Hibbertia tontoutensis is an endemic tree found in abundance in basse vallée de Tontouta and in the surroudings area as well as in Plaine des lacs area. It occurs in ligno-herbaceous shrubland on ultramafic substrate at an altitudinal range 20-760 m asl. Its area of occupancy (AOO) and extent of occurrence (EOO) are respectively 56 km² and 935 km². Most of the population is gathered on the riverbank of Tontouta river, which is a locality directly impacted by mining activities. The population of creek Pernod locality is also under extinction due to induced effects of mine. The three other localities are : forêt de Thy, Ouénarou and Yaté. Due to the mining activities, resulting erosion and regularly eroded riverbank, a continuing decline of quality of habitat and mature individuals is inferred. Using criteria B, H. tontoutensis does qualify for Endangered (EN) B1ab(iii,v)&2ab(iii,v).

Geographical area

Hibbertia tontoutensis is an endemic tree found in abundance in basse vallée de Tontouta and in the surroudings area as well as in Plaine des lacs area.

Population

Population size is estimated to be fewer than 2,500 mature individuals with a drecreasing of population size for the sub-population on ferralitic soil. The biggest part of population is located on riverbank of Tontouta river. Low regeneration is observed (no apparent reasons).

Habitat

It occurs in ligno-herbaceous shrubland on ultramafic substrate at an altitudinal range 20-760 m asl.

Threats

This species occurs on area intensively mined and impacted by mining activities and related activites like road construction for engines. An important threat to biodiversity in New Caledonia comes from past, present and future mining activities. New Caledonia contains between 20 - 30% of the world’s nickel resources. Intense mining activities since the late 19th century 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 (rise in nickel production from 60,000 to 200,000 tonnes per year between 2013 and 2015). Apart from the degradation on concessions, mining activities are resulting on erosion which increase impact on H. tontoutensis. It is recommended to monitor the population to enlarge prospecting on Creek Pernod, tributaries of Tontouta and Kalouehola River to have a precise idea of damage that mining activities are causing. The sub-populations of forêt de Thy and Yaté do not appear under threat but the sub-population of Ouenarou may affect by bushfire.

Conservation

H.tontoutensis is not protected by legislation but occurs in protected areas (réserve naturelle de la Vallée de la Thy, Parc Provincial de la Rivière Bleue, réserve naturelle du Barrage de Yaté). It is recommended to prospect actively H. tontoutensis on the riverbank of Kalouehola river, where H. favieri is present, and Chutes de la Madeleine. Include this species in the list of protected species may be beneficial.

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. The taxonomic database « FLORICAL » and characteristics of the indigenous flora of New Caledonia. Adansonia(334) , p.177-219.

Hély-Alleaume 2012. INC : Incendies et biodiversité des éco-systèmes en Nouvelle-Calédonie.

Gomez C.; Mangeas M.; Curt T.; Ibanez T.; Munzinger J.; Dumas P.; Jérémy A.; Despinoy M. and Hély C. 2014. Wildfire risk for main vegetation units in a biodiversity hotspot: modeling approach in New Caledonia, South Pacific. Ecology and Evolution(5) , p.377-390.

Veillon J.-M.; Müller I.H.; Goldblatt P. 1990. Flore de la Nouvelle-Calédonie et dépendances. Volume 16 : Dilléniacées, Goodéniacées, Iridacées, Campynématacées.

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

Experts

Assessor(s): Veillon, J., Amice, R., Pain, A., Butin, J., Cazé, H., Garnier, D., Lannuzel, G., Leborgne, T., McCoy, S.

Reviewer(s): Tanguy, V.

Contributor(s): Fogliani, B.

Facilitator(s): Chanfreau, S.