Professor Hugh Possingham, mathematical ecologist

Professor Hugh Possingham. Interview sponsored by the Australian Research Council.

Professor Hugh Possingham completed a DPhil at Oxford University in 1987 on 'A model of resource renewal and depletion'. He has held appointments at Stanford University, the Australian National University, the University of New South Wales and the University of Adelaide, doing research on the application of mathematical and computational tools to understanding ecological systems.

In 2000 he took up a joint appointment between the Departments of Zoology and Entomology, and Mathematics at the University of Queensland and in 2001 became the Foundation Director of the University's Ecology Centre.

Possingham has done pioneering work on the viability of populations of endangered species and the application of decision theory to conservation biology. He has made contributions to marine, behavioural, population and community ecology and is also a vocal conservation spokesperson and consultant to government on ecological planning issues.

Interviewed by David Salt in 2002.


Mathematical equations for a young birdwatcher

Hugh, let's begin with what led you into science.

It was probably because from about the age of 12 I started birdwatching. My father and I would go out and look at birds in the desert or around our beach house at Victor Harbor, in South Australia, talking a lot about the birds we saw. Once you identified them you'd start to think about what they were doing, and then sometimes when you went back to the same place you'd see the same birds but sometimes you didn't, or certain birds would appear to be in the same habitat, or using the same plants and trees, in different places. Slowly we went beyond what they were and what they were doing, to why they were doing that and why they were in those places – and that is ecology. So, from a reasonably early age, we started thinking about ecological questions.

One of the early things that changed my life was reading a book by Martin Cody called Bird Communities. My father gave it to me because I was interested in birds, and although it had no coloured pictures or anything like that I found it was full of discussions about bird communities around the world, which Cody said were the same in the same habitat. In the Mediterranean woodlands of Chile, South Africa and southern California, or Australia, you actually get completely different birds but the communities are structured and organised in almost entirely the same way – two or three flycatchers, some birds that hammer at wood or pick at bark. Cody understood all this largely through mathematical equations. He was using mathematics to understand convergent evolution of bird communities, why there was always a certain number of species of each type in each place. That was a first sign to me that mathematics was useful, and useful to what I was passionate about.

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Interdisciplinary ecological research

Let's zoom forward and talk about your current position, to which those early interests have brought you.

I direct the Ecology Centre at the University of Queensland, as a professor of both mathematics and zoology and entomology. This centre cuts across the university, trying to coordinate ecological research regardless of which department or school you're in. My position is unusual, in that not many Australian academics are actually 50/50 in two completely different departments, much less two completely different faculties. I don't know why Australian universities tend to have such a compartmental view of science and to like people to be in their boxes. But times change, and now a lot more people are interested in interdisciplinary science, mixing and matching very fruitfully across disciplines like mathematics and ecology.

What sorts of investigations are you and the Ecology Centre currently involved in?

We are doing research on a wide variety of things. Something I'm fairly interested in at the moment is marine park system design. When I was at the University of Adelaide, together with one of my former PhD students, Ian Ball, we started working on how you could optimally design and construct reserve systems. Given information about the species and the habitats in a landscape, we asked, how can you efficiently achieve conservation goals such as viable populations of all the rare and threatened species?

This is an optimisation problem. You could just take everything, but people are not going to allow Australia to be one big national park. And you don't want to get all of the same habitat, or so much of one habitat that you can't get enough of other habitats. In the end, you're trying to find an efficient way to minimise your total costs but still achieve all these conservation objectives. So we formulated that mathematically.

Our mix of maths and ecology, together with relatively simple ideas, is now widely used and has had a very big impact, particularly in the United States.

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Modelling for a desirable future

Tell us about your interest in marine park design.

We were looking at terrestrial landscapes but then we found, most intriguingly, that those same models and algorithms, solution methods, can be applied very well in the marine sector. Marine park design is booming all around the world. All the countries of the planet seem to be wanting a marine park system. And Australia is in there: the Great Barrier Reef Marine Park Authority is using our software to work out how to efficiently redesign the entire marine park, to take it up from the 5 per cent that is conserved at the moment. Also, the Nature Conservancy, as the second biggest non-government conservation organisation in the world, uses our software for all its eco-regional planning.

On land, for several years we have been trying to work out what is a viable population. This is work that I started a long time ago with David Lindenmayer on the viability of Leadbeater's possum, a small endangered marsupial in the mountain ash forests of Victoria. We make computer models of the dynamics of the population, putting in fire, logging, and the birth, movement and death of the possums, and simulate different scenarios of forest management to work out what scenario will ultimately deliver a population of possums that can persist into the future. We've adapted the technologies and now we've got more exciting computer graphics, using geographic information systems – basically, coloured maps in a machine.

