Waging war on Russell lupin

A collective volunteer effort saw 78 hectares of Arthur’s Pass covered on a mission to cull the harmful purple pest plant, Russell lupin.

Environment Canterbury Community Partnerships Coordinator Alison Bower and Councillor Cynthia Roberts were among volunteers who ventured out to Arthur’s Pass recently as part of the ‘Let’s Lose the Lupins’ working bees.

‘Let’s Lose the Lupins’ is an annual event conceived by Colleen Philip of ECO Canterbury in support of Arthur’s Pass Wildlife Trust (APWT) with the aim of bringing together as many groups as possible to remove the plant, the presence of which makes the environment uninhabitable for many native plants.

Russell lupin in the foreground, with its distinctive purple flowers

Many volunteers, including from ECO Canterbury, ECan, North Canterbury Forest & Bird, Conservation Volunteers NZ, and the Department of Conservation (DOC), volunteered their time which made a huge difference to the area. By the end of the season the APWT and other volunteers will have covered a total of 250 hectares.

Alison said, “Community based organisations like APWT, and the dedication of the volunteers that coordinate them, is an incredibly generous contribution to the war on weeds in our region. Without them, our iconic landscapes would look very different.”

APWT’s Graeme Kates has been working almost single-handedly on the weeds in the Waimakariri headwaters. He’s particularly concerned about the lupin spread from the big infestation on Turkey Flat, which is the seed source from downstream areas. Lupins have been sown in the area to attract tourists who like to take photographs of the weed’s distinctive purple flowers, which poses a challenge to those who are trying to eradicate it.

Alison and Graeme at the DOC office in Arthur’s Pass

Pest management in action

The manual method of hand-pulling lupins is effective as the remains of the plant rot quickly, allowing the land to recover quicker. However, due to the scale of the problem, chemical is being used to reduce further spread. The best time to spray lupins is while they are flowering, giving a window of about 2-4 weeks. The timing of the working bee meant the volunteers caught the lupins in their early stage of flowering, which can make spraying difficult, but is better than the flowers already being developed and seeding. You can also fool the plant into thinking it's already seeded by stripping the flowers off it.

Straight seed pods (3-5cm) containing mottled dark brown seeds are covered in dense, soft hairs

Lupin seed only remains viable in the Arthur’s Pass area for 4-5 years due to the harsh conditions, whereas in other areas the seed can remain viable for as many as 15 years. With a sustained effort, helped greatly by the annual ‘Let’s Lose the Lupins’ working bees, lupins can be eradicated from Arthur’s Pass.

Find out more about Wild Russell Lupin (Lupinus polyphyllus)

Volunteers in action at the ‘Let’s Lose the Lupins’ working bees

Protecting our braided rivers

Russell lupin also seriously impacts our braided river birds, such as the endangered ngutu-parore/wrybill and tarapirohe/black-fronted tern, by taking over their open shingle breeding space and allowing predators hidden by the weeds to ambush the females and their nests.

The weeds also damage a braided river’s ability to move and behave as it should. For example, during the recent floods in Arthur’s Pass, some 150-year-old native plants were taken out by the river being forced to flow away from areas that have been unnaturally stabilised by weeds.

One such plant is the indigenous matagouri which is very slow-growing, and some plants on undisturbed river terraces can be over 100 years old. Matagouri thorns were used by early Māori as tattooing needles when no other materials were available. It’s flowers also make very good honey.

Cynthia and Marion of APWT taking the opportunity to attack some wildrose which, along with the lupin, is infesting floodplains that support matagouri

Cynthia said, “ECan continues to get many accolades for including lupins in the Canterbury Pest Management Plan – giving more credence to work such as this in the headwaters of one of our iconic braided rivers.”

If you’re interested in volunteering in 2019, the APWT will be running the ‘Let’s Lose the Lupins’ working bees again from 9-12 November. Follow APWT on Facebook to keep up with their events.

Arthur’s Pass National Park

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