Risks impacts and management of invasive plant species in vietnam

Risks, impacts and management of invasive plant species in Vietnam Thi Anh Tuyet Truong BA MSc Submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy School of Veterinary and Life Sciences, Murdoch University, Australia 2019 i Declaration I declare that this thesis is my own account of my research and contains as its main content work which has not previously been submitted to a degree or diploma at any tertiary education institution. Human ethics The research in chapter 5 presented and reported in this thesis was conducted in accordance with the National Statement on Ethical Conduct in Human Research (2007), the Australian Code for the Responsible Conduct of Research (2007) and Murdoch University policies. The proposed research study received human research ethics approval from the Murdoch University Human Research Ethics Committee, Approval Number 2017/033 Thi Anh Tuyet Truong 2019 i Statement of co-authorship The following people and institutions contributed to the publication of work undertaken as part of this thesis: Chapter 3: Truong, T. Contemporary remotely sensed data products refine invasive plants risk mapping in data poor regions.

Frontiers in Plant Science, 8, 770. Truong, Environmental and Conservation Sciences, School of Veterinary and Life Sciences, Murdoch University, Perth, Australia. Giles Hardy, School of Veterinary and Life Sciences, Murdoch University, Perth, Australia. Margaret Andrew, Environmental and Conservation Sciences, School of Veterinary and Life Sciences, Murdoch University, Perth, Australia.

Author contributions: TT prepared input data, performed models and interpreted results, wrote manuscript and acted as corresponding author. MA supervised development of work, provided guidance throughout the project, and edited manuscript. GH contributed to editing manuscript. We the undersigned agree with the above stated “proportion of work undertaken” for the above published peer-reviewed manuscripts contributing to this thesis.

Signed: __________________ Signed: __________________ Thi Anh Tuyet Truong Margaret E. Andrew Signed: __________________ Giles E. Hardy Date: ___________________ ii Acknowledgements There are many people that have earned my gratitude for their contribution to this thesis. My appreciation to all of them for being part of this journey and making this thesis possible.

Special mention goes to my principle supervisor, Dr Margaret Andrew, for her unflagging academic support, sage advice and attention to detail for every single part of this thesis. I greatly benefited from her scientific insights and deep knowledge on invasion science, species distribution modelling and data analysis. My heartfelt thanks go to Prof. Giles Hardy for accepting me to Murdoch University, proofing my work and giving me motivation to boost my self-confidence.

I owe many thanks to Prof. Bernie Dell for his invaluable advice and especially his thoroughly edition for the field experiment chapter. Thank you for always encouraging me, sharing with me lots of great ideas and also your wittiness. I am much grateful to Dr Mike Hughes for the time he gave in Chapter 5 to check every transcript, coding and helping me to redirect myself out of the mess of preliminary results as well as proofing over and over long, tedious policy drafts.

Profound gratitude also goes to Prof. Pham Quang Thu for his advice on fieldwork design and for the connections he bridged with interviewees. I am grateful to all my supervisors for your unwavering mentoring and thoroughly reviewing all of my work. I consider myself very fortunate being able to work with very considerate and encouraging supervisors like you.

I am also hugely appreciative to Cuc Phuong National Park Management Board for their support during my experiment. Special thanks to Mr. Quang Nguyen for supporting and companying me for the three years of the experiment and for sharing taxonomic expertise so willingly. I am grateful to all interviewees who were willing to participate in the interviews and openly share with me their thoughts.

Each person I met, each story I heard was of valuable experience that encourages me to continue to follow the path I am pursuing. Many thanks to everyone in the Plant Protection Centre of the Vietnam Academy of Forest Science for hosting cozy lunches. I am grateful for their welcome and support iii during the time I was in Hanoi. To my Murdoch friends Harish, Rushan, Louise and Agnes, thank you for coffee time and sharing hard times with me.

My thanks also go to many other Murdoch postgrad students who were willing to share their knowledge in data analysis and research skills with me. My special thanks to Australia Award Scholarship (AAS) for financial support to my thesis and tremendous support to my life in Australia. This project would not have been possible without this funding and support. I also would like to acknowledge a Murdoch University Grant to my principal supervisor for funding my field work in Vietnam.

Last but not least, gratitude goes to my family. Words fail to express how indebted I am to my parents and parents-in-law for their unconditional love, care, and support throughout my life. Thanks to my brother who accompanied me for day after day during the experiment in Cuc Phuong National Park. To my husband Hoang Ha and my son Lam Ha, thank you for patiently bearing with me throughout the up and down PhD journey and for rebalancing me in times of hardship.

Your love gives me the extra strength and motivation to get things done. I dedicate this thesis to my beloved family! iv Abstract In Southeast Asia, research on invasive plant species (IPS) is limited and biased by geography, research foci and approaches. This may hinder understanding of the extent of invasion problems and effective management to prevent and control IPS. Because biological invasions are a complicated issue involving multiple disciplines, this thesis utilized diverse approaches to evaluate risk, impacts, and management of IPS in Vietnam.

