The kagu (Rhynochetos jubatus) is an iconic endemic flightless bird from New Caledonia, red-listed as endangered according to the International Union for Conservation of Nature (IUCN) criteria.Feral cats are among the most successful and damaging invaders for island biodiversity.They have been directly responsible for the extinction of numerous birds worldwide, especially small-and medium-sized flightless species.Our study evaluates the feral cat threat to the kagu by analysing 772 cat scats from the two main sites housing major remaining populations (eight quarterly sampling sessions conducted per site over 2 years).Surprisingly, we detected no predation evidence against this endangered species (including chicks) although it falls within the cats' prey size range and exhibits life-history traits typical of island endangered naïve birds.We recommend a multi-species approach to invasive mammal management to mitigate direct and indirect pressures against remaining kagu populations.

Feral cats (Felis catus) are one of the most successful and harmful invasive predator species, leading to dramatic loss of biodiversity across the globe. Our study assessed feral cat predation in a major biodiversity hotspot: the New Caledonian archipelago. We focused on the consequences of this predation for the outstanding endemic fauna found throughout the rich range of New Caledonian natural habitats. We analyzed >5300 cat scats sampled from 14 selected sites representing the 4 main natural habitats, with 4 to 6 sampling sessions per year over >4years per habitat. Our study reveals previously unreported patterns of cat predation on both alien and endemic species. Throughout the archipelago, cats prey strongly upon squamates, flying foxes and petrels. Feral cat prey included at least 44 native vertebrate species, 20 of which are IUCN Red-listed threatened species. This study adds some 44.4% to the number of IUCN threatened species vulnerable to and preyed upon by feral cats on the world's islands. New Caledonia, while it represents only 0.12% of the total area of islands worldwide (Australia included), hosts 30.8% of IUCN threatened species known to be predated by feral cats. This study recommends prioritizing management and conservation strategies by focusing actions on maquis mosaic and humid forest habitats, where feral cats pose the greatest threat. To limit the impact of feral cats, we recommend conducting targeted management actions on sites key to threatened species conservation, and preventing arrival or promoting eradication on islets.

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.

We report the recent arrival and subsequent spread of the Sida Leafbeetle, Calligrapha pantherina Stål, 1859, in the archipelago of New Caledonia. The species seems to have a rapid spread as it is now recorded all along the west coast and also have spread to the Loyalty Islands. The first specimen was caught in November 2012. This is a biocontrol agent which was introduced in the Pacific Region against invasive Malvaceae (Sida spp.). This accidental arrival would help to control the alien weed, Sida acuta Burm. f., in New Caledonia. But this establishment raises some questions about potential threats on the two endemic New Caledonian Sida species. We also discuss this arrival and subsequent installation in the context of global change and biosecurity issues, particularly in such a biodiversity hotspot.

The causes of the species richness of tropical trees are poorly understood, in particular the roles of ecological factors such as soil composition. The nickel(Ni)-hyperaccumulating tree genus Geissois (Cunoniaceae) from the South-west Pacific was chosen as a model of diversification on different substrates. Here, we investigated the leaf element compositions, spatial distributions and phylogeny of all species of Geissois occurring on New Caledonia. We found that New Caledonian Geissois descended from a single colonist and diversified relatively quickly into 13 species. Species on ultramafic and nonultramafic substrates showed contrasting patterns of leaf element composition and range overlap. Those on nonultramafic substrates were largely sympatric but had distinct leaf element compositions. By contrast, species on ultramafic substrates showed similar leaf element composition, but occurred in many cases exclusively in allopatry. Further, earlier work showed that at least three out of these seven species use different molecules to bind Ni. Geissois qualifies as a cryptic adaptive radiation, and may be the first such example in a lineage of tropical forest trees. Variation in biochemical strategies for coping with both typical and adverse soil conditions may help to explain the diversification and coexistence of tropical forest trees on similar soil types.

Due to its unique biodiversity and extreme endemism rates, New Caledonia archipelago is listed as one of Earth's 35 biodiversity hotspots.New Caledonian biota is now threatened by invasive species, with introduced rats considered to be particularly damaging.At the initiative of local institutions and NGOs, an innovative scientific experiment has been launched to quantify the Response of Forest Ecosystems to Rodent and Cat Control (REFCOR) and to test the relevance of such control at a large spatial scale (200 ha) on a dense evergreen rainforest (Mont Panié Wilderness Nature Reserve).Rat control will begin mid-2014 with a short toxin knockdown, and will thereafter involve intensive trapping sessions over the next 6 years, together with biodiversity monitoring and experiments.Rat impact studies initiated in early 2013 also aim to identify possible biodiversity indicators that could be used for a rapid assessment of rat control efficiency and effects.One of the major impacts of invasive rats is the disruption caused to plant and bird reproduction processes, placing them at high risk.Pre-and post-control experiments include the assessment of palm fruit consumption rates and of predation risk to artificial bird nests.Initial surveys of both rat populations and palm fruits (2 species), as well as artificial bird nest predation experiments, were conducted in 2013.Rat abundance was high, fluctuating among study areas and seasons, with more individual reproducers in December than in May.Fruit predation was high for one of the two species, in line with the rat abundance pattern.Surprisingly, artificial bird nest predation by rats was far lower than expected.These first results corroborate the influence of rats on some taxa.Monitoring and experiments will be repeated after and throughout rat control.This "before-after-control-impact" project, conducted in close collaboration with local stakeholders (Dayu Biik NGO), offers a unique opportunity to evaluate 1) the feasibility of controlling rat populations in the New Caledonian rainforest by trapping as an alternative to long-term poisoning, and 2) the benefits of rat control for native biodiversity and rainforest ecosystem functioning.

