People are seriously damaging the environment across the world. It is therefore reasonable to presume that its recovery may require many years, offering little hope for a future world driven by sustainable use.
However, Holly Jones and Oswald Schmitz (Yale University, Connecticut) instead propose that ecosystems may be able to recover much faster than commonly thought. An extensive analysis of the scientific literature suggests that damaged ecosystems can recover within half a century, rather than multiple centuries.
Finding and categorizing the scientific studies.
The scientists based their investigation on 240 studies (conducted throughout much of the world) related to ecological recovery in the scientific literature, each one independently published sometime from 1910 through 2008. Their focus was on large-scale, not small-scale or single species, ecological recovery, after human disruption had ceased.
In order to find such studies in a relatively unbiased manner, the scientists conducted their search using the Web of Science search tool, utilizing one of ten keywords or phrases (e.g., deforestation). In their search, they combined these keywords/phrases with the words resilience and recovery, to ensure that the results of the search were on-topic.
The scientists examined both natural and experimental ecosystem disruptions, as well as both active and passive recoveries. The ecosystems were subsequently grouped into one of five categories (e.g., terrestrial), and the recoveries were grouped into one of three categories (e.g., plant community), each comprised of numerous variables (e.g., species composition).
The scientists then calculated the reported time that had elapsed between the end of the disturbance and full recovery. They further eliminated bias in their data acquisition by statistically considering the total number of variables that had or had not recovered by catageory, instead of utilizing a per-study evaluation.
Ecosystem recovery.
The scientists found that many of the studies reported at least some ecological recovery. Thirty-five percent of the studies reported recovery of all variables, 37% reported some recovery, and 28% reported no recovery.
On average, 42 years was the most time required for ecological recovery on a per-ecosystem level (in this case, forest recovery), when any was observed at all. Typically, only approximately 10 years was required for recovery on this level.
On average, 56 years was the most time required for ecological recovery on a per-variable level (in this case, in the face of multiple ecological disruptions), when any was observed at all. Typically, only approximately 20 years was required for recovery on this level, faster when the disturbance was natural rather than human-caused.
Terrestrial forest ecosystems required the most time to recover, and agricultural and multiple disruptions also resulted in a longer ecological recovery time. However, the overall results are quite evident: ecosystems do not require multiple centuries to recover.
Implications.
The scientists studied both human-caused and natural environmental disruptions, including many ecosystems and variables. The large number of variables in this evaluation (94) gives much credence to their main finding, which is that ecosystems can recover much faster than is currently appreciated.
The scientists emphasize that their results should not be used an excuse to exploit the environment in an unsustainable manner. They instead wish to highlight that fact that sustainable environmental exploitation is possible, when the will to manage it and correct for any damage is present.
A possible weakness in this conclusion is that it is based on the opinions of the original publications' authors as to whether an ecological system had recovered; certainly, a complete assessment of the pre-exploitation state of the ecological system was not conducted (and was probably not even feasible) in many of these studies. However, the large number of variables that were examined overall still provides reasonable hope that human civilization is not fundamentally unsustainable.
for more information:
Jones, H. P., & Schmitz, O. J. (2009). Rapid Recovery of Damaged Ecosystems PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005653