School of Agriculture, Food and Ecosystem Sciences - Theses
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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.