No Two Savannas Are Exactly Alike

Which means climate change will impact them differently

Photo: Marcel Oosterwijk

At a glance, a savanna doesn't appear to be the most diverse of ecosystems. Sure, there are exotic animals like zebras and lions running around, but how varied can one sprawling, grassy plain in Africa be from another sprawling, grassy plain in Australia or South America? 

Quite, as it turns out. According to new research published in Science, savannas found in Africa, Australia and South America all have distinct enough features that, ecologically speaking, it doesn't work to lump them under a "one-size-fits-all" model, the authors said in a release

Rather than concerning themselves with animals, the authors of the new study turned to plants and the abiotic components of the savanna ecosystem. They surveyed 2,100 savanna sites and took measures on temperature, rainfall, soil characteristics and fire occurrence. All of these factors impacted tree density in savannas, they found, but all to varying degrees, depending on which side of the Earth the researchers were surveying. In Australia and Africa, for example, more rain meant more trees, but in South America, rain didn't matter so much for new trees. Fire, on the other hand, was counterintuitively egged on by excess rain, as more water led to more grass—a great fuel for fire. 

As things heat up due to climate change and rainfall patterns change, savanna ecosystems on the three continents will respond differently. Fine-tuning of the climate models to take this into account, the researchers conclude, is clearly needed. And given that savannas cover around 20 percent of the planet's surface, having a well-informed idea of what will happen to these places in the future can only benefit us.  

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