Plerandra memaoyaensis is an endemic tree of New Caledonia occurring in high altitude shrubland on ultramafic substrate restricted to the single massif of Me Maoya in Poya.Population size reduction cannot be assessed because a lack of data.There is an evident threat due to the mining activities that impact ultramafic massifs of North-West Grande Terre. With an extent of occurrence (EOO) of 8 km², an area of occupancy (AOO) of 8 km² and 1 location based on the principal threat of past and present mining activities, despite the fact some of the population used to occur within the Nodela reserve, Plerandra memaoyaensis is assigned a status of Critically Endangered (CR) with an observed and estimated continuing decline of the quality of habitat: CR B1ab(iii)+2ab(iii).

Geographical area

Plerandra memaoyaensis is an endemic tree of New Caledonia restricted to a single ultramafic massif (Me Maoya) in Poya.

Population

Population size is not precisely known.

Habitat

Plerandra memaoyaensis occurs in high altitude shrubland on ultramafic substrate at an altitudinal range of 1200-1500 m.

Threats

This species occurs on an ultramafic massif threatened by mining activities and related threats. An important threat to biodiversity in New Caledonia comes from past, present and future mining activities. New Caledonia contains 20-30% of the worlds 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 massifs (such as the Me Maoya) are actively mined. These sites experience major impacts from mining activities and are not protected by local legislation. Another threat comes from Rusa Deer (Rusa timorensis), which was introduced in the 1880s and adapted extremely well to Caledonian habitats. Its population may have reached over 100,000 individuals in the wild. This rusa deer (Rusa timorensis) consumes a wide variety of plant species and causes severe damage to trees, which results in very little regeneration.

Conservation

This species is not protected by local legislation and it does not occur in a protected area. However, one subpopulation occurred in the area of Nodela reserve created in 1996, area where mining activites are from now on forbidden. This species would benefit from additional in situ and ex situ conservation actions. It is recommended to extend the Nodela reserve and to legally protect the species in the Code de l'environnement. It is moreover recommended to survey the Me Maoya mountain to get a better estimation of the population.

Bibliography

Lowry, P. P. II; G. M. Plunkett and D. G. Frodin 2013. Revision of Plerandra A. Gray (Araliaceae). I. A synopsis of the genus with an expanded circumscription and a new infrageneric classification. Brittonia(65) , p.42-61.

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

Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.

Lowry, P. P. II; G. M. Plunkett; D. G. Frodin; C. Rodrigues Vaz; M. Gostel and A. N. Nicolas 2016. Revision of Plerandra A. Gray (Araliaceae). III. A taxonomic treatment of Plerandra subg. Dizygotheca..

Experts

Assessor(s): Tanguy, V.

Reviewer(s): Schatz, G.

Contributor(s): Birnbaum, P., Villegente, J., Gailhbaud, P., Garnier, D., Fogliani, B., Lowry, P.

Facilitator(s): Schatz, G.