Distribution models of 14 species predicted that large areas of Vietnam are susceptible to IPS, particularly in parts bordering China. Native IPS, which are often overlooked in assessment, posed similar risks as non-native IPS. From the model results, a native grass Microstegium ciliatum was selected to quantify its impacts on tree regeneration in secondary forests. A field experiment in Cuc Phuong National Park found that tree seedling abundance and richness increased within one year of grass removal; this effect strengthened in the second year.

These results highlight the impacts of IPS on tree regeneration and the importance of IPS management to forest restoration projects. Given the risks and impacts of IPS, strategic management is needed to achieve conservation goals in national parks (NPs). However, interviews with both state and non-state entities revealed poor and reactive management of IPS in Vietnamese NPs from national to local levels. Institutional arrangements challenge IPS management in Vietnam.

Involvement of multiple sectors with unclear mandates leads to overlaps in responsibilities and makes collaboration among sectors difficult. Lack of top-down support from the national level (legislation, guidance, resources) and limited power at the local level weakens implementation and ability of NPs to respond to IPS. The findings of this thesis provide important information for achieving effective management of IPS in Vietnam. Knowledge of vulnerable areas and species likely to invade and cause impacts can help Vietnam efficiently allocate management resources to prevent and control IPS, but adjustments to institutional arrangements and enhanced cooperation may be necessary to ensure management occurs.

i Statement of co-authorship. 1 Aims and objectives of the thesis. 2 Structure and significance of the thesis. A systematic review of research efforts on invasive species in Southeast Asia.

5 Background on invasion science and management. 28 Conclusions and future invasion research in SE Asia. Contemporary remotely sensed data products refine invasive plants risk mapping in data poor regions. Impact of a native invasive grass (Microstegium ciliatum) on restoration of a tropical forest.

Influences of institutional arrangements on invasive plant species management from multilevel perspectives: Case study in Vietnam National Parks 98 Abstract. 99 Context of IPS management in Vietnam. 126 Coarse scale management of invasive plant species. 126 Fine scale management of invasive plant species.

129 Recommendations for further research. Chapter 3 supplementary material. Chapter 4 supplementary material. Human ethic’s approval.

Refereed journal papers. 207 vii Chapter 1 Chapter 1. Introduction Introduction Invasive species (IS) are one of the most important threats to global biological diversity (Mack et al. They have colonized virtually every ecosystem type on Earth, affected the native biota (Vitousek et al., 1997) and contributed to the local and global extinction of hundreds of species (Pimentel et al., 2005; Vitousek et al., 1996; Wilcove et al.

In extreme cases, the environmental changes wrought by IS can be irreversible (Kumar, 2012). While the number and impact of IS are increasing, resources for management are limited (Perrings et al. Thus, prioritization for management is required (Gaertner et al., 2014; Kumschick et al. Recognizing this challenge for countries, Aichi target 9 from the 2011–2020 Convention on Biological Diversity Strategic Plan emphasizes the importance of identifying species and prioritizing control measures for IS management (Convention on Biological Diversity, 2010).

While developed countries have advanced programs for establishing priorities for preventing and controlling invasive species, less developed countries have slow responses to IS. One of the regions susceptible to biological invasion is Southeast (SE) Asia but the region has the greatest shortfall in responding to both existing and potential IS (Early et al. Lack of awareness by the public and managers (Pallewatta et al., 2003), as well as institutional constraints on IS management, are hindering the region in the prevention and control of IS. The constraints include unclear responsibilities, lack of political commitment and collaboration, and insufficient law enforcement (Elahi, 2003).

A deficit of studies on IS in SE Asia (Nghiem et al., 2013; Peh, 2010) may substantially preclude the delivery of sound scientific advice to secure political and public support and identify priorities for IS management. As IS are understudied in the region, impacts of current invasion as well as future ecological or economic harms are not fully recognized (Lowry et al. Furthermore, the complexity of IS management involves multiple 1 Chapter 1 parties with differing views on both facts and values (Courchamp et al., 2017; Hulme, 2006; Maguire, 2004), necessitating a good understanding of human dimensions as well as political viewpoints. However, these types of studies are rare in invasion studies in SE Asia (see Chapter 2).

In recent decades, Vietnam has suffered severe impacts from IS, and invasive plant species (IPS) are now threatening biodiversity especially in highly protected areas such as national parks. The invasion of the exotic Mimosa pigra in Tram Chim National Park, for instance, not only quickly replaced natural vegetation but also caused a marked decline in the population of the Eastern Sarus Crane (Grus antigone sharpii) (Triet et al. Recently, some native plant species have become problematic for Vietnam, including Merremia boisiana and M. eberhardtii, which are invading forests in the centre of Vietnam (Hoe, 2011; Le et al.

However, research on IPS in Vietnam is geographically scattered and incomplete. Generally, studies have been undertaken as field surveys over short periods of time and have focused mainly on the impacts of M. pigra in the Mekong Delta (Thi et al., 2001; Triet & Balakrishna, 1999; Triet et al., 2004) or on inventories of IPS in some national parks (Le et al., 2016; Tan et al. Aims and objectives of the thesis Given the potential magnitude of risks and impacts of IPS to SE Asia and Vietnam, and insufficient resources to manage all invasive plant species, the overall aim of this thesis is to broaden the knowledge for decision-making in IS management in SE Asia and Vietnam.