You’re regarded as one of the world’s leading scientists in the field of invasion biology. Can you tell us more about your research?

My field of research is “invasion science”. I used to call myself an “invasion biologist” or “invasion ecologist” because most of my work dealt with the biology or ecology of invasive species and invaded ecosystems. In the last decade or so, however, the study of the phenomenon of biological invasions has expanded greatly in scope. We still need to know a lot about biology and ecology, but the complex problems associated with invasive species and their interactions with humans means that people who try to understand invasions and find ways to manage them also need to know about sociology, economics, philosophy, ethics and other disciplines outside the domain of biology. This is because we need to understand the factors that lead humans to move species around the world, and the values that different stakeholders attach to particular species and ecosystems.

My own research focusses mainly on plant invasions, and in particular woody plants – trees and shrubs. Because South Africa is poor in native tree species, hundreds of species of trees were introduced from all over the world to provide wood, paper and to serve many other purposes. Many of these species are commercially important crops that provide many essential goods and services. Some introduced trees, however, have spread widely from plantations to cause huge environmental problems. Examples are the acacias and pines that have spread over huge areas in the mountains of the Western Cape, reducing water production from our catchments, threatening biodiversity, and making fires more intense and difficult to control. Prosopis (mesquite) trees introduced for shade and to provide fodder in the Karoo, now cause major impacts in rangelands by reducing groundwater resources and reducing carrying capacity.

A large part of my work has sought to understand the “invasion dynamics” of these species, the impacts they cause and to formulate ways of mitigating their environmental impacts.


Why is this work so important, especially from an environmental point of view?

Almost every ecosystem on Earth has been invaded by non-native species. Some have little or no obvious impacts, but others have devastating impacts that reduce the value of these ecosystems for delivering services and impact directly on human livelihoods. South Africa has major problems with invasive species in terrestrial, freshwater and marine ecosystems that are eating away at the natural capital that is so crucial for our livelihoods.


Were you always interested in invasion biology or is it something that came later?

I studied Forestry at Stellenbosch, with majors in Nature Conservation and Forest Science. I had a vague idea that my career lay in the field of nature conservation. However, towards the end of my final year, I applied for a research position at the Jonkershoek Forestry Research Centre just outside Stellenbosch. This centre was part of the now defunct South African Forestry Research Institute, part of the government Forestry Department. My task was to undertake research on invasive plants in fynbos mountain catchments. Fortuitously, a large international programme on biological invasions was launched soon after I arrived at Jonkershoek and I participated in this as junior researcher. This gave me opportunities to meet with many researchers from around the world and to participate in exciting international meetings and workshops. This was a hugely useful foundation and I quickly realised that the study of biological invasions was an exciting and rewarding career option.

I spent a decade working at the University of Cape Town’s Institute for Plant Conservation before moving to Stellenbosch University in 2004 when the Centre for Invasion Biology (CIB) was launched as one of South Africa’s first national centres of excellence funded by the Department of Science and Technology. The CIB is now one of the most productive organisations worldwide in the field of invasion science and undertakes research, trains students and provides inputs to policies for the management of invasive species in South Africa and other regions.


You recently won an award for scientific excellence from the African Union. What does this type of recognition mean to you?

Such recognition is always gratifying. However, I sincerely hope that the award and the associated publicity will help to raise awareness of the huge challenges that face us in managing escalating problems with invasions. We urgently need improved strategies to prevent the arrival of new invaders and to deal more effectively with those that are already invading and causing impacts. We need better ways of addressing the conflicts of interest that complicate efforts to manage many invasive species.


What aspects of your work do you enjoy most?

I really enjoy research – identifying problems, setting out to solve them and then making sure that the results of the work are adopted by managers. I love working with students and collaborating with many people from a wide range of disciplines and from all over the world in my research. Often research on biological invasions requires a lot of detective work, tying together evidence from multiple clues and drawing on data and evidence from diverse sources to “crack the case”.


How do you like to spend your free time?

I enjoy music, photography, birding, reading, travel, enjoying fine food and wine, and spending time with my family. First prize is when I can do all these things at the same time.

Gallery / 22 November 2019

Five new professors delivered their inaugural lectures in the last quarter of 2019. Here are some pictures from the events.

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Inaugural lectures November 2019
Gallery / 07 October 2019

These professors of Stellenbosch University delivered their inaugural lectures in September.

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Inaugural lectures September 2019
Gallery / 30 August 2019

Five Stellenbosch University professors delivered their inaugural lectures over the past two months.

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Inaugural lectures August 2019