School of Ecosystem and Forest Sciences - Theses

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    Modelling the biogeography of Australian Fungi
    Hao, Tianxiao ( 2021)
    Biogeography – the study of biological patterns in space – has often overlooked the Kingdom Fungi in the past, because the geographic distributions of fungi are difficult to document and study. However, increasing availability of fungi data collected across large spatial scales, and development of modelling-based methods allowing the interpolation of patterns between sampled locations, have enabled for the first time the study of continental scale mycogeography (biogeography of fungi) using quantitative methods. Focusing on Australia, this thesis explores this new research direction in detail, by accessing fungi distribution data at continental scales, interrogating the issues and characteristics of such data and developing appropriate ways to deal with them, and studying the prominent biogeographic trends and patterns emerging from the data using the species archetype modelling approach. This thesis has several major findings. First, for studying continental-scale mycogeography, data based on observations and specimen collections are the most readily available, but contain errors in geocoordinates and taxonomy and require thorough quality filtering and taxonomic curation. The sampling effort of these data is incomplete in space and biased towards easier-to-access areas, and such biases need to be addressed in analyses. Methods for checking data quality and dealing with biases are proposed. Second, environmental DNA (eDNA) collections of fungi in the soil provide an important alternative source of data, but exploring these data in detail reveals that their spatial patterns are different from observational data on the same species, and archetypal patterns based on eDNA data can be biologically unrealistic, signalling issues in identifying sequences to species and in detection success. The need to better understand the caveats of eDNA data motivates future systematic side-by-side observational and eDNA surveys. Third, by using species archetype models to group species into archetypes according to their shared environmental responses, this thesis reveals several main archetypal distribution patterns across Australia. Specifically, spatial patterns of Australian fungi can be partitioned into those strongly aligning with the southeast and the southwest coastal regions, those occurring in the arid centre, and those occurring in either the dry or the wet tropical regions. These analyses produce the first continental scale quantitative maps linking fungi to regions, and provide important support for further research on these fungi. Finally, by applying the relatively new species archetype modelling approach on challenging datasets at a continental scale, this work produces a valuable methodological knowledge base on the use of the method, and identifies worthwhile directions for future development, such as developing new approaches for selecting the number of archetypes in the model. Overall, this thesis thoroughly explores and applies appropriate methods for processing data and recently developed analytical methods, and significantly advances knowledge on continental scale patterns of mycogeography. The knowledge produced by this thesis provides a foundation for further research in Australia, and demonstrates a novel approach for mycogeography suitable for applications across the globe.
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    Environmental filtering shapes plant turnover and species occurrence in post‐logging regrowth forest in southeastern Australia
    Singh, Anu ( 2021)
    Environmental factors play a more influential role in shaping plant community composition, while disturbance shapes plant community composition in southeastern Australian temperate forests. Plant communities in forests subjected to timber harvesting have been found to differ from wildfire sites in the montane forests of the Central Highlands in Victoria; however, a quantitative understanding of the factors that shape post harvesting plant communities is lacking. Quantifying the factors that shape plant community composition in post logging regrowth forest is important for understanding how timber harvesting influences plant biodiversity. Here, I aimed to explore the role environmental filtering species turnover and composition of the species in post logging regrowth forests. I focused my studies on the forested landscapes of southeastern Australia, where bushfires and timber harvesting are the primary catalysts for regeneration in Eucalyptus regnans, E. delegatensis, and high elevation mixed species forests. I investigated the post disturbance regeneration dynamics in these forests and sought to determine the direct impact of climate variability on regeneration and the interactive effects of climate, topography, and edaphic factors on the regeneration success of Eucalyptus. Untangling the roles of climate, topography and edaphic conditions on plant regeneration is important for understanding current and future risks of climate change to plant species richness. To test the influence of climatic, topographic, and edaphic