New Caledonia is a global biodiversity hotspot facing extreme environmental degradation. Given the urgent need for conservation prioritisation, we have made a first-pass quantitative assessment of the distribution of Narrow Endemic Species (NES) in the flora to identify species and sites that are potentially important for conservation action. We assessed the distributional status of all angiosperm and gymnosperm species using data from taxonomic descriptions and herbarium samples. We characterised species as being NES if they occurred in 3 or fewer locations. In total, 635 of the 2930 assessed species were classed as NES, of which only 150 have been subjected to the IUCN conservation assessment. As the distributional patterns of un-assessed species from one or two locations correspond well with assessed species which have been classified as Critically Endangered or Endangered respectively, we suggest that our distributional data can be used to prioritise species for IUCN assessment. We also used the distributional data to produce a map of “Hotspots of Plant Narrow Endemism” (HPNE). Combined, we used these data to evaluate the coincidence of NES with mining activities (a major source of threat on New Caledonia) and also areas of conservation protection. This is to identify species and locations in most urgent need of further conservation assessment and subsequent action. Finally, we grouped the NES based on the environments they occurred in and modelled the habitat distribution of these groups with a Maximum Entropy Species Distribution Model (MaxEnt). The NES were separable into three different groups based primarily on geological differences. The distribution of the habitat types for each group coincide partially with the HPNE described above and also indicates some areas which have high habitat suitability but few recorded NES. Some of these areas may represent under-sampled hotspots of narrow endemism and are priorities for further field work.

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Conservation priorities in a biodiversity hotspot: analysis of narrow endemic plant species in New Caledonia.

New Caledonia is renowned as one of the world’s most significant biodiversity hotpots. The nutrient-deficiency and cations imbalances of ultramafic soils, which cover a third of the island, harbor a disproportionally high proportion of the plant diversity and endemism of New Caledonia. This review explores how ultramafic soils have influenced the exceptional endemism and richness of New Caledonia trough the concomitant occurrences of habitat patchiness, climatic instability, environmental gradient, and edaphic heterogeneity of ultramafic soils. We focus on the unique ‘maquis’ vegetation where selective pressures by nutrient deficiency and trace element surplus are at their acme. We aim to synthesize our current understanding of diversification and speciation of lineages that have been phylogenetically studied to date. Fragmentation of the peridotite mantle in isolated massifs, and as such spatial heterogeneity of ultramafic soils types, appear to promote plant endemism and speciation. Repeated independent dispersal events of pre-adapted species and persistence of paleo-endemic lineages have contributed to the phylogenetic diversity and the endemism of the ultramafic flora. Finally, historical climatic instability has caused shifts of rain forest species in refugia thereby favoring the extension of maquis species.

How did the ultramafic soils shape the flora of the New Caledonian hotspot

New Caledonia is a widely recognised marine and terrestrial biodiversity hot spot. However, this unique environment is under increasing anthropogenic pressure. Major threats are related to land cover change and include fire, urban sprawling and mining. Resulting habitat loss and fragmentation end up in serious erosion of the local biodiversity. Mining is of particular concern due to its economic significance for the island. Open cast mines were exploited there since 1873, and scraping out soil to access ores wipes out flora. Resulting perturbations on water flows and dramatic soil erosion lead to metal-rich sediment transport downstream into rivers and the lagoon. Conflicting environmental and economic aspects of mining are discussed in this paper. However, mining practices are also improving, and where impacts are inescapable ecological restoration is now considered. Past and ongoing experiences in the restoration of New Caledonian terrestrial ecosystems are presented and discussed here. Economic use of the local floristic diversity could also promote conservation and restoration, while providing alternative incomes. In this regard, Ecocatalysis, an innovative approach to make use of metal hyperaccumulating plants, is of particular interest.

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Mining in New Caledonia: environmental stakes and restoration opportunities

Impact of plant root functional traits and associated mycorrhizas on the aggregate stability of a tropical Ferralsol

In order to improve knowledge about the role of arbuscular mycorrhizal fungi (AMF) in the tolerance to heavy metals in ultramafic soils, the present study investigated the influence of two Glomus etunicatum isolates from New Caledonian ultramafic maquis (shrubland), on nickel tolerance of a model plant species Sorghum vulgare, and of two ultramafic endemic plant species, Alphitonia neocaledonica and Cloezia artensis. In a first step, plants were grown in a greenhouse, on sand with defined concentrations of Ni, to appreciate the effects of the two isolates on the alleviation of Ni toxicity in controlled conditions. In a second step, the influence of the AMF on A. neocaledonica and C. artensis plants grown in a New Caledonian ultramafic soil rich in extractable nickel was investigated. Ni reduced mycorrhizal colonization and sporulation of the fungal isolates, but the symbionts increased plant growth and adaptation of endemic plant species to ultramafic conditions. One of the two G. etunicatum isolates showed a stronger positive effect on plant biomass and phosphorus uptake, and a greater reduction in toxicity symptoms and Ni concentration in roots and shoots. The symbionts seemed to act as a barrier to the absorption of Ni by the plant and reduced root-to-shoot Ni translocation. Results indicate the potential of selected native AMF isolates from ultramafic areas for ecological restoration of such degraded ecosystems.

