Scientists’ warning: Extinction of big land animals forever alters environment

Extinctions of large animals — a fate that could soon befall elephants and rhinoceros — have a cascade effect on local ecosystems, including Northern California, where many smaller animals and plants died off after mammoths were wiped out, a team of scientists has discovered. The size of elephants, wildebeest and other big plant-eaters not only makes them impressive and fascinating, but vital to the many species, including flora and fauna, that live with and depend on them, according to a joint report by UC Berkeley, Stanford University, California State University Sacramento and the University of Chile. “Ecological studies have shown that if you pull out a top predator or a key herbivore today, you get dramatic change in the ecosystem,” said Anthony Barnosky, a UC Berkeley professor of integrative biology and the study leader. The study, which was released Monday and is to be published in the journal Proceedings of the National Academy of Sciences, looked at past extinctions in North and South America since humans arrived about 15,000 years ago. The scientists found that the number and diversity of small animals and vegetation decreased all along the Pacific Northwest, as well as the western and northeastern United States, after mammoth and mastodon extinctions. The study released Monday explains how large browsing animals like mammoths, mastodons and today’s elephants, bison and moose change the ecosystem by eating small trees and shrubs, uprooting trees and trampling and churning up soil. “You see the impact of defaunation today in Africa, where the removal of elephant populations has led to these shrubby, scraggly acacias filling the savanna landscape,” said co-author Charles Marshall, a professor of integrative biology and director of the UC Museum of Paleontology.