CHENGDU- It's already winter, but a forest in southwestern China's Sichuan province is still thick with colorful trees, in sharp contrast to the barren hills in the same area two decades ago.

The Xiaozhaizigou area in Beichuan Qiang autonomous county, home to more than 47 giant pandas and hundreds of other animal species, is part of the country's Giant Panda National Park.

In mid-October, China officially designated its first group of five national parks, including the Giant Panda National Park.

The Xiaozhaizigou area covers 443.8 square kilometers, but more than 360 sq km was once covered by tree plantations that were logged regularly, causing severe damage to the environment.

After more than 20 years of reforestation and ecological restoration efforts, the area has become an ideal habitat for giant pandas and other wild animals.

"The giant pandas have 'taken over' the former logging farms," said Zhao Jun, manager of the part of the park in Xiaozhaizigou, adding that the number of giant pandas in the area rose from zero in 1977 to 47 in 2015.

"The population of the species is still on the rise," Zhao said.

Forest ranger Liu Xiandong, who used to be a logger, remembers the area being reduced to a barren hill by 1997.

"The trees were gone. Wild animals disappeared. Natural disasters like landslides became common," Liu said.

In 1998, Sichuan launched a natural forest protection project, with loggers putting down axes and picking up shovels to plant trees.

Fu Yong, a forest ranger manager, has been planting trees in the area ever since.

"The tree was as thin as my thumb back then," he said, pointing to a tree with a trunk diameter of more than 40 centimeters.

After the trees became a forest with growing populations of wild animals, the focus of the rangers shifted from planting trees to monitoring, researching and protecting wildlife, Fu said.

Fifteen wild animal species under China's top-level protection have been recorded in the Xiaozhaizigou area.

This year, infrared cameras installed in the area have recorded 12 video clips of giant pandas.

Golden snub-nosed monkeys and takins are among the other rare species captured by the cameras.

China's total area of giant panda habitat surged to 25,800 sq km in 2015 from 13,900 sq km in 1988, national survey results show.

Over the past 20 years, forest rangers in the Xiaozhaizigou area have each trekked an average of about 20,000 km.

"Seeing the hills turning green again and wild animals wandering around, I feel our efforts are worthwhile," Liu said.

Xinhua