Elephant extinction will raise carbon dioxide levels in atmosphere

Elephant extinction will raise carbon dioxide levels in atmosphere
 Central African elephant. Credit: Stephen Blake, Ph.D.

One of the last remaining megaherbivores, forest elephants shape their environment by serving as seed dispersers and forest bulldozers as they eat over a hundred species of fruit, trample bushes, knock over trees and create trails and clearings. Their ecological impact also affects tree populations and carbon levels in the forest, researchers report, with significant implications for climate and conservation policies.

In a paper recently published in Nature Geoscience, a Saint Louis University biologist and his colleagues found that elephant populations in central African forests encourage the growth of slow-growing trees with high wood density that sequester more carbon from the atmosphere than fast growing species which are the preferred foods of elephants.

As elephants preferentially browse on the fast growing species, they cause high levels of damage and mortality to these species compared to the slow growing, high wood density species. The collapse of forest elephant populations will likely therefore causes an increase in the abundance of fast growing tree species at the expense of slow growing species, and reduce the ability of the forest to capture carbon.

Stephen Blake, Ph.D., assistant professor of biology at Saint Louis University, spent 17 years in central Africa doing, among other things, applied research and conservation work with elephants. While there, he collected a data set on forest structure and species composition in the Nouabalé-Ndoki Forest of northern Congo.

In the current study, Blake's collaborators developed a mathematical computer model to answer the question 'What would happen to the composition of the forest over time with and without elephant browsing?'

To find out, they simulated elephant damage through browsing in the forest and assumed they browse certain plant species at different rates. Elephants prefer fast-growing species in more open spaces. As they feed and browse, they cause damage, knocking off a limb or breaking a shrub. The model calculated feeding and breakage rates along with elephant mortality rates to see their effect on certain woody plants.

"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 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."

These findings suggest far-ranging ecological consequences of past and present extinctions. The loss of elephants will seriously reduce the ability of the remaining forest to sequester carbon. Trees and plants use carbon dioxide during photosynthesis, removing it from the atmosphere. For this reason, plants are helpful in combating global warming and serve to store carbon emissions.

Without the forest elephants, less carbon dioxide will be taken out of the atmosphere. In monetary terms, 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."

The study authors note that forest elephant conservation could reverse this loss.

"Elephants are a flagship . People love —we spend millions every year on cuddly toys, they are zoo favourites 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 for free."

Explore further

Forest elephants are allies in the fight against climate change, finds research

More information: Fabio Berzaghi et al, Carbon stocks in central African forests enhanced by elephant disturbance, Nature Geoscience (2019). DOI: 10.1038/s41561-019-0395-6
Journal information: Nature Geoscience

Citation: Elephant extinction will raise carbon dioxide levels in atmosphere (2019, July 25) retrieved 21 August 2019 from https://phys.org/news/2019-07-elephant-extinction-carbon-dioxide-atmosphere.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

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User comments

Jul 25, 2019
I would hate for elephants to go extinction and I don't think we should make them go extinct regardless of their net effect on climate, but, did they take into account in their research of the greenhouse effect of the large amounts of methane their digestion system makes and releases?

Jul 25, 2019
hunny i think recent research showing less methane emissions from cattle, then previously believed?

i'm just guessing here
but perhaps that may also prove true for he elephants?

okay, before anyone else thinks of it "pachydermcene induced global climate change"

Jul 25, 2019
The greatest threat to the planet and humanity is AGW Cult bullshit.
How quickly the Chicken Shites ignore the fact that their Cult's "solution" to their fabrication was bio-fuels from food crops.

Gobble up, Chicken Shites.

Jul 25, 2019
oh deer auntieoral!
what a mess all over your face...
here's a washcloth to get all that "fowl" excrement off your lips
here's a toothbrush & mouthwash to finish cleaning you up

i hope you didn't scare the hens into stop laying, again!

Jul 25, 2019
I would hate for elephants to go extinction and I don't think we should make them go extinct regardless of their net effect on climate, but, did they take into account in their research of the greenhouse effect of the large amounts of methane their digestion system makes and releases?

collect dna put in freezer problem solved.

Jul 26, 2019

collect dna put in freezer problem solved.

Unfortunately, it won't solve the problem. We don't have the technology yet to resurrect an extinct species using DNA. Even if we did, we still need an egg cell from a closely related species (what do we use - a hyrax?) and a womb to grow it in. After that, come the problems of social adaptation of complex animals like elephants.

Extinction is not a joke. Science fiction movies are not documentaries. I, for one, want my grandkids to see these majestic creatures in real life.

Jul 26, 2019
... was bio-fuels from food crops.

Bio fuels is ONE of the many things we need in order to halt (it's probably too late to reverse) AGW. Others include - sustainable sources of energy, reducing deforestation, carbon sequestration, and the most painful for the people who pay trolls like you - reducing the use of fossil fuels.

Selling out the future of your kids for a few roubles is a pathetic way to make a living, don't you think? Find yourself a better job.

Jul 26, 2019
Another braying Chicken Shite surfaces from their cesspool of ignorance, with a gem.

Jul 26, 2019
oh deer, auntieoral has clambered out of her playpen again...

those poor hens!

oh well, oatmeal for breakfast again

Jul 26, 2019
@tehgaighalgore hates elephants.

Jul 26, 2019
Selling out the future of your kids for a few roubles is a pathetic way to

You are the only ones in the grand scope of people: from blacks, to hispanics, to asians, to libertarians, to conservatives, to independents; only white liberals have a negative view of their race. THE ONLY GROUP. And things are better than ever before in human history.

Yes, delusional.

Jul 26, 2019
"Peasants could only hunt on common land, to hunt elsewhere required a royal licence.The punishment for poaching included hanging, castration, blinding, or being sewn into a deer skin and then hunted down by ferocious dogs."

-Time for a change in perspective.

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