Case Studies

Area of concern	Scale of effects	Process	Examples of outcomes for area of concern
Environmental	Population	Mortality	Phytopthora kills individuals within populations of rare species in Grampians, NSW.
		Recruitment	Dense infestations Mimosa pigra prevent the recruitment of native species.
		Change in resource availabiltiy	Indian miner displaces native birds that use tree branch hollow for nestin.
		Change in resource availabiltiy	Changes in seed abundance (a food resource for magpie geese) in floodplains grasslands due to invasion of pasture species para grass, in NT.
	Community	Vegetation structure	Change from woodland to open woodland due to gamba grass invasion of savannas in the NT.
		Vegetation structure	Invasion and removal of rainforest patches by Thunbergia vine in tropical Queensland.
		Species compostion	Big-headed ants displace native communities of ant species in the NT.
		Species compostion	Para grass, an invasive grass species, displaces native grasses on NT floodplains.
		Interactions among species	Para grass, an invasive grass species, displaces food resources for primary consumers (native rats) on NT floodplains, thus reducing the abundance of this important vertebrate prey species.
	Ecosystem	Fire regimes	Changes in fuels loads due to the invasion of savannas by Gamba grass, increases fire intensity in NT.
		Nutrient cycling	Nutrient cycling is altered in areas invaded by Buffel Grass.
		Hydrology	Melaleuca species, introduced from Australia, lower the water table in Florida Everglades, US.
Social & cultural	.	Life-stye changes	Impeded access for tourists to billabongs in Kakdau National Park, NT, due to invasion of the aquatic weed Salvinia molesta.
Social & cultural	.	Human health	Illness caused by people contacting plants of Parthenium weed, Parthenium hysterophorus , India
Economic	.	Control costs	Costs to community of the control of Fire ants.
		Production costs	Increased production costs in pastoral industry due to weed control, NT.
		Production costs	Increased operational costs in shipping industry due to outbreaks of invasive molluscs.
		Loss of income	Reduced capacity for cattle production due to competition with high numbers of feral goats in Mulga Lands of Queenssland.