Integrated Catchment Management

Rider on using root results

This trial was carried out in Gisborne in the North Island. At the time the trial commenced, advice was sought from plant ecologists in the North Island on appropriate species to study and the work was not part of the Motueka ICM research programme.

Shannel Courtney from DOC has kindly highlighted that not all the trialled plants we studied may be suitable for use in the Motueka area - his comments are below:

"I noted that there were a few species studied that, while suitable for Gisborne, were not in fact native to the Motueka catchment, namely: Hoheria populnea (native to NI only) Sophora tetrptera (NI only) and Knightia excelsa (NI and Sounds). Tasman District readers, who are looking for appropriate native plants to restore riparian zones in the Motueka catchment, need to be aware that these three species are not appropriate for their area.

In fact, the hoheria acts very weedily where it is cultivated and actually excludes native plants. Thorps Bush in Motueka township is a great example of this. There is also the problem of hybridisation of NI kowhai with the native S. microphylla. I am in the process of producing various native species lists for habitat restoration throughout the Tasman and Golden Bays partly funded by TDC. There are currently 24 lists for the various ecosystems including the "Motueka-Riwaka Plains and Valleys Ecosystem" which is relevant for riparian restoration of this area. I make a point of promoting ecosourcing and only using species which I know are native to the ecosystem so that there is ecological integrity to any restoration project. Copies of this list are free from TDC."

Given these comments it is probably advisable, no matter where you are in New Zealand, that you check with your local DOC office, Regional Council or city council or seek assistance from agencies such as the New Zealand Ecological Restoration Network.

Nevertheless, it is important to realise that data on the below-ground characteristics of our native plants is rare and very hard to come by!

Final note: our purpose in doing this research is to gather data on the differences between species in terms of their soil stabilising functions. It is not possible to study every native plant and the plants selected have been those commonly used in restoration/revegetation efforts. Any recommendations made on choosing a particular species is based on its performance from our trial and it may be possible to get better or poorer performance in a different locality as many factors contribute to growth of above and below-ground parts of a plant.