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Science:
Damaged landscape can still be helpful, researchers say
by Cornelia Dean
Researchers who study coastal mangroves, sea-grass beds, coral reefs
and sand dunes are reporting that, contrary to widely held views,
environmental preservation on the coast does not have to be an
all-or-nothing proposition and that landscapes can perform "services"
like storm protection even if they have been somewhat disturbed by
development.
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Mangroves |
Most coastal researchers believe that the relationship between
landscape integrity and ecosystem services is linear. For example, the
researchers said in the new report, it is thought that if any coastal
mangroves are lost to development, storm protection would decline by a
comparable amount.
That is not necessarily so, said Edward R. Barbier, an environmental
economist at the University of Wyoming who led the study. In the case of
mangrove forests in Thailand, Dr. Barbier said, researchers calculated
that 20 percent could be given over to shrimp farming without
significantly affecting storm protection, habitat for fish or production
of wood for local uses.
"This result suggests that reconciling competing demands on coastal
habitats should not always result in stark
preservation-versus-conversion choices," the researchers said. The
researchers from 14 universities and institutes around the world
reported their findings in the Friday issue of the journal Science.
Dr. Barbier said in an interview that a balance between the value of
development and the value of the environment could be struck only if
people could calculate the monetary value of the natural services the
environment provides, a notoriously difficult task.
By using techniques refined over many years, he said, the team
concluded that with mangroves "you can lose 20 percent and have the same
amount of protection." Once 40 percent are gone, "you drop off steeply,"
he said. "There's a threshold here."
But in a commentary on the report, Ivan Valiela and Sophia E. Fox of
the Marine Biological Laboratory in Woods Hole, Mass., said the issues
raised by the new work were critical, but they questioned whether, as
yet, "ecological function can be converted into a currency directly
equivalent to money" without unwarranted leaps of faith.
Dr. Barbier conceded the task was difficult, but said it was vital
for the success of ecosystem-based management, an approach that tries to
reconcile conservation and development.
"If we fail to try to get a handle on the value we can calculate,"
Dr. Barbier said, "then policy makers are going to make decisions on the
values they know, which is the commercial return on development." |
