Exinction of Large Animals Linked to Earth's Nutrient Deficiency
19 October 2018 22:37 WIB
TEMPO.CO, London - Around 12,000 years ago, the Amazon forest was home to gigantic animals such as elephants or huge rhinos. However, around 10,000 BC, these animals started to disappear, allegedly as a result of being hunted down by humans and climate change.
However, a study by Nature Geoscience has produced a new theory: the mass extinctions of big animals around 12,000 years ago was caused by a severe reduction in the earth’s key nutrients.They estimate that extinctions back then reduced the dispersal of phosphorus in the Amazon by 98 percent, with extensive environmental consequences that continue up until today.
Vital nutrients are contained in the feces and bodies of big animals. As they eat and move more than small animals, they have a particularly important role in transporting nutrients into areas where the soil is otherwise infertile.
"Large animals play a disproportionately important role in this translocation of nutrients because they travel farther and have longer food passage times than smaller animals," the scientists write, as cited from Mongabay, Tuesday.
Yet nowadays, much of the nutrient dispersal in the Amazon is conducted by abiotic factors, such as rivers and air, which tend to concentrate nutrients in just a few places.
Therefore, with the loss of massive creatures in South America (including the extinction of 70 pecent of animals weighing over 10 kilograms), scientists believe the ecosystem of the Amazon forest has lost its ability to disperse nutrients, an impact that is still visible up until today and plays a large role in Amazon’s history.
Through a computer model, scientists estimated that nutrient dispersal was reduced by 98 percent when the big animals vanished.
"Aspects of the Anthropocene may have begun with the Pleistocene megafaunal extinctions," the researchers write. The Anthropocene is a geologic term that highlights the massive impact the human species has had on the current epoch. During the Pleistocene era (2.6 million up until 12,000 years ago) many gigantic mammals roamed the earth replacing extinct dinosaurs.
"Most of the planet's large animals have already become extinct, thereby severing the arteries that carried nutrients far beyond the rivers into infertile areas," lead author Christopher Doughty from the University of Oxford told the BBC.
ROSALINA | MONGABAY | PHYSORG