Taxonomy

endemique
protegee
UICN

Red List Status -

Critically Endangered (CR) , assessed in 20/02/2015

Protected species -

in Northern Province

Podonephelium subaequilaterum 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 agriculture on the west coast. Today, the main threat toPodonephelium subaequilaterum comes from habitat degradation due to Rusa Deer (Rusa timorensis) and uncontrolled fires. The population size reduction cannot be assessed because of a lack of data. Its area of occupancy is estimated to be 12 km² while its extent of occurrence is around 15 km². The number of locations, based upon Rusa rusa deer (Rusa timorensis) as the main threat is estimated to be two. The two known subpopulations are small, isolated and separated by a distance of 40 km with a much reduced probability of natural recolonization. There is moreover an apparent lack of regeneration. Podonephelium subaequilaterum is therefore in a situation of severe fragmentation. A continuing decline has been observed or estimated in its extent of occurrence, area of occupancy, quality of habitat, number of subpopulations and number of mature individuals. Using criteria B, P. subaequilaterum is assigned a status of Critically Endangered B1ab(i,ii,iii,iv,v). The population size is not precisely known but it would be highly recommended to get a better estimation in both sub-populations. Under criteria D, P. subaequilaterum would be VU D2.

Geographical area


Podonephelium subaequilaterum is an endemic tree of New Caledonia restricted to the west coast of Grande Terre. Is is only known from the area in the vicinity of La Foa, in southwestern Grande Terre.

Population


Population size is unknown. The subpopulation in Ouaménie has been highly impacted by introduced deer. We were able to locate more than 10 individuals, but regeneration has clearly been impeded (the smallest tree seen had a DBH of 7.5 cm and no seedlings or saplings were seen).

Habitat


Podonephelium subaequilaterum grows only in sclerophyllous and mesic forest on volcano-sedimentary substrates at low elevation (100-500 m).Sclerophyllous forests in New Caledonia are the most heavily impacted native vegetation type in New Caledonia, of which just 1–2% of the original cover remained as of the mid-1990s (Bouchet et al. 1995) and even less today. Because of their propensity to become pastures and their susceptibility to fire, dry forests have 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.

Threats


Tropical dry forests are probably among the world's most endangered of all lowland tropical forests. Because of their propensity to become pastures and their susceptibility to fire, dry forests have reduced dramatically, in size as well as in quality. In New Caledonia, they've 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. Today's main threat to Podonephelium subaequilaterum 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 and very little regeneration. 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.

Conservation


Podonephelium subaequilaterum is not protected by local legislation. None of the subpopulations occur within a protected area while dry forests benefit from a conservation programme managed by the Conservatoire des Espaces Naturels.Dry forests are a patrimonial ecosystem protected by the Code de l'Environnement of the Province Sud. This species would benefit from in-situ and ex-situ emergency conservation actions.

Bibliography


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.

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): McCoy, S., Cazé, H., Wulff, A., Isnard, S., Munzinger, J.


Geographical distribution