More is Better for the World's Species

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WORLDWIDE FOREST/BIODIVERSITY CAMPAIGN NEWS

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Forest Networking a Project of Ecological Enterprises

2/24/96

OVERVIEW & SOURCE

The following Reuters article details recent advances in

understanding that "loss of species threatens ecosystem

functioning and sustainability.

g.b.

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Subject: More is better for the world's species -scientists

Date: Wed, 21 Feb 1996 7:10:41 PST

LONDON (Reuter) - Scientists reported Wednesday they had found yet

more reason to worry about the estimated 27,000 species which die

out every year.

Their research had reinforced the view that ecosystems do better

the more species there are in them, they said.

David Tilman, an ecologist at the University of Minnesota and

colleagues who have been studying and reporting on grasslands,

tried out their theories on little plots of prairie land

containing varying numbers of plant species.

"Our results demonstrate that the loss of species threatens

ecosystem functioning and sustainability," the scientists wrote

in the science journal Nature.

They found that the more different species of plants there

were, the better all the plants in the plot did. More grew, they

grew bigger and were more efficient in their use of nitrogen, a

major source of nutrition for plants.

"If you look at the plot, you see less bare soil," said

Johannes Knops, a plant ecologist who worked on the study, the

first such experiment in the field as opposed to a greenhouse.

"Our 147 plots ... were planted with either one, two four, six,

eight 12 or 24 species ... from a pool of 24 North American

prairies species," they wrote.

"Ecosystem productivity ... increased significantly with plant

biodiversity. Moreover ... nitrogen was utilized more completely

when there was a greater diversity of species," they found.

The same happened in natural grasslands nearby, they noted.

Last year, Tilman's group found that grasslands with most

species were most resilient to a sudden and severe drought.

Theirs is not the only group to find that more diverse ecosystems

work better. Last year, John Lawton of London's Imperial College

of Science and Technology created simple ecosystems using plants,

insects and other invertebrates.

The more different plants and insects there were, the healthier

all the creatures in the miniworld were.

Peter Kareiva, zoologist at the University of Washington in

Seattle, said there should be more such studies.

"The new work is a milestone on the road to ecological research

whose results can be directly related to debates about the

preservation of Earth's variety of life forms," he wrote in a

commentary.

Not just science was involved, he added. "No one wants to tell

their grandchildren that they passively watched as ignorance and

greed led to the loss of richness of the world's flora and fauna."

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