Gulangyu, a small scenic island off the southeast coast of China, is bothered by a tiny climbing plant nicknamed Cat's Claw.
Many old western-style mansions on the island, built in the early 20th century, have been blanketed by thick Cat's Claw vines and people worry they will slowly destroy the buildings.
"Cat's Claw grows everywhere and it is almost impossible to clear it up," said Wang Huade, who lives at No. 3 St. Bishan on the island, a mansion built in the 1920s.
A 290-year-old Chinese banyan on the island is suffering from Cat's Claw as well. Vigorous Cats Claw vine will strangle the tree if it covers all its trunk one day.
Cat's Claw (Macfadyena unguis-cati), originating in South America, was first planted on the island in the 1920s as an ornamental but was seldom seen some ten years ago. Things have changed since then.
"Cat's Claw has harmed the biological diversity on the island. Many trees have died from it," said Prof. Lu Changyi from the Environmental Science Institute of Xiamen University.
A similar problem is troubling southwest China's Sichuan Province. In Liangshan, in the western part of the province, hillsides are covered densely with Crofton weed, believed to have migrated across the border from Southeast Asian countries, leaving no room for local weed.
By air, over ocean or on land, biologic invaders break into China with growing international trade.
Every 30,000 tons of grain imported through Shanghai port carried 120 tons of exotic grass seeds in 1996 when China imported 10 million tons of food.
Besides invaders from foreign countries, those introduced from other regions in China also caused disasters. In southwest China’s Yunnan Province, two third of local species of fish were endangered when new fishes were introduced there from the middle and lower reaches of the Yangtze River.
The annual output of an unique fish in Fuxian Lake of Yunnan dropped from about 500 tons in the 1960s to one ton in 2002.
"Our defense against biologic invaders has severe weakness," said Dr. Xie Yan from the Chinese Academy of Sciences who worked out the first report and book on exotic biologic invaders in China with her colleagues.
"The problems result from human activities," she said. "New plants and animals are carelessly introduced from other regions and countries to meet the needs of agriculture, gardening or environmental purpose but the result is hard to tell. Half of harmful exotic biologic invaders in China were introduced purposely."
Green land in the downtown is favorable but Chinese had imported over 2,000 tons of grass from abroad in 1997 to green their cities, many of which now have elbowed away local species of grass.
"The laws and regulations are not sound enough to hold against exotic invaders," said Yang Chaofei, former director of the Natural Ecology Protection Department of State Environmental Protection Administration (SEPA).
Present quarantine laws and regulations are mainly against plant diseases and insect pests and few dabble in supervising plant and animal introduction to keep out biologic invaders, Yang said.
Lack of awareness of the danger of biologic invaders is another major reason, Xie said.
On the island of Gulangyu, a plant resource census made in the early 1990s had found a seaside wood overwhelmed by Cat's Claw vines but that roused little attention from the public and the government.
"Pressure is also from the trade section that introduces exotic plants and animals for profit yet usually no evaluation is imposed on the environmental impact of such deals," Xie said.
China now has found several hundreds of exotic biologic invaders in some 30 provinces, autonomous regions and municipalities, including 1,900 natural reserves.
Environmental experts are calling to build a strong linkage among relevant government departments such as environmental protection, agriculture, forestry, trade and quarantine.
Many government departments are just talking about holding against biologic invaders and no effective policy has been put forward, Xie said.
"Items to protect biological diversity should be added into laws, then followed by supervision and punishment," she said.
Some also suggested that the Law on the Protection of Wildlife be amended to ban natural reserves from introducing dangerous external species and forbid people to feed wild animals in natural reserves.
(Xinhua News Agency June 15, 2004)
