Last week, a new study reported that the Antarctic’s second largest colony of emperor penguins continues to decline, after warming weather and high winds led to the loss of over 15,000 eggs in 2016. With reports like these becoming depressingly commonplace, environmental biologists are thinking of out-of-the-box solutions to fight the destruction of ecosystems around the world. One popular solution: Rewilding.

Rewilding involves active and deliberate interventions by scientists to restore certain properties of ecosystems that make them healthy and diverse. Contrary to ‘pure conservation,’ the goal of rewilding is not necessarily to bring back previous lost habitats, but rather to restore ecosystems to support plant and animal life and be resilient to changes. While pure conservationist approaches try and protect lands from destructive human interventions, rewilding recognizes that passive conservation alone cannot always keep pace with rapid global change.

As Helen Wheeler and her team explain in their review in Science, rewilding strives to maximize three central properties of healthy ecosystems: trophic complexity, stochastic disturbances, and dispersal. Trophic complexity recognizes that species within an ecosystem are highly connected and often depend on one another. Particularly, large herbivores can be critically important for modifying the physical environment (e.g. by grazing, trampling, and fertilizing the land) to generate hospitable environments for birds, small mammals, insects, and plants. A rewilding approach to maximize trophic complexity might consider translocating similar species from other habitats if certain species have gone extinct. Perhaps the ‘wildest’ example of this approach comes from the laboratory of George Church. Church and his team are working to introduce elements of the extinct Woolly Mammoth genome into its living cousin, the Asian elephant, so that these large animals can once again inhabit cold tundra environments, hopefully making them hospitable to smaller mammals.

In addition to restoring the diversity of species within an ecosystem, rewilding also recognizes the importance of stochastic disturbances and dispersal. Natural disturbances such as wildfires are often important for ecosystems, but can be suppressed or altered by human behavior. Additionally, ecosystems depend on the exchange of individuals from different populations to increase gene flow and lead to more resilient habitats. Human interventions, like putting up fences or other physical barriers, can suppress dispersal and result in ecosystems that are more vulnerable to change. Rewilding efforts might attempt to increase stochastic disturbances, for example, by removing dams to restore natural flooding patterns, or support dispersal by deliberately connecting different populations.

Proponents of rewilding recognize that at its core, this approach is a societal choice that involves complex questions about what we desire from our natural environments, and how we wish to co-exist with the plant and animal life on our planet. Critics of rewilding point out that its effects may not be predictable. The habitats on Earth may never be what they once were before human intervention, but perhaps, they can approach a happier and healthier co-existence.

News article: https://science.sciencemag.org/content/364/6438/eaav5570.full

Managing Correspondent: Radhika Agarwal

Image Credit: CC BY-NC 2.0

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