In 1992, Kent H. Redford of the University of Florida used the term “empty forest” to describe the result of the decline of animals in tropical forests. Using this phrase as inspiration, in 2015 an international team of wildlife researchers are using the term “empty landscape” to describe the likely impact of the extinction of the world’s large herbivores.

In the grasslands, savannahs, deserts and forests of the world animals such as rhinoceroses, elephants, camels, tapirs and zebras are endangered and diminishing. This is particularly true in Africa and Asia.

Led by William Ripple of Oregon State University the team conducted a comprehensive analysis of the world’s large herbivores, focusing on animals weighing more than 220 pounds. The researchers looked at the animals endangered status, current threats to the species and the likely consequences of population decline on the animal’s ecosystems. In total they focused on 74 species.

In a paper published in Science Advances, they concluded that “without radical intervention, large herbivores (and many smaller ones) will continue to disappear from numerous regions with enormous ecological, social, and economic costs.”

According to Ripple the study began after a global analysis of the related decline of large predators.

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

According to the researchers the largest number of endangered herbivores live in developing countries, especially those in India, Africa and Southeast Asia. The European bison is the only endangered large herbivore on that continent and North America has already lost most of its large mammals due to habitat changes and prehistoric hunting.

According to the report, 25 of the largest wild herbivores now live on an average of 19 percent of their historical range. In addition to hunting, habitat loss due to livestock production has drastically reduced the access of wild herbivores to land and water and increased the transmission of diseases. Livestock production has tripled worldwide since 1980.

Globally, an estimated 1 billion people rely on hunting as part of their sustenance. However, hunting to feed the global trade in animal parts is also a significant factor.

“The market for medicinal uses can be very strong for some body parts, such as rhino horn. Horn sells for more by weight than gold, diamonds or cocaine,” said Ripple.

Co-author Taal Levi, an assistant professor in Oregon State’s Department of Fisheries and Wildlife, added that “it’s inconceivable that we allow demand for horns and tusks to drive the extirpation of large herbivores from otherwise suitable habitat. We need to intensify the reduction of demand for such items.”

The researchers also note that the decline in large herbivores will set off chain reactions in wild ecosystems including the reduction in food for large carnivores, reduced dispersal of seeds from wild plants, increased wildfire due to excess vegetation, a slow cycling of soil nutrients and dramatic changes in the environment for smaller animals including amphibians, birds and fish.

Ripple and his team hope that the report will draw attention to the problem and convince policymakers to take action to preserve endangered large herbivores.

The researchers are calling for a coordinated research effort on endangered species in developing countries and solutions that involve local populations.

“It is essential that local people be involved in and benefit from the management of protected areas. Local community participation in the management of protected areas is highly correlated with protected area policy compliance,” they write.

In addition to habitat loss and hunting, climate change will soon play a significant role in the decline of all species.

A recent study by the International Union for the Conservation of Nature (IUCN) Species Survival Commission (SSC) Climate Change Specialist Group.

“Climate change will be a major driver of biodiversity decline in the coming decades, and accurate predictions of species expected to be affected are essential for gaining time for conservation action — the sooner we start, the wider the range of options we have,” says lead author Michela Pacifici of the Global Mammal Assessment Program at Sapienza University of Rome in a statement.

That paper, is published in the journal Nature Climate Change. The IUCN has a regularly updated database containing information on the status of thousands of species.