Land management methods
When weeds are present, they are part of a complex ecological system.
This system involves:
- useful plants
- native vegetation
- wild animals
- pest animals.
It also includes many other factors such as climate zone and landscape.
Managing so many factors can be very difficult and unpredictable.
Good land management techniques means understanding the ecological processes that affect weed growth and management and knowing how to use them to minimise their growth.
Unmanaged land can be affected by disturbances such as inappropriate clearing, overgrazing and uncontrolled fires. This can lead to weed takeover because the disturbances have left available space, sunlight and nutrients for the weeds to invade.
Removing stock from areas which have been treated for weeds is a common management technique used by land managers.
This can be done in short periods (pasture spelling), or it can be a reduction in stock numbers rather than complete removal.
Supplementary feeding will also reduce grazing pressure on the land and allow the re-establishment of desirable plants which will compete with the undesirable weeds.
Re-planting native vegetation or desirable pasture or crop species creates competition for the weeds that are present.
It is especially useful when weeds have been removed, as an established desirable plant will compete with the new weed seedlings as they emerge.
Fire as a management technique is more effective when it is used with other methods.
Deliberate controlled burning can be used to kill and remove some weeds. Either burning or preventing fire can manipulate the conditions to make them more suitable for the desirable species, allowing them to compete more effectively with the weed species.
The choice of whether to burn depends on lots of different factors.
Different fuel loads will create different fires that can either wipe out and destroy weeds, or in some cases they can scarify seed and induce weed seed germination.
Generally following an initial burn, fire should be excluded to give desirable plants and optimal conditions to establish and compete with any emerging weed seedlings.
Unmanaged fires can exacerbate weed establishment by burning hot and fast.
These fires cause minimal damage to the soil-stored weed seed bank, but can significantly damage native vegetation, which creates a perfect environment for post-fire weed regeneration.