Many conservation organizations and governments around the world have enthusiastically adopted Marxan to design and manage protected areas. The Australian government, for example, recently used Possingham’s analysis to guide a series of major conservation decisions. Marxan helped identify regions off Australia’s northeast coast that collectively maximized biological diversity in the Great Barrier Reef Marine Park, leading to the rezoning of the park boundaries. The government also used Marxan in designating 50 million hectares of new reserves in other parts of the country.

Not everyone raves about Possingham’s work. Some claim his software-driven approach is at times unnecessary. Conservation ecol­ogist Stuart Pimm of Duke University thinks that Possingham’s models make sense in places like Australia, where there is still a lot of intact biodiversity; he has reservations about its use in places where biodiversity is fast declining. For instance, Pimm and a small group of other scientists are now buying up cattle pastures in Brazil to try to connect fragments of highly diverse—and highly threatened—coastal forests. Pimm calls this action so “obvious” that it requires no methodical cost-benefit analysis. “When you’ve got a lot of land to play with,” Pimm says, “it makes sense to think of these formalized processes [like Possingham’s], but in practice, in areas that are particularly badly degraded, you don’t have a lot of choices.”


To many others, though, Marxan’s process is part of the appeal. “For years people have sat around with maps and pens and drawn lines on the maps and said, ‘We should protect this and protect that,’” says Ray Nias, conservation director for the WWF-Australia, based in Sydney. “What Hugh has done is to make that a mathematical and logical process rather than an intuitive one. It’s far more sophisticated and robust than the old way of doing things.”

Possingham and his colleagues are currently working on making Marxan faster and easier to use and adding additional routines to consider the effects of catastrophes like hurricanes. Not a bad thing, if we are to save as many as possible of the 16,306 species currently listed as threatened by the World Conservation Union.