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.

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.

Focus questions

• If you were trying to model how an animal population changes over time, what information would be useful to make your model as realistic as possible?

• How does ‘ecology’ differ from ‘applied theoretical ecology’?