variables on the occurrence and abundance of Eucalyptus regeneration, I used machine learning models. Declines in number of seedling regeneration of eucalypt during the period of drought were greater in E. regnans and E. delegatensis than HEMS forests, suggesting that regeneration in the HEMS forests is more resistant to drought. I furthermore found that seasonal precipitation and temperature had the greatest influence on regeneration success of Eucalyptus. My findings highlight the importance of seasonal and annual climate variability on Eucalyptus regeneration and portend potential declines in regeneration success in a warmer and drier future, particularly for E. regnans and E. delegatensis. A fundamental requirement of sustainable forest management is that stands are adequately regenerated after harvesting. To date most research has focused on the regeneration of the dominant timber species and to a lesser degree on plant communities. Relatively few studies have explored the impact of regeneration success of the dominant tree species on plant community composition and diversity. Therefore, I quantified the influence of environmental filtering on plant species diversity in montane regrowth forests dominated by Eucalyptus regnans in mainland southeastern Australia. I found that Acacia density shaped plant biodiversity more than Eucalyptus density. I also found that edaphic factors, in particular soil nutrition and moisture availability, played a significant role in shaping species turnover and occurrence. My findings suggest that the density of Acacia is a key biotic filter that influences the occurrence of many understorey plant species and shapes plant community turnover. This should be considered when assessing the impacts of both natural and anthropogenic disturbances on plant biodiversity. In this thesis, I also explore the role of soil seedbank as a source of plant propagules in these forests. Our ecological understanding of plant community response to disturbance and environmental variation is largely restricted to the above ground species pool. Plant community composition often changes dramatically after disturbance due to mortality of above ground vegetation and recruitment of species that respond to a change in resource availability. To quantify the relative importance of environmental gradients on individual species occurrence and community composition, I used a joint analysis approach. In total there were 113 plant species in the combined species pool. A total of 39 species were shared between above ground and soil seedbank pools. There were 41 species exclusive to the above ground vegetation. Aridity was the main environmental covariate explaining plant community across all pools of plant diversity and across non woody and woody life forms. Environmental covariates explained more than 59 percent of the variance for 43 species in the combined species pool. The composition of the soil seedbank and above ground diversity was distinct, with low similarity 14 percent, which highlights the importance of the soil seedbank as a reservoir for plant diversity not captured in above ground vegetation. Finally, I aimed to quantify the influence of Acacia and Eucalyptus composition and configuration on species turnover to provide an important tool for mapping patterns of plant diversity in post disturbance forests. To achieve this, I combined remotely sensed UAS imagery with ground survey data of plant composition from post logging regrowth forests. I found that spatial predictions of forest configurations providing Eucalyptus and Acacia cover metrics such as spatial aggregation were useful in estimating understorey plant beta diversity. Significant relationships between the aggregation metrics derived from UAS imagery as well as site aridity and beta diversity were observed. Increasing aggregation of Acacia, aridity and number of Acacia patches had a significant negative effect on plant beta diversity, whereas number of patches of Eucalyptus had a positive influence. This research highlights how remote sensing can provide and improve measures of forest plant biodiversity in regrowth forests which can support forest managers and conservation efforts to quantify and map patterns of plant diversity at the stand scale and beyond. Overall, my findings highlight that post logging regrowth forests are systematically shaped by soil and climatic factors while also being filtered by stand structure and composition. I demonstrate the role of climate, topography, soil, and light availability in shaping plant communities in post logging regrowth forests. The success of eucalypt regeneration in the stand reinitiation phase influences overstorey composition and structure. I found that that soil nutrition and moisture availability played a significant role in shaping plant community composition at fine scales and aridity at broad scales. I further found that Acacia density shaped plant biodiversity more than Eucalyptus density. My study highlights the role of environmental filtering on plant community composition in post logging regrowth and how it must be considered when assessing the impacts of anthropogenic disturbances on plant biodiversity in the temperate forest of southeastern mainland Australia.
