One of the biggest challenges we face in revegetating our dunes is removing weeds before we begin planting. Historically the local native plants that were so beautifully adapted to our Cottesloe coast were not valued and “improvement” efforts on the dunes removed everything. Replanting with “foreign” species such as Victorian tea tree and marram grass was tried to stabilise the sand. Robust weeds from South Africa such as sea spinach or Tetragonia decumbens also took hold. These invasive species overwhelm any natural regeneration of local species and become an unattractive monoculture.
We hand weed as much as possible but some weeds, such as couch, are so tenacious that it is necessary to use herbicides before we can replant. Fortunately, this is usually only necessary in the first few years. This is a common problem amongst others involved in ecological restoration and the Invasive Species Council has recently released a report on the use of herbicides in managing environmental weeds. You can see the report here.
Cottesloe Coastcare also undertook a small trial to assess the effectiveness of different treatment on the weeds on our dunes. Results indicated that judicious use of herbicides does improve survival of native species in the dunes and that optimal timing and dosing reduce the overall demand for chemical use. You can read the details here.