The loss of large herbivores from South America about 12,000 years ago led to a reduction in the lateral transport of nutrients across Amazonia, and may explain the limited phosphorus availability seen in the Amazon Basin today, reports a paper published online in Nature Geoscience.
Christopher Doughty and colleagues use models to show that ancient megafauna such as giant sloths and armadillo-like glyptodonts would have transported nutrients from areas of high concentration to the surrounding region in their dung and flesh. Using a series of calculations, they find that the extinction of these animals was accompanied by a dramatic decrease in the lateral transport of nutrients across the landscape. The effect was most pronounced in the Amazon Basin, where the lateral flux of nutrients fell by up to 98%, but was also seen throughout the Americas, Eurasia and Australia.
In an accompanying News & Views article, Tanguy Daufresne states that “as the imprint of the megafauna on nutrient distribution is fading, now may be the time to question the implications for the global biogeochemistry of the Earth.”