As megaherbivores, forest elephants have a significant effect in the environment around them. Now, new research is revealing that their impact also extends to tree populations and carbon levels in the forest.
This is because elephant populations assist in the growth of slow-growing trees that sequester more carbon from the atmosphere. They do this by eating the fast-growing species. This means that the extinction of forest elephants would see a reduction of slow-growing species as fast-growing species would take over.
A mathematical computer model
Stephen Blake, Ph.D., assistant professor of biology at Saint Louis University, and his team developed a mathematical computer model to explore what would happen to the forest with and without elephant presence.
"Lo and behold, as we look at numbers of elephants in a forest and we look at the composition of forest over time, we find that the proportion of trees with high density wood is higher in forests with elephants," Blake said.
"The simulation found that the slow-growing plant species survive better when elephants are present. These species aren't eaten by elephants and, over time, the forest becomes dominated by these slow-growing species. Wood (lignin) has a carbon backbone, meaning it has a large number of carbon molecules in it. Slow growing high wood density species contain more carbon molecules per unit volume than fast growing low wood density species. As the elephants "thin" the forest, they increase the number of slow-growing trees and the forest is capable of storing more carbon."
The team found clear ecological benefits to the elephant populations. In fact, in monetary terms, they estimated that forest elephants represent a carbon storage service of $43 billion.
"The sad reality is that humanity is doing its best to rid the planet of elephants as quickly as it can," Blake said. "Forest elephants are rapidly declining and facing extinction. From a climate perspective, all of their positive effect on carbon and their myriad other ecological roles as forest gardeners and engineers will be lost."
An environmental advantage
Besides being intelligent beings, elephants clearly represent an environmental advantage. As such, it is in our best interest to protect them from extinction.
"Elephants are a flagship species. People love elephants -- we spend millions every year on cuddly toys, they are zoo favorites and who didn't cry during Dumbo? and yet we're pushing them closer to extinction every day. On one hand we admire them and feel empathy and are horrified when they are murdered and on the other hand we're not prepared to do anything serious about it. The consequences may be severe for us all. We need to change our ways.
"Besides, it just makes good sense to keep them around. They're doing an amazing job of helping the planet store carbon for free."
The study is recently published in Nature Geoscience.