With support from the Australian Koala Foundation we (Jonathan Rhoes and Clive McAlpine) are applying these ideas to koalas. We can ask how Port Stephens Shire in New South Wales or Noosa Shire in Queensland, say, can have a development plan that allows some development in the shire, so people can build houses and still conserve koala habitat. You're not going to be able to conserve it all. What are the critical patches? Are there certain sizes of patch that are essential? For example, are little patches useless, so you may as well get rid of them? Is any patch below 100 hectares useless? If so, you need to concentrate your efforts to conserve big patches. How important are corridors between patches? We know roads can increase koala mortality. Where can somebody put in a road, or widen one, with least impact on the koala population? We hope to deliver planning tools to the local and State governments to help them decide how they can most efficiently have koalas in 100 years' time.

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The attractions of converting ecology to an applied science

What is it about this kind of work that keeps you motivated and interested?

I suppose it would be the combination of science with trying to solve real problems. A lot of ecology involves pure ecologists asking fairly theoretical questions about the world, such as why crimson rosellas are so red, or how they have evolved or why their numbers fluctuate so much. These are interesting questions and we need fundamental science, but it doesn't actually allow you to solve any problems. If crimson rosellas weren't doing as well as they are, knowing they are red would not mean we could save them. Such knowledge doesn't tell you exactly what to do to conserve them – nor how to conserve and manage functioning landscapes and ecosystems.

To turn ecology into theoretical applied ecology we need to put a mathematical, decision-theory layer over it. To manage populations and ecosystems we need to be able to predict the future. To predict the future we need models. To be able to manage a landscape or a population of a threatened species such as kangaroos you need to be able to say, 'If we do this, that will happen to the population. If we do that, the population is likely to do something else.' You can use the model to predict the future and therefore choose the best management decision to help you get to the future you want.

What I find motivating is that adding the modelling, the predicting, on top of the basic ecological science enables you to make management decisions and so to make the world a better place. Hopefully, in 100 years' time, at the end of this century, we will still be able to see koalas in Noosa Shire and Leadbeater's possum in Victoria's mountain ash forests. If we can't, then I suppose we will have failed.

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Finding inspiration when science seemed too big

Did you have any mentors, or role models?

Yes, at different parts of my life I did have people who inspired me to keep going, and it is always useful to gain ideas from somebody a few steps ahead of you. Having both parents involved in science and mathematics was very encouraging.

My early years at university were crucial for where I went as a scientist. I wanted to do science at university, but science is very broad! I didn't really know what I wanted to do, so like most first-year students I tended to think largely about the opposite sex and not particularly about my subjects. I drifted on into second year, doing zoology, biochemistry and applied maths – largely as an accident of timetabling. I still had no real plan; I was just doing what was interesting, things I could do reasonably well. But by the end of second year you've got to start making some decisions, because you then have to specialise: by third year you're doing only two subjects, and in fourth year you're focusing on just one.

I was still passionate about ornithology, so zoology seemed the logical place to end up. But Professor Elliott in biochemistry and Professor Ren Potts in maths both gave me very, very inspiring lectures during second year (I was ready to be excited by biochemistry, but up to that point I had seen mathematics as just something I probably should be doing, and not at all exciting). Also in second year I had some maths lecturers such as Ren Potts, Charles Pearce and Bill Henderson who made their subject come to life as a real thing which was enabling me to solve real problems. I learnt about applied maths, how to model complicated systems, how to model things like traffic management – how you can use maths in managing traffic and controlling traffic lights, or to understand the behaviour of birds. Eventually the biochemistry disappeared and I turned my mathematical skills back to ecology.

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Mathematical prediction: a key player in the science team

Would you recommend maths to anyone wanting to make a difference in ecology and conservation?

Oh, definitely. I think many people go into biology for the unfortunate reason that although they like science, they hate maths. If they liked maths they'd probably do physics or engineering, or possibly chemistry. People who think they don't really like maths are often good at it but just have a crisis of confidence. Biology fills up with a lot of very good scientists who are not strong statistically, mathematically or confident with computers.

Yet as disciplines mature they become more mathematical. It's almost unavoidable. Mathematics adds rigour and definition to theories and frameworks for understanding the world. Physics and then chemistry quickly embraced mathematics, and today everything in physics involves a huge amount of maths. Homo sapiens has done business for thousands of years, but in the last 100 or so years economists have had to become very mathematical. Nash, who was portrayed in A Beautiful Mind, is a good example. This mathematician's work has had profound influence on the discipline of economics and in a whole series of other areas of the social sciences and even ecology.

