Surveying pest plants in the Residential Red Zone

If you think that it’s hard keeping on top of the weeds in your own backyard, imagine looking after nearly 600 hectares of former garden in the Christchurch Residential Red Zone. 

The Residential Red Zone (RRZ) in Christchurch has been uninhabitable since the earthquakes, and nature has slowly taken over the vast open space, with weeds growing through roads and the addition of plenty of bird life.

As it stands now, some of the land is under the responsibility of Land Information New Zealand (LINZ); and about one-third — riverbanks, roads, footpaths and parks — is owned by the City Council.

LINZ commissioned Boffa Miskell to conduct a pest plant audit of the RRZ in order to gain an understanding of the issues and to measure the success of management efforts. Ecologist Dr Jaz Morris and two LINZ staff undertook a four-day survey of the Avon River/Otakaro Residential Red Zone and the Port Hills Red Zone.

The survey focused on detecting and estimating the abundance of pest plants. The team walked 50 km in four days, logging pest plants along the way, in order to produce maps detailing any problem areas and species of concern.

The team reported “very few” pest plants in the flatlands and low numbers in the Port Hills, which reaffirmed that current control methods are working well.

Jaz says, "The quality of efforts in the RRZ was found to be such that a solitary gorse bush in Avonside received its own GPS point!"