The rainforests of central and western Africa, which are the second largest on Earth, could lose 6-9% of their atmospheric carbon-capture capacity if elephant communities were wiped out. In the end, this will further accelerate the warming of the Earth.
Forest elephants play an important role in the carbon cycle, as they 'thin' the rainforest canopy by eating tall, fast-growing trees that capture less carbon. This creates more space and sunlight for the slower growing trees beneath which capture more carbon from the environment.
"If we lose forest elephants, we will be doing a global disservice to climate change mitigation," said biologist Stephen Blake of Saint Louis University in Missouri, quoted from Science Alert.
"The importance of forest elephants for climate mitigation must be seriously considered by policy makers to generate the support needed for elephant conservation. The role of forest elephants in our global environment cannot be ignored," he added.
Using data from previous studies and new information gathered in the field, the team analyzed nearly 200,000 dietary records of African forest elephants, which cover more than 800 plant species.
The preference elephants have for trees with a lower carbon density appears to be due more to the nutritional value they obtain, not to their availability. The trees are more palatable to elephants and easier to digest.
For fruit, elephants prefer trees with a higher carbon density, which have bigger and sweeter fruit. This means elephants also help distribute the seeds of these carbon-heavy trees further around the forest. Some tree species cannot even survive without the help of these animals.
"Elephants eat lots of leaves from lots of trees. They will strip leaves from trees, tear entire branches or uproot saplings while eating, and our data shows most of this damage occurs in low-carbon-density trees," Blake said.
"If there are a lot of trees with high carbon density around the environment, it means one less competitor, which is destroyed by elephants," he added.
It is estimated that there are less than 500,000 African elephants in the wild today, down from 3-5 million during the last century. Poaching for ivory led to this drastic decline, with as much as 80% of livestock lost in some areas. In addition, habitat loss and human-elephant conflict are further reducing population numbers.
This new study emphasizes the importance of protecting the African elephant, the largest living animal on Earth. They are one of nine species of megaherbivores, terrestrial plant eaters with a body mass of over 1,000 kilograms.
Now, the number of megaherbivores is much smaller than before. As a result, tropical forests suffer. Studies are currently planned to look at other areas and species, to examine how other large herbivores such as Asian elephants and primates can affect rainforest health.
"Elephants are the gardeners of the forest. They plant forests with high carbon density trees and remove weeds which are low carbon density trees. They do an excellent job of maintaining forest diversity," concluded Blake.
