Elephants play a key role against global warming

Elephants in the Tsavo National Park in Kenya. / Archive

Science | Ecology

The tropical forest of central and western Africa would lose between 6-9% of its capacity to sequester atmospheric carbon if these threatened animals became extinct.

Elena Martin Lopez

"Elephants are the gardeners of the forest." This is stated by Stephen Blake, assistant professor of biology at the University of Saint Louis, in Missouri (United States), and lead author of a study, published this Monday in the journal 'Proceedings of the National Academy of Sciences' (PNAS), about the key role elephants play in creating forests that store more atmospheric carbon in African rainforests. According to their analysis, if elephants, already severely threatened, were to go extinct, the West and Central African rainforest, the second largest on Earth, would lose between six and nine percent of its capacity to sequester atmospheric carbon, amplifying global warming.

Elephants modify forest structure and increase carbon stocks through multiple pathways. One of them is the way they feed themselves. Within the forest, some trees have light wood (called low-carbon trees, meaning those that capture less CO2 from the atmosphere), while others have heavy wood (high-carbon trees, which capture more CO2 and help fight global warming). The former grow quickly and are among the tallest, because they grow above other plants in search of sunlight. The second ones, on the other hand, develop slowly and do so even in the shade. Elephants, and other megaherbivores, feed primarily on low-carbon trees, which are more palatable and nutritious than high-carbon species. Such 'pruning' reduces competition between trees and provides more light, space and soil nutrients to high-carbon trees.

"Elephants do a lot of damage to trees when they eat, because they tear the leaves and tear off entire branches. Our data shows that most of this damage occurs in trees with low carbon density, “says Blake, so the elephants remove the trees from the forest that least combat global warming, giving more space to the rest.

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Likewise, these mammals are excellent dispersers of the seeds of trees with a high carbon density. When elephants eat their fruits, the seeds pass unaltered through their intestines and are released to the ground through feces, where they germinate and produce new shoots of these plants. "African forest elephants do an enormous job of maintaining forest diversity, encouraging the growth of trees that sequester more carbon and removing those that sequester less CO2, but these animals have been hunted by humans for millennia and as a result are critically endangered," laments Blake.

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The researcher says that “the argument that 'everyone loves elephants' has not sufficiently increased support to protect them and stop their illegal killing and trade. Nor has the argument that these animals are essential to maintain the forest's biodiversity succeeded, since their population continues to decline. We can now add the strong conclusion that if we lose forest elephants, we will be doing a global disservice to climate change mitigation.”

“Years ago,” Blake recounts, “millions of elephants roamed Africa. Now there are less than 500,000 - their numbers have plummeted by more than 80% in the last 30 years - and most of the populations live in isolated areas. Although they are protected by national and international law, poaching continues. These illegal killings must be stopped to prevent the extinction of forest elephants. We have two options: we can continue to hunt these highly social and intelligent animals and watch them go extinct; or we can find ways to stop this illegal activity. The importance and protection of these mammals must be taken seriously by policy makers in order to generate the necessary support for their conservation. Their role in our global environment is too important to ignore. Save the elephants and help save the planet, it really is that simple."