Herb Decline Linked to Ice Age Megafauna Extinctions
Posted on February 5, 2014
Scientists say woolly rhinos and woolly mammoths enjoyed eating graminoids and forbs. These herbs and wildflowers flourished in the Arctic over 25,000 years ago. New analysis of 50 thousand years of Arctic vegetation history, lead by researchers from the University of Copenhagen, has determined that the plants the megafauna needed to survive stopped thriving during the Last Glacial Maximum, 25,000 to 15,000 year ago.
The climate was very cold and dry during the Ice Age and there was a major loss of plant diversity. As a result, it became very difficult for the giant woolly creatures to survive. After the Ice Age, the planet warmed, but protein-rich herbs the mammoths needed did not fully recover. Reuters reports that a new type of vegetation - grasses and shrubbery appeared - but it did not have enough nutritional value to sustain the massive plant eaters. The researchers say this is what caused the megafauna extinction and not hunting by humans (the overkill or Blitzkrieg hypothesis).
Eske Willerslev, an ancient DNA researcher and director of the Centre for GeoGenetics at the Natural History Museum of Denmark, says in a statement, "We knew from our previous work that climate was driving fluctuations of the megafauna populations, but not how. Now we know that the loss of protein-rich forbs was likely a key player in the loss of the ice age megafauna. Interestingly one can also see our results in the perspective of the present climate changes. Maybe we get a hold on the greenhouse gases in the future. But don't expect the good old well-known vegetation to come back when it becomes cooler again after the global warming. It is not given that the 'old' ecosystems will re-establish themselves to the same extent as before the warming. It's not only climate that drives vegetation changes, but also the history of the vegetation itself and the mammals consuming it."
The research was published here in the journal Nature.