ConservationBytes.com

This series on ConservationBytes.com takes a page out of our book Tropical Conservation Biology (Sodhi, Brook & Bradshaw) – therein we produced a series of ‘Spotlights’ describing the contributions of great thinkers to conservation science. Each highlight of a Conservation Scholar includes a small biography, a list of major scientific publications and a Q & A on the person’s particular area of expertise.

Our ninth Conservation Scholar is Stuart Pimm…

Biography

I am the Doris Duke Professor of Conservation Ecology at the School of the Environment at Duke University and have a secondary appointment of Extraordinary Professor at the Conservation Ecology Research Unit at the University of Pretoria, South Africa. My interests are endangered species conservation, biodiversity, species extinction, and habitat loss. I’m the author of over 200 scientific publications, many of them in Nature and Science, and have written four books, the most recent being the critically acclaimed World According to Pimm: a Scientist Audits the Earth. In 2006, Prince Willem-Alexander presented me the Dr. A.H. Heineken Prize for Environmental Sciences on behalf of the Royal Netherlands Academy of Arts and Sciences. How did all this happen?

Like many peers, I started out as a naturalist during my adolescence, read zoology at university, and then did a PhD in ecology. Unlike others, I worked in Hawai’i soon afterwards where I was deeply shaken by the total absence of many of the birds I expected to see – they were either extinct or close to it. I was curious about why some species succumbed while other survived. Importantly, these losses were an outrage. Scientists, I realized, could help prevent extinctions. Vitally, they had an obligation to do so. Thereafter, my research group has sought out the species and ecosystems that are in most urgent need of protection. That work takes us to the Everglades, the Amazon and the coastal forests of Brazil, to southern Africa, and to Madagascar. We work with local organisations and governments to provide the best possible advice to solving conservation problems. We’re problem driven and that means we develop whatever skills are needed to their solution. We’ve always had good quantitative skills, but in addition, my group members all use geographic information system and analyses of satellite imagery – skills we developed only in the last decade. And yes, some of the solutions come from sharing our knowledge with politicians and advising on policy issues.

Major Publications

• Pimm S., Raven P., Peterson A., Sekercioglu C. H. & Ehrlich P. R. (2006) Human impacts on the rates of recent, present, and future bird extinctions. Proceedings of the National Academy of Sciences of the USA 103, 10941-10946
• Pimm S. L. (1991) Ecological Issues in the Conservation of Species and Communities. University of Chicago Press, Chicago, USA
• Pimm S. L. (2001) The World According to Pimm: a Scientist Audits the Earth. McGraw Hill, New York
• Pimm S. L. & Jenkins C. (2005) Sustaining the variety of life. Scientific American 293, 66-73
• Pimm S. L., Russell G. J., Gittleman J. L. & Brooks T. M. (1995) The Future of Biodiversity. Science 269, 347-350

Questions and Answers

1. The current biodiversity crisis has been termed the “sixth extinction”; an allusion to the five largest mass die-offs in Earth’s past. Is this comparison justified?

In the previous five die-offs – the last killed off the dinosaurs – more than half the variety of life disappeared. It took roughly ten million years to recover the former numbers of species. Human actions in the last thousand years have probably wiped out about 10 % of species, while actions in the last century have threatened at least 10 % of the remainder. By threatened, I mean that expert opinion judges that these species will become extinct in the next few decades if we do nothing to protect them. It gets worse. Tropical forests hold perhaps two-thirds of all species on land and tropical oceans, especially coral reefs, the great majority of marine species. If current trends continue, human actions will so massively reduce these ecosystems that a third or more of the remaining species will be on a path to extinction within a few decades.

2. How reliable are biogeographic proxies such as the species-area relationship for inferring extinction rates?

Our ability to predict future trends on land comes from the species-area relationship. It’s one of the great ecological laws – that is, a commonly observed pattern across different species groups in different areas. An oceanic island, half the size of larger island, will have about 15 % fewer species according to this law. Imagine we convert what was once a continuous forest – say, eastern North America – into islands of about half the forest cover. There are about 30 species of bird endemic to the forests of the region, so we’d expect to lose 4.5 species. And, indeed, four species of bird became extinct as eastern North America lost its forests in the four centuries since European colonisation – and another species in threatened with extinction! Detailed calculations like this one have now been done on many areas of tropical forest, which often contain hundreds of endemic species. The numbers of species the model predicts to go extinct and those that have done so are very similar (or are presently in danger of doing so, for extinctions take time to happen.). These excellent calibrations of the law mean that we can predict how many species will go extinct if we reduce tropical forests further.

3. How can scientists most effectively engage the often pseudo-scientific arguments posed by environmental ‘sceptics’, who claim global hazards, such as the large-scale death of species and climate change, are illusory or inconsequential?

The most effective strategy is not to engage the sceptics. I’m for honest scientific debate – it’s what I do every day. The evidence for global change and massive loss of species is unassailable, however. Sceptics ignore the evidence, usually in my experience, because they are paid to do so. There is nothing honest in the debate, indeed, it usually isn’t a debate. Would you debate someone who thought the world was flat? If you were so foolish as to do so, what would happen? You’d present all the familiar observations -Earth’s shadow on the Moon, for example, – and demolish your opponent. Would he continue with his foolish ideas? You bet! He would loudly trumpet that he’d debated a competent, thoughtful scientist at the University of Somewhere. To outsiders, his pathetically ignorant ideas would gain credibility and his sponsors would continue to pay him. Lots of good people work hard to address ways to reverse global change and reduce species loss. Get on with solving problems and don’t waste time with fools.

4. What is the future of tropical biodiversity… ‘according to Pimm’?

The important message is that we can stem the loss of tropical biodiversity – its future is not yet written. We can slow the rate of deforestation and we know enough about the patterns of where the most vulnerable species live to make their protection a priority.

CJA Bradshaw

(with thanks to Navjot Sodhi, Barry Brook, Ward Cooper, Wiley-Blackwell and Stuart Pimm for permission to reproduce the text – buy your copy of Tropical Conservation Biology here)