Rethinking Biodiversity, What Plants do Counts
8/28/97
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Headline: Rethinking Biodiversity, What Plants do Counts.
Source: Reuters
Date: 8/28/97
Copyright 1997 Reuters.
Copyright 1997 ABCNews and Starwave Corporation
W A S H I N G T O N, Aug. 28 -
How plants grow and use nutrients may be just as
important to an ecosystem as how many different
plants there are, researchers said Thursday.
Three separate reports in the journal Science
challenge the prevailing wisdom that
biodiversity-having many different species living
all together-is the prime factor in a healthy
environment.
David Wardle of Landcar Research in Lincoln, New
Zealand and colleagues at the Swedish University
of Agricultural Sciences studied 50 remote
Swedish islands in the north of the country that
were prone to lightning strikes.
They found that on islands frequently hit by
fires from lightning strikes, those with a
lower biodiversity seemed to recover faster than
those with a greater diversity of species.
They measured this by looking at standard
indicators of plant health such as the
breakdown of litter like leaves and branches, and
the rate that trees absorbed nitrogen. Islands
dominated by one species of pine tree often fared
better than islands with many different species,
they found.
Different Functions Key
David Tilman of the University of Minnesota and
colleagues planted grassland-savannah plants that
varied by species and function-such as the ways
they gathered nutrients. They found different
function was the most important factor in change
and evolution.
David Hooper and colleagues at California's
Stanford University came up with similar results.
They said their findings had implications for
conservation and for farming.
"If the only goal is the short-term maximization
of production, in some cases less diverse
cropping systems may perform as well as more
diverse systems," they wrote.
But More Costs
But, they added, growing just one kind of plant
meant added expense in terms of fertilizers,
energy and pesticides.
"The results of our experiment also indicate that
in aiming to protect natural ecosystems we cannot
just manage for 'species diversity' alone,"
they wrote.
J. Philip Grime, a plant ecologist at the
University of Sheffield, said the studies
showed biodiversity was not the only important
factor.
"It would be naive to assume that species-poor
ecosystems are always malfunctional; some of the
world's most extensive and ancient ecosystems-
boreal forests, bogs and heathlands-contain few
species," he wrote in a commentary.
Diversity Still Important
But Grime said it was still important to preserve
diverse environments.
"This problem is serious enough that the United
States and the United Kingdom have invested
recently in costly ventures specifically designed
to test experimentally the consequences
of reduced diversity on ecosystems," he said.