Pest plant control

I used to do biosecurity animal programmes for another council, so I went from dealing with a handful of pest animals to dealing to hundreds, if not thousands, of plants.

We probably have four to five thousand plants that we call invasive, and another 20,000 that are introduced, naturalised. Every year there are probably two to three new naturalised species that will fall into the invasive bucket.

One of our big projects is the wilding conifer programme in central plateau, managing pine trees in an environment that is tussock. It should be tussock. The natural succession should not be pines, but tussock isn’t going to outgrow pines.

Geothermal areas are also a problem. Plants that seem to grow in geothermal areas are small. Invasive pests such as pampas and pines are huge, so they dominate the area because the natives can’t compete.

Then you get estuaries and dunes. They are also susceptible ecosystems. Grasses and other herbaceous plants like saltwater paspalum threaten those areas. They take over the landscape, so the habitat of oysters, birds and animal life gets destroyed.

We run a pest plant programme. We target highly invasive pest plants that are low in numbers to make sure they don’t establish in the Waikato. Old man’s beard, spindleberry, boneseed … We are setting up more local site-led programmes around wild ginger, climbing asparagus, woolly nightshade; working with community groups, DOC, landowners to protect particular ecosystems.

The council’s responsibility is for private land, so we work with landowners and link in where we can with the likes of DOC. Eighty per cent of what we do is about relationships. We want people to tell us when they see something out of place on their land. If a farmer says, heck, I’ve never seen that bush before, or that was one bush last year and now there are a thousand of them, that’s what we want to know.

Controlling pest plants is difficult. It is hard work. We are dealing with seed banks that have drifted across 100s of kilometres and seeds can lie dormant for 60 to 100 years. There’s also human assisted movement of pest plants, such as dumping garden waste in areas that is free of pest plants. The best way is to manage pest plants onsite. Don’t give it to someone else, don’t give them your monkey.

A lot of people are getting more interested in pest plants, however. They are doing all this great work in protecting birdlife and invertebrates and they think, hey, if we don’t start managing pest plants this species will have nowhere to live. There is a big value in habitat protection, if animals and plants don’t have habitats they don’t exist.