Wang Dezhi recalls the first time he visited the Old Creek forest farm in 2010.

Then, fish used to be poisoned and wild animals were shot for cash.

Now a nature reserve in Southwest China's Sichuan province, Old Creek plays a key role in a planned national park that will unite the isolated habitats of 1,864 giant pandas in the wild.

The transformation has changed the fortunes of both the people and the wildlife in the area.

The national park, covering 27,134 square kilometers, will be three times the size of Yellowstone National Park in the United States.

It will have four major parts: a core protection area; a restoration area; a touring and education zone; and an area for living and production.

The park will have corridors linking 67 panda reserves on six mountain ranges.

A state-owned forest farm established in the 1970s, Old Creek is one of the natural corridors linking habitats in northern Gansu and Sichuan. In 1998, China halted logging there.

Recalling how difficult it was to make changes, Wang, the chief scientist of the Paradise Foundation, a Sichuan-based conservation group, says: "Poaching and collecting herbs were easy ways to make money. So, the villagers did not care much about the environment."

Then, after two years of research and negotiation, the foundation and Pingwu County, where the farm is located, signed a 50-year land trust contract where the foundation was charged with protecting Old Creek Nature Reserve.

"We then realized that there were two key factors for conservation: fending off poachers and finding environmentally sustainable ways for locals to make a better living," says Wang.

Meanwhile, the foundation is promoting organic farming at nearby Minzhu village, in Gaocun township.

Speaking about the initiative, Shu Cheng, who liaises with the farmers, says: "We buy the produce so long as the farmers use environment-friendly methods and the produce is free of chemical fertilizers. We pay higher prices than the local market."

Chen Xiaohong raises free-range chickens and pigs and grows walnuts, peanuts and corn. Last year, Chen's family earned around 50,000 yuan ($7,355), almost double their income six years ago.

Now, 90 rural families have joined the organic farming program and each family had increased their income by at least 10,000 yuan a year, says Sun Jun, the head of the Gaocun township.

Sun says this has kept poachers at bay and Old Creek Nature Reserve has regained its biodiversity.

Since 2016, infrared cameras captured photos of giant pandas 55 times within the 110 sq km of the reserve.

Giving details, Hou Rong, director of Chengdu Research Base of Giant Panda Breeding, says: "We used to stress on protecting the pandas, but the lack of capital and a unified plan rendered many reserves unable to keep the system on track."

Since the park plan was announced in March, two mines have closed within Gaocun township. But many workers have found new jobs as Old Creek Nature Reserve rangers.

Chen Xianghui, a former worker at Old Creek forest farm, now leads patrols around the mountains four times a week to deter poachers and check that the 80 infrared cameras are working.

The foundation has also trained local people as tour guides.

"We are also helping families renovate their homes as commercial accommodation," says Wang.

Sichuan is also planning to create an international panda tourist trail by integrating the panda research centers and the reserves.

"In such a vast area with such a diverse ecology, conservation needs the support of the locals," says Wang. "This park is in the interest of both pandas and humans."