The Grange Small Blue Arrow Managing Small Blue Arrow Plants

Introduced-Plant Management

What Are Weeds?

There are many plants that are undesirable in the heathland of The Grange. These are usually referred to as weeds or weedy species. Many weeds have been introduced from other countries for agricultural or ornamental purposes. Others have been were accidentally introduced.

There are also some native species which have been brought to areas where they previously did not exist and become weeds. Sometimes these natives breed with indigenous species and produce hybrid plants.

Weed Management

A Vegetation Management Plan has been developed for The Grange. The reserve has been divided into 26 management zones. These zones aid the planning and implementation of vegetation management including weed removal, revegetation and control burns. 

The Vegetation Management Plan for The Grange identifies five different categories of weeds. These categories are based on the lifecycles and characteristic forms of the plants.  The methods of eradication of the weeds are based on these characteristics.

Weed Categories

Annual Grasses and Herbs
The annual grasses that are weeds in The Grange, to varying degrees, include Large Quaking Grass (Briza maxima), Annual Veldt Grass, (Ehrharta longiflora) and Common Mouse-ear Chickweed, (Cerastium glomeratum).
Perennial and Biennial Grasses, Herbs, and Succulents.
These are usually understorey plants. Panic Veldt Grass (Ehrharta erecta) is a serious perennial weed in The Grange and a main target of weed management.
Woody Weeds
These include bushes, shrubs and trees. In The Grange examples of woody weeds include the Coastal Tea-tree (Leptospemum laevigatum), and the Sallow Wattle (Acacia longifolia).
Climbers and Vines
These plants can smother native plants as they climb up Asparagus (Asparagus asparagoides) is a difficult weed that smothers native vegetation.
Geophytes
Geophytes that have been present in The Grange include Bulbil Watsonia, (Watsonia bulbilifera).

Weed Removal

There are four main types of weed removal techniques:

  1. Manual
  2. Chemical
  3. Seed-head Burning
  4. Mechanical
Their use depends on the type of weed and the area in which it is found.

Manual Weed Control

Manual weeding, where areas are weeded by hand, is generally used in sensitive areas of heathland. The Bradley Method is used in The Grange. This involves following three basic principles (Buchanan 1989):
  1. Work from areas that have high numbers of native plants towards the more weed infested areas.
  2. Try to disturb the native plants and soil as little as possible (so as to prevent more weed infestation).
  3. Let the rate of native regrowth determine the rate of weed removal.

The Bradley Method of weeding does not involve planting natives in the areas that have been weeded.  The native seeds and rootstock should recolonise without weed competition.

Chemical Weed Control

Herbicides are used in a number of situations. They are used to remove large areas of weeds where there is no danger to native plants, or when the weed growth is vigorous and needs quick attention. Herbicides are effective in removing woody weeds. Drilling into the tree and inserting the herbicide can be less damaging to the heathland plants and animals, than felling trees and removing the roots.

Seed-Head Burning

Seed head burning is a technique used to destroy the seed-heads and flowers of annual weeds such as Large Quaking Grass and Common Mouse-ear Chickweed.

A flamethrower tool is used to burn targeted weedy plants. This is carried out in The Grange from May to October. The aim is to destroy seeds before they are viable.

Mechanical Weed Removal

Mechanical weed removal involves the use of different machines. Slashers and mowers are used in firebreak areas to stop introduced grasses from setting seed and spreading into the heathland.

Chainsaws are sometimes used to remove large woody weeds.