Rangers from the Mount Guanyin Nature Reserve and social volunteers have began planting bamboo on top of a 1,900-meter-long highway tunnel that runs through the Qinling Mountains.

Built in 1999, the tunnel led to the abandonment of a 13-km-long section of the No. 108 national highway that separated two groups of giant pandas living in the Mount Tianhuashan area and Mount Xinglong more than two decades ago.

Approximately 90 hectares of bamboo will be planted on the Qinling tunnel, forming a passage for free exchanges between the two isolated panda groups, said Yong Yange, head of the research center of the state-level Fuping Giant Panda Protection Zone.

The World Wide Fund for Nature (WWF), Shaanxi Provincial Forestry Bureau and provincial-level Mount Guanyin Nature Reserve jointly launched the bamboo planting program early this week.

Local farmers say they have spotted giant pandas four to five times a year after the abandonment of this section of the highway, said Zhu Yun, an official with the Mount Guanyin Nature Reserve.

It is estimated that there are now approximately 1,590 giant pandas living in the wild worldwide, most in the mountainous areas of southwest China's Sichuan Province. There are only 273 giant pandas living in the Qinling area.

"Qinling pandas are a rare group of these hairy creatures. People should be more concerned with their living environment and take more measures to protect them," said Ke Gao, a noted Chinese photographer of pandas.

Giant pandas were first spotted in Qinling Mountains in 1964, a century after the discovery of pandas in Sichuan. Scientists have found that Qinling and Sichuan pandas have evolved differently in recent decades.

WWF made a socio-economic survey and worked out the threats to giant pandas, including disturbance from humans and traffic, in the area in 2005. The international conservation organization cooperated with the Mount Guanyin Nature Reserve to begin restoring the giant panda habitat in the area in Sept. of the same year. Bamboo planting is part of the protection program.

According to the plan, four more such passages for pandas will be built in the Qinling area in the future, which is expected to bring new hope to the conservation of wild giant pandas in the region.