Plerandra letocartiorum is an endemic tree of New Caledonia occurring in sclerophyllous forest.This species has suffered from sclerophyllous forest reduction and fragmentation. This is particularly linked to agricultural development on the west coast of Grande Terre. Other threats come from habitat degradation due to Rusa Deer (Rusa timorensis) and uncontrolled fires.The extent of occurrence is 50 km² and the area of occupancy is 16 km². The number of locations is determined to be two based on the most serious threat of rusa deer (Rusa timorensis). Population size is estimated to be less than 250 mature individuals with two subpopulations, one in Sarraméa and one in Bourail. Sarraméa's subpopulation contains no more than 10 individuals. It is estimated that the number of mature individuals is declining. Using criteria C, Plerandra letocartiorum qualifies for Critically Endangered [CR C2a(ii)].This species is not protected by local legislation and does not occur in any protected areas.

Geographical area

Plerandra letocartiorum is an endemic tree of New Caledonia restricted to the central chain (Bourail and Sarraméa).

Population

Population size is not precisely known but it is very likely that there are less than 250 mature individuals

Habitat

Plerandra letocartiorum occurs in mesophyllous/sclerophyllous forest at an altitudinal range of 40-250 m, on ultramafic (serpentine) substrate. Tropical dry forests are probably among the worlds most endangered of all lowland tropical forests. Because of their propensity to become pastures and their susceptibility to fire, dry forests have been reduced dramatically in size as well as in quality. In New Caledonia, they have been extensively cleared for agricultural purposes for a century; what remains today are highly fragmented patches that have been estimated at 2% of the original area.

Threats

Tropical dry forests are probably among the worlds most endangered of all lowland tropical forests. Because of their propensity to become pastures and their susceptibility to fire, dry forests have been reduced dramatically, both in size as well as in quality. In New Caledonia, they have been extensively cleared for agricultural purposes or urbanization for a century; what remains today are highly fragmented patches that have been estimated at 2% of the original area. Uncontrolled fires sweep across lowlands of New Caledonia each year, especially during the dry season (an average of 20,000 ha of land is burnt each year, with dramatic peaks of 70,000 ha). They have slowly transformed remnant patches of dry forest into scrubland dominated by Acacia spirorbis and Leucaena leucocephala, or Niaouli (Melaleuca quinquenervia) savannahs. Another main 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

It is recommended to investigate the surroundings of Nétéa, Ipoa, Ponérihouen, Néavin to find new subpopulations and to estimate precisely the number of mature individuals in Bourail.Plerandra letocartiorum is not protected by local legislation and does not occur in any protected areas. Dry forests are a patrimonial ecosystem protected by the Code de l'environnement of province Sud. This species urgently requires in situ and ex situ conservation measures.

Bibliography

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..

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.

Bouchet, P.; Jaffré, T. and Veillon J.-M. 1995. Plant extinction in New Caledonia: protection of sclerophyll forest urgently needed. Biodiversity and Conservation(4) , p.415-428.

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

Experts

Assessor(s): Tanguy, V.

Reviewer(s): Schatz, G.

Contributor(s): Butin, J., Lowry, P., Vandrot, H., Isnard, S., Gâteblé, G., Birnbaum, P., Garnier, D., Cazé, H., Amice, R., Barrabé, L., Anquez, M., Fleurot, D.

Facilitator(s): Schatz, G.