Arbuscular mycorrhizal fungi from New Caledonian ultramafic soils improve tolerance to nickel of endemic plant species

Presentation de l'editeur : Les substrats ultramafiques - ou terrains miniers - a l'origine du minerai de nickel, couvrent pres du tiers de la Nouvelle-Caledonie, qui se place parmi les premiers producteurs de ce metal dans le monde. Mais l'exploitation miniere a ciel ouvert necessite d'importants decapages qui generent des problemes d'erosion des sols, de dereglement des debits hydriques, de pollution des cours d'eau et de perte de biodiversite. Ces substrats datant de 37 millions d'annees portent une flore riche et originale, qui a largement contribue au classement de la Nouvelle-Caledonie comme un des principaux hotspots de biodiversite de la planete. Elle comprend environ 2150 especes vegetales dont 82 % sont endemiques. Ces especes sont en outre specialisees, adaptees a des sols tres pauvres en plusieurs elements nutritifs et inversement tres riches en magnesium, en nickel et en d'autres metaux. Ces milieux abritent egalement une faune d'une grande diversite. Ainsi la Nouvelle-Caledonie est confrontee a un double defi : celui d'exploiter une ressource miniere considerable a meme d'assurer au pays un developpement economique important, et celui de proteger cette biodiversite exceptionnelle au nom des principes fondamentaux edictes mondialement. Dans ce contexte, la conservation des milieux abritant la plus grande part de la biodiversite, ainsi que la restauration des sites degrades par l'exploitation miniere s'imposent comme des necessites incontournables. L'ouvrage decrit et illustre tout d'abord la variete des substrats ultramafiques, ainsi que la diversite des ecosystemes et de leurs composantes floristiques, zoologiques et microbiologiques. Le concept de restauration ecologique des sites degrades et les moyens necessaires pour sa mise en oeuvre sont ensuite developpes ; puis les modes de collecte, de germination, de conservation des semences et de production de plants d'especes locales sont decrits, de meme que les methodes de revegetalisation. Enfin pres de 100 especes vegetales utiles pour la restauration sont presentees. Cet ouvrage est destine a un large public, allant des professionnels du secteur minier (societes minieres, operateurs de la revegetalisation, bureaux d'etude...) aux personnels des collectivites impliquees dans la gestion du patrimoine minier et biologique du pays, ainsi qu'aux scientifiques, enseignants, etudiants, et plus largement a toute personne interessee par les terrains miniers et leur gestion environnementale

Mines et environnement en Nouvelle-Calédonie : les milieux sur substrats ultramafiques et leur restauration

Van der Ent et al-2015-Agromining -- Farming for metals in the future-ES&T+Cover

The identification and use of hyperaccumulator plants in mining projects has been recognized as an important component of life of mine planning at several sites around the world. Mine planning that includes hyperaccumulator plants requires operators to maximize the biological resources of a site by discovering and utilizing these unusual plant species at the early stages of a mine’s development. These locally adapted hyperaccumulator species can then be used for rehabilitation in and around the mine area or be utilised for their potential to extract ecocatalysts and metals. These opportunities should be more widely explored so that these unique plants can become an integrated and valuable part of the mining process. This chapter concentrates on the experiences of integrating hyperaccumulating plants into mine rehabilitation projects in Indonesia and New Caledonia to highlight some of the opportunities and challenges encountered when attempting to incorporate these species into the mining cycle.

The Integration of Hyperaccumulator Plants into Mine Rehabilitation in the Asia Pacific Region

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Caractérisation et fonctionnement du système sol/plante/microorganismes dans les maquis miniers : perspectives d'application à la restauration écologique : rapport final du projet Ecomine Biotop

Bruno Fogliani

Papers

Mines et environnement en Nouvelle-Calédonie : les milieux sur substrats ultramafiques et leur restauration

Van der Ent et al-2015-Agromining -- Farming for metals in the future-ES&T+Cover

The Integration of Hyperaccumulator Plants into Mine Rehabilitation in the Asia Pacific Region

Caractérisation et fonctionnement du système sol/plante/microorganismes dans les maquis miniers : perspectives d'application à la restauration écologique : rapport final du projet Ecomine Biotop