Ecosystem Recovery Review Suggests Optimism

Damaged Environments May Heal More Rapidly Than Originally Thought

Jun 1, 2009

A recent review of research papers indicates some human impacted environments may quickly return to their pre-impact state. But are there biases in the papers reviewed?

The literature review and analysis by Holly P. jones and Oswald J. Schmitz, entitled Rapid Recovery of Damaged Ecosystems, was recently published on PLoSone. But a critical reading brings up questions about the results.

The review looked at several ecosystems, including forests, grasslands, prairies and both fresh and marine waters. The types of impacts reviewed included agriculture, deforestation, eutrophication, introduction of alien species, oil spills, power plants, logging and trawling. It also compared these impacts with the recovery from natural disasters including hurricanes and cyclones. All papers included in the analysis were peer-reviewed. No single species recovery papers were included and 236 cases were not within the database maintained by the Resilience Alliance, an organization which encourages collaboration in the study of the dynamics of complex social-ecological systems.

The statistical analysis done on the data showed that forest ecosystems are the slowest to recover and, not surprisingly, agricultural, logging and multiple stressors resulted in slower recovery times than other impacts. According to the authors, the average recovery time as 10-42 years and was not more than 56 years.

This would seem like good news. In that, if recovery work is initiated now, many ecosystems may be restored within 50 years. It also suggests that initiating restoration work on damaged ecosystems in one place may allow that area to recover in the time that another area is being exploited.

Critique of the Conclusions Drawn Regarding Environmental Restoration

One area of concern is that this retrospective review includes, of necessity, papers from the time before researchers had to declare any competing interests. So studies funded by industry and government agencies with a vested interested in proving that an ecosystem was fully recovered are likely included. Some of these studies may be biased.

In the first few years following the Exxon Valdez Oil Spill, there were papers produced indicating full recovery. But some critical long-term impacts of oil spills on the environment are just beginning to be understood. The same is true of the ongoing damage caused by other persistent chemicals, including pesticides some of which have a half-life of more than 50 years.

How long full recovery from exposure to these chemicals will take is simply not known. And it is not clear from the paper whether these more subtle impacts are taken into account in the declaration that an area is recovered.

While it is certainly encouraging that some aspects of environmental impacts may be mitigated reasonably quickly, and the authors’ focus on using the information to work toward sustainability makes sense, the data provided in Rapid Recovery of Damaged Ecosystems needs to be interpreted with some caution.

The copyright of the article Ecosystem Recovery Review Suggests Optimism in Ecosystem Preservation is owned by Dawn M. Smith. Permission to republish Ecosystem Recovery Review Suggests Optimism in print or online must be granted by the author in writing.