Scientific name: Araucaria humboldtensis J. Buchholz 1949

Synonyms: Eutassa humboldtensis (J.Buchholz) de Laub.

Common names: Mount Humboldt araucaria

Description

Tree to (6-)10-15(-20) m tall, with trunk to 0.3(-0.5) m in diameter. Bark light gray, smooth, peeling in scales or horizontal strips. Crown very sparse, with a few scattered, short branches along the trunk overreached by a shallow, flat-topped umbrella at the very summit composed of a few tiers of four to six upwardly angled, thin branches with tufts of branchlets at their tips densely clothed with foliage. Branchlets coarse, nearly upright, remaining green 2-3 years before being shed intact, essentially hidden by the leaves. Leaves scalelike, broadly pointed, keeled, 5-6 mm long, 3-5 mm wide, dark green with yellow-green tips. Stomates with no preferred orientation, in two bands without obvious discrete lines on the inner (upper) face and two basal patches on the outer face. Pollen cones 5-8 cm long, 15 mm thick, each pollen scale with five to eight pollen sacs in a single row. Seed cones nearly spherical or a little longer, to 9 cm long, 8 cm wide, waxy bluish green. Seed scales about 3 cm long by 3 cm wide, including the two papery wings about as wide as the seed-bearing portion, with an upturned, narrowly triangular free tip 4-7 mm long. Seeds almond-shaped, 2.5 cm long and 9 mm wide. Cotyledons emerging above ground during germination.

Mountains in the southern fifth of New Caledonia. Scattered as a common emergent above short lower montane forest on serpentine soils often mixed with other species of Araucaria; 750-1,550 m.

Conservation Status

Red List Category & Criteria: Endangered

Previously this species had been regarded as Lower Risk/conservation dependent due to its restricted distribution and narrow ecological niche and the fact that it was largely confined to protected areas. Field work over the last decade has indicated that this species should now be regarded as Endangered on the basis of a decline in the quality of habitat due to an increased frequency of fires and die back in some subpopulations.

Subpopulations on the summits and ridges of Mt Humboldt, Mt Kouakoué and Montagne des Sources are quite extensive although there has been significant die back over the last decade at Mt Humboldt. The subpopulation at Mt Mou is much smaller and more degraded. At Mamie, in an area that represents an atypical habitat at an altitude of 400-500 m asl, a relatively extensive and healthy subpopulation has recently been tentatively identified as Araucaria humboldtensis.

Restricted to the highest ridges and summits on ultramafic soils. Recent die back may have caused the death of at least 10% of the Mt Humboldt subpopulation. The cause is unknown but may relate to drought induced stress or perhaps an unknown pathogen. Wildfires are currently the main threat. As subpopulations are restricted to a narrow altitudinal range with little possibility for upward expansion, this species may be very susceptible to some of the potential impacts of climate change.

The main subpopulations are within protected areas such as Montagne des Sources and Mont Humboldt although it should be noted that some reserves are open to mining. Fire prevention measures are in place with fire brigades and water-bombing helicopters available if needed.

References

Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland