Restoring the dwindling populations of large herbivores could protect forests, jungles and tundra from increasingly frequent wildfires and other disasters associated with global warming. This was the theme of the latest issue of the journal Philosophical Transactions of the Royal Society B.
The reintroduction of lost or endangered species — also known as “rewilding” — to their natural habitats can have profound effects on an ecosystem. For example, the reintroduction of wolves to the Yellowstone National Park in the 1990s led to some of the park’s rivers changing their course. Since the wolves brought down the populations of elk and deer, the amount of vegetation in the park went up, resulting in reduced soil erosion, which eventually caused the river to change course.
Liesbeth Bakker of the Nederlands Instituut voor Ecologie — who was the editor of the theme issue — has stated, “There is increasing evidence that this global wildlife loss does not only imply the loss of charismatic animals, but also the functions they have in ecosystems.” She added that “humans have overexploited large vertebrates. From the Late Pleistocene extinctions of terrestrial megafauna to the current poaching of elephants and rhinos.”
According to researchers from the German Centre for Integrative Biodiversity Research (GCIBR), who also published a study in the theme issue, rewilding could restore the damaged self-regulating food webs that have helped maintain the Earth’s ecosystems so far.
One of their key findings is that replacing ruminant livestock (animals that chew cud) with non-ruminant wildlife could significantly reduce methane emissions.
Additionally, a study by Christopher Johnston of the University of Tasmania in Hobart which analyzed data from 1945 to the present day has found a recurring pattern of wildfire frequency increasing when herbivore populations are dwindling.
Fire seasons have become 25 percent longer than they were three decades ago. This is because there are less herbivores to eat plant material, giving wildfires more fuel.
However, sceptics have warned that the long-term effects of human-engineered rewilding could be difficult to predict. Others such as Andrew Tanentzap of the University of Cambridge have argued that bringing back herds of Arctic herbivores big enough to make a difference is an impractical goal. “They could become a drop in the bucket in the sea of melting permafrost,” he argued.