QINGDAO -- Qingdao city on China's eastern coast has launched a campaign to control the large-scale spread of cordgrass, native to North America.

The Qingdao Municipal Marine Development Bureau said about 1,312 hectares of cordgrass in Qingdao had been mowed, and tillage has been carried out on 80 percent of the area.

The grass, also known as Spartina, was listed among the first batch of 16 invasive species announced by the former State Environmental Protection Administration in 2003, which caused serious ecological harm and economic loss.

Cordgrass has exploded rapidly in China's coastal areas in the past decade.

Jiao Mingwei, director of the bureau in Qingdao of Shandong Province, said that the city had introduced equipment such as pontoon excavators, boat tractors and lawn mowers to improve the mowing efficiency.

"After mowing, the plowing depth has reached 20 cm to 30 cm. In areas where plowing equipment cannot work, the grass was smashed and buried over one meter deep," Jiao said.