Biology is in that phase. Of the biological disciplines, ecology is probably the most mathematical and theoretical, the most physics-like. I think that as people who are interested in biotechnology, biochemistry, molecular biology, immunology, learn more about these things, they will find their discipline becoming more and more mathematical. They will have to build models of their systems. Already there is the discipline of bio-informatics – understanding genes, how cells function. We are starting to model those things, and all biologists will soon need at least an understanding of models and mathematics.

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The crucial role of science communication

What skills outside of science are necessary if a scientist is to make it these days?

They are probably the networking and communication skills. I often tell my graduate students that there is no point in just doing your PhD and writing a thesis, expecting it to be read. It is generally true in life that doing your work is only half the job – the other half is to tell people what you did, otherwise nobody will believe it happened and it will be of no use to anybody. (Or somebody else will take the credit for it.) If you discover or invent something, you've got to communicate it. You can either write well about it, or speak effectively, preferably both.

A lot of the great science being done is not well communicated. The scientist may think, 'I understand this now. I've made this great discovery. I'll write a little paper on it, and that's my job done. I know what I've done.' She publishes her paper in an obscure journal and maybe 3 years later somebody reads it and says, 'That's interesting,' does more work, 10 years later it's seen as having been really important, and after 20 years it's useful. You can cut through all that if you are willing to take the work you've done out to people, show how it is relevant; write about it – not just in scientific journals but through the media, the more popular magazines – and give talks, public lectures, papers at conferences.

Unfortunately, some of the people who really like science don't like talking. They prefer solving problems in a lab or solving mathematical problems, often because they don't think their communication skills are very good. Well, in the end they're going to have to work at learning all those things, because they are essential.

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Networking in a world scene

Is it important for a developing scientist to get overseas experience?

Yes, at some stage. It gives you an enormous number of advantages. But it's not good if, when you come back from overseas, people think you must be good because some cultural cringe says that Australians can only become real scientists by going away. I don't think the quality of the science overseas is any higher than here. In fact, in ecology and conservation, I'd say Australia is the world leader per capita. It is true that the United States and also Europe have 20 times as many people as we have in the science discipline, and those countries have a lot more money. But without doubt we have some of the best conservation ecologists in the world. Americans know that, and they come here all the time to learn from us.

Again networking is one of the key features. People don't read your papers unless they've seen you. They don't know who you are, they don't know whether you're good or bad unless they've heard you give a talk at a conference. So even if you don't work overseas for a while, going to overseas conferences is essential for networking, talking about your science, convincing people that it's interesting. If nobody picks up on what you have done, people reinvent things because they don't know your work exists. Publishing papers and books does not guarantee that the entire world knows what you do. Nobody can look at all the million or so scientific papers written every year; it's very easy to get lost in the volume of science. Ultimately, doing the science has to be accompanied by a little bit of a networking and advertising game.

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International comparisons of scientific interaction

Having spent time in both the United Kingdom and the United States, do you notice any difference from Australia in the way they do science?

To a certain extent, yes. I did my PhD in Oxford and then a postdoctoral research period at Stanford straight afterwards. I visit the United States frequently, probably twice a year, and less frequently I visit Europe. For my discipline – mathematical ecology, ecology and conservation – the United States is probably where most of the things happen, aside from Australia.

The big difference, I suppose, is in the level of interaction. My experience in the United Kingdom and some parts of Europe is that people tend to work on their own problems. They have small groups – maybe one academic and a couple of PhD students – and they tend to be fairly distant. They don't necessarily like talking much about science. At Oxford we had lots of friends, but typically you didn't talk about your work. And we were in colleges, where your friends tended to have nothing to do with maths and biology. Doing my work was very much like a 9 to 5 job – you'd turn up at 9am, go to the library, read, think, write, write computer programs, solve problems and go home at 5. That was it.

Going to Stanford was a culture shock for me. It seemed that people arrived at 7am and worked till 10pm, with no obvious lunch or coffee breaks. In England, not to have a tea break is considered unacceptable. They have lots of breaks and social events, though again not talking about work. In America, if they had those breaks they'd then talk about work, at their parties they'd talk about work. Sporting events were organised around groups at work. You became so immersed in the system that it was almost impossible to escape – which may be going too far. The Americans are very, very serious and the competition for jobs in the United States as ecologists or mathematicians, any sort of scientist, is quite intense. They worry a lot about those things, and I find the intensity of competition consumes their life.

