She said inspectors came and visited every month to ensure the new restrictions were being enforced, adding that permission was needed even to fell a tree.

Home to around half the country’s protected animal and plant species, Yunnan is on the front line of China’s efforts to redefine its relationship with nature and reduce health risks.

It has already put nearly a third of its territory behind an “ecological protection red line” that restricts human activities. Much of that is in Xishuangbanna on the border with Laos and Myanmar. It is the home of China’s last surviving elephant community, located in a sliver of forest about 8km (5 miles) from the Mekong River.

Experts say decades of deforestation in China and elsewhere have disturbed ancient ecosystems, destroyed habitats and let loose countless potentially lethal pathogens.

“There are deforestation events, and wildlife trade, and until we deal with that we are going to see more and more pandemics.”

Acknowledging the role played by habitat destruction in the coronavirus outbreak, China last year imposed tough curbs on wildlife trading and drew up policies to better protect rivers, wetlands and forests.

The policies are already having an impact. Though the 300 ethnic Dai inhabitants of Mandian village had subsisted comfortably off the forest for years, they were now unwilling to risk being fined, residents said.

Yunnan is also under pressure to enforce its so-called red lines more rigorously and crack down on the illegal occupation of protected land. Xishuangbanna also launched a campaign in December to stop local farmers from illegally expanding their tea plantations.

A local wildlife protection officer said he and his team had been inundated with work since the start of 2020.

“There’s been a much bigger emphasis on protection and a greater awareness of the risks among the public and the government,” said the officer, who did not want to be identified.

But Xishuangbanna had also struggled to find the means and the manpower to enforce the rules, he added.

“We are spending longer and longer inside the forest, but we need more facilities – and we need more Toyotas.”

Although signs warn against trespassing in protected areas, sites visited by Reuters still show considerable human activity, including farming and logging.

The protection officer said it was impossible to track every encroachment in a region where total forest coverage – including rubber plantations – stood at 80 per cent. Authorities have also struggled to prevent farmers from intruding on ecosystems to plant more crops.

“In some areas, the residents would take one line of trees a year,” said Alice Hughes, a botanist based at the Xishuangbanna Tropical Botanical Gardens, a research facility and tourist attraction.

Beyond Yunnan’s fragmented nature reserves, the churn of urbanisation continues. Xishuangbanna’s population has doubled in 40 years, its ethnic minorities subsumed in an urban sprawl centred on Jinghong, the region’s political centre.

Researchers worry that while the “red line” scheme protects 30 per cent of Yunnan’s territory, little is being done elsewhere.

A study published last year said existing schemes “do not offer adequate protection”, with nearly 25 per cent of the region’s biodiversity hotspots not covered. Another 2020 paper showed Jinghong had lost a quarter of its tropical forest since 1999.

“Ecological redlining has huge potential,” Hughes said. “But there’s a lot of biodiversity that is falling through the cracks.”

Coronaviruses could have been endemic for years, but the range of human exposure has been vastly increased by the arrival of thousands of migrants and tourists, together with the construction of new high-speed road and rail links and the extension of wildlife trade networks into new ecological niches.

“The world has become a much smaller place,” Hughes said. “Local populations will often be immune to local pathogens because they’ve been exposed repeatedly at low doses.

“But if then their relatives from the big city or from overseas come, they have no immunity and that means they can contract it and they can spread it.”

In 2018, more than a year before Covid-19 was discovered in the city of Wuhan, Daszak and his team set out to explore the risks of zoonotic disease in rural southern China. They found that human-animal interactions were frequent and conducted with “low levels of environmental biosecurity”.

“It is not one person every 10 years that leads to an outbreak, but thousands of people, maybe millions every year,” Daszak said.