Biodiversity Loss Seen as Harmful as Pollution
Washington - When species in an ecosystem die off, the productivity of the
system declines, and the damage done ranks with the harm caused by climate
change, pollution or other major forms of environmental stress, according to new
research.
This work, made public May 2, is the first comprehensive examination of
biodiversity loss as it compares to other forms of environmental decline.
"Some people have assumed that biodiversity effects are relatively minor
compared to other environmental stressors," said biologist David Hooper of
Western Washington University, the lead author of the paper. "Our results show
that future loss of species has the potential to reduce plant production just as
much as global warming and pollution.
Previous work has shown that the more biological diversity present in a
given system, the greater is the system's productivity. Funded by the Division
of Environmental Biology of the National Science Foundation (NSF), this work
sought to discover if the corollary would be true - the less the diversity, the
less productivity.
"Loss of biological diversity due to species extinctions is going to have
major effects on our planet, and we need to prepare ourselves to deal with
them," said ecologist Bradley Cardinale of the University of Michigan, another
co-author. "These extinctions may well rank as one of the top five drivers of
global change."
Hooper, Cardinale and researchers from other institutions in the United
States, Canada and Sweden combined ecosystem data from a large number of
previously published studies and focused on two system processes - plant growth
and the decomposition of dead plants by bacteria and fungi. They built a
database from existing research, drawing on almost 200 experiments that examined
these processes.
"Within the range of expected species losses, we saw average declines in
plant growth that were as large as changes in experiments simulating several
other major environmental changes caused by humans," Hooper said. "Several of us
working on this study were surprised by the comparative strength of those
effects."
For example, plant growth could decline by 5 percent to 10 percent in
ecosystems where species loss fell within 21 percent to 40 percent of the
species. Where species loss rises over 41 percent, the ecosystem effect became
comparable to the effects of climate warming or increased ultraviolet
radiation.
The study authors say the findings are strong enough that policymakers
should begin to take heed of how adverse effects on biodiversity could have
broader consequences, but more research must be done to understand how the
combined effects of the environmental problems might alter ecosystems.
The NSF supported the work through the National Center for Ecological
Analysis and Synthesis, a research center at the University of California, Santa
Barbara, where researchers use existing data to better understand fundamental
issues in ecology and allied fields.
(Distributed by the Bureau of International Information Programs, U.S.
Department of State.)
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