In Australia we are probably like a hybrid of the United States and the United Kingdom. Our original academic culture was British, more laid-back, gentlemanly science, but the world has changed a lot. The American way of doing science is coming to dominate – bigger groups, bigger pyramids, a lot more networking and communication. You notice at conferences that the Americans generally explain themselves well, they want to talk to you, they network aggressively.

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Strategy skills for fun and for serious planning

What are your interests outside of maths and ecology? What do you do when you get away from work?

I do a lot of things that anybody else does. I spend a lot of time watching TV, which upsets my third-year maths class. Recently they were yawning in one of my tutorials so I asked, 'Were you all up last night watching Survivor, or Big Brother?' and they said, 'No, we don't have TVs,' or 'We don't watch TV.' When I said I did, they told me to get a life!

If I'm with my family, one of the things we like doing is playing games. I obsessively play games. I played a lot of chess when I was young, and I can't resist a new board game. At the moment we're absorbed in Warhammer, which has little soldiers – it takes you days to paint them – and a great fat rule book about how you battle with these soldiers and move them around on the landscape. Effectively, it's an enormous strategy game – chess with dice. My 12-year-old and 11-year-old son and daughter love it; it's been our obsession for the last five months. We talk about it all the time. And the game has chewed up about $600 worth of books and little soldiers and paints.

As well as having amusement value, the game is interesting for the strategies. You can see the children working on strategy and on understanding all the rules. They're continually optimising. They've got to work out, 'Well, here's my cavalry, here's my cannon and here's my spearmen. How far shall I move them? Shall I shoot them and at what? What shall I do to maximise the chance that I'm going to beat the other person?' They learn a lot by facing this plethora of decisions, all with the one final clear objective: winning the game.

There's chance in the game, too. Through the dice they learn about the randomness of the world. Much of my research involves stochastic modelling. In a classical physical system, if you move this here it happens – there's not a lot of stochasticity. But in ecology randomness is important. If you think you've got a policy for managing kangaroos, there might be a 3-year drought and 90 per cent of all the kangaroos in Australia might die. Games that combine chance and strategy are a good way of learning how to manage the world – managing species or a big company. If you're managing BHP you have stochastic events imposed upon you: the stock market goes up and down, oil prices go up and down, some of your senior staff suddenly leave. Ultimately you're playing a game, trying to optimise the company's profits and make the company grow, but in an uncertain world. All those wargame strategy skills are very applicable to life.

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Taking virtual reality for granted

What do you think about computer games? We hear about children spending enormous amounts of time these days playing them.

Well, I play a lot of computer games when the TV gets too boring. Often I'll still be sitting there at 1am playing against people on the other side of the world. My children play computer games a lot too, but they're both also in sports teams. There is a balance there, because they need to keep physically active if they are not to become couch potatoes. As somebody who is in science and maths I've happily picked up on computer games, but I am interested in my children's capacity to play some of them. Regardless of my desire to win, in certain games – especially the spatial, individual-based games – they annihilate me. I can't win, and that annoys me; because I'm good at games I think I should be able to beat my children at anything!

I think their ability to relate to the computer or Nintendo, PlayStation, whatever it is, their capacity to put themselves inside a simulation, is better because they grew up with three-dimensional graphics. When they move their joystick they actually believe they're in there, I think. It's almost as though they're destined to be able to deal with virtual reality. You didn't see three-dimensional simulations, individual-based games, until maybe 7 or 8 years ago. It's very, very recent that the graphics have been good enough. And so my capacity to play those games is limited.

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Predicting your future

You've been enormously successful in your career to this point. Where do you think you might be in 10 years' time?

I don't know. I'd be disappointed to know. I like thinking about the future – I'm not particularly interested in the past – but if I knew what I was going to be doing in 10 years' time then I might as well not do it. In fact, the more I think I know what I'm going to do, the less likely I am to do it.

Being just under 40, I figure that I've got at least a good 5 or 10 years in active research, thinking, working with people, solving problems. I like the discovery and problem-solving aspects of what I do, and I like making a difference.

However, I was a full professor at the age of 32. In the research scene that can be the end of your formal career path. When your wife's father or your aunts and uncles ask, 'What do you do now? Where's your next promotion?' it seems there is nothing. So do you just sit there for 30 years as a professor? I suppose there are other things to do – taking more administrative roles and more senior roles in universities, positions overseas, even looking outside to places like CSIRO or more political positions. I wouldn't close the door on anything that was interesting.

The question will be how much I really like doing science, and how much I want to change the world. Maybe I'm better changing the world as a scientist for the rest of my life rather than by more political or administrative activities. I don't know.

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