Wetland restoration 2012 - 2013

From January to March 2012, we had embarked on a series of working bees dead-heading and pulling out nut grass, umbrella sedge, beggars ticks and other weeds threatening the native grasses, ferns and shrubs. The aim here was to release the 1250 grasses and other natives we planted last year.

In February, we met on site with Paul Duffy the new Auckland Council Parks Department volunteer and biosecurity coordinator. Paul has great experience in wetland restoration and has given some valuable advice on how to manage the carex ecosystem alongside the raupo which is spreading rapidly since the shade provided by the crack willows was removed.

Following his advice we have embarked on a programme of planting shade trees along the border this winter to control the spread of the raupo and retain the carex diversity. We met on site in early March to identify the issues and to plan the species, number and size of the trees to plant.

In mid 2012, we planted over 1000 manuka and other plants across the wetland on either side of the Glade Place Bridge.

And in November we planted another big batch of manuka and other native plants below the bridge.

In 2013, the planting programme covers over 3000 plants in the upper and lower wetlands.

Another very important component of the Wetland Restoration, is the weed control in the LSB wetland. The major funding here comes from Auckland Council EIF (Enviornmental Improvement Fund) grants and also from volunteer working bees. We have been very grateful for working bees from the BNZ and ASB Banks.

The EIF funding allows us to employ EcoScience Limited who have been controlling crack willow, pampas grass, wattle, privet and many other invasive plants in the wetland since 2008. The difference is amazing. Steve of EcoScience uses a balloon wheeled Argo to drive over the raupo from which he can more easily identify and control the many seedlings re-emerging from the seedbank and spreading from neighbouring properties.

A major component of the wetland restoration has been working with local residents around the reserve to control pest plants on "both sides of the fence".

Here are some notes on the main weeds we hope to suppress by the planting programme:

Paul's advice has been invaluable in our approach to the wetland weed control. He notes that there are so many seeds of these invasive species in the ground that the best way to tackle the problem is to shade them out with suitable native species. He has also recommended that we use our limited physical resources and time more wisely by trampling on weeds to give the natives room to grow rather than the more exhausting approach of pulling or digging them out.

Exotic nut grasses and umbrella sedges are difficult to eradicate. A lot of the sedge is purple umbrella sedge which also leaves roots and nodes under the ground allowing it to regenerate. Purple umbrella sedge is a common weed around gardens and streets and seeds prolifically. It regrows from nodes under the ground which will regenerate ever after agrichemical control or manual pulling. (Note - the native umbrella sedge is present in LRB - but not be confused with the invasive varieties)

Beggars Ticks (Bidens frondosa - see http://ecan.govt.nz/publications/General/weed-of-the-month-beggars-ticks-001205.pdf)

grows to up to 2 metres tall and is a threat to wetlands and waterways. It grows quickly, pushing out existing native plant species and prevents new plants from establishing. It also produces barbed seeds which are easily transported on clothing and animals, assisting with distribution.