Non-Native Invasive Plants

Invasive Species Primer

A non-native plant occurs outside its

normal range

Not all non-native plants have negative

effect, some are harmless or even beneficial

Definition

Criteria of invasive plants

◦ Habitat: Colonize natural and semi-natural

habitat

◦ Effect: Negative impacts on the ecosystem,

biodiversity, human health and economy

◦ Population: Expanding in distribution and

abundance

Occurrence of Clidemia hirta, a shrub originated from Tropical America

Intentional

◦ Brought to a new region for ornamental,

medicine, dye, food and erosion control amongst

others

Dispersion

Accidental

◦ Plant propagules adhere to human, transport or

animals, transported in ship ballast, dispersed via

livestock, mixed with crop seeds and spread from

gardens

Negative effects on biodiversity

◦ Compete with native plants for resources

◦ Alter habitat structure and local species richness

◦ Resulting in reduction in biodiversity and increase

in dominance

Impacts

Consume limited resources otherwise

available for native species

◦ Take up ground water and nutrient

◦ Cover large amount of space resulting in

exclusion of local species

Disrupt ecosystem process encompassing

biological interaction and abiotic characters

◦ Pollination

◦ Frugivory

◦ Succession

◦ Fire regimes

Clidemia hirta

◦ Originated from

Tropical America

◦ Threatens endemic

island species e.g.

Hawaii and Fiji

◦ Potentially alter forest

regeneration

Examples

Piper aduncum

◦ Originated from South

and Central America

◦ Dense colony

excludes native flora

◦ Habitat for agricultural

crops pathogens

Mimosa pigra

◦ Originated from

Central America

◦ Block irrigation and

reduce grazing land

◦ Disable accessibility

to wetland

Physical

◦ Adapted the method in agriculture such as

mowing, pulling, cutting and tilling

Chemical

◦ Use herbicide to kill invasive plant by decreasing

the plant ability to grow and survive

Control