Wilding conifers can have significant impacts on native ecosystems, by shading out low-stature native plants. Where there is thick wilding conifer growth, this can lead to local extinction of native plant communities, the drying of wetlands and riparian areas, and resulting impacts on native fauna through the loss of habitat. Soil and soil fauna are also altered when wilding conifers replace native ecosystems.

Otago’s iconic landscape is vulnerable to the invasion of wilding conifers. If not controlled, they would significantly change the landscape and impact on our recreational, hydrological and conservation values. Particularly at risk is our high country and tussock grasslands. The growing problem has been recognised for some years and as a result, the Whakatipu Wilding Conifer Control Group and the Central Otago Wilding Control Group established themselves solely to fight wilding conifers.

It is estimated that wilding conifers are spreading at around 5% annually. Failure to control their spread at an early stage can quickly lead to increasing numbers of trees taking hold, and the costs of control escalating exponentially.

Wilding conifers (also known as wilding pines) are introduced conifer trees which have self-seeded and are growing where they are not wanted — they are the wrong tree in the wrong place.

Unlike commercial forests, wilding conifers are weeds and pose a serious and increasing pest issue in New Zealand which, if left uncontrolled, threaten to permanently alter our ecosystems, landscapes, and farms, and impact on our economy.

Managing wilding conifers is an issue that can only be addressed through landowners, community groups, industry, researchers, and local and central government working together. To achieve the vision of the right tree in the right place, there is a role for all New Zealanders to be aware of this expanding issue, and support taking action.

Seeds from inappropriately located plantings or from existing wildings can be blown many kilometres by wind, and spread into areas such as farmland, our high country and public conservation land. If not removed, seedlings can quickly grow into dense, impenetrable wilding conifer forests that out-compete native plants and animals, reduce water yield, limit productive land use, and severely alter natural landscapes. Wilding conifers may also increase the risk of wildfires and harbour diseases.

Wilding conifers are any introduced conifer tree, including (but not limited to) any of the species listed in Table 3, established by natural means. This doesn’t apply to conifers within a forest plantation that don’t create any greater risk of wilding conifer spread to neighbouring or nearby land than the forest plantation that it is a part of. For the purposes of this definition, a forest plantation is an area of 1ha or more of predominantly planted trees. This excludes planted conifers of less than 1ha, such as windbreaks and shelterbelts existing before March 2019.

Most wilding conifer species do not pose a significant threat to established native forests, however some species are adapting to new areas. Douglas fir in particular has a higher shade tolerance than other introduced conifer species and can consequently spread into shrublands, regenerating native forest and mature forest where there are canopy gaps and a relatively sparse understory.

Contorta (lodgepole) pine, Corsican pine, Scots pine, dwarf mountain pine, mountain pine and larch have very limited commercial value and are also highly invasive. Contorta (lodgepole) pine has been declared an unwanted organism under the Biosecurity Act 1993 since 2001, which means it cannot be bred, propagated, distributed or sold.

Contorta in particular, is an unwanted organism and is the most invasive introduced conifer species.

Over the life of the pest plan (10 years) the goal is to ensure that the spread of wilding conifers don't cause unreasonable costs to the occupiers of neighbouring properties where control operations have taken place, or where the neighbouring occupier is undertaking active wilding conifer management.

Below are the rules for wilding conifers in our pest plan, these can be complex so if you want to someone in our biosecurity team about these rules call ORC on 0800 474 082 or email biosecurity@orc.govt.nz.

Contorta shelter belts and other conifer shelter belts are often used to provide shelter for stock. It can be difficult to successfully control or manage the spread of wilding conifers over the long-term if the existing planted seed sources are not removed or appropriately managed and contained. The pest plan does not require you to remove existing shelter belts and other existing planted conifers less than 1ha. However, ORC’s Biosecurity Strategy sets out transition arrangements for their long-term removal, starting with the removal of Contorta shelter belts.

Otago is divided into 17 management units (geographical areas) for the purposes of controlling wilding conifers, with funding allocated to the management units where wildings are most prone to spreading. Control work in each management unit is undertaken through a collaborative partnership between the Otago Regional Council, Department of Conservation, Whakatipu Wilding Conifer Control Group (WCG) and Central Otago Wilding Conifer Control Group (CWG), with project managers overseeing landowner consultation, funding agreements and the contracting workforce delivering the ground or aerial operations. Landowners are eligible, on a priority basis, to be included in the Programme where management units are funded.

In 2016 the National Wilding Conifer Control Programme was established to ensure a collaborative, coordinated and effective approach to national wilding management. The delivery of the programme is led by Biosecurity New Zealand in partnership with regional councils and unitary authorities who coordinate the activities regionally and support a wide range of stakeholder groups and community groups. The Programme is informed by the New Zealand Wilding Conifer Management Strategy 2015-2030 and is supported by central government funding.

Wilding Pines

The graph below shows the estimated increase across Otago in hectares infested by wilding conifers over the next 20 years if the present management regime continues.

Preventing the spread of wilding conifers is one of the most important actions landowners can take to protect our region’s unique landscapes, primary industry, tourism, and the economy from the impact of wilding conifers.

If you're a landowner and want to find out more about control work in your area or funding opportunities which may help with your wilding conifer problem, please get in touch with our Biosecurity Team by emailing biosecurity@orc.govt.nz or calling 0800 474 082, or the community wilding conifer control group nearest you.

The western, central and northern areas of the region have various levels of wilding conifer invasion. Many affected areas contain scattered trees, but heavily infested areas exist in western inland locations that are lightly vegetated and lightly grazed. The infestation is somewhat less in the middle areas and increases slightly in the north-east.

Wilding conifers are a significant issue in the Queenstown Lakes district, where dense infestations are associated with historical plantings around settlements, eroding slopes and recreation areas, as well as commercial plantations and woodlots.