vulnerable to urban development, whereas C. signifera and L. ewingii may be better suited for adapting to these novel environments. However, this study was unable to identify the direct links between urbanisation and the persistence of terrestrial breeding species such as G. victoriana, and this should be experimentally examined in future research. The findings presented in this research have important management implications for all amphibians in the greater Melbourne region, and highlights the need to encourage a variety of different habitat types and their persistence in an urban context.
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ItemClimate-smart agriculture: a review assessing the merits and future applications of a holistic agricultural paradigm that addresses climate change and development challenges.( 2015)Agriculture is facing significant challenges into the future, especially related to food security when faced with climate change. Climate-Smart Agriculture seeks to address these challenges by providing a holistic framework for agricultural adaptation to, and mitigation of climate change, while also alleviating food security problems in a triple-win context. Climate-Smart Agriculture has origins in other agricultural paradigms, such as the Green Revolution, Conservation Agriculture and Sustainable Intensification. However it has the advantage of amalgamating the best responses from all three. Theoretically, Climate-Smart Agriculture is a universal paradigm able to solve all agricultural issues. In practice, Climate-Smart Agriculture has significant flaws. It has broad principles that cause conflicts and trade-offs even when a triple-win outcome is promised. Climate-Smart Agriculture also suffers from significant funding, insurance and technical issues, while there is little detail as to how the three arms of Climate-Smart Agriculture (adaptation, mitigation and food security) works together in practice. With some perseverance, Climate-Smart Agriculture can be the paradigm to address all these concerns, especially in a developing country context. Climate-Smart Agriculture has the platform for success, through policy formulation, pushing technologies and intervening in local agricultural systems. Even with potential trade-offs, Climate-Smart Agriculture utilises a best-practice approach to increase agricultural resilience through improving ecosystem service by utilising agroforestry and other methods. Climate-Smart Agriculture can still achieve its goals, through a mixture of novel approaches and proven techniques, it can also succeed further with biodiversity and poverty alleviation gains. However for this to occur Climate-Smart Agriculture must improve evidence building, local effectiveness, climate and agricultural policy cohesion and funding. Scientific endeavour must be prioritised with Climate-Smart Agriculture becoming more water, energy and nutrient-smart. Further research needs to occur into potential synergies and trade-offs, with more Climate-Smart Agricultural involvement in food systems, with a push for more integrated food-energy systems. Furthermore barriers to adoption need to be better understood. Funding has been highlighted as the most important issue facing Climate-Smart Agriculture. Overall funding is not well targeted, nor coalesced between adaptation and mitigation strategies. There is a lack of accountability regarding adaptation funding and an overall disjoin between Climate-Smart Agriculture, climate finance and carbon markets that must be rectified. Overall agriculture requires significant transformation. Climate-Smart Agriculture provides the framework to do this. Yet in its current state, Climate-Smart Agriculture provides nothing new, it faces significant problems that must be rectified if it is to become more than just another theoretical agricultural concept.