Wilding conifers are an invasive pest tree affecting landscapes and pastoral productivity across New Zealand. They are advancing exponentially across the country - establishing dense stands around some of our tourist destinations, on farmland and threatening our economy and environment on a number of levels.

Wilding conifers suffocate native vegetation, dry up precious, biologically diverse wetlands, blanket cover productive pastoral land, dramatically increase the risk of uncontrollable wild fires and permanently alter unique and recognisable landscapes.

Hawke's Bay is the worst affected North Island region. Recent figures estimate nearly 500,000ha of wilding conifers across the North Island, nearly 200,000ha of which are located in the Hawke's Bay region and they have a high risk of spreading.

While the issue is not yet as devastatingly serious as in Marlborough, Canterbury, Southland and Otago, lessons can be learned before the situation worsens.

Advertisement

The spread of wilding conifers is altering habitats for New Zealand's unique fauna, including sweeping tussock lands, alpine shrub lands, braided river beds, and posing a risk to the precious birds and animals that rely on these ecosystems.

Significant infestations of wilding conifers have taken hold at Waiouru and also at Tongariro - New Zealand's oldest national park with Unesco World Heritage Site status. Both sites have an extreme risk of spreading.

Elsewhere throughout the region there are pockets of infestation where the risk of spreading is ranked from high to very high. Wilding conifers are even causing issues for the NZ Army. At the military training grounds at Waiouru they now have a management programme in place with the Department of Conservation.

There is support from the Government to address this problem, and a national strategy is in place. But we also need better awareness about the scale of this problem. It can take a while for people to become aware of these pest weeds because where they are spreading is not always visible.

Those who do know about wildings might think it's a South Island problem but make no mistake, this is actually a national issue. While the problem is currently most acute in the south, wildings are starting to wreak their havoc in almost every part of New Zealand. They have been branded the number one pest in some regions.

We have reached tipping point for the control of wildings. If we cannot mount a co-ordinated national control approach now, involving central and local government, industry sectors, communities and individual landowners, there will be devastating long-term impacts for New Zealand's environment and economy.

The potential negative impact of wildings on our economy is estimated at $1.2 billion over 20 years with the figure increasing exponentially after that.

If we don't act now, wilding conifers will get away on us so fast it will become uneconomic to attempt to begin and we will have to resign ourselves to widespread landscape and land-use changes.

Advertisement

They grow in dense stands and cannot be managed as a plantation so have no economic value for wood. Their effect on one of New Zealand's most valuable commodities - water - is significant and this is already a major issue in some drier catchments in Canterbury and Central Otago.

They also exacerbate drought and bushfire risks and their impact on biodiversity can be extreme. Fallen needles form dense carpets taking a heavy toll on native flora and fauna and can affect freshwater habitats.

Wilding conifers are a threat to some of our most iconic landscapes - and therefore our tourism industry. These potentially include the Remarkables, Tongariro, the Mackenzie Basin, views of Aoraki Mt Cook, Lake Pukaki and the Marlborough Sounds, the Tasman/Nelson area, the Ruahine Ranges and the rare geothermal ecosystems of Rotorua.

I'm told fire services are concerned about the increased risk of bush fires caused by dense stands of wilding conifers - for instance in Queenstown.

Wilding conifers now cover around 1.8 million ha, nearly 6 per cent of New Zealand's land area.

It is estimated that, without immediate increased effort, by 2035 they will have invaded 20 per cent of New Zealand's land area and, within 50-100 years, 40 per cent.

Advertisement

In some places, the landscapes we treasure will be forever changed - covered in wilding conifers.

There are many localised initiatives to halt the march of wilding conifers, with investment by landowners, councils, community organisations and other agencies, and spending of $6.7 million by central and local government last year alone.

Yet they are still spreading at a rate of 90,000 hectares per year.

LGNZ hopes that through approaching this threat in a co-ordinated way we can make progress and get the traction needed to stop and reverse the spread of wilding species.

- Stephen Woodhead is chairman of the Otago Regional Council and Local Government New Zealand's Regional Sector
- Views expressed here are the writer's opinion and not the newspaper's. Email: editor@hbtoday.co.nz