Ochrosia sevenetii is a tree endemic to the north-western part of Grande Terre in New Caledonia. This species is only known from a single subpopulation in Tiébaghi. This species occurs in shrubland and dense humid forest on ultramafic substrates at an altitudinal range of 350-400 m asl. The main threat is ongoing mining activities in Tiébaghi area and a twenty five year projection for mining operations indicates that all individuals may be affected in the Tiébaghi area. Neisosperma sevenetii is assessed as Critically Endangered (CR) under criterion A4c with an inferred population reduction of more than 80 % over three generations (75 years) starting in 1970 and projected to 2045; and under criteria B1ab(i,ii,iii,v) with only one single threat-defined locations, a continuous decline of all concerned subcriteria and extent of occurrence (EOO) and area of occupancy (AOO) are both estimated to be of 16 km²; and finally under C2a(ii) with an estimated number of mature individuals fewer than 250.

Geographical area

Ochrosia sevenetii is a tree endemic to the north-western part of Grande Terre in New Caledonia. This species is only known from a single subpopulation in Tiébaghi.

Population

Population size is estimated to be fewer than 250 mature individuals based on a recent study made by the mining company (SLN, Société Le Nickel) and IAC (Institut Agronomique Caledonien), a local Agronomic Institute. The mining extraction projections for the coming 25 years could lead to a reduction of more than 80% of the population.

Habitat

Ochrosia sevenetii occurs in shrubland and dense humid forest on ultramafic substrates at an altitudinal range of 350-400 m asl.

Threats

The main threat is ongoing mining activities in the Tiébaghi area. Furthermore, side effects are significant, making an irreversible impact on the environment by drying up entire landscapes and producing dust rising from the ground. The twenty five year projection for mining operations indicates that all individuals may be affected. 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 rise in nickel production from 60,000 to 200,000 tonnes per year between 2013 and 2015).

Conservation

Ochrosia sevenetii is protected by legislation in Province Sud and Province Nord, but does not occur in any protected area. It is reported that conservation measures are implemented by SLN (Société le Nickel) through a partnership with IAC (Institut Agronomique néo-Calédonien). Technical guidelines were drawn up in 2015, propagation tests were conducted and planting operations are ongoing (129 individuals were planted in 2015 in Tiébaghi). This species would benefit from ex situ and in situ emergency conservation actions. It is proposed to ensure the monitoring of the only known population, to better estimate population size, and to preserve a viable population on delimited perimeters on Tiébaghi.

Bibliography

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.

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

Experts

Assessor(s): Tanguy, V., Veillon, J., Amice, R., Barrière, R., Fleurot, D., Gailhbaud, P., Garnier, D., Suprin, B.

Reviewer(s): Vandrot, H.

Contributor(s): Wulff, A.

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