Vascular – Exotic
Trees & Shrubs - Gymnosperms
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
Terrestrial. A plant of montane and subalpine habitats. The plant grows in sites with low fertility. A plant of tussocklands. Areas at risk from invasion by the plant are indigenous and introduced scrub, tussock grassland at medium to high altitude, pasture and open forest.
Large shrub or small to medium-sized tree (sometimes large in cultivation); habit erect or spreading. Branches straight or somewhat twisted. Bark reddish-brown, grey on surface, fissured and forming small plates. Shoots brown, glabrous. Buds cylindric or cylindric-ovoid, purplish-brown, strongly resinous; scales tightly appressed. Leaves 2 per fascicle, 3.5~6.5cm x .8~1.5mm, sometimes twisted, usu. pointed forward, generally yellowish-green; resin canals median; sheath very short after first year. Male strobili 5~15mm long, cylindric or broadly cylindric. Conelets sessile; scales aristate. Mature cones long-persistent, often not opening until long after maturity, subsessile, usu. directed downwards or backwards, 3~6 x 2~3.5cm, generally broad-ovoid; base asymmetric; apophyses shining yellowish-brown or brown before maturity, convex; umbo with short, slender, occasionally deciduous prickle. Seed wing asymmetric but almost oblong, approx. 1cm long. (-Webb et. al., 1988)
The combination of short needles in pairs, and small cones with a spikes on the cone scales distinguishes Pinus contorta from other naturalised Pinus species in NZ.
Perennial. 15 000 viable seeds/year are produced by a 12 year old, 5m tree. Germination of seeds after 4 years (in dry storage at 4 degrees celsius will last 10-20 years). Prolific quantities of viable seed is produced. Trees are precocious and recorded as coning at 3 years old. Seed is dispersed by wind that are dispersed over many kilometres.
Rocky mountains, N.W. America
Reason for introduction
Agricultural (to stabilise high country pasture which were eroding due to excessive burning and high stocking rates and impacts of rabbits).
The plant is tolerant to drought and frost (once established) and is slightly tolerant to poor drainage. The plant will not establish in dense forest but is tolerant to partial shade. Regrowth occurs after physical damage and grazing unless all foliage is removed. Trees larger than 2m can withstand fire, a hot fire will kill seed.
Environmental pest species
Pinus contorta is the most vigorous spreading conifer species in New Zealand and threatens landscape values, biodiversity and farming productivity by out-competing pasture areas and forming dense stands, even above the natural tree-line. For these reasons, it is the most targeted “pest” conifer species in New Zealand, as shown in Regional Pest Management Strategies. It is banned from sale, propagation and distribution. See also the National Wilding Conifer Control Strategy produced by the Ministry of Primary Industries.