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    Investigation of bark properties and cambium cell viability of Eucalyptus in relation to heat exposure
    Subasinghe Achchige, Yasika Medhavi ( 2021)
    Fire is integral to many temperate forest ecosystems. Given increasing occurrence of wildfires around the world, forest management applications such as low and moderate intensity burnings are required to reduce fuel loads to decrease the severity of wildfires. However, little is known about the effect of low to moderate intensity fires on vascular cambium necrosis in trees. During a fire, heat is transferred through the tree bark towards the vascular cambium (i.e., a vital tissue layer inside a tree stem which ensures the perennial growth of a tree) potentially increasing cambium temperature to lethal levels. As tree bark shields the vascular cambium from thermal damage, a better understanding of the bark traits that protect the vascular cambium during fires is required. Genus Eucalyptus is broadly distributed in fire-prone ecosystems thus, exhibits different fire adaptive traits such as post-fire regeneration strategies (i.e., resprouting via epicormic strands) and has a wide range of different bark types. As a native plant genus and the dominant species in open forests of southern Australia, Eucalyptus species present a great opportunity to investigate bark properties in relation to cambium cell viability. In this study, firstly, cambium sections were exposed to heat treatments in vitro to determine the best method to estimate a cell viability index (CVI) to allow a detailed investigation of heat degradation of cellular function in relation to fires. A tetrazolium reduction method (TTC method) was compared to a Neutral Red method applied to different tissue sizes to quantitatively determine CVI and to derive a critical temperature threshold for cambial cell viability in vitro (Chapter 2). The interactive effect of temperature and exposure time on cambium cell viability in vitro was investigated in the third Chapter. Based on findings of Chapters 2 and 3, properties of the bark i.e., bark thickness, moisture content, bark density, thermal diffusivity, and thermal conductivity of the three Eucalyptus species of contrasting bark types (E. obliqua - stringy bark, E. radiata - Fibrous bark and E. ovata - Smooth bark) were investigated in Chapter 4. In Chapter 4, stem sections of freshly felled trees were exposed to a fixed heat flux which simulated conditions of low to moderate intensity fires; thermocouples were inserted into sapwood, cambium and bark to measure the temperature and time to reach critical temperature of 60oC was recorded. Cell viability was measured against the untreated control samples. Bark properties of three species were measured and analyzed against cell damage. The key results of this study were: (i) Tetrazolium reduction method (TTC method) is the preferred method to assess cell viability of Eucalyptus species, while Neutral Red method can be used to cross check the results of the TTC method; (ii) Critical temperature for cambium cell viability is 60oC; (iii) A prolonged exposure to sublethal temperatures (40-50oC) causes similar effect as a short exposure to lethal temperatures (>50oC); (iv) Critical exposure time in-vitro for cambium cell viability of Eucalyptus species is 1-5 minutes; (v) Bark moisture and thickness play the major roles in regulating heat transfer through bark; (vi) A thicker, dryer, lower density and lower thermal conductivity stringy bark of E. obliqua shows greater insulation ability than the other two bark types tested; (vii) Critical exposure time for cambium cell viability in-vivo may vary between 20 to 40 minutes depending on bark type and bark thickness; (viii) Among the trees tested the radiant energy required for the cambium-phloem cells to reach critical temperature ranged between 3.5 and 13.6 MJ m-2; (ix) Prolonged exposure to low heat flux like 10 kW m-2 can also cause significant cambium damage. Findings of this study have provided significant insights in relation to properties of tree bark, to better understand the heat tolerance levels of Eucalyptus species during low to moderate intensity fires. The study developed a novel method to assess the cambium cell viability of Eucalyptus species following heat exposure. Overall, this study provides a better understanding for land managers to perform low intensity fuel reduction burns to avoid tree damage. Findings of this work will guide and expand future research on stem heat transfer models and fire behavior models to improve tree survival following fires.
