Extinction of Species .ORG

As it trudges through the dense rainforests of West and Central Africa, the forest elephant creates a maze of green corridors by grazing and trampling on small trees in its path. Standing at 3m (almost 10ft), this gentle giant is smaller than its better-known counterpart, the savannah elephant, and remains an elusive, solitary creature. The forest elephant causes mayhem amid the rainforest's lush vegetation as it strips bark from saplings, digs for roots in the soil and munches on leaves and berries. But this destruction does more good than harm to the forest: it helps forests to store more carbon in their trees and preserves one of the planet's most vital ecosystems.  

Companies and governments around the world are racing to slash their emissions and develop innovative technology to capture carbon. But the African forest elephant is remarkably efficient at storing carbon with no technological aid at all.

African forest elephants are known as "mega-gardeners of the forest", because of their ability to boost carbon stocks and disperse vital nutrients. A 2019 study found that the elephant's destructive habits help boost the overall amount of carbon stored in the central African rainforest. Each forest elephant can stimulate a net increase in carbon capture of these rainforests of 9,500 metric tonnes of CO2 per sq km. This is equivalent to emissions from driving 2,047 petrol cars for one year.

Scientists initially carried out fieldwork at two sites in the Congo Basin, one where elephants were active and one where they had disappeared, and recorded the differences in tree cover and wood density. They then built a model that tracked the dynamics of the forest, such as biomass, tree height and carbon stocks, and simulated elephant disturbance by increasing the mortality of smaller plants.

The model showed that the forest elephants reduced the density of stems in the forest, but increased the average tree diameter and the total biomass above ground. The reason is that the elephants graze and trample on trees smaller than 30cm (1ft) in diameter, which compete with bigger trees for light, water and space. By taking out the competition, the larger trees flourished.

As a result, the larger trees grew even taller thanks to the elephants' habits, says lead author Fabio Berzaghi, a researcher at the Laboratory of Climate and Environment Sciences in Gif-sur-Yvette, France.

The smaller trees, which elephants prefer to eat, have lower wood density, which is linked to a faster growth rate and higher mortality. The elephants' behaviour promotes the growth of slower growing trees that store more carbon in their trunks, says Berzaghi. The carbon storage capacity of trees mainly depends on their volume and wood density, although denser wood takes more resources and time to build, he adds.

"You can think of the elephants as forest managers," he says. They are a "keystone species", meaning that they play a vital role in maintaining the biodiversity of their habitat.

Besides eliminating competition, the elephants also disperse seeds and nutrients as they brush past vegetation and distribute poo around the forest, helping trees grow faster, says Berzaghi. "Elephants help disperse trees, which other animals rely on. The trees promoted by elephants support primates and many other animals."

The extinction of forest elephants would result in a 7% loss of carbon stores, 3 billion tonnes in total, in the central African rainforest, according to the study. That is equivalent to emissions generated by more than 2 billion petrol-powered cars over the course of a year.

"It sends a pretty strong message for the conservation of forest elephants," says Berzaghi.