Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Araucariaceae of New-Caledonia: endemic species in danger


New Caledonia harbours 45% of species of the family Araucariaceae, belonging to the conifers, recorded in the world, divided between the two genera Araucaria (columnar pines) and Agathis (kaoris). These species are valuable for their ecological, economic and heritage interest, but some are under threat. IRD botanists, who have been studying the flora of New Caledonia for many years, jointly with the Natural Resources Department of the Southern Province of New Caledonia, have just published the first review of current knowledge on the local Araucaria and kaori species. The report highlights their position in terms of ecology, taxonomy and conservation. The findings should contribute to better understanding of how the diversity of these species evolved, their affinities and the role of each in the New Caledonian flora. They emphasize the need for improved protection for the endangered species if the biodiversity of this family of plants is to be conserved.

New Caledonia harbours 18 species of the Araucariaceae family of conifers, all of them endemic. On the global scale, that figure represents 45% of all species of this family. They are divided between two genera, Agathis (or kaoris) and Araucaria (columnar pines), consisting respectively of 5 and 13 species. Several of them are important economically, as a source of timber, and also have an ecological significance owing to their frequent occurrence on diverse substrates in plant communities ranging from pioneer associations to dense tropical rainforest level. Moreover, the stands of columnar pines give the New Caledonian landscape an impressively unusual character. Araucaria columnaris, widely planted near villages, also possesses a symbolic cultural value in the Kanak tradition.

The five species of Agathis and the 13 of Araucaria are on IUCN Red List of endangered species (1). The continuous regression of populations of several species, brought on by human-induced bush fires, mining and urban expansion is putting their genetic integrity at risk. Yet little research has been devoted to New Caledonia Araucariaceae, in spite of their special features (richness, unusual character, economic and heritage significance). For this reason botanists from the IRD, who for many years have been studying the local flora, and from the Natural Resources Department of the Southern Province of New Caledonia, have produced a bibliographic review of current knowledge on this family. Many questions remain concerning the identification of certain species of the genus Araucaria, owing to polymorphism of vegetative characters. Furthermore, although it is recognized that the Araucariaceae family has diversified since the emplacement of ultramafic igneous rocks (2) 39 million years B.P., molecular genetics investigations have not yet elucidated the origin and phylogeny of the different species.

The Araucariaceae in New Caledonia are all trees. The Agathis species are voluminous trees developing some of the densest, most closed canopy of the forests. Agathis lanceolata can be up to 2.5 m in diameter and reach 40 m high. Four of the five Agathis species are essentially forest trees. Only A. ovata develops also in the evergreen heath-like maquis of the mining areas. Two species are strictly associated with ultramafic substrates (A. lanceolata and A. ovata), two with acid rocks (A. corbassonii and A. montana), and one species is spread over both types of substrate (A. moorei).

The diameters of the Araucaria species are not so large, but these trees commonly reach heights of about 50 m. They are found in the forest and the maquis, most often on steep slopes or on ridges exposed to the prevailing winds. Ten species are encountered only in zones with ultramafic rocks. One species (A. montana) grows just as well on ultramafic rocks as on acid rocks and another (A. schmidii) mainly on acid rocks. There is just one species (A. columnaris) which favours mainly coastal forests on calcareous formations. Among the species encountered on ultramafic rocks, three (A. subulata, A. biramulata, A. bernieri) are essentially forest adapted, whereas the other seven grow in both the forest and the maquis. These distribution patterns express a clear affinity of Araucaria for exposed sites and for substrates originating from ultramafic rocks which often act as refuge areas where interspecific competition is less fierce. That situation favours specialized species, adapted to the strong constraints imposed by the available habitats.

In the maquis, Agathis ovata and the different species of Araucaria appear capable of continuous regeneration. Nevertheless, although the tall individual trees are fairly fire-resistant, the regeneration process is often thwarted by fires which destroy the plant embryos and young plantations. In the forest, the Araucaria and the Agathis dominate the high ground and regrowth only develops with the help of gaps caused by clearances, which indicates heliophilous affinities (3) of the two genera.

This state-of-the-art review of knowledge on the Araucariaceae could provide keys to a better understanding of the origins of the species diversity, their affinities and the role of each in the flora of New Caledonia. The scientists consider that it is now necessary to protect better the endangered Araucariacaean species in order to conserve the biodiversity of this plant family. They recommend modification and reinforcement of the classification of some of these species relative to the IUCN 2000 Criteria.

(1) IUCN, International Union for the Conservation of Nature, now renamed World Conservation Union.
(2) Nearly one-third of New-Caledonian soils are derived from ultrabasic massifs particularly rich in nickel and chromium but poor in nutrient elements essential for plant growth, such as nitrogen, phosphorus, calcium or potassium.
(3) especially appreciating sunlight.

For further information:

J. Manauté, T. Jaffré, J.-M. Veillon, M.-L. Kranitz, Revue des Araucariaceae de Nouvelle-Calédonie, Publication IRD/Province Sud de la Nouvelle-Calédonie, 2003, 28 pages

Bénédicte Robert | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>