What is an invasive species?

An alien invasive species is one that...
Is found outside its natural range (other countries or other regions of China)
has been introduced by either intentional or unintentional human activity
has established self-reproducing populations in the wild
has caused obvious changes in local artificial or natural ecosystems

Common Lantana
（Lantana camara）

An ecosystem comes into being by long term evolution. The close relationships between species in the ecosystem have been developed by hundreds and thousands years of competition, exclusion, adaptation and cooperation. Following introduction to an ecosystem, alien species are either excluded from the ecosystem and can only survive under artificial help owing to their inability to adapt to the new environment, or they become a real invader who will break the balance and change or destroy the local ecosystem due to absence of natural enemies.

What are the effects of an invasive species?

Directly reduce the number of native species
Indirectly reduce the number of other species that relied on local species
Change local ecosystem and landscapes
Lower resistance ability of native species to pests and fire
Inhibit normal functions of soil conservation
Inhibit normal functions of water conservation and
Reduce biodiversity of native species

What will we lose if we allow invasive species to invade and spread?

Biodiversity provides three main forms of benefit
Ecosystem Services
Biological Resources
Social Benefits
More than 40% of the world's economy and some 80% of the needs of the world's poor are derived from biodiversity.

Rainbow lorikeet (Trichoglossus haematotus)

Endemism of local species and landscapes
Ecotourism income
Special local biological products
Social benefits
The more globlization, the higher value of local endemism.

Surrounding agriculture and forestry income
Cost of pest control
Cost of weed control
Soils provide less nutrition
Unadjusted water supply
Sustainable agriculture and forestry rely on ecological functions of surrounding healthy ecosystems (pest and fire barren, soil, nutrition and water conservation).

The intentional introduction of alien species is one of the most dangerous programmes affecting biodiversity and the economy of China

Farmlands are being returned into forests with alien species
Eucalyptus, pine trees, larch and economic trees
There are large programmes to import grass seeds from foreign countries (such as the USA) for erosion control and forage, instead of making the effort to cultivate, research and utilize local grass species

Nature reserves and scenic sites
Restoring vegetation by using alien species
Gardening in nature reserves and scenic sites

Urban horticulture
Many invasive species are introduced as ornamental plants
Forest restoration uses alien species

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

Intentional introduction and spread of Alien species has to be limited according to the following dimensions
What is the species?
Where will it be introduced?
How much will be introduced?
How large an area will it occupy?
Ban the introduction of alien species in or adjacent to nature reserves

Prohibit deliberate introductions unless they can be proved to be safe to health and the environment and where it can be demonstrated that domestic species cannot perform the same functions
Forbid the use of imported alien species in all vegetation restoration schemes

Promote use of local species
Research sustainable use of local species
Research seedling sources of local species
Promote the public to collect and nurse seeds of local species

Develop an invasive species warning network
Develop Alien Species Information System in China
Develop a global information system to share information and experiences globally
Develop and update a list of dangerous invasive species and establish a convention to limit the spread of these species