Several of these plants, including willow,  broom, and Russell lupin, have invaded braided rivers, changing their natural dynamic nature destroying their specialised ecology and vital ecosystem functions, including helping to clean water from the high level of nitrates generates by dairy farms.

These weeds are:

• Easily established
• Become dense stands, shading out and displacing threatened plants and whole native plant communities such as the cushion forming ‘forget-me-not’ (Myosotis uniflora) and the rare dwarf woodrush (Luzula celata)
• Many fix nitrogen, which changes the chemistry of the soil, making it unsuitable for native plants
• Some suck up huge quantities of water like a sponge, lowering the river level and water table
• Entwined roots hold the gravel together, forming stable areas. The river erodes the edges, creating steep banks and restricting the water so that instead of braiding, it develops deep, fast-flowing channels unsuitable for wading birds to feed in
• Dense stands take over the open spaces where braided river birds like to nest. This is deeply concerning for rare and endangered birds that nest exclusively along braided rivers, particularly the wrybill, black-fronted tern and kakī/black stilt, which normally feeds in shallow river braids
• Provide cover for introduced predators to sneak up on nesting birds