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.
Bénédicte Robert | EurekAlert!
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