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    Enhancing Environmental Benefits of Rainwater Harvesting Systems Using ‘Smart’ Real-Time Control Technology
    Xu, Wei ( 2021)
    Urban centres face numerous challenges related to the urban water cycle, including flooding, degradation of receiving waters, and scarcity of water resources. Among the stormwater control measures (SCMs) being increasingly adopted worldwide to improve the way stormwater is managed, rainwater harvesting (RWH) systems can potentially simultaneously address all of these issues. However, their performance has, until now, been limited by their passive and static nature, lacking the ability to adapt to changing conditions, such as rainfall variability, and climate and urban expansion. Recent advances in real-time control (RTC), so called “smart” technology, offer great promise to transform the conventional RWH systems into highly adaptive systems. To date however, little is known about the benefits of such technology in improving the performance of RWH systems. Understanding, testing and exploring this potential is the primary focus of my research. My thesis aims to develop and test RTC strategies that improve the simultaneous objectives of RWH systems related to water supply, flood mitigation and restoration of more natural flow regimes. This analysis is undertaken at a range of scales, given the potential for such technology to be applied to rainfall captured from individual buildings, or to networks of rainwater storages distributed throughout a catchment. This thesis comprised four major components. It first comprehensively reviewed the literature and examined the state-of-art of the application of RTC technology in a range of SCMs. Many studies have shown that the use of RTC can improve the performance of various type of SCMs at the site scale, in terms of both runoff quality and quantity (hydrology). On the other hand, there is a relatively untested potential to apply such technology at a mix of scales. The second component developed and modeled a range of RTC RWH systems that utilised a 7-day rainfall forecast to examine the impact of increasing rainfall forecast window on the performance of these systems in water supply, flood mitigation and restoration of more natural flow regimes. Using a relative long lead-time rainfall forecast was shown to enhance the ability of RTC in mitigating flood risks, while delivering an outflow regime that is close to reference streamflow. Such a design has also demonstrated to minimise the effect of forecast errors, given that the longer prediction window provides greater opportunity to adapt, before the forecast rainfall event occurs. Based on such RTC strategies, the network-scale impacts of RTC RWH systems on the behaviour of a stormwater network were also assessed through a modelling study. RTC was found to substantially reduce the risks of urban flooding in both current and future climates, while simultaneously providing a decentralised water supply. Applying RTC on a greater proportion of the RWH systems showed larger relative benefits than simply increasing the storage capacity, providing an important insight to guide investment in flood mitigation by storage. To advance the control strategy at the network scale, the final component developed and evaluated the performance of a centralised optimisation-based RTC model that enabled collaboration between multiple RWH systems. Modelling results have shown that such a strategy was able to deliver a synergy benefit in achieving better baseflow restoration, without any real detriment to the supply and flood mitigation performance of the integrated system. This is achieved by allowing larger storages to compensate for smaller, underperforming storages, thus achieving higher overall performance. More importantly, analysis across the three modelling components has shown that RTC-based rainwater harvesting systems can fundamentally modify the flow regime of stormwater runoff, leading to a promising potential to restore the natural flow regime in urban streams. While future work is required to address both technical and social-economic challenges, this research demonstrates the technical feasibility of using smart technology to better manage urban stormwater in a range of contexts and for a suite of environmental objectives. Its application has the potential to fundamentally transform the way rainwater harvesting—and stormwater management more broadly—are applied. Doing so will maximise the benefits to urban communities and to receiving environments.
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    The influence of land-use change on soil microbial communities in riparian ecosystems
    Waymouth, Vicky Jayne ( 2021)
    Riparian ecosystems are areas with elevated soil fertility due to nutrient rich sediment deposition, topography, and high water availability, all of which result in high biomass productivity. The increased availability of ecosystem services makes riparian ecosystems vulnerable to land clearing, where the native riparian forest is converted to agricultural pastures. Efforts to revert this land-use change and restore native riparian vegetation focus on revegetation with native plant species. To what extent these concatenated land-use changes influence soil microbial communities is still uncertain, despite the key role that soil microbiota play in the biogeochemical cycles and vegetation dynamics. This thesis addresses that knowledge gap and pursues three main aims: - To assess how the spatial distribution of soil microbial communities varies in relation to the spatial structure of vegetation and soil properties, thus informing sampling strategies (Chapter 2). - To identify how taxonomic and functional composition of soil bacterial community change through the conversion from a remnant native riparian forest to agricultural pasture, that is later revegetated with native species, and whether this change is related to vegetation, soil properties, and/or soil depth (Chapter 3). - To identify how taxonomic and functional composition of soil fungal community change with the land-use conversion mentioned above, and whether this change is related to vegetation, soil