School of BioSciences - Theses
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ItemBirds in the sky, fish in the sea, money in the bank: quantitative methods for more effective conservation( 2021)My approach in this thesis was to explore how to wring more information out of existing data to reduce uncertainty, improve decision-making and hope to generate better conservation outcomes. I explore and develop a range of quantitative tools to this end. I look at three key areas: dealing with uncertainty, structuring decision making, and improving the use of existing information. I consider these concepts over three thematic case studies: monitoring the abundance of three vulture species in Cambodia, trading-off the costs and benefits of releasing information publicly when a new species or population is discovered, and comparing use of optimisation and project prioritisation protocols to allocate funding to species conservation efforts. In the first case-study, I develop new Bayesian hierarchical model to estimate vulture abundance, and compare the inferences available from this approach with less specialised approaches previously used. In the second case-study I develop a decision-making framework to allow decision-makers to explicitly trade-off costs and benefits, and apply the method to data collected from informants who have made these types of decisions themselves. In the final section, I explore whether additional information can improve optimisation to allocate funding, and compare performance in terms of expected avoided extinctions of the optimisation approach with a project prioritisation protocol. I find that there is indeed much more we can learn from the information we have. But this is not a free lunch – work needs to be done to uncover opportunities, and technical skills are often needed to make best use of them, and assumptions must often be made to draw conclusions.
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ItemTraits-based and perception approaches for management of invasive exotic species from tropical botanic gardens( 2018)The factors driving plant invasion are key questions in invasion ecology. Traits also can act as indicators of plant invasion processes. If traits are proven to be a significant proxy for plant invasiveness, then invasiveness of exotic species may be efficiently predicted by measuring traits. Botanic gardens have consistently supported ex-situ plant conservation, research, and environmental education. However, botanic gardens can also be pathways of exotic invasive species introduction. Botanic gardens should become a strategic stakeholder for exotic invasive plant species management. For exotic invasive species management, we cannot solely rely on ecological approaches. Social perception is an important component of invasive species management. Social perception may become either a problem or a solution for invasive species management. These perceptions should be clarified among relevant stakeholders to minimize conflicts of interest among relevant stakeholders of invasive species management. This study focuses on invasive plant species in tropical environments and the aim of this study is to answer the following questions: (1) Focusing on the relationship between exotic species abundance and traits in the tropical ecosystem, what traits or sets of traits are relevant and useful as proxies for examining the relationship between traits and local abundance in invaded tropical forest ecosystems? Assuming biological characteristic of invaders involved in the invasion pathways, what are the plausible and relevant traits?; (2) To what extent can these selected traits explain the proxies of invasion processes: local abundance and dispersal distance of naturalised exotic collections of botanic gardens in native ecosystems?; (3) To what extent these selected traits may be useful to differentiate naturalised from non-naturalised exotic collections?; (4) How robustly can the traits explain the detectability of exotic plant species in tropical rainforests adjacent to botanic gardens?; and (5) What are the perceptions of internal stakeholder’s (staff of botanic gardens) of exotic and invasive plant species? Assuming they like these exotic species, what are the reasons? I conducted literature review studies from relevant resources to answer question 1. Then, I conducted trait-based studies to answer questions 2, 3, and 4 by examining local density, their spread distance from gardens, and measured relevant traits of these detected naturalised exotics. The study sites consist of four Indonesian botanic gardens (Bali, Baturraden, Cibodas, and Kuningan) and their adjacent native forest ecosystems. I used Biophilia theory to examine the positive perception of botanic gardens staff on exotic invasive species to answer question 5. By analyzing data that was collected during line transect distance sampling surveys, I used a multi-species hierarchical distance sampling model to evaluate how plant height, leaf size, leaf shape, and survey location influence exotic species detectability. Detectability of these exotics increased with plant height and leaf size. This study demonstrates the effect of plant height and leaf characteristics on the detectability of exotic species. The results of this study also indicated that information on traits might improve predictions about exotic species detection, which can then be used to optimize the allocation of the search effort for efficient species management. I showed that SLA strongly differentiates naturalised from non-naturalised botanic gardens’ exotic collections. This finding suggested that exotic species plausibly relied on high growth rate and forest opening gaps to establish in the tropical forests. I showed that traits can strongly differentiate naturalised from non-naturalised exotic species and this is a good sign for trait-based risk assessment application in the tropics. In general, the dominionistic type dominated the social perception of botanic gardens’ staff towards exotic invasive plant species. There was only minor variation in perception type dominance across demographic factors. These findings indicate that the inspiration to manage or ‘to rule’, and curiosity to learn about exotic species were the main motivations behind the Biophilia-based perceptions among Indonesian botanic gardens’ staff. This information may help to enhance strategies to increase stakeholders’ involvement in exotic invasive species management and to avoid or minimize conflict of interests among stakeholders. I demonstrated that traits are a useful proxy for multiple aspects of exotic invasive plant species management, particularly for botanic gardens. I also showed that social perceptions can be quantified effectively and Biophilia theory is a relevant framework to analyze the social perception of exotic invasive plant species. We cannot simply rely on ecological traits to support exotic species management. Exotic species can benefit humans, so human perception and behavior are also a critical consideration for exotic species studies either in botanic gardens or in general. For invasive species management contexts, social aspects should be synergized with ecological aspects to maximize social acceptance and minimize conflict of interest among stakeholders. This, in turn, will link the exotic invasive species management plan and its implementation in practice.