In the South Island, they threaten 210,000 hectares of public land administered by the Department of Conservation. They are also present on privately owned land and other public land such as roadsides. The wilding conifers are considered to be a threat to biodiversity, farm productivity and to landscape values. Since they often invade tussock grasslands – which are characterised by low-lying vegetation that is considered to be a natural environment – the tall trees become a prominent and unwanted feature.
There are ten main species that have become wildings:
- Bishop pine (Pinus muricata)
- Corsican pine (Pinus nigra)
- Dwarf mountain pine (Pinus mugo)
- Lodgepole pine (Pinus contorta)
- Maritime pine (Pinus pinaster)
- Ponderosa pine (Pinus ponderosa)
- Radiata pine (Pinus radiata)
- Scots pine (Pinus sylvestris)
- Douglas fir (Pseudotsuga species)
- European larch (Larix decidua)
The various species dominate in different areas of New Zealand. Radiata pine (Pinus radiata) is used for 90% of the plantation forests in New Zealand and some of the wilding conifer is a result of these forests.
Without any control measures, wilding conifers will spread over an increasing area with economic and environmental consequences. As well as volunteers organised by environmental groups, regional councils and the Department of Conservation invest in wild conifer removal.
Mechanical removal by hand pulling seedlings, and the use of brush cutters and chainsaws are common control methods. Spray trials are also being carried out. In 2004 a spraying operation by the Department of Conservation at Mid Dome in the Southland Region caused spray drift onto surrounding areas including the towns of Athol and Kingston.
Wilding conifers by region
Pest management is administered by regional councils. There are sixteen different regions in New Zealand and wilding confers only occur in a few of these regions, predominately in the South Island. The Department of Conservation manages wilding conifers on public land under its jurisdiction.
In its 2005 Pest Management Strategy the Canterbury Regional Council (Ecan) has the objective of eradicating all self-sown wilding conifers in ecologically sensitive areas in its jurisdiction. To do this a range of measures are used, including carrying out wilding conifer control operations, encouraging reporting of the presence of wilding conifers, encouraging the removal of seed sources and advocating changes to the district plans of the territorial authorities to prevent or control the planting of inappropriate conifers.
Wilding conifers infest the Kaweka Forest Park.
Pinus contorta infests the south Marlborough area and is classed as a "Containment Control Pest", which are pests that are managed to prevent spreading to new areas. Other wilding species exist in Marlborough but Lodgepole Pine is the focus for pest management.
A major area of wilding conifer spread is in the Mid Dome Area in the Southland region. The Mid Dome Wilding Trees Charitable Trust was set up in 2006  and in 2008 the government allocated $54,000 from the Biodiversity Funds to control wildings on about 1,000 hectares (2,500 acres) in the area.
- Wilding conifers - New Zealand history and research background, a presentation by Nick Ledgard at the "Managing wilding conifers in New Zealand - present and future" workshop (2003)
- "Situation and outlook for New Zealand agriculture and forestry" (PDF). NZ Ministry of Agriculture and Forestry. 2007. Retrieved 2010-10-19.
- "The Project". South Island Wilding Conifer Management Group. Retrieved 2009-01-17.
- Wallace, Euan (2004-04-23). "A review of herbicide drift at Athol and surrounding area" (PDF). Agro-Research Enterprises. Retrieved 2009-04-18.
- Canterbury Regional Council (June 2005). Canterbury Regional Pest Management Strategy (2005) (PDF). Christchurch, New Zealand: Canterbury Regional Council. ISBN 1-86937-563-7. Retrieved 2008-09-06.
- "2007 Regional Pest Management Strategy". Marlborough District Council. 2007. Archived from the original on 6 December 2008. Retrieved 2009-01-17.
- "Pest Management Strategy for Otago" (PDF). Otago Regional Council. Archived from the original (PDF) on 22 May 2010. Retrieved 14 August 2010.
- Parker, David (16 August 2006). "Mid Dome Wilding Trees Charitable Trust – inaugural meeting". New Zealand Government. Retrieved 14 January 2011.
- "Mid Dome project receives biodiversity funding". New Zealand Government. 19 October 2008. Retrieved 14 January 2011.
- R.L. Hill, S.M. Zydenbos and C.M. Bezar, ed. (2004). Managing Wilding Conifers in New Zealand: Present and Future (PDF). NZPPS. ISBN 0-478-10842-7. (Individual chapters can be downloaded from the New Zealand Plant Protection Society)
- Ledgard, Nick; Langer, Lisa (1999). Wilding Prevention (PDF). Forest Research Institute. ISBN 0-477-02186-7.
- Harding, M. (May 1990), Wilding pines — a growing problem, Forest and Bird magazine, pp. 38–41
- Hansford, Dave (2 June 2010). "Wilding Pines". New Zealand Geographic (102).
- Froude, Victoria A (December 2011). Wilding conifers in New Zealand: Status report (PDF). Pacific Eco-Logic Ltd. ISBN 978-0-478-40010-6.
|Wikimedia Commons has media related to Wilding conifers in New Zealand.|
- Wilding pines at the Department of Conservation
- South Island Wilding Conifer Strategy (2001), Department of Conservation
- South Island Wilding Conifer Management Group
- Wilding Conifers in Canterbury at Environment Canterbury
- Wakatipu Wilding Conifer Strategy at the Queenstown Lakes District Council
- Waimakariri Ecological and Landscape Restoration Alliance
- Royal Horticultural Society Encyclopedia of Conifers