The Importance of Biodiversity to Ecosystem Health Is in Dispute

If environmentalists were to write down their Ten Commandments, one of the sacred principles would surely be, “Honor thy species.” The green movement takes as a truism that ecosystems are healthier when they contain many species of plants and animals. Ecological scientists have even coined a term for this riot of life: biodiversity.

Though the idea now seems natural to environmentalists, scientists have long wondered whether an abundance of species truly improves the health of ecosystems and the way they work. Experiments to test that link were not completed until the mid-1990’s, when some large-scale, much-heralded studies seemed to provide a positive answer. In 1999, the Ecological Society of America enshrined the importance of biodiversity to ecosystems in a report intended for educators and policymakers. The report concluded that, because ecosystems are vital to human welfare, we must “adopt the prudent strategy of preserving biodiversity in order to safeguard ecosystem processes vital to society.”

It sounded harmless enough. But the publication of the article touched off a firestorm of debate that had been smoldering within ecology.

A group of scientists charged that the society’s report ignored a different viewpoint held by many. The studies cited by the report, the scientists said, were flawed and didn’t justify the conservation recommendation. Diversity is worth saving for moral, aesthetic, and even economic reasons, the critics said, but it might not make ecosystems healthier or more efficient.

The altercation went public when, in a letter in the July 2000 issue of the Bulletin of the Ecological Society of America, eight ecologists bluntly charged that the report was “biased” and “little more than a propaganda document”; made “indefensible statements”; and set a “dangerous precedent” for scientific societies by presenting only one side of the debate, even though the report seemed to represent the entire 7,600-member society.

They wrote, “Our concern is that unjustifiable actions are being made to protect this single rationale for biodiversity conservation, and that scientific objectivity is being compromised as a result.”

Today, the controversy encompasses issues beyond scientific disagreement.

Some scientists claim that the eminent researchers who lead the movement to link biodiversity to ecosystem health, including John H. Lawton at the Imperial College of Science, Technology, and Medicine’s Silwood Park campus, in England, and David Tilman at the University of Minnesota-Twin Cities, have exerted so much influence in the field that the major journals are silencing the critics.