Mamie Plateau

Mamie Plateau

© M.F.Gardner, RBGE
Immature female cone

Immature female cone

© M.F.Gardner, RBGE

Araucariaceae

Agathis ovata (Moore ex Veill.) Warb.

One of four Agathis species endemic to New Caledonia on the main island of Grande Terre where it has become endangered as a result of fire and mining

Description

Habit

Shrub to 1m or tall tree up to 10m tall (rarely taller) and 80cm d.b.h., bole clear to 12m, branching from near the base forming a massive flat-topped spreading crown. Bark with deep fissures, exfoliating forming irregular patches, grey when mature

Foliage

Leaves (mature) almost opposite, almost sphere-shaped, 4‒8.5 x 1.5‒5cm leathery, multiveined, glabrous, apex truncate or sometimes notched, pale green or glaucous.

Cones

Male pollen-cones axillary, solitary, cylindrical, peduncles thick (4‒20mm), 3‒5 x 1.0‒1.5cm, subtended by two leaf-like bracts and 4‒5 pairs of overlapping rounded bract scales. Female seed-cones solitary, globose, 1.6‒2.0 x 2.0‒2.6cm , green or glaucous green, brown when mature. Seeds 9‒11 x 7‒11mm, with two unequal wings.

Distribution

Endemic to New Caledonia on the main island of Grand Terre. Most locations are restricted to Province Sud but a few occur in Province Nord as far north as Kouaoua on the east coast. Subpopulations are usually very small (in areas of less than 2ha) and isolated.

Habitat and Ecology

Agathis ovata occurs as an emergent tree in open shrublands (maquis) and as a canopy emergent (to 25 m) in angiosperm-dominated (closed) rainforests. It is restricted to ultramafic soils and in the maquis; it tends to be restricted to rocky outcrops. It has an altitudinal range of between 150 to 1,150m

Conservation Status

Global status and rationale

Endangered B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)

Agathis ovata is assessed as Endangered on the basis of its limited extent of occurrence (2814km²) and area of occupancy (100km²) which in both cases there is a projected decline. It also meets further criteria including the poor quality of habitat, number of locations and number of mature individuals due to mining activities and fires. Although there are eight general locations known (three more than the threshold for Endangered), there is severe fragmentation of subpopulations due to their geographic isolation, large areas of intervening unsuitable habitat and low dispersal and reproduction rates.

Global threats

Mining activities and fires are the main threats. Mature trees have some fire resistance but this depends on frequency and severity. Regeneration and general growth rates are very slow

Conservation Actions

Several subpopulations at higher altitudes occur in protected areas such as the Rivière Bleue Provincial Park, Montagne des Sources and Mt Do

References and further reading

  1. de Laubenfels, D.J. (1972). Flore de la Nouvelle-Caledonie et Dependances. (4). Gymnospermes. Paris: Museum National d'Histoire Narurelle. 167 pp.
  2. Enright, N.J. & Goldblum, D. (1998). Stand structure of the emergent conifer Agathis ovata in forest and maquis, Province Sud, New Caledonia. J. Biogeogr. 25: 641-648
  3. Enright, N., Miller, B.P. & Perry, G.L.W. (2003). Demography of the long-lived conifer Agathis ovata in maquis and rainforest, New Caledonia. Journal of Vegetation Science 14: 625-636.
  4. Jaffre, T., Bouchet, P. & Veillon, J.-M. (1998). Threatened plants of New Caledonia: Is the system of protected areas adequate? Biodiversity & Conservation 7(1): 36.
  5. Jaffré, T., Munzinger, J. & Lowry, P. P. (2010). Threats to the conifer species found on New Caledonia's ultramafic massifs and proposals for urgently needed measures to improve their protection. Biodiversity & Conservation: 19(5):1485-1502.
  6. L'Huillier, L. Jaffré,  & Wulff A. (2010). Mines et environnement en Nouvelle-Calédonie : les milieux sur substrats ultramafiques et leur restauration. Editions IAC, Nouméa, Nouvelle-Calédonie, 412 p.
  7. McCoy, S., Jaffré, T., Rigault, F. & Ash, J.E. (1999). Fire and succession in the ultramafic maquis of New Caledonia. J. Biogeogr. 26: 579-594.
  8. Manauté, J., Jaffré, T., Veillon, J.-M. & Kranitz, M. (2003). Revue des Araucariaceae de Nouvelle-Calédonie. IRD, Nouméa.
  9. Nasi, R. (1982). Essai pour une meilleure connaissance et une meilleure comprehension des Araucariacées dans la végétation Calédonienne. Nouméa: École Nationale des Ingénieurs des Travaux des Eaux et Forêts, Centre Technique Forestier Tropical. 134 p., 10 plates, 44 p. appendices.
  10. Suprin, B. (2011). Florilège des plantes en Nouvelle-Calédonie angiospermes ou plantes à fleurs (lauracées à zingibéracées). Tome 1. Éditions Photosynthèse, Nouméa. 519 pp.
  11. Thomas, P. (2010). Agathis ovata. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.1. www.iucnredlist.org. Downloaded on 29 June 2012.
  12. Whitmore, T. C. (1980). A monograph of Agathis. Plant Systematics & Evolution 135: 41-69.