properties, and/or soil depth (Chapter 4). In Chapter 2 I found that variation in the taxonomic composition of soil microbial communities (fungi, bacteria, archaea) was related to vegetation properties, particularly sub-canopy composition, and to a lesser extent soil chemical properties. Relationships between microbial communities and vegetation composition were stronger in top-soil than sub-soil. The exception was phylum Glomeromycota, where the relationship was stronger with ground cover composition and only for top-soil. In contrast to the taxonomic composition, the functional composition of the soil microbial community showed no relationships with vegetation properties or soil physical and chemical properties. I conclude that soil microbial communities within areas with similar vegetation communities show little variation, therefore a small sampling effort would be needed to adequately describe the characteristics of such soil communities. In Chapter 3 I found that taxonomic and functional composition of soil bacterial community varied across land uses, with cleared riparian forest converted to agricultural pastures being different from remnant forest and revegetated areas. Land-use differences were phylum-specific. For instance, Acidobacteria were more abundant in remnant soils whereas Actinobacteria were more abundant in pasture soils. Overall, bacterial metabolic activity and soil carbon and nitrogen content decreased with soil depth, while bacterial metabolic diversity and evenness increased with soil depth. Soil bacterial taxonomic composition was related to soil texture and soil chemical properties, but the functional composition was only related to soil texture. My results suggest that the conversion of riparian forests to pasture is associated with significant changes in the soil bacterial community, and that revegetation contributes to reversing such changes. Nevertheless, the observed changes in bacterial community composition (taxonomic and functional) were not directly related to changes in vegetation but were more closely related to soil properties. In Chapter 4 I found that taxonomic and functional composition of soil fungi infrequently varied with land-use change or depth, with differences only observed for a few taxa. In contrast, fungal community composition was strongly related to soil chemical properties in both top-soil and sub-soil. My results indicate Ascomycota and Basidiomycota were more abundant in areas with low relative soil fertility (N, P, K and Ca) and little ground cover, whereas the opposite was true for Glomeromycota. Sites with high clay content, low sub-canopy cover, and high tree basal area tended to harbour more plant pathogens, dung saprotrophs, and arbuscular mycorrhizae. In contrast, areas with high sub-canopy cover and less tree basal area encompassed a greater abundance of animal pathogens, wood saprotrophs, and ectomycorrhizae. In conclusion land-use change had little effect on taxonomic and functional composition of soil fungal communities. In conclusion, I found that soil bacterial communities were more responsive to land-use change and depth than soil fungal communities. Relationships with vegetation were complex: within a community of soil microbes, I found relationships with sub-canopy vegetation; however, across multiple communities, bacteria showed no relationship to vegetation, and fungi were related to ground cover vegetation and canopy, not sub-canopy vegetation. My research suggests that the impact of land-use change on soil microbial communities is related to the extent that it influences soil physical and chemical properties. Therefore, monitoring or quantifying the extent land-use change alters soil physical and chemical properties may indicate the impact of land-use change on soil microbial communities.
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    On the predictive performance of correlative species distribution models
    Valavi, Roozbeh ( 2021)
    Species Distribution Modelling (SDM) is a widely used tool in ecological studies and wildlife conservation. Despite the vast literature on this topic developed to date, species distribution modelling remains an active area of research because there are so many potential uses for the models but also many challenges to fitting them well. Therefore, it is important to have a clear understanding of how these methods work and how they can be best used in each setting. My thesis focuses on advancing methodological aspects of SDM in particular assessing and improving the predictive performance, including providing tools and guidelines for their use. One key aim of my PhD is to test a broad range of common SDM algorithms across several datasets. As a step towards that goal, in my first research chapter I compared newly developed algorithms and novel implementations of established ones to update a landmark study by Elith and colleagues in 2006, using their data. In summary, I evaluated 13 modelling methods (and several implementations of some) on an independently collected testing dataset. The dataset used includes presence-only records for 226 species across the world with presence-absence data for model evaluation. This dataset is now published, and the manuscript provided as an appendix to my thesis as I contributed to its publication. The result of the first research chapter showed that some models perform generally better than others. An ensemble of five tuned models was the best model in averaged and ranked performance. In contrast, the model implemented by biomod modelling framework with the default parameters was an average performer indicating that ensemble models per se are not the best solution to all modelling problems. Overall non-parametric models with the capability of optimising the bias-variance trade-off performed strongly. This includes boosted regression trees (BRT), MaxEnt and a variant of Random Forest (RF). All the data and code with working examples are provided with the manuscript of this chapter to make this study fully reproducible. One striking result of my methods comparison study was the remarkable improvement of some machine learning models (e.g., RF) when the imbalanced nature of presence-background