Damaged Landscape Can Still Be Helpful, Researchers Say

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.

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.

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