NZ’s super-sized weed problem

Wednesday 21 Nov 2018

A new report shows rural landowners are finally waking up to a weed which covers 1.8 million hectares of the country. Their chainsaws are out, but they’re also supportive of “novel approaches” to management.

The invader is not gorse, blackberry or Scottish broom. It’s wilding pines spread by seeds from plantation forests and shelter belts.

Unlike their well-groomed plantation parents which contribute $5 billion a year to GDP, wilding pines are worthless with harvest often costing more than the wood is worth.

There are 100,000 more hectares of wilding pines than there are of plantation pines and the wind-blown seeds are populating an additional 90,000 hectares a year. Without intervention, wilding pines could cover 20 percent of New Zealand by 2035.

For farmers, wilding pines encroach on grazing land and suck water from pasture. For native flora and fauna, wildings are an invading pest, offering little in the way of food for birds and insects, and dropping an acidic carpet of pine needles which native plants can’t regenerate through.

More than $11 million a year is spent on eradication by land managers, government agencies and community trusts around the country.

The report from Landcare Research, which is based on survey results, shows a shift in awareness and attitude from landowners as well as support for the breeding of sterile pines.

In the survey report Landcare Research economist Pike Brown says: “The results clearly show that wilding conifers are perceived to be a serious threat and that individual land owners are a key part of a national strategy for managing wilding conifers across New Zealand.”

The report also shows just 2 percent of those surveyed are involved in a national wilding control programme and 54 percent don’t even know it exists. Most landowners are going it alone and removing wilding pines themselves.

A growing awareness - In 2015 just 25 percent of landowners were aware of wilding pines in their region, which has now increased to 60 percent. Attitudes to wildings have changed too. The 2015 survey found 22 percent of landowners surveyed thought wildings were more beneficial than harmful, now just 7 percent think they have any benefit.

South Island respondents were the most aware of the issue. Federated Farmers North Otago president Simon Williamson said wilding pines were the biggest issue high country faces.

“Rabbits we’ve got on top of since the diseases have come, they were decimating the high country, but wilding pines are the biggest single threat to biodiversity and the outlook of the high country. We’ll end up like Canada if nothing is done while we’ve got the chance.”

Williamson also pointed out another impact. Left unchecked wildings could steal the country’s electricity.

“If they [wilding seedlings] go into trees, in another 10 or 15 years the water loss going down the hydro rivers is equivalent to 53 cumecs, which is a massive cost to the generation industry and New Zealand. It’s probably a quarter of the flow of the Waitaki river.”

The Waitaki hydro station generates enough electricity each year for about 51,000 average New Zealand homes.

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Source: Newsroom

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