WASHINGTON — Many polluted or damaged environments can recover within a human lifetime if people commit to restoring them, researchers at the Yale School of Forestry & Environmental Studies report in an article published Wednesday.
"The message is that if societies choose to become sustainable, ecosystems will recover. It isn't hopeless," said Yale ecologist Oswald Schmitz, who co-authored the study with Holly Jones.
The environments studied included areas of Alaska damaged by the Exxon Valdez oil spill in 1989, and deforestation in the Amazon River basin.
The study's upbeat findings, Schmitz said, justify making restoration a more popular option for civic groups and conservation organizations entrusted to protect habitats.
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The researchers' conclusion, which is optimistic compared to conventional wisdom, is based on an analysis of 240 peer-reviewed studies since 1910 of recovery — or not — from logging, mining, overfishing and other ecological disturbances.
Schmitz and Jones found that forest ecosystems recovered in 42 years on average, while ocean bottoms recovered in less than 10 years. Much of the difference, Schmitz and Jones reported, lay not in the extent of degradation but in the shorter life cycles of marine life.
Generally, ecosystems recovered from natural events such as hurricanes faster than from human-induced disturbances, the researchers found. Nonetheless, some disruptions, such as oil spills and seabed trawling, were memories within as little as five years.
Of the 240 studies the Yale researchers analyzed, 83 found that all systems studied had recovered while 90 found a mixture of recoveries and non-recoveries. The remaining 67 reported no recovery. Of these, 36 of the ecosystems appeared truly beyond it, Jones said. In most of the other cases, the studies ended before it was clear whether the ecosystem in question would eventually recover. Both the Exxon Valdez spill and Amazon logging studies produced a mixture of recoveries and non-recoveries.
Jones said that she's optimistic because, "Whatever type of ecosystem it is — forest, lake, grassland, whatever — we're seeing some recoveries. That says that where human will exists, it's possible to restore an ecosystem."
Bill Jordan III, a founder of the Society for Ecosystem Restoration who reviewed the study for McClatchy, questioned its definition of recovery. That depends, as it probably must, on the admittedly varied definitions of the original researchers, Schmitz and Jones write. They propose that researchers come up with a consistent one.
Robert Twilley, a wetlands restoration ecologist at Louisiana State University in Baton Rouge who was not involved in the study, agreed with its overall findings. "Nature has this tremendous capacity for recovery," Twilley said, once apt conditions are restored.
The Yale study appears in the latest issue of the peer-reviewed journal PLoS ONE.
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