TRAITS-BASED AND PERCEPTION APPROACHES FOR MANAGEMENT OF INVASIVE EXOTIC SPECIES FROM TROPICAL BOTANIC GARDENS DECKY INDRAWAN JUNAEDI Submitted in the total fulfillment of the requirements of the degree of Doctor of Philosophy June 2018 School of Biosciences University of Melbourne 1 Abstract ABSTRACT 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, 2 Abstract 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. 3 Chapter outline CHAPTER OUTLINE CHAPTER 1 outlines the general scope, context, and objectives of the thesis. This chapter elaborates the coherence of all chapters in the thesis (Chapter 2 to Chapter 7). This chapter presents the literature review of the research background, research questions and objectives of the thesis. CHAPTER 2 describes the details of the study sites and survey locations and the scope of the study. Survey locations consist of four botanic gardens (Cibodas, Bali, Baturraden, and Kuningan) and adjacent native ecosystems (Mount Gede, Mount Tapak, Mount Slamet, and Mount Ciremai). CHAPTER 3 conveys the reason why trait-based invasive plant species studies are essential for botanic gardens in Indonesia. CHAPTER 4 demonstrates the use of traits in hierarchical detection modelling of exotic plant species in tropical forests, under line-transect distance sampling. This chapter mainly describes the benefit of using traits to increase the detectability of naturalised exotics from botanic gardens, given imperfect detection. CHAPTER 5 presents the results of trait-based studies on naturalized exotic collections of botanic gardens into adjacent native tropical rainforests. This chapter demonstrates that traits are promising proxies to predict the probability of an exotic species to become naturalized and how large are their density in these adjacent native forests. CHAPTER 6 presents the Biophilia-based perception of botanic gardens’ staff of exotic invasive plant species in the botanic gardens. This chapter utilizes Biophilia concept as a framework to quantify the social perception types. CHAPTER 7 elaborates the general conclusions and the implications for exotic species management of the thesis results. 4 Declaration DECLARATION This is to certify that: 1. The thesis comprises only my original work towards the PhD except where indicated in the Preface 2. Due acknowledgment has been made in the text to all other material used 3. The thesis is less than 100,000 words in length, exclusive tables, maps, bibliographies, and appendices ………………………… Decky Indrawan Junaedi Preface PREFACE CHAPTER 1 This chapter is solely written by the candidate with editorial assistance from Mark Burgman and Cindy Hauser. CHAPTER 2 This chapter is solely written by the candidate with editorial assistance from Mark Burgman. This chapter describes the details about the study sites and survey locations. CHAPTER 3 This chapter is solely written by the candidate with editorial assistance from Mark Burgman, Jane Catford, and Jan Carey. Most of the chapter appears in a paper authored by the candidate (> 75 %) and planned to be submitted to Tropical Conservation Science. CHAPTER 4 This chapter is solely written by the candidate with editorial assistance from Mark Burgman, Stuart Jones, Gurutzeta Guillera-Arroita, Jane Catford and Michael McCarthy. Gurutzeta Guillera-Arroita work on the detectability model simulation in Bayesian analysis framework. Part of the chapter presented as a poster presentation in 9th International Conference on Biological Invasion NEOBIOTA 2016 in Vianden, Luxembourg and ESA EcoTas conference 2017 in Hunter Valley, Sydney, Australia. The chapter is based on a paper that was submitted as a stand-alone paper to PLOS One (in-review). CHAPTER 5 This chapter is solely written by the candidate with editorial assistance from Mark Burgman, Peter Vesk, Gurutzeta Guillera-Arroita, and Jane Catford. Gurutzeta Guillera- Arroita work on the detectability model simulation in Bayesian analysis framework. Part of the chapter presented as an oral presentation in the Society for Risk Analysis Australia and New Zealand (SRA-ANZ) Conference 2017 in Melbourne and ESA EcoTas conference 2017 in Hunter Valley, Sydney, Australia. It planned to be submitted to Biological Invasions. CHAPTER 6 This chapter is solely written by the candidate with editorial assistance