Xylosma inaequinervia is an endemic shrub of the north-western part of Grande Terre in New Caledonia. This species is known from 3 massifs : Kopéto, Paéoua and Boulinda. It is found in humid forest and shrubland on an ultramafic substrate at an altitudinal range of 800-1,000 m asl. The main threat is presented by ongoing mining development in Kopéto and potentially future mining development in Paéoua and Boulinda. Extraction projections for the coming 25 years may mean that most individuals are affected. Xylosma inaequinervia is assessed as Endangered (EN) under criterion A4c with an inferred population reduction of more than 50% over three generations (75 years) starting in 1970 and projected to 2045; and under criteria B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) with the number of threat-defined locations estimated to be three, a continuous decline of all concerned subcriteria and extent of occurrence (EOO) and area of occupancy (AOO) are respectively estimated to be of 81 km² and 28 km².

Geographical area

Xylosma inaequinervia is a shrub endemic to the north-western part of Grande Terre in New Caledonia. This species is known from 3 massifs: Kopéto, Paéoua and Boulinda.

Population

Population size is unknown. Although subpopulations are scattered, field surveys emphasise that individuals have a grouped occurrence. Mining extraction projections for the coming 25 years could lead to a 50% reduction in the impacted subpopulations and thus contribute to the potential reduction of the total population size.

Habitat

Xylosma inaequinervia is found in humid forest and shrubland on an ultramafic substrate at an altitudinal range 800-1,000 m asl.

Threats

The main threat is presented by ongoing mining development in Kopéto and potentially by future mining development in Boulinda and Paéoua (as well as being impacted by bushfires). New Caledonia contains 20 - 30% of the world’s nickel resources and has experienced intense mining activities since the late 19th century which has 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 (there was a rise in nickel production from 60,000 to 200,000 tonnes per year between 2013 and 2015).

Conservation

Xylosma inaequinervium is protected by legislation in Province Nord and Province Sud but does not occur in any protected area. It is noted that KNS has conducted prospections and phenologic monitoring since 2015. This species would benefit from ex-situ and in-situ emergency conservation actions. It is proposed to ensure the monitoring of known subpopulations, and to preserve a viable population on delimited perimeters on Kopéto. It is proposed to conduct propagation tests in order to assist future planting operations.

Bibliography

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

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

Morat, P.; Jaffré, T.; Tronchet, F.; Munzinger, J.; Pillon, Y.; Veillon, J.-M. and Chalopin, M. 2012. Le référentiel taxonomique Florical et les caractéristiques de la flore vasculaire indigène de la Nouvelle-Calédonie [The taxonomic database « FLORICAL » and characteristics of the indigenous flora of New Caledonia]. Adansonia sér 3(34) , p.177-219.

Wulff AS, Hollingsworth PM, Ahrends A, Jaffré T, Veillon J-M, L’Huillier L, et al. 2013. Conservation Priorities in a Biodiversity Hotspot: Analysis of Narrow Endemic Plant Species in New Caledonia.

Experts

Assessor(s): Tanguy, V., Veillon, J., Amice, R., Barrière, R., Chambrey, C., Fleurot, D., Lannuzel, G.

Reviewer(s): Vandrot, H.

Contributor(s): Wulff, A.

Facilitator(s): Chanfreau, S., Tanguy, V.