data is considered during model fitting. This triggered the idea behind my second research chapter, where I explored why common implementations of RFs fitted to presence-background data appear highly sensitive to how the imbalance between number of presence records and number of background samples is treated. It turned out that class imbalance was not the only source of the problem, but class overlap played a central role (class overlap is when different classes happen in the same environmental range – here classes are presences and background samples). Although the commonly used default implementation of RF in R programming is problematic when modelling presence-background data, I identified several solutions that work well with such data without losing the environmental representativeness of background samples. A novel part of this chapter was its clear demonstration of reasons for differing performance, and evidence that several implementations overfit imbalanced and overlapped data. To enable new approaches for evaluating SDMs, I developed an R package that facilitates flexible use of block cross-validation with species distribution data. This is important for testing predictive performance at sites spatially or environmentally separated from the training sample. My package covers several common blocking methods and supports different types of species data; it is available freely and I published a manuscript, forming the next chapter, to explain its use. This underpins the last research chapter where I ask whether methods that did well in my first research chapter – many of which fit quite complex models – still perform well when evaluated with spatially separated testing data. They did. In comparing models with spatial vs random partitioning, the order of models did not change. The best model in both random and spatial partitioning was an ensemble model followed by MaxEnt, a variant of RF and BRT. These are models that are capable of fitting complex fitted functions compared to simple and smoother models such as generalised linear and additive models that did not perform as strongly. However, complexity is not in itself the key: some complex models performed poorly, and some smoother models, well. Recently popular methods for tuning MaxEnt did not improve its performance. Finally, I have provided all the data and code from my thesis to make the methods accessible to other researchers.
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    Using stormwater to promote the growth and transpiration of street trees
    Thom, Jasmine Krystel ( 2021)
    Creation of cities leads to extensive impervious surfaces as part of the built environment, which alter the natural hydrological cycle and local climate. Rainfall on impervious surfaces can generate large volumes of stormwater runoff which degrades receiving waterways, while also reducing the volume of rainfall infiltrated to urban soils. Trees provide numerous benefits, which may mitigate these negative impacts of impervious surfaces. However, growing conditions may lead to drought stress that limits the benefits trees can provide, such as cooling. Irrigation can support the growth and transpiration of trees, two processes that are intrinsically linked to their benefits. Directing excess stormwater runoff to street trees (passive irrigation) therefore has the potential to support transpiration and growth, while reducing the volume of stormwater runoff received by downstream waterways. This thesis quantified growth and transpiration of trees to assess whether passive irrigation systems can be designed to i) support transpiration and growth, and ii) reduce the volume of stormwater received by downstream waterways through transpiration losses and species selection. To do this, growth and transpiration of establishing and established trees were assessed for several system designs in the field, and the transpiration behaviours of young trees were measured in a glasshouse experiment. Further, key factors influencing the water balance of passive irrigation systems to support future design and species selection were investigated. Drained passive irrigation systems doubled the growth of establishing trees relative to control trees in the first two years, which meant they transpired twice the volume of water. Higher growth rates were not sustained in years three and four, likely because the trees outgrew the small volume of growing media. Conversely, passive irrigation systems had no impact on the transpiration of established trees, likely because they already had access to sufficient water resources. Hence, when passive irrigation systems support greater growth and water availability, they can support higher transpiration, thereby providing greater transpiration-related ecosystems services, such as urban cooling and stormwater runoff reduction. Designing passive irrigation systems with a larger volume of growing media may sustain greater growth rates and associated benefits for longer. The potential contribution of transpiration to the reduction of stormwater volumes depended on canopy and catchment sizes, species selection, and rainfall. For established trees in the field, transpiration was equivalent to 17% of annual runoff, much greater than typically reported for other vegetation types. The glasshouse experiment identified several species that had the potential to maximise transpiration losses from passive irrigation systems and improve stormwater outcomes by balancing moderate to high transpiration, moderate drought avoidance, and high transpiration recovery. Several other critical factors that should be considered in the design of passive irrigation systems include internal water storage, drainage, and soil volume. This thesis demonstrates that passive irrigation systems have the potential to improve urban greening and stormwater management outcomes by establishing greater canopy cover, leading to greater transpiration, and reduced volumes of runoff received by downstream waterways. Delivering on this potential depends on good design, which takes into account the impacts of species selection, canopy area, catchment area, and design considerations influencing the soil moisture regime.
