Image via Joachim S. Müller on Flickr.

Scientists are “re-wilding islands and even continents” in order to remedy sickened or damaged ecosystems. In one example of re-wilding ecosystems, scientists introduced a species of giant tortoise, from Aldabra Atoll in the Seychelles, to take on the ecological role that was played by a similar species of giant tortoise that went extinct on Ile aux Aigrettes, which is an island associated with Mauritius. More via Scientific America:

In 1965 the largely denuded 25 hectares of [Ile aux Aigrettes] were declared a nature reserve. But even in the absence of logging, the slow-growing ebony forests failed to thrive. Why? Because they had lost the animals that ate their fruit and dispersed their seeds. So in 2000 scientists relocated four giant tortoises from the nearby Aldabra atoll in the Seychelles, and by 2009 a total of 19 such introduced tortoises roamed the island, eating the large fruits and leaving behind more than 500 dense patches of seedlings. The team reported its results in April in the journal Current Biology.

For this tiny island, at least, rewilding appears to have worked. And that holds out hope for other restoration ecology projects in the midst of the sixth mass extinction in the earth’s history. In Europe conservationists have received €3.1 million to begin bringing bison, bovines and horses back to “abandoned” agricultural lands in places such as western Spain or the Carpathian Mountains. Ecologists have proposed repopulating parts of the U.S. with elephants, which would replace extinct mastodons. The Dutch, for their part, have already built what amounts to a Pleistocene park at Oostvaardersplassen, adding Konik horses and Heck cattle to replace extinct wild horses and cattle.

Of course, humans have a mixed track record when it comes to interfering in natural ecological systems—the introduction of the cane toad to Australia to manage other pests has resulted in a frog march of havoc across the continent. “There are no guarantees when trying to manipulate nature,” notes ecologist Mark A. Davis of Macalester College in Minnesota. Others argue that humans should fix what they have broken. “There is no place on this planet that humans have not interfered with, and it is time for us to become actively involved in engineering solutions,” says marine biologist Ove Hoegh-Guldberg of the University of Queensland in Australia. “There are no other options except extinction at this point.”

Continue reading this article at Scientific America.