Agathis australis
Past favourite plant finalist
Common names
kauri
Biostatus
Native
Category
Vascular
Structural class
Trees & Shrubs - Gymnosperms
Detailed description
Stout, monoecious forest tree 30–60 m tall, with trunk 3–4–(7) m diameter typically devoid of branches for majority of its height. Trees at ricker development stage have a columnar growth form with trunk scarcely free of branches. As tree matures the basal branches are progressively abscissed, eventually leaving bare trunk typical of mature specimens. Bark blue-grey, falling in large thick flakes with scalloped margins, undersides of discarded bark and freshly exposed underbark rust brown. Leaves (needles) alternate to subopposite, sessile, thick and leathery; juvenile leaves 50–100 mm × 5–12 mm, lanceolate, pinkish green, often black-spotted (a fungus specific to kauri causes this); adult leaves 20–35 mm, oblong, apex obtuse. Male cones 20–50 mm long, stout, cylindrical. Female cones globose 50–75 mm diam., cone-scales (carpidia) deciduous, at first broad but then gradually narrowing toward base, bearing one ovule per scale. Seeds ovoid, compressed, margins winged.
Similar taxa
None—though could be confused with the distantly allied Queensland kauri (Agathis robusta) which is commonly cultivated in warmer parts of New Zealand. Kauri can be distinguished from that species by its smaller, narrower needles, and by the needles often spotted with black. Queensland Kauri is much faster growing but adult trees are not nearly as massive as kauri.
Distribution
Endemic. New Zealand: North Island from Te Paki south to Pukenui (near Kawhia) in the west and near Te Puke in the east. Over much of its former range it has been heavily logged, such that the best stands now only occur in the Coromandel and Waitakere Ranges, on Great Barrier Island (Aotea Island) and Te Hauturu-o-Toi / Little Barrier Island, and in Northland at Waipoua, Trounson, Omahuta, Puketi, Herekino, Warawara and Radar Bush forests. Despite its northerly limit this species has been successfully grown as far south as Oban, Stewart Island, and seedlings have been observed near planted adults in Wellington, Nelson and Christchurch.
Habitat
The species forms its own forest type—kauri forest—which is typified by dense canopies of kauri. Common associates in the northern half of its range may include taraire (Beilschmiedia tarairi), northern rata (Metrosideros robusta), rimu (Dacrydium cupressinum), towai (Pterophylla silvicola), and makamaka (Ackama rosifolia). Historically kauri forest seems to have been best developed on river terraces, coastal plains and the generally flat flood basalts of the Tangihua complex, which make the dominant geology of Waipoua, Omahuta, Puketi, Trounson. Some people believe that the hill and range occurrences, which is where most stands can now be seen, are relictual stands not truly favoured by the species, but merely examples of where it can grow, and of course locations where it was usually left because log extraction was less feasible.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | At Risk – Declining | Qualifiers: CI, CR, DPT
Threats
Now listed as threatened because of the ongoing decline caused by Phytophthora agathidicida for which as yet there is no known effective preventive or treatment. Aside from ongoing losses caused by this disease, kauri on private land remain vulnerable to illegal logging, while trees are still peridoically removed (although only by permit or with approval) for cultural purposes, such as for making waka (canoes) or other Maori buildings and structures. Some small southerly populations are rather vulnerable to goat browse destroying regenerating seedlings and saplings.
Phytophthora agathidicida remains the main threat to kauri. This fungus-like organisim has caused the death of kauri trees throughout large parts of that species range and it is now a serious threat to the species (see the information and links provided below and see images above of lesions and thinning caused by the disease).
Detailed taxonomy
Family
Araucariaceae
Synonyms
Dammara australis D.Don in Lamb., Podocarpus zamiaefolius Richard
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
Female cones produced from September–December. Male cones throughout the year but most common September–January.
Fruiting
Mature cones occur anytime from December through to May, with rare persistent examples found on trees right up to about August
Life cycle
Winged seeds are dispersed by wind (Thorsen et al., 2009).
Propagation technique
Easy from fresh seed. Very difficult from cuttings. Can be grafted onto seedling kauri.
Other information
Kauri dieback
Kauri dieback is a microscopic fungus-like plant pathogen (a disease causing agent) that only affects kauri. Research has identified PTA as a distinct and previously undescribed species of Phytophthora. Kauri dieback is believed to be a soil-borne species spread by soil and soil water movement, plant to plant transmission through underground root-to-root contact, and human and animal vectors. Symptoms include yellowing of foliage, loss of leaves, canopy thinning (see image above) and dead branches. Affected trees can also develop lesions that bleed resin, extending to the major roots and sometimes girdling the trunk as a ‘collar rot’. Kauri dieback can kill trees and seedlings of all ages.
Follow this link for an up-to-date FAQ (December 2017). Other information can be found here:
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for January 2013 for the full story.
Etymology
agathis: From the Greek agathis ‘ball of thread’
australis: Southern
NVS code
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.
AGAAUS
Chromosome number
2n = 26
Previous conservation statuses
2017 | Threatened – Nationally Vulnerable | Qualifiers: DP
2012 | Not Threatened | Qualifiers: DP
2009 | Not Threatened
2004 | Not Threatened
Referencing and citations
References and further reading
Allan HH. 1961. Flora of New Zealand, Volume I. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. Government Printer, Wellington, NZ. 1085 p.
Ogden J. 1988. Kauri: Key to Auckland’s past. Auckland Botanical Society Journal 43: 17–19.
Enright N, Cameron EK. 1988. The soil seed bank of a kauri (Agathis australis) forest remnant near Aukcland, New Zealand. New Zealand Journal of Botany 26(2): 223–236. https://doi.org/10.1080/0028825X.1988.10410114.
Sem G, Enright NJ. 1995. The soil seed bank in Agathis australis(D. Don) Lindl. (kauri) forests of northern New Zealand. New Zealand Journal of Botany 33(2): 221–235. http://dx.doi.org/10.1080/0028825X.1995.10410485
Mirams RV. 1957. Aspects of the natural regeneration of the kauri (Agathis australis Salisb.). Transactions of the Royal Society of New Zealand 84(4): 661–680.
Sando, C.T. Notes on Agathis australis. NZ Journal of Forestry.
Dickie JB, Smith RD. 1995. Observations on the survival of seeds of Agathis spp. stored at low moisture contents and temperatures. Seed Science Research 5(1): 5–14. https://doi.org/10.1017/S0960258500002531.
Wyse SV, Burns BR. 2013. Effects of Agathis australis (New Zealand kauri) leaf litter on germination and seedling growth differs among plant species. New Zealand Journal of Ecology 37(2): 178–183.
Attribution
Fact Sheet Prepared for NZPCN by P.J. de Lange May 2004. Description adapted from Allan (1961).
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Agathis australis Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/agathis-australis/ (Date website was queried)