Taxonomy

Nothofagus aequilateralis (Baum.-Bod.) Steenis
endemique
protegee
UICN

Synonyms

Trisyngyne aequilateralis Baum.-Bod.

Red List Status -

Near Threatened (NT) , assessed in 20/09/2017

Protected species -

in Northern Province

The species is endemic to New Caledonia and occurs mostly within the southern portion of the island with a few fractured subpopulations in the north. It is considered the most widespread and most frequent Nothofagus species in New Caledonia with an extent of occurrence (EOO) of 6,843 km2. The species has experienced historical population decline from a number of threats including climate change, nickel mining and fire. All of these factors still threaten the species but there is little literature available to project population decline. It has been noted that the subpopulations are largely made up of older individuals of a similar age and require major disturbance to initiate regeneration. To conclude, it is clear that there has been habitat and population decline which could suggest its fractured localities, yet the specific cause of decline is only speculative as the specific threat is currently unknown. This species has been globally assessed as Near Threatened, it almost qualifies for Vulnerable B1ab(v) but the population is not severely fragmented or in fewer than 10 locations.

Geographical area


This species is endemic to New Caledonia and occurs fairly extensively in the south of the island with a few smaller sites in the north of the island (Povila, Ouen Sieu, and Mé Ori). The species occurs over the full altitudinal range of the combined species of Nothofagus baumanniae and N. discoidea, although it is most common below 600 m. It has been noted that the species can range from 160–1,150 m. The species has an extent of occurrence (EOO) of 6,843 km2.

Population


There is limited population information for this species, yet it is considered the most widespread and frequent Nothofagus species in New Caledonia. The subpopulation is largest in the south but within the central portion of its range the subpopulation is fairly fractured. Subpopulations are largely made up of older individuals of a similar age (Veblen et al. 1996). At some sites of Nothofagus sp. seedlings and regeneration is occurring but large scale disturbance is required for widespread regeneration e.g. from cyclones.

Habitat


Nothofagus aequilateralis grows as a tree to roughly 20 m in height and is the most widespread and frequent species in New Caledonia. It has been recorded infrequently on greywacke and schists, where it is often confined to skeletal soils on ridge tops (Veblen et al. 1996). Within a Nothofagus forest, there is often little overlap between species stands. The under canopy of trees typically occur 5-10 m lower often containing species that comprise the upper canopy in mixed rain forest. This layer commonly includes several genera in the families Podocarpaceae, Araliaceae, Cunoniaceae, Lauraceae, Myrtacee, Sapindaceae, Euphorbiaceae and Apocynaceae along with many species.

Threats


The major threats to the species are mining and fire. It is also impacted by climate change. The region is experiencing rapid economic growth, rising population and constant mining for nickel which is causing many species to become fragmented and extinct in parts of the island. Many of the species habituate to lower montane forests (600–800 m) which suggests that these species are unlikely to be able to shift in response to a changing climate due to poor wind dispersal and the need for specialised soil conditions. With temperatures beginning to rise and more sporadic rain has shown fires to become more common in parts of New Caledonia. Fires have burnt in to the boundaries of Nothofagus forests in many localities and are directly responsible for the sharp boundaries often formed between rainforest and woodland or maquis. Therefore, once forest cover is lost at low altitudes following intense and or frequent fires, regeneration is less likely. Few recent Nothofagus invasions into adjacent woodland or maquis has been found that could indicate successful recovery of this species (Veblen et al. 1996). There is some regeneration in some sites where canopy cover is lost and other growth conditions ideal. It is unknown how these pressures are affecting the species to date.

Conservation


According to the BGCI Plant Search (2017), there are currently no ex situ collections of this species ; collections of this species should be made. This species is found in five protected areas: Rivière Bleue, Pic du Pin, Montagne des Sources, Yaté Barrage and Thy.

Bibliography


Munzinger J., Morat Ph., Jaffré T., Gâteblé G., Pillon Y., Tronchet F., Veillon J.-M., & M. Chalopin 2016. FLORICAL: Checklist of the vascular indigenous flora of New Caledonia. vers. 22.IV.2016.

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

Experts


Assessor(s): Baldwin, H.

Reviewer(s): Barrabé, L., Tanguy, V., Read, J.

Contributor(s): Barstow, M., Rivers, M.


Geographical distribution