To better understand the role played by alien invasive species in China and make policy recommendations to ensure that they do not negatively affect China's biodiversity, researchers have conducted comprehensive surveys and impact assessments since 1999.

This work has attracted attention of national administrative sectors and the public and provided the basis for further research and control of the invasive species.

What is an invasive species?

An alien invasive species is one that is found outside its natural range - from other countries or other regions of China. It has been introduced either intentionally or unintentionally by humans. It has established self-reproducing populations in the wild and has caused obvious changes in local artificial or natural ecosystems.

Why are the species invasive?

An ecosystem comes into being by long term evolution. The close relationships between species in the ecosystem have been developed by hundreds and thousands of years of competition, exclusion, adaptation and co-operation.

Following their introduction to an ecosystem, alien species are either excluded from the ecosystem and can only survive with artificial help because of their inability to adapt to the new environment, or they become a real invader which will disturb the balance and change or destroy the local ecosystem because of the absence of natural enemies.

What are the effects of an invasive species?

They directly reduce the number of native species and indirectly reduce the number of other species that rely on local species. They also cause changes in the local ecosystem and landscapes and lower the resistance of native species to pests and fire.

Invasive species also inhibit normal functions of soil and water conservation.

What will happen if invasive species are allowed to invade and spread?

Biodiversity provides three main forms of benefit: ecosystem services, biological resources and social benefits.

More than 40 per cent of the world's economy and 80 per cent of the needs of the world's poor are derived from biodiversity.

The intentional introduction of alien species is one of the most dangerous programmes affecting biodiversity and the economy of China. Farm lands are being returned into forests with alien species, eucalyptus, pine trees, larch and other trees useful for timber.

There are ambitious programmes to import grass seed from foreign countries (such as the United States) for erosion control and forage, instead of effort to cultivate, research and use local grass species.

Other projects that are likely to introduce alien species include nature reserve restoration and scenic site development projects. Urban horticulture is also susceptible as many invasive species are introduced as ornamental plants.

Studies have shown that freshwater and coastal aquaculture have caused great damage to biodiversity and ecosystems in aquatic areas.

What can we do to limit invasion?

Intentional introduction and spread of alien species has to be limited while researchers conduct serious studies about what the species is, where it will be introduced, and the amount and area it will occupy.

There should be a ban on the introduction of alien species in or adjacent to nature reserves and prohibition of deliberate introduction unless scientists prove that the introduction is safe for health and the environment and also where it can be demonstrated that domestic species cannot perform the same functions.

We should also forbid the use of imported alien species in all vegetation restoration schemes, promote the use of local species and research on sustainable use of local species and the seedling sources of local species.

We should also encourage the public to collect and nurse seeds of local species.

Above all, the country should develop an invasive species warning network and alien species information system in China, and help develop an information system to share information and experiences globally.

Development and updating of a list of dangerous invasive species and the establishing of a convention to limit the spread of these species are also a priority.

(China Daily 05/29/2004 page3)