Taxonomie
Statut liste rouge -
Vulnérable (VU) , évaluée le 27/04/2015Espèce protégée -
en Province Nord
Description
Description Générale
Arbuste 1-3 m, port buissonnant,; tronc 1m et 10 cm de diam.; branches courtes sinueuses, bien ramifiées.
Type : Vieillard 2277 (P00180596)
Répartition en Nouvelle-Calédonie
Cette espèce s'observe sur la Grande Terre uniquement sur les pentes du Massif de Taom.Habitat
Maquis minier assez haut, entre 200 et 700 m d'altitude.Substrat
Sur sol érodé d'origine ultramafique.Feuille
Feuilles sessiles, goupées en rosettes denses au sommet des axes, lancéolées, asymétriques, coriaces, concolores et glauque sur le frais, les adultes glabres; à marge révolutée; nernures visibles sur les 2 faces.Phénologie (Fleur)
Fleurs jaunes,1,5 cm de diam., 15-20 sur des inflorescences peu velues, simples, scorpioïdes, terminales parfois plus grandes que les feuilles.Fruits
Follicules ovoïdes plus d'1 cm avec chacun 1-2 graines mûres.Reproduction
Floraison et fructification de novemmbre à février.Particularité
Lépithète attribuée à cette espèce rend compte de la teinte rougeâtre que prennent les feuilles une fois séchées. Sur le terrain le feuillage est d'un glauque soutenu rendant facile son repérage dans le maquis.H.rubescens is an endemic tree of New Caledonia restricted to a shrubland located on the slopes of Massif Taom. It precisely occurs at an altitudinal range 200-700 m asl. Population size reduction cannot be assessed because of a lack of data but it would be plausible that it ranges over 1,000. A geographical barriers between Ouazangou and Taom seems to preserve H.rubescens from mining activity located on near massif. However, monitoring of the situation (impact of mine's reopening anf bushfire ) is highly recommended as this microendemic species is Vulnerable (VU D2) because of its tiny area of occupancy (AOO).
Aire géographique
H.rubescens is an endemic tree of New Caledonia restricted to a shrubland located on the slopes of Massif Taom.
Population
Population size is estimated higher than 1,000 mature individuals.
Habitat
It occurs on shrubland, mostly dominated by Gymnostoma chamaecyparis on altered peridotite at an altitudinal range 200-700 m asl.
Menaces
Uncontrolled bushfires sweep across 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 contribute to habitat fragmentation and decline in the quality of habitat. Some fire observed on west downward slope of Mount Taom may affect H. rubescens. However, reopening mining activities remains the main threat. Planned exploitation for nickel, on the ultramafic massif Mont Taom will very likely result in a decline in the extent and quality of habitat and decline of mature individuals in the foreseeable future. Monitoring of the situation is highly recommended as this microendemic species is Vulnerable (VU D2) because of its tiny area of occupancy (AOO).
Conservation
H. rubescens is protected by legislation in Province Nord. It does not occur in any protected areas. To avoid any risks of fire, it is recommended to inform the department of civil defense that H. rubescens is present on Mont Taom. It would also be benefical to put under protection a part of its habitat.
Bibliographie
Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.
Veillon J.-M.; Müller I.H.; Goldblatt P. 1990. Flore de la Nouvelle-Calédonie et dépendances. Volume 16 : Dilléniacées, Goodéniacées, Iridacées, Campynématacées.
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.
Hély-Alleaume 2012. INC : Incendies et biodiversité des éco-systèmes en Nouvelle-Calédonie.
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.
Experts
Assessor(s): Veillon, J., Amice, R., Butin, J., Cazé, H., Garnier, D., Lannuzel, G., Leborgne, T., McCoy, S.
Reviewer(s): Tanguy, V.
Facilitator(s): Chanfreau, S.