[Scpg] Most Polluted Ecosystems Can Recover, New Study Finds

[Wesley Roe and Santa Barbara Permaculture Network]

Most Polluted Ecosystems Can Recover, New Study Finds

  http://opa.yale.edu/news/article.aspx?id=6712
Published: May 27, 2009


A new meta-analysis finds that most ecosystems 
can recover from environmental damage. But 
ecosystems take longer to recover from 
human-induced destruction and depend on societies 
committed to their cleanup and restoration.

New Haven, Conn. - Most polluted or damaged 
ecosystems worldwide can recover within a 
lifetime if societies commit to their cleanup or 
restoration, according to an analysis of 240 
independent studies by researchers at the 
<http://environment.yale.edu/>Yale School of 
Forestry & Environmental Studies. Their findings 
appear today in the journal PLoS ONE.

The researchers found that forest ecosystems 
recovered in 42 years on average, while ocean 
bottoms recovered in less than 10 years. When 
examined by disturbance type, ecosystems 
undergoing multiple, interacting disturbances 
recovered in 56 years, and those affected by 
either invasive species, mining, oil spills or 
trawling recovered in as little as five years. 
Most ecosystems took longer to recover from 
human-induced disturbances than from natural 
events, such as hurricanes.

“The damages to these ecosystems are pretty 
serious,” said Oswald Schmitz, an ecology 
professor at the Yale School of Forestry & 
Environmental Studies and co-author of the 
meta-analysis along with Yale graduate student 
Holly Jones.

“But the message is that if societies choose to 
become sustainable, ecosystems will recover. It 
isn’t hopeless.” The analysis focuses on seven 
ecosystem types and major anthropogenic 
disturbances, such as agriculture, deforestation, 
invasive species, logging, mining, oil spills, 
overfishing, power plants and trawling. Major 
natural disturbances, including hurricanes and 
cyclones, are also accounted for.

The researchers analyzed data derived from 
peer-reviewed studies conducted over the past 
century that examined the recovery of large 
ecosystems following a disturbance. The studies 
measured 94 variables that were grouped into 
three categories: ecosystem function, animal 
community and plant community.

The researchers quantified the recovery of each 
of the variables in terms of the time it took for 
them to return to their pre-disturbance state. 
The analysis found that 83 studies demonstrated 
recovery for all variables; 90 reported a mixture 
of recovered and non-recovered variables; and 67 
reported no recovery for any variable. Schmitz 
said 15 percent of all the ecosystems in the 
analysis are beyond recovery. Also, 54 percent of 
the studies that reported no recovery likely did 
not run long enough to draw definitive 
conclusions.

In addition, the analysis suggests that an 
ecosystem’s recovery may be independent of its 
degraded condition. Aquatic systems, the 
researchers noted, may recover more quickly 
because species and organisms that inhabit them 
turn over more rapidly than forests, for example, 
whose habitats take longer to regenerate after 
logging or clear-cutting.

The researchers point out that a potential 
“pitfall” of the analysis is that the ecosystems 
may have already been in a disturbed state when 
they were originally examined. Many ecosystems 
across the globe that have experienced 
extinctions and other fundamental changes as a 
result of human activities, combined with the 
ongoing effects of climate change and pollution, 
are far removed from their historical, natural 
pristine state. Thus ecologists measured recovery 
on the basis of an ecosystem’s more recent 
condition. The Yale analysis points out the need 
for the development of objective criteria to 
decide when a system has fully recovered.

The researchers said the study rebuts speculation 
that it will take centuries or millennia for 
degraded ecosystems to recover and justifies an 
increased effort to restore degraded areas for 
the benefit of future generations. “Restoration 
could become a more important tool in the 
management portfolio of conservation 
organizations that are entrusted to protect 
habitats on landscapes,” Schmitz said.

Jones added: “We recognize that humankind has and 
will continue to actively domesticate nature to 
meet its own needs. The message of our paper is 
that recovery is possible and can be rapid for 
many ecosystems, giving much hope for a 
transition to sustainable management of global 
ecosystems.”

Citation: Jones HP, Schmitz OJ (2009) Rapid 
Recovery of Damaged Ecosystems. PLoS ONE 4(5): 
e5653. doi:10.1371/journal.pone.0005653



PRESS CONTACT: <mailto:tom.conroy at yale.edu>Tom 
Conroy 203-432-1345, 
<mailto:david.defusco at yale.edu@yale.edu>Dave 
DeFusco 203-436-4842
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