Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Araucariaceae of New-Caledonia: endemic species in danger

07.01.2004


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:

References:
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:
http://www.paris.ird.fr/

More articles from Ecology, The Environment and Conservation:

nachricht Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>