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    Emerging sustainability governance paradigms: a case study of the blue carbon initiatives in the Indo-Pacific
    Contreras Morales, Cynthia Carolina ( 2021)
    Sustainability and governance are two core elements that shape the interaction and connection between human and non-human beings, framing the societal arrangements across numerous spheres of influence. The Anthropocene marks an epoch dominated by human activities driving earth system transformations, including, but not limited to, climate change and its impacts. Concerns about these changes also influence emerging expressions of governance beyond the classical structures (e.g., nation-states, institutions), with voices from civil society progressively occupying decision-making spaces and influencing political agendas. Using Earth System Governance as a starting point, this research aimed to investigate the emergence of alternative sustainability governance paradigms and how they might play out in future environmental governance. Blue carbon is a relatively new notion in global climate policy that addresses the capacity of coastal and marine ecosystems to capture carbon dioxide (CO2) and sequester it for long periods of time. As a result, blue carbon initiatives have been developed worldwide to support and implement the concept. Given the ecological, cultural, economic, and social complexity of the settings in which blue carbon is being implemented, these activities can illustrate the direction and form of sustainability governance and its alignment with emerging paradigms. Coastal blue carbon is biophysically situated at the interface between land and sea; thus, it represents a negotiation space where values, interests, and priorities overlap and often contradict each other (i.e., the social dimensions of carbon). As a result, we encounter a complex scenario with the potential to determine future policy formulation that will directly impact the character and extent of the human-oceans and deep ocean interactions. The Indo-Pacific region has a high concentration of mangroves, seagrass meadows and tidal marshes. Coastal blue carbon extends across these highly dynamic and biocultural diverse habitats where numerous stakeholders interact and negotiate interests and priorities. Blue carbon activities in this region were selected to explore the interactions between stakeholders and the differentiated governance and leadership modes being adopted in these sustainability governance arrangements in practice. A multi-level case study analysis was used to identify the characteristics of blue carbon initiatives and their alignment with emerging sustainability governance paradigms. Integrating constructivism and critical theory, a mixed-methods approach was applied to understand the interplay between numerous stakeholders and organisations at local scales. A particular interest of this research was to address practitioners’ perspectives as one of the multiple social dimensions of carbon, an area of knowledge that remains considerably underexplored. Analysis of the literature identified three emerging paradigms in sustainability governance (i) Deep Institutionalism, (ii) Stronger States, and (iii) New Sustainability Governance. In analysing blue carbon activities, while states remain the dominant actors, non-governmental organisations and civil society stakeholders are increasingly influential. These initiatives are consistent with the New Sustainability Governance model, often led by new types of institutions under a partnership umbrella, requiring new forms of leadership. Interviews with practitioners in these activities identified differentiated perspectives on blue carbon as 1) a ‘blue economy’ component; (2) an add-on for ecosystems conservation; (3) a new ecosystem service; (4) a tool for science communication, and (5) a prosperity generation mechanism. These alternative perspectives frame different understandings of carbon and highlight the indivisible link between carbon and the biocultural diverse contexts. Overall, these findings contribute a new conceptual framework on sustainability governance, enabling a deeper understanding of how these emerging paradigms influence political agenda-setting, policy, and decision-making in the context of blue carbon.
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    Larger tuber size improves Microseris walteri (Murnong; Yam Daisy) transplant success
    Roberts, Eilish ( 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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    Forest Transport Payload Management in the Delivery of Efficient Forest Supply Chains
    Brown, Mark William ( 2021)
    Operation payload management investigated the impact of two weighing technologies (truck and loader installed scales), operated by hired drivers and owner-operators on two route types; gazetted (classified for increased GVW limits) and non- gazetted (standard GVW limits for public roads). On non-gazetted roads the two approaches proved equally effective but when used together appeared to be less effective, while the owner operators appeared to have better management of the payload compared to hired drivers. On the gazetted roads all vehicles were under loaded by roughly the extra payload amount offered by the gazetted routes, which highlights the importance of communication and overall management to ensure payload potential is realised.