少妇无码精品23p_亚洲一区无码电影在线观看网站 _悠悠色一区二区_中文字幕亚洲无码第36页

Are "alien species" endangering the native ones? This is what the Beijing municipal government has been prying about as a key program for the city's eco-environmental protection. Alien species intrusion is listed on the survey for the first time.

According to State Environmental Protection Bureau, alien species intrusion refers to that alien species are brought in from human activities on purpose or aimlessly, then non-native species grow up and propagate speedily, begin to bring adverse effect on local production and life and change local eco-environment.

Despite Beijing has not received any alarm for alien species intrusion, but whether it has been invaded by alien species still needs further probe.

Reports have revealed a moth species from America indulging in north China's forest. In recent years they have flown to Tianjin and are nearly at an arm's length to Beijing.

In our daily life, alien species make a part of our life, the wheat which we consume every day is produced in central Asia and Near East. Pomegranate, walnut, grape, coriander are from Near East, carrot, pineapple are from India.

While 70% plants grown in California, 40% of flowers in Holland and more than 1000 varieties of plants in Germany are from China.

As people's knowledge progresses, experts come to realize the bad effects of alien species intrusion.

Rabbit Disaster in Australia

Australia's rabbit disaster provides a typical example of the intrusion: in 1859, migrants from England took 12 rabbits to the country, but Australia did not have eagles, foxes and other natural enemies, rabbits began to multiply on a very large scale.

Till 1907, rabbits proliferated all over the country. They fought for grass with cows and sheep, so Australia's animal husbandry suffered a heavy loss during the time.

Water Hyacinth Intrusion in China

The earliest example of alien species into China is water hyacinth (Eichhornia crassipes). An alien species from South America, it has been listed as one of the worst weeds in the world--aquatic or terrestrial.

It was brought to China around the 1930s as livestock feeds. After it was introduced to Dianchi Lake, due to the rich water in the lake, water hyacinth grew at a crazy speed and wild over 1000 hectares of the lake.

50 Billion Yuan of Loss Every Year

China suffers most from alien species. According to statistics, American white moth, loblolly pine mealybug (Oracella acuta), pine scale (Hemiberlesia pitysophila) and other harmful intruding insects take about 1.5 million hectares of the country's area.

Once those alien intruding creatures enter into a country, it is very hard and expensive to root them out. Related statistics show that those alien species bring China 50 billion yuan of loss every year.

(July 09, 2002)