Native animals and plant species are adapted to our climate and conditions. They support each other providing essential food and shelter. When an introduced species occurs the whole ecosystem can be affected. This has happened to many waterways that have become dominated by willows. Below are some of the reasons why willows should be removed from local waterways.
Willows (compared to native species) are dense and do not allow understorey such as shrubs and native grasses to grow underneath. Understorey provides habitat and bank stability.
Willows drop their leaves all at once (i.e. one day the creek is in full shade and the next in full sun). Native animals and riparian plants like dappled shade and constant litter fall (food source and shelter) provided by native vegetation. Animals that hide in the shade become exposed to predators during willow leaf drop.
When willows drop their leaves all at once, a large amount of organic matter ends up in the stream. This can kill sensitive aquatic life and favour more tolerant species of animals and plants such as weeds and algae.
Willow-lined streams may support less than half the numbers of aquatic animals than those streams with native vegetation.
Willow roots undercut streamsides and change the course of flow. This can cause severe erosion and loss of vegetation in the surrounding area.
All willows that are removed should be replaced with more suitable indigenous trees, shrubs and grasses to ensure continued bank stability and stream health.
Willow removal programs should commence at the most upstream area and gradually work in a down-stream direction.
There are three methods for removing willows: organic, poisoning and physical.
Any large-scale removal and replacement program should be carefully planned with advice from staff at your local Catchment Management Authority or Department. Officers can assist in planning and advising on removal and replacement suitable for your property.
When lopping/pruning willows, it is essential that the branches are removed from the site so they do not regenerate in that area or further downstream. Stack and burn as soon as possible. Consider fire restrictions.
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