Taxonomy
Common name :
Bois bouchon
Synonyms
Nageia minus CarrièreRed List Status -
Endangered (EN) , assessed in 03/07/2017Protected species -
in Southern Province
Retrophyllum minus was more widespread in southern New Caledonia in the recent past. There has been a significant reduction in the last century due to fires, the construction of dams and mining activities. These threats are ongoing. Currently this species is restricted to a few watercourses and lakes (five locations). Its extent of occurrence is estimated to be 269 km2 with an area of occupancy of about 152 km2. A continuing decline in mature individuals is projected. On the basis of these data an assessment of Endangered is appropriate. Conservation actions include the re- inforcement of some sub-populations.
Geographical area
This small rheophyte is restricted to the margins of a few watercourses and lakes in the Plaine des Lacs area (at 5 to 250 m asl).
Population
The population is estimated to be well over 2,500 mature individuals although there is a continuing decline
Habitat
Grows on river banks and lake shores on ultramafic soils. This species often grows as a rheophyte and its stems and roots have a specialised anatomy that allow it to tolerate constant inundation (Carlquist and Nazaire 2016)
Threats
The most direct threats come from wild fires and developments associated with mining such as the construction of a major metallurgical plant several kilometres upstream from a major subpopulation. Other longer term threats come from fluctuations in the water flows and the water table.
Conservation
This species is legally protected in province Sud. One subpopulation occurs in a reserve at the Chute de la Madeleine Reserve. Before 1997, this area was freely accessible to the public and was becoming degraded. Since 1997, a management plan has been implemented and some restoration work undertaken. Other subpopulations are not protected. Protecting globally the wetlands of Plaine des Lacs recently recognized by RAMSAR through a management plan would benefit this species This species is monitored and propagated by the mining operator Vale NC and is included in an ex situ conservation plantation (Rare species conservation plan). A hundred young plants are due to be introduced in the Grand Lac area as part of that programme (S. McCoy pers.comm.)
Bibliography
Jaffré, T., Bouchet, P. and Veillon, J.-M. 1996. Threatened plants of New Caledonia: Is the system of protected areas adequate?. Biodiversity and Conservation (7(1)) , p.109-135.
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.
Munzinger J., Morat Ph., Jaffré T., Gâteblé G., Pillon Y., Rouhan G., Bruy, D., Veillon J.-M., & M. Chalopin 2020. FLORICAL: Checklist of the vascular indigenous flora of New Caledonia [continuously updated].
Endemia.nc 2016. Faune et Flore de Nouvelle-Calédonie.
de Laubenfels, D.J. 1972. Flore de la Nouvelle-Calédonie et dépendances..
Carlquist, S, and Nazaire, M. 2016. SEM studies of two riparian New-Caledonian conifers reveal air channels in stem wood; field observations.. Aliso(34(1)) , p.1-7.
Cornu, A., Sarrailh, J.-M. and Marion, F. 2001. Espèces endémiques et restauration écologique en Nouvelle-Calédonie.. Bois et Forêts des Tropique(268(2)) , p.57-68.
Enright , N.J., Miller, B.P. and Jaffré ,T. 2009. Ecology and population dynamics of the endemic NC conifer, A. muelleri (Araucariaceae). In: M.D. Wilcoxand and R.L. Bielelski (eds), Araucariaceae: Proceedings of the 2002 Araucariaceae Symposium.
Herbert, J., Hollingsworth, P.M., Gardner, M.F., Mill, R.R. and Thomas, P. 2002. Conservation genetics and phylogenetics of New Caledonian Retrophyllum (Podocarpaceae) species.. New Zealand Journal of Botany(40) , p.175-188.
Jaffré, T., Munzinger, J. & Lowry, P.P. 2010. Threats to the conifer species found on New Caledonia’s ultramafic massifs and proposals for urgently needed measures to improve their protection.. Biodiversity and Conservation (19) , p.1485-1502.
Experts
Assessor(s): Amice, R., Cazé, H., Dumontet, V., Fleurot, D., Garnier, D., Héquet, V., Lagrange, A., Lannuzel, G., McCoy, S., Suprin, B., Veillon, J.
Reviewer(s): Munzinger, J., Gardner, M., Jaffré, T., Thomas, P.
Contributor(s): Butaud, J., Gueugnier, C.
Facilitator(s): Maura, J., Tanguy, V.