Assessing biosecurity risk of 'living dinosaur'

A unique Gondwanaland plant, the Wollemi pine, was the focus for a recent Biosecurity New Zealand (BNZ) biosecurity risk assessment. Not only is the plant unique in many ways, but the project itself is the first by BNZ to use the new risk analysis procedures for plant material (see Biosecurity 64:24 December 2005)

Wollemia nobilis, more commonly referred to as Wollemi pine (Jones, Hill and Allen, 1995), is the plant equivalent of the New Zealand tuatara. Its closest relatives appear to be plants found in fossils over 100 million years old.

Despite its long history, it is the world's newest-known conifer, being discovered only in 1994 by a New South Wales National Parks and Wildlife Service officer, David Noble (Jones et al, 1995). There is only one species known in this new genus, the name of which reflects where it was first found, Wollemi National Park, and the person who first found it. In fact, Wollemia nobilis is a relict species, currently known to occur in only two sites about 1 km apart in Wollemi National Park. The park is on the Central Tablelands of New South Wales in south eastern Australia, 200 km northwest of Sydney. Fewer than 100 adult trees are known in the wild. There is believed to be no discernible genetic variation in the population, suggesting that it is entirely clonal (NPWS, 1998).

History and relatives

Wollemia nobilis is a member of the Araucariaceae family, which appears closest in taxonomic terms to the genus Agathis (including New Zealand kauri, Agathis australis), but it has many features in common with extinct Cretaceous and early Tertiary fossil groups and is probably more closely related to these. The only known living members of the Araucariaceae family are around 40 species within the Agathis and Araucaria. The most notable examples currently growing in New Zealand include the Norfolk pine, Araucaria heterophylla, and the Hoop pine, Araucaria cunninghamii. Only one species of Araucariaceae is considered native to New Zealand, Agathis australis or the kauri. While the common names of many members of the Araucariaceae family indicate that these trees are “pines”, they are not true pines such as radiata pine (Pinus radiata), which belong to another conifer family, the Pinaceae.

The Araucariaceae had a world-wide distribution in the Cretaceous. Fossil representation of the family is known from the Triassic period (c.200 million years BP). The distribution of the Araucariaceae contracted at the end of the Cretaceous (c.65 million years BP) when the family is believed to have become extinct in the northern hemisphere. The genera in the southern hemisphere have slowly declined in distribution and diversity since that time (Hill, 1995). It seems likely that the Wollemi pine was once present over an extensive area, with fossil remains found in Australia, New Zealand and Antarctica. It is also likely it was widely present over a vast time span from the Mesozoic era to the Tertiary period (250-1.6 million years ago).

An attractive tree

Wollemi pine is an erect conifer with attractive, unusual dark-green foliage and unusual bubbly bark (resembling bubbling chocolate). The tallest Wollemi pine in the wild is 40 metres high, with a trunk diameter of over 1 metre. The leaves on adult lateral shoots are one of the most distinctive features of the new discovery, being arranged in four ranks, with two ranks at about 150-175° and the other two ranks lying between the first two at about 50-90°.

The Wollemi pine has potential to grow in a wide range of locations, from outdoors in the full sun to well-lit indoor areas in air-conditioning, and in a wide range of climatic regions. The tree will survive a range of temperatures from -5°C to 45°C (23°F to 113°F) and it could even be hardier than this. Not only has it survived through ice ages and many millions of years, but Wollemi pine relatives such as the Monkey Puzzle (Araucaria araucana), Hoop and Bunya pines (Araucaria bidwillii) grow in climatic conditions ranging from freezing to very warm and humid. Wollemi pine can also be maintained in a container, which is great news for those who do not have the space to plant one in their garden.

In optimal conditions, the growth rate for the pine is about half a metre a year for young plants and up to a metre a year on more mature plants. The Wollemi pine responds well to fertiliser and can be pruned and shaped at any time of the year to become bushier. They are strong plants with flexible stems and leaves that are not easily damaged, so we also expect them to be wind tolerant and relatively salt tolerant, and could be planted by the ocean, just like other members of the family such as Norfolk pine.

But before New Zealanders can get the opportunity to grow this rare and attractive plant, the biosecurity risk it presents needs to be analysed. That process is now well under way.

Assessing the biosecurity risks

Being found on two sites in Australia, Wollemia nobilis is a 'new organism' in New Zealand under the Hazardous Substances and New Organisms Act 1996. ERMA New Zealand first approved an application to import Wollemia nobilis with controls in February 2002, later approving the import of Wollemia nobilis for full release (no controls) in September 2005.

Even after the ERMA approvals, the Wollemi pine nursery stock could not immediately be imported into New Zealand as it is considered a 'risk good' under New Zealand's Biosecurity Act 1993. This requires the development of an import health standard by BNZ. Assessing the biosecurity risks to New Zealand presented some unique problems, as Wollemi pine is new to science and there is a lack of published technical information about associated pests. In fact, only two potentially pathogenic organisms have been identified on Wollemi pine to date, a Botryosphaeria species and Phytophthora cinnamomi. The import risk analysis currently being completed to support the development of the import health standard has attempted to anticipate the types and nature of pests likely to be associated with Wollemi pine nursery stock by assessing the risks of pests associated with the whole Wollemi pine family, the Araucariaceae. This risk analysis is close to completion and will soon be made available for public consultation. Stakeholders will be informed as soon as consultation begins.

For ERMA approvals:

For more information about Wollemi pine:

References

  • Hill KD, 1995, The Wollemi Pine, watch out, look around you, The Gardens, 27: 8-9.
  • Jones WG, Hill KD & Allen JM, 1995, Wollemia nobilis, a new living Australian genus and species in the Araucariaceae, Telopea, 6: 173-176.
  • NPWS, 1998, Wollemi Pine Recovery Plan, NSW National Parks and Wildlife Service, Sydney. www.wollemipine.com/ (offsite link to www.wollemipine.com)

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Page last updated: 30 April 2008