Caring for Country : Weed Management : Top End Invaders

Home Page : Search : Site Map : Permits
Introduction Connection to Land Climate & Landscape Sea Management Land Management Feral Animal Management

Land Management

Caring for Country Unit Key Issues Fire Management
Weed Management

Weed Management

Top End Invaders Management

Top End Invaders

The Top Invaders

Group of people looking at Needlebush infestation
Needlebush infestation

Weeds are a major threat to the cultural and environmental values of traditional lands.

In the Top End, some plants are considered weeds by all land users (eg mimosa and salvinia), while other plants (eg introduced pasture grasses) are considered weeds by some land users (eg tourism operators, conservationists, anglers) but not by others (eg pastoralists).

Since the European settlement of Australia, exotic weeds have naturalised (developed self-sustaining populations) in Australia at alarming rates.

Weeds are spreading faster than they can be controlled and plant introductions to Australia are likely to occur with increasing frequency.

Problems caused by weeds include:

	competition for natural resources with other plants;
	alterations to soil structures, water movement and nutrient content of soil;



	effects to fire regimes and effects on the abundance of Indigenous fauna.

For Aboriginal people, weed infestations can reduce the amount of food available (both animal and plant) as well as restricting access to sacred sites.

Activities which have been found to exacerbate the weed problem include:

	land degradation from overgrazing and land clearance;
	increases in all types of vehicle movement eg mining exploration, recreational and tourist four wheel drives, military vehicles, cattle trains etc;



	increased population pressure causing changes to the environment eg disturbance, urbanisation etc;


	and pollution through unsustainable land management practices eg increased levels in nutrients which favour some weeds.

The Top Invaders

There are a number of weed species currently threatening Top End wetlands. The three most invasive species are:

Man at Mimosa pigra infestation
Mimosa pigra infestation

	the spiny central American shrub Mimosa pigra (mimosa)
	the free-floating South American aquatic fern Salvinia molesta (salvinia)



	and the South-American pasture grass Urochloa mutica (para grass).

In savanna woodlands, the major invasive weeds are tall, vigorous, perennial grasses such as Pennisetum polystachion (mission grass) and Andropogon gayanus (gamba grass).

These introduced grasses alter fire regimes by increasing the fuel load and therefore the number of hot, late dry season fires. Over time, the number of trees are reduced resulting in a change from woodland into grassland.

Home Page : Search : Site Map : Permits

An Overvie w : About the NLC : Jobs : Media/Publications
Caring for Country : Land & Sea Rights : Visiting Aboriginal Land
Doing Business on Aboriginal Land : Contacts : Photo Gallery

CLICK HERE to increase text size