Podonephelium plicatum is an endemic tree of New Caledonia occurring in shrubland on ultramafic substrate ("maquis minier"). It is restricted to ultramafic massifs on the west coast of the northern half of Grande Terre. There is an evident threat due to mining activities which impact the ultramafic massifs of North-West Grande Terre. Population size reduction cannot be assessed because of a lack of data. With an extent of occurrence (EOO) of 1,157 km², an area of occupancy (AOO) of 64 km² and 9-10 estimated locations, none of them occurring within a protected area, Podonephelium plicatum is assigned a status of Vulnerable with a continuing decline in the EOO, AOO, quality of the habitat and number of mature individuals. Population size is unknown.

Geographical area

Podonephelium plicatum is an endemic tree of New Caledonia restricted to the northwest coast of Grande Terre, where it occurs on a series of isolated ultramafic mountains, from Mé Maoya in the south to Tiébaghi in the North, although it has not been recorded from the Kaala and Ouazangou-Taom massifs, which have similar eco-geographic conditions.

Population

Population size is unknown.

Habitat

This species grows in shrubland vegetation: in particular both mixed woody-herbaceous and high shrubland, generally on rocky slopes and almost exclusively on substrates derived from serpentinite. Podonephelium plicatum appears to be a pioneer in areas that have recently been subjected to rock slides, and then survives as progressively denser shrubland becomes established. It occurs at elevations ranging from 200-900 m.

Threats

An important threat to biodiversity in New Caledonia comes from past, present and future mining activities. New Caledonia contains between 20 - 30% of the world’s nickel resources. Intense mining activities since the late 19th century generated soil erosion (1.2% of bare ground mapped by SPOT5 in 2007). Based on the distribution of metal-rich soils and site accessibility, these threats are predictable and planned (rise in nickel production from 60,000 to 200,000 tonnes per year between 2013 and 2015). The west coast ultramafic mountains (such as the Tiebaghi dome, Mont Kaala, Ouazangou-Taom Mountains, Mont Koniambo, Mont Kopéto, Mont Paéoua and Mont Boulinda) are actively mined. These sites experience major impacts from mining activities and are not protected by local legislation. Most of the subpopulations of Podonephelium plicatum are situated on mining concessions and current or planned nickel exploitation will very probably result in a sharp decline in the quality of habitat in the foreseeable future.Moreover, fires, which often burn large areas of low to mid-elevation shrubland, are clearly a threat to this species.As this species appears to be a pioneer in areas that have recently been subjected to rock slides, it is suggested that fire is considered as the main threat.

Conservation

This species is not protected by legislation and does not occur in a protected area. As it has not been not been recorded from the Kaala and Ouazangou-Taom massifs, which have similar eco-geographic conditions as the existing sub-populations, it is recommended to investigate those areas.

Bibliography

L'Huillier L.; Jaffré T. and Wulff A. 2010. Mines et Environnement en Nouvelle-Calédonie : les milieux sur substrats ultramafiques et leur restauration.

Munzinger J. et al. 2013. A Taxonomic Revision of the Endemic New Caledonian Genus Podonephelium Baill. (Sapindaceae). Systematic botany(38) , p.1105-1124.

Experts

Assessor(s): Tanguy, V.

Reviewer(s): Schatz, G.

Contributor(s): Gâteblé, G., Tron, F., Amice, R., Letocart, D., Veillon, J., Munzinger, J.