Professor Helen Roy of the UK Centre for Ecology & Hydrology reflects on her experiences as co-chair of the IPBES Assessment on Invasive Alien Species and their Control as well as the huge collaborative effort that went into producing the report. It was discussed and approved at a meeting of IPBES (the Intergovernmental Science-Policy Platform on Biodiversity) in Bonn, which concluded on 2 September.

Four years, 86 experts from more than 49 countries, one technical support unit, over 13 000 references, three workshops with indigenous peoples and local communities, information and knowledge from different value systems, six chapters, one Summary for Policymakers (including some amazing data visualisations) resulted in the approval of the Thematic Assessment of Invasive Alien Species and their Control by all 143 governments that are IPBES members. I had the honour of being one of the three co-chairs, alongside Anibal Pauchard (Chile) and Peter Stoett (Canada), leading the expert team. 

The process of biological invasion involves the expansion of species from one region of the world to another through human activities, with the four stages being transport, introduction, establishment and spread. The rate at which species are being moved around the world is higher than at any time in human history. Some of these species establish self-sustaining populations in regions where they would not naturally occur – so called established alien species. A subset of these alien species threatens biodiversity and are referred to as invasive alien species. 

There are many ways in which invasive alien species adversely affect other species and ecosystems. Some outcompete other species, in some cases displacing them altogether. Others have voracious appetites and deplete populations of prey species. An alien species may hybridise with a native species. Some carry diseases. 

Invasive alien species can have catastrophic effects on biodiversity and ecosystems and are one of the five main causes of biodiversity loss alongside climate change, land and sea-use change, overexploitation of natural resources and pollution (IPBES, 2019). All these drivers can interact with one another resulting in dramatic outcomes. There has been much in the news in recent weeks about the devastating fires on Hawaii in which highly flammable invasive alien grasses have played a major part.


IPBES co-chairs Peter Stoett, Helen Roy, Anibal Pauchard

Peter Stoett, Helen Roy and Anibal Pauchard, co-chairs of the IPBES Invasive Alien Species Assessment. Photo: @IPBES.

IPBES-10 plenary

The IPBES-10 plenary discussed and approved the Invasive Alien Species Assessment.

Providing solutions

The IPBES Invasive Alien Species Assessment is a timely and comprehensive global synthesis presenting evidence on the threat posed by biological invasions but also potential solutions to address the problem. 

It has been an incredible privilege and an amazing experience to work on the Invasive Alien Species Assessment over the last four years. For me it is inspiring to reflect on the number of people involved in such a process and the varied and diverse ways that they contribute. It has been a pleasure to work with Anibal and Peter in leading the assessment alongside Tanara Renard Truong, assessment coordinator of the IPBES Technical Support Unit.

Each chapter comprises a team of lead authors led by a few coordinating lead authors who work tirelessly to bring together all the available evidence. Some of the lead authors are part of the IPBES Fellowship Programme and these outstanding early-career researchers have been instrumental in leading themes and activities within and across chapters. 

My UKCEH colleagues Dr Tom August, data visualisation expert for the Invasive Alien Species Assessment, and Kate Randall, our graphic designer, worked with many of the authors to translate key findings into beautiful figures and tables. Additionally, the chapter teams have called upon the expertise of many contributing authors to enrich the information provided with case studies, figures or sections on specific topics.

At points along the way the chapters and Summary for Policymakers have been circulated for external review resulting in submission of thousands of comments from many different stakeholders. The contribution from each and every expert has made an immeasurable difference to the assessment.

The entire process is overseen by the IPBES Secretariat, with guidance from the multidisciplinary expert panel, bureau, expert groups and task forces, and coordinated by an appointed technical support unit – the work they all do is incredible and goes far beyond just keeping the assessment and the experts on track. Indeed, it is impossible to put into words the critical role they have all played in the assessment. 




water hyacinth

Water hyacinth can cover vast area of water, preventing movement of people and animals. It is not yet established in Britain.

Asian hornet

There have been an increase in reports of Asian hornets in the UK this year.

Overcoming challenges

Since approval of the assessment at IPBES-10, I have enjoyed reflecting on the last four years and all that we have achieved working in this collaborative way. We have shared so much. Of course, knowledge but so much more too:

  • Supporting one another through the moments of feeling overwhelmed by the enormity of the task.
  • Satisfaction as we delve deeply into the evidence to deliver new insights.
  • Appreciation of the breadth and depth of expertise across the team.
  • Recognition of the immense benefits of bringing together information and data from across knowledge systems.
  • Respect and understanding of the value of the different perspectives that experts from diverse disciplines bring. 

There have been challenging times along the way. Of course, working across time zones is not always easy but we have also worked through the pandemic and extreme weather events (all too frequent reminders of the urgency of the environmental issues we are facing). However, the sustained engagement of the team has been utterly incredible. I have approached every meeting with excitement and anticipation of what we will be able to achieve together and come away inspired and energised to meet the demands of the next step of the process. 

I am extremely proud of the collaborative report that we presented to more than 140 governments at IPBES-10. It was incredibly exciting to share our synthesis of evidence through this global thematic assessment on invasive alien species and their control with national focal points from around the world. The long days of discussions, on a few nights extending until midnight, at the IPBES-10 plenary in Bonn provided the assessment team with the opportunity of many rich and insightful discussions with the national focal points.

Hour after hour the team supported one another working tirelessly to ensure the evidence from across the assessment was presented clearly to underpin major discussion points. The lead authors and fellows located around the world were sending messages of encouragement as they watched the proceedings on-line. Simply an incredible and inspiring team. We hope that the evidence-based solutions and options that we outline will bring benefits for people and nature around the world. 


I offer particular thanks to our fantastic technical support unit: Tanara Renard Truong (assessment coordinator), Ryoko Kawakami (assessment administrator), Naoki Amako (head of the technical support unit). I am grateful to Defra for supporting my nomination to be an expert within the IPBES Thematic Assessment of Invasive Alien Species and their Control. I have also benefited from the coordinating role of the Non-Native Species Secretariat which ignited my interest in science policy. So many people within the UK Centre for Ecology & Hydrology have supported and encouraged my involvement in the IPBES Thematic Assessment of Invasive Alien Species and their Control and I thank them all.