Shanghai has put trees at least 300 years old into a global positioning system (GPS) map to monitor and protect these "witnesses of the city's history".

All the 1,566 registered ancient trees have been equipped with a GPS device, which can help officials monitor if any trees are moved.

The modernization of the metropolis has become a major threat to the "invaluable" trees, many of which have been damaged or even chopped down at construction sites.

"We will share the digital ancient tree map with construction companies and the municipal construction administration so that they can take protective measures for the trees before construction starts," said Ma Yun'an, head of the city's greening administration.

According to Ma, people can see information about each tree -- species, age and height -- by double-clicking on a digital map. The administration has also marked the exact location of each tree on a new city map to raise public awareness of the need to protect these trees, said Ma.

The trees, the oldest of which dates back more than 1,200 years, include gingko, London Planetree, camphor and Lotus Magnolia.

(Xinhua News Agency March 13, 2008)