Construction of the Qinghai-Tibet railway and roads has caused no major environmental problems as earth-removal spots and building sites were strictly selected, said Chen Guichen, a researcher of the Chinese Academy of Sciences.

However, human activity has an unavoidable influence on the growth of the local vegetation.

"The research work aims to eliminate the negative effects of construction on the environment," Chen said.

The research should answer which kinds of plants are suitable to be artificially cultivated and if the artificially-cultivated plants can survive under the natural conditions in Qinghai-Tibet region.

Some seeds of the native-born plants have been selected for experiments from three experimental bases located in Qinghai Province and Tibetan Autonomous Region.

Species which grow well will be selected after considering the stability of the community, the influence on the aboriginal plants and the feasibility of technology and economy.

"The research work will be finished ahead of the railway's completion so as to start the restoring job in time," said Chen.

Construction of the Qinghai-Tibet Railway started in June 2001 and a total of 2 billion yuan (242 million US dollars) will be invested in environmental protection works such as building routes for wild animals and conservation of vegetation.