Threat From Plummeting Biodiversity Qualified

by Kate Melville

A new meta-study in Nature has analyzed more than 100 previous species diversity studies and come to the conclusion that accelerating rates of species extinction will pose substantial problems for humanity in the near future. The analysis, by Bradley J. Cardinale, from the University of California, Santa Barbara, shows that biodiversity is intrinsically linked to the ecological "services" that nature provides to humanity. Examples of ecological services include composting, pest control, sequestering of pollutants and the absorption of greenhouse gases.

The significance of loss of species versus types of species has been an area of scientific controversy for years, but Cardinale says his analysis demonstrates that the preservation of biodiversity - both the number and type of species - is needed to maintain ecological services.

Cardinale's research team analyzed 111 field, greenhouse and laboratory experiments performed on species from around the world. "Until recently, scientists knew a lot about the causes of extinctions, but surprisingly little about their consequences," said co-researcher Diane S. Srivastava.

"Our study shows that biodiversity matters. Ecosystems with more species function better, that is, they are more efficient in moving energy and matter."

The researchers cited an experiment into controlling agricultural pests that demonstrated how diversity can often deliver more than the sum of its parts. It showed the critical importance of the synergistic "team" of three aphid predators to alfalfa farmers. The team of predators (the ladybug, the damsel bug, and the parasitic wasp) can reduce the density of aphids, in turn increasing the yield of alfalfa. The study showed that all three natural enemies together reduce the aphids to a greater extent than is predicted from each natural enemy alone. This service, provided by species diversity, is of substantial benefit to farmers but is not generally recognized as a function of biodiversity, according to the researchers.

Cardinale believes that action needs to be taken now to save humanity from a serious biodiversity crash. "We were able to conclusively show that the extinction of species from our planet will change the way pests and diseases are controlled, organic wastes are broken down and recycled, food is produced by ecosystems, and water is purified. If we value these services, then we need to protect biodiversity," he added.

But is it too late, given that one-third to one-half of all the species on the planet are expected to be lost in the next 100 years? We need to move quickly says Cardinale, and establish marine protected areas, national parks, and ecological reserves. He also believes it is important to consider biological "hot spots," where biodiversity is high. "We could save a lot of species with only small areas, by putting aside hot spots," he suggests.

27 October 2006

Threat From Plummeting Biodiversity Qualified

by Kate Melville

Source: University of California - Santa Barbara