The science is in, and we need more ginormous critters. Well, ok, not exactly, but this research does remind me a bit of the ecosystem benefits of whales that I’ve mentioned before. The idea that elephants are good for the ecosystems in which they live is not at all new. When it comes to the forest elephants, it has long been clear that, as with whales, the ecosystem seems likely to collapse if they go extinct. With that as context, it makes sense that the presence or absence of elephants can have pretty big implications for the global climate:

In findings published in Proceedings of the National Academy of Sciences (PNAS), Saint Louis University researchers and colleagues report that elephants play a key role in creating forests which store more atmospheric carbon and maintaining the biodiversity of forests in Africa. If the already critically endangered elephants become extinct, rainforest of central and west Africa, the second largest rainforest on earth, would gradually lose between six and nine percent of their ability to capture atmospheric carbon, amplifying planetary warming.[…]

An elephant looks into the camera as it moves through the rainforest. Photo by Stephen Blake, Ph.D. The elephant’s face forms a gray, wrinkled wall in the background of the picture. Out-of focus leaves in the foreground give a sense of depth. The elephant’s eye is visible just above the middle of the right half of the picture. It’s facing to the right, and you can see that the eye is turned forward, off-camera. The iris looks to be a light gold or yellow with a dark ring around it, and the eye’s white has a tinge of pink to it. The trunk is off-screen to the right, and you can see its ear extending off screen to the left.

“Elephants have been hunted by humans for millennia,” Blake said. “As a result, African forest elephants are critically endangered. The argument that everybody loves elephants hasn’t raised sufficient support to stop the killing. Shifting the argument for elephant conservation toward the role forest elephants play in maintaining the biodiversity of the forest, that losing elephants would mean losing forest biodiversity, hasn’t worked either, as numbers continue to fall. We can now add the robust conclusion that if we lose forest elephants, we will be doing a global disservice to climate change mitigation. The importance of forest elephants for climate mitigation must be taken seriously by policy makers to generate the support needed for elephant conservation. The role of forest elephants in our global environment is too important to ignore.”

Elephants play multiple roles in protecting the global environment. Within the forest, some trees have light wood (low carbon density trees) while others make heavy wood (high carbon density trees). Low carbon density trees grow quickly, rising above other plants and trees to get to the sunlight. Meanwhile, high carbon density trees grow slowly, needing less sunlight and able to grow in shade. Elephants and other megaherbivores affect the abundance of these trees by feeding more heavily on the low carbon density trees, which are more palatable and nutritious than the high carbon density species. This “thins” the forest, much like a forester would do to promote growth of their preferred species. This thinning reduces competition among trees and provides more light, space and soil nutrients to help the high carbon trees to flourish.

“Elephants eat lots of leaves from lots of trees, and they do a lot of damage when they eat,” Blake said. “They’ll strip leaves from trees, rip off a whole branch or uproot a sapling when eating, and our data shows most of this damage occurs to low carbon density trees. If there are a lot of high carbon density trees around, that’s one less competitor, eliminated by the elephants.”

Elephants are also excellent dispersers of the seeds of high carbon density trees. These trees often produce large nutritious fruits which elephants eat. Those seeds pass through the elephants’ gut undamaged and when released through dung, they are primed to germinate and grow into some of the largest trees in the forest.

“Elephants are the gardeners of the forest,” Blake said. “They plant the forest with high carbon density trees and they get rid of the ‘weeds,’ which are the low carbon density trees. They do a tremendous amount of work maintaining the diversity of the forest.”

This kind of thinking is part of the ecosystem management that I think we should be doing. This doesn’t mean that we should try to introduce elephants (or mastodons, or wooly mammoths) to areas that haven’t had them in recent centuries, but it does mean that our conservation efforts, even those focused on getting plants to absorb carbon, need to include the various big mammals that we’ve pushed to the brink of extinction. Once again, this isn’t particularly new information. In addition to what we already knew about elephants, there’s also plenty of evidence that restoring bison herds also dramatically helps prairie ecosystems, and moose play a big role farther north.

This is also why I like the notion of local organizing with global networking and a global perspective. Different regions will have different needs, from a social perspective, from an engineering perspective, and from an ecological perspective. Folks on the left talk about the intersection between social dynamics like race, sex, gender, class, and so on, and bringing environmental justice into that has brought us to the point where it’s pretty clear that the social, engineering, and ecological perspectives aren’t really different things at all. They’re just different parts of the same big, complex system. The bad news, as always, is that we’re headed in the wrong direction. The good news, as always, is that we’ve got a pretty good map showing us where we need to go.