6 ACKNOWLEDGEMENTS
We are indebted to the hundreds 
of experts, policymakers, and 
practitioners, including members 
of Indigenous Peoples and local 
communities, who generously 
contributed their time and 
knowledge as authors, fellows, review editors (all of them 
listed below) and contributing authors of the Assessment 
of Invasive Alien Species and their Control, as well as 
to the management committee who provided oversight 
and guidance to its development. The Assessment team 
has contributed thousands of hours of collaborative and 
voluntary work to provide the best available knowledge 
on invasive alien species and their control. We have all 
encountered various challenges, not least the COVID-19 
pandemic, throughout the assessment, but the dedication, 
determination and commitment of everyone involved has 
been outstanding.
Throughout our time working on the Assessment we have 
benefited enormously from the invaluable advice, dedication, 
and constructive contributions from the IPBES secretariat, 
particularly from the Executive Secretary, Anne Larigauderie, 
and from Simone Schiele, Bonnie Myers and Hien Ngo, the 
IPBES Chair, Ana Maria Hernandez Salgar, representatives 
of member States, and the Multidisciplinary Expert Panel 
(MEP) and Bureau, especially members of the management 
committee, Eric Fokam, Shizuka Hashimoto, Rizwan Irshad, 
Ruslan Novitsky, Rashad Allahverdiyev, Vinod Bihari Mathur, 
and Youngbae Suh. We have been honored to work with 
such talented people. The Invasive Alien Species Assessment 
would not have been possible without the phenomenal 
contributions and excellent guidance of our technical support 
unit, headed by Naoki Amako and Noriko Moriwake and 
supported by Ryoko Kawakami and Tanara Renard Truong 
during the four years of its production. These colleagues 
went far beyond expectations, ensuring sustained quality 
while being thoughtful of and responsive to the needs of the 
assessment process and our many authors. Further, Tanara 
is listed as an author on both Chapter 1 and the summary 
for policymakers, recognizing her incredible contributions to 
the knowledge and information gathered. We are extremely 
appreciative of her insights and leadership. We also thank 
Tom August, Kate Randall and Maro Haas for their skillful and 
experienced work on data visualization and graphic design. 
We hugely appreciated the many contributions from Peter 
Bates who also facilitated collaboration with Indigenous 
Peoples and local communities. We thank the IPBES 
communications team for their outstanding work providing 
expert guidance, training and support through every stage of 
the Assessment, to ensure the widest outreach of the main 
page 2
FOREWORD
page 4
STATEMENTS FROM KEY PARTNERS
page 6
ACKNOWLEDGEMENTS
page 8
DEFINITIONS, CONCEPTS AND THE 
CONTEXT OF THE ASSESSMENT
SUMMARY FOR POLICY MAKERS
page 12
Key messages
Background messages:
page 20
A. Invasive alien species are a major threat to nature, 
nature's contributions to people, and good quality of life
 page 26
B. Globally, invasive alien species and their impact are 
increasing rapidly and predicted to continue rising
in the future
page 31
C. Invasive alien species and their negative impact can be 
prevented and mitigated through effective management
page 37
D. Ambitious progress to manage biological invasion can be 
achieved with integrated governance
page 46
APPENDICES
Appendix 1: Communication of the degree of confidence
Appendix 2: Synthesis of knowledge and data gaps
Appendix 3: Examples of data and knowledge products
Table of Contents
5 STATEMENTS FROM KEY PARTNERS
The thematic assessment report on
INVASIVE ALIEN SPECIES
AND THEIR CONTROL
David Cooper