Xylosma kaalense is an endemic shrub/small tree found in the north-western part of Grande Terre in New Caledonia. This species is known from six subpopulations (Tiébaghi, Kaala, Koniambo, Paéoua, forêt de Sailles, Mont Kouakoué). It is found in shrubland on ultramafic substrate at an altitudinal range 500-1050 m asl. The main threat is presented by ongoing mining development (Thiébaghi, Kaala, Koniambo), future mining project at Paéoua and bushfires and insvasive species at Forêt de Sailles and Kouakoué. Extraction projections for the coming 25 years could lead to most individuals being affected. Therefore, Xylosma kaalense 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.

Geographical area

Xylosma kaalense is an endemic shrub/small tree of the north-western part of Grande Terre in New Caledonia. This species is known from six subpopulations (Tiébaghi, Kaala, Koniambo, Paéoua, Forêt de Sailles, Mont Kouakoué).

Population

Population size is unknown. Mining extraction projections for the coming 25 years could lead to a 50% potential reduction of the total population size.

Habitat

Xylosma kaalense is found in shrubland on ultramafic substrate at an altitudinal range of 500-1,050 m asl.

Threats

The main threat is presented by ongoing mining development in Tiébaghi, Kaala, Koniambo, bushfires at Forêt de Sailles and by bushfires and future mining development in Paéoua. 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). Furthermore this species can be potentially impacted by feral pigs (Sus domesticus).

Conservation

he Xylosma genus is protected by legislation in Province Nord, but not in Province Sud. Nevertheless it is known from two protected areas managed by Province Sud: Réserves Naturelles de la Forêt de Saille and Massif du Kouakoué. This species would benefit from ex situ and in situ emergency conservation actions. It is proposed to ensure the monitoring of the known populations and to preserve a viable population within delimited perimeters. It would be moreover advised to conduct propagation tests in order to assist future planting operations. Xylosma kaalense should be taxonomically clarified because it may be difficult to distinguish from X. molestum, which is a widespread species.

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.

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.

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.

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): Tanguy, V., Chanfreau, S.