This document discusses invasive species and provides criteria for identifying invasive plants. It notes that while not all non-native plants are invasive, invasive species are defined as those that colonize natural habitats, have negative impacts on ecosystems and the environment, and continue to increase their population and distribution. Examples are given of specific invasive plant species like Clidemia hirta, Piper aduncum, and Mimosa pigra that were intentionally or accidentally introduced from other regions and threaten native species through competition for resources and alteration of habitats. Physical and chemical control methods are mentioned for dealing with invasive plants.

1. Invasive Species Primer

2.  A non-native plant occurs outside its normal
range
 Not all non-native plants have negative
effect, some are harmless or even beneficial

3.  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

4. Occurrence of Clidemia hirta, a shrub originated from
Tropical America

5.  Intentional
◦ Brought to a new region for ornamental, medicine,
dye, food and erosion control amongst others

6.  Accidental
◦ Plant propagules adhere to human, transport or
animals, transported in ship ballast, dispersed via
livestock, mixed with crop seeds and spread from
gardens

7.  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

8.  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

9.  Disrupt ecosystem process encompassing
biological interaction and abiotic characters
◦ Pollination
◦ Frugivory
◦ Succession
◦ Fire regimes

10.  Clidemia hirta
◦ Originated from
Tropical America
◦ Threatens endemic
island species e.g.
Hawaii and Fiji
◦ Potentially alter forest
regeneration

11.  Piper aduncum
◦ Originated from South
and Central America
◦ Dense colony excludes
native flora
◦ Habitat for agricultural
crops pathogens

12.  Mimosa pigra
◦ Originated from
Central America
◦ Block irrigation and
reduce grazing land
◦ Disable accessibility
to wetland

13.  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