This has been a key factor in the emergence of viral outbreaks in West Africa, Malaysia, Bangladesh and Australia, said Andrew Dobson, one of the authors of the paper and a professor of ecology and evolutionary biology at Princeton University.

Wildlife markets and the legal and illegal trade of wildlife for pets, meat or medicine add to these risks by bringing humans into close－and often poorly regulated－contact with animals that may carry a virus, said Stuart Pimm, one of the authors of the paper with the Nicholas School of the Environment at Duke University.

"Surprise, wild animals can harbor a lot of nasty things," Pimm said. "The good news is, by investing ...we could stop future pandemics before they start and substantially reduce the odds of having something like COVID-19 happen again."

Li said China has endeavored to maintain the ecosystem and conserve wildlife in past decades.

The Law of Wild Animal Protection took effect in China in 1988 and a national pilot program to return grain plots to forest land started in 1999.

Recent years have also seen the country uphold the concept that clear waters and green mountains are valuable assets.

In addition, the country has enhanced regulations on wildlife protection by cracking down on illegal trading or eating wildlife during the novel coronavirus and proposed last month to upgrade 55 species of wild animals to top-level protection status.

"More effort may be needed to supervise the enforcement of the policies," Li said.