Regional Surveillance Pest
Pinus contorta is a native of western North America, where it can be found from Mexico to Alaska and from sea-level to nearly 3,000 metres in the Rockies. It was introduced to New Zealand in the 1880s and planted on sites that were too frosty for the more common production species. It was later used for afforestation of severely eroding sites in mountain lands. It is slower-growing than the more common plantation-grown conifers, approaching 15–25 metres by age 30, and can be distinguished by its short paired needles (6–9 centimetres in length), its small prickly cones (4–6 centimetres) and the irregular plates formed by the bark of mature trees.
Reasons for the Strategy
Pinus contorta is capable of producing viable seed from the age of four years. In exposed situations, this seed is capable of being carried moderate distances by gale-force winds. It rapidly colonises alpine tussock grasslands and shrublands, and is capable of growing above the native bushline up to 2,000 metres, but is light-demanding and will not establish under a closed canopy of shrubs or trees. In open shrubland, it is capable of outgrowing most native species and can become the dominant species. In treeless areas, it can have a dramatic impact on landscape values and the formation of dense stands can restrict access. Within the Tasman-Nelson region, the primary area of concern is around Inwood’s Lookout, where stands of Pinus contorta have been distributing seed into the adjoining areas of Mt Richmond Forest Park. It is classified as an unwanted organism.
Pinus contorta is assessed at “2” on the infestation curve.
To gather information on the distribution, density and impact of Pinus contorta in the Tasman-Nelson region during the term of the Strategy.
The inclusion of Pinus contorta in the Strategy will ensure the Management Agency is actively involved in surveillance and monitoring, as well as encouraging forest owners to voluntarily control infestations of Pinus contorta. The alternative option of “do nothing” will allow seed from existing stands of Pinus contorta to continue to spread. The principal alternative measure is to adopt a greater level of regional intervention, such as requiring all occupiers to control infestations of the plant. However, this option is considered inappropriate, given the very high costs of clearing the extensive areas involved; however, the Management Agency would encourage this to happen on a voluntary basis.
Biosecurity Act Requirement
No person shall knowingly sell, propagate, breed, release, or commercially display Pinus contorta, under Sections 52 and 53 of the Act.