Scientists claim that the whole planet is at risk of becoming an empty landscape or desert because of the rapid decline in the population of large terrestrial herbivores.

An international research team, helmed by Professor William Ripple from Oregon State University, studied 74 species of the world's biggest herbivores (weighing over 220 pounds or 100 kilograms), including tapirs, rhinoceros and zebras.

The team analyzed data, such as key threats, endangerment status, and ecological consequences of population declines, and discovered that 25 out of the 74 now only occupied 19 percent of their historical range on average and around 60 percent of the giant herbivore population is gravely threatened with extinction.

The scientists also noted in the journal Science Advances that the population decline is due to several factors.

For instance, livestock production, which has tripled in developing countries since 1980, often leads to the encroachment of land that should be for wildlife instead. This translates into land herbivores' reduced access to water and food and also the increased risk of transmission of animal diseases.

The global trade in animal parts, such as skin and horns, and hunting for exotic meat consumption have also contributed to the diminishing number of the hervibores.

When rhinoceros horn prices soared more than did cocaine, gold, or diamonds in illegal markets, Africa's western black rhinoceros ended up becoming extinct in 2011.

There would be several consequences if large herbivores were to vanish from the face of the planet, the scientists note. It would greatly affect the food chain since their demise would rob carnivores, such as tigers and lions, of their natural prey. Seed dispersals would be minimized since bigger herbivores are carriers of seed over long distances, thus slowing the cycle of nutrients from vegetation to the soil.

Without the elephants stamping and clearing vegetation, other smaller animals would most likely lose their natural habitats. This vegetation clearance also creates natural fire breaks, so wild forest fires could become stronger and more frequent.

Approximately 4,000 species of herbivores on land are known, and they occupy different types of ecosystems on every continent, except Antarctica.

A majority of threatened large herbivores live in developing countries, particularly in India, Southeast Asia, and Africa. North America and Europe have already lost most of their large herbivores in a previous wave of extinctions, scientists believe.

"We hope this report increases appreciation for the importance of large herbivores in these ecosystems. And we hope that policy makers take action to conserve these species," Ripple said.

Some endangered species, such as wild pigs in Southeast Asia, capture too little attention, he added. To face this challenge, a coordinated international campaign is needed to make wildlife protection a top priority for the entire planet.

Photo: Daniel Ramirez | Flickr

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