Invasive species are plants, animals and microorganisms that are exotic, non-native, introduced or non-indigenous, with respect to a particular ecosystem. They become invasive when accidentally or deliberately introduced to new areas beyond their native ranges, and are able to survive, reproduce, and then spread and cause a negative impact on local biodiversity. Generally, the spread of an invasive species involves four stages: Introduction, Establishment, Invasion and Spread.
Invasive species can cause negative impacts at the species, population and community levels, and the most significant harm is altering ecosystem functions. Invasive species can potentially caused a range of problems such as the following:
- Threaten the survival of native plants and animals by competing for resources
- Threaten the survival of native plants and animals by competing for resources
- Alter vegetation structures and community composition, thus upsetting the ecosystems balance
- Spread easily if not managed properly
- Costly to control if not managed properly
- Endanger human health if organisms harbour foreign pests and diseases
- Hydridise with native species, resulting in negative genetic impacts
- Costly to control if not managed properly
- Endanger human health if organisms harbour foreign pests and diseases
- Hydridise with native species, resulting in negative genetic impacts
Invasive species can be introduced via 2 means: a) Unintentional & b) Intentional.
An unintentional introduction occurs as a result of accidental or unplanned means, utilising humans or human delivery systems as vectors for dispersal outside its natural range.
- Ballast water releases from ships, hull fouling
- Organisms in or on timber/wood products, in packing materials and shipping containers/cargos
- In or on various modes of transportation like cars, trucks, boats, airplanes, ships, etc
- Organisms in imported nursery soils
- Organisms in imported fruits and vegetables
- Tourists and their luggage/equipment
An intentional introduction is a deliberate introduction of an alien species by humans, involving the purposeful movement of a species outside of its natural range and dispersal potential.
- Release of unwanted pets and aquarium animals into the wild (e.g. Red-eared Slider)
- Plants introduced for gardens/landscaping
- Biological control (e.g. House Crow)
Singapore's Action
| LAWS | DESCRIPTION | AGENCY |
|---|---|---|
| Animals and Birds Act | Regulates the import, export and transshipment of animals | AVA |
| Control of Plants Act | Regulates import and export of plants and plant products | AVA |
| Endangered Species (Import and Export) Act | Regulates trade in endangered species of plants and plant products | AVA |
| Parks and Trees Act | Regulates the planting, maintenance and conservation of trees and plants within national parks, nature reserves, tree conservation areas, heritage road, green buffers and other specified areas. The Act also specifies that release of animal is prohibited in the nature reserve. | NParks |
| Prevention of pollution of the sea Act | Regulates the prevention of sea pollution, whether originating from land or from ships (with reference to ballast water). | MPA |
Conservation Management NParks actively clears exotic plant species from Singapore’s forests. Over the years, exotic plants, mostly climbers and creepers, have been thriving along the rainforest edges and are a threat to the native plant species. These creepers strangle trees, and often cause their collapse during heavy thunderstorms because of the intertwining creepers that connect several trees together. In addition, the creepers also compete with saplings of native plants for space. Hence, there is an urgent need to manage these exotic species before they penetrate further into the rainforest.
Outreach One of the ways to minimise the release of non-native is through public education. Members of the public can increase their knowledge on the potential impacts of non-native species on our local biological diversity and ecosystems by obtaining information through talks, brochures, internet and books.
Examples of Invasive Species
http://www.nparks.gov.sg/cms/docs/redbook/List-of-alien-species-in-Singapore-2009May.pdf
Strangling Fig
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