What is a weed?
- A plant out of place (environmental weed that may be either exotic or native)
- A pest plant
- A plant where local natural control methods have not developed
How are weeds spread in the catchment?
- Animal fodder
- Ornamental gardens
- Ornamental parks and forestry planting
- Inappropriate disposal of garden waste
- Clearing of land for farming activity
- Plants used to prevent erosion or used as wind breaks etc
- Dispersal of seeds by means of – wind, water, birds, animals, humans, machinery
- Spread underground- new shoots, bulbs, tubers, rhizomes
- Self pollination
Weeds are extremely opportunistic. Disturbances to natural habitats by human activities such as clearing for farming, animal grazing, forestry, urbanisation and introduction of feral animals such as hares result in rapid colonisation of weeds. Weeds thrive for example where fertilisers, dumping of garden refuse, organic wastes, etc are washed onto bushland due to the extra nutrients they contribute to the soil.
Effects of weeds on the catchment
- Reduce the survival of native plants and animals
- Choke waterways such as creeks, wetlands and flood plains
- Degrade water quality
- Compete with native vegetation for sunlight, space and nutrients
- Decrease biodiversity
- Decrease food, shelter and natural habitat for native fauna