大型食草动物数量下降可能造成“空旷的景观”

The decline of the world's large herbivores, especially in Africa and parts of Asia, is raising the specter of an "empty landscape" in some of the most diverse ecosystems¹ on the planet, according to a newly published study. Many populations of animals such as rhinoceroses², zebras, camels, elephants and tapirs are diminishing or threatened with extinction³ in grasslands⁴, savannahs, deserts and forests, scientists say.

 

An international team of wildlife ecologists led by William Ripple⁵, Oregon State University distinguished⁶ professor in the College of Forestry⁷, conducted a comprehensive analysis of data on the world's largest herbivores (more than 100 kilograms, or 220 pounds, on average), including endangerment status, key threats and ecological⁸ consequences of population decline. They published their observations in Science Advances, the open-access online journal of Science magazine.

 

The authors focused on 74 large herbivore species -- animals that subsist⁹ on vegetation -- and concluded that "without radical¹⁰ intervention¹¹, large herbivores (and many smaller ones) will continue to disappear from numerous regions with enormous ecological, social, and economic costs." Ripple initiated¹² the study after conducting a global analysis of large-carnivore decline, which goes hand-in-hand, he said, with the loss of their herbivore prey¹³.

 

"I expected that habitat change would be the main factor causing the endangerment of large herbivores," Ripple said. "But surprisingly, the results show that the two main factors in herbivore declines are hunting by humans and habitat change. They are twin threats."

 

The scientists refer to an analysis of the decline of animals in tropical forests published in the journal BioScience in 1992. The author, Kent H. Redford, then a post-doctoral researcher at the University of Florida, first used the term "empty forest." While soaring trees and other vegetation may exist, he wrote, the loss of forest fauna¹⁴ posed a long-term threat to those ecosystems.

 

Ripple and his colleagues went a step further. "Our analysis shows that it goes well beyond forest landscapes," he said, "to savannahs and grasslands and deserts. So we coin a new term, the empty landscape." As a group, terrestrial herbivores encompass¹⁵ about 4,000 known species and live in many types of ecosystems on every continent except Antarctica.

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