New Caledonia is a remote archipelago of the South-West Pacific, whose flora is rich, distinctive, and disharmonic. The interest of botanists has long been attracted by the spatio-temporal origin of this flora, but little attention has been paid to the modes of colonization and the diversification processes that have led to the archipelago's modern flora. To date, no explosive plant radiation has yet been highlighted for New Caledonia. A dated phylogenetic framework on the second richest New Caledonian genus--Psychotria s.l. and its allied genera (tribes Psychotrieae and Palicoureeae, Rubiaceae; ca. 85 species)--is provided in this study to explore its patterns of colonization and diversification in the archipelago. This study is based on a comprehensive species sampling, two nuclear and four plastid loci. Results show that New Caledonia was colonized four times by Psychotria and its allied genera during the Neogene long after its mid-Eocene re-emergence from the sea. The Pacific clade of Psychotrieae, one of the largest plant diversifications in the Pacific islands and the Indo-Pacific region, is absent from New Caledonia, possibly due to niche competition. Although the four lineages colonized New Caledonia relatively simultaneously during the Neogene, they express different evolutionary histories, as revealed by unevenness in species richness and net diversification rates. The genus Geophila has not diversified on New Caledonia, as a non-endemic single species has been documented in the archipelago. The genus Margaritopsis had a moderate level of diversification (four species) similar to that on other Pacific islands. The Psychotria clade NC1 appears to be a relictual lineage, which probably underwent a drastic extinction, with a narrow ecological habitat and dispersal limitations. The Psychotria clade NC2 is the largest and youngest New Caledonian plant radiation, and has undergone the fastest recorded diversification of any endemic lineage in the archipelago, and could be the result of a 'non-adaptive radiation', originating from Australian rainforests.

Aims: To describe the structural and floristic diversity of New Caledonian mixed tropical rain forest and investigate its environmental determinants.Location: New Caledonia (SW Pacific), a biodiversity hotspot.Methods: Structural (stem density, basal area) and floristic characteristics (composition, species richness and dissimilarity) were investigated along environmental gradients (elevation, rainfall and slope) on different substrates (ultramafic and non-ultramafic) through the New Caledonian Plant Inventory and Permanent Plots Network (NC-PIPPN, 201 plots each measuring 20 m x 20 m).Results: A total of 28,640 trees (DBH >= 5 cm) belonging to 749 species, 240 genera and 92 families were inventoried in the NC-PIPPN. The New Caledonian mixed rain forest studied was characterized as having high stem density, basal area and species richness, and many small stems (60% of the trees <10 cm DBH and almost a quarter of species did not exceed this threshold). More than one-third of the species were rare (i.e. inventoried in less than three plots or represented by fewer than three individuals) in the plot network and floristic dissimilarity was high (Bray-Curtis index >0.70). The presence of ultramafic (UM) and non-ultramafic substrates (non-UM) combined with altitudinal and rainfall gradients were the main drivers of floristic dissimilarity, whereas the effect of geographic distance between the plots was surprisingly low. Floristic dissimilarity was very high between UM and non-UM substrates from species up to family level. About 75% of the species occurred on a single substrate type. The mixed rain forest on UM and non-UM substrates differed in floristic composition but not in structure.Conclusions: NC-PIPPN proved to be an effective tool for investigating the woody species richness of New Caledonia as containing ca. 46% of its non-herbaceous species. However, the network's design, and more specifically its small plots, restricts its capacity to capture beta diversity and forest structure. High species richness and floristic dissimilarity confirm that New Caledonian mixed rain forest is exceptionally rich.

1. ABSTRACT The floristic richness and endemicity rates of vascular plants of different vegetation units, defined by edaphic and physiognomic bases, are compared. Flora on ultramafic rocks (2145 species of which 81.4% are endemic species) is richer and more specific than flora on acidic rocks (1888 species, 63.7% endemic) or calcareous rocks (485 species, 39.2% endemic). Flora of wetlands and aquatic areas as well as flora on salty soils and mangroves, each with fewer than 200 species, are on limited areas. The first one with its endemicity rate of 55 % is more particular than the second one (only 10.4%). Flora in the dense humid forests has 2013 species and an endemicity rate of 82 % i.e 870 species more than in the ultramafic maquis (shrubland), but this one has a higher endemicity rate (88.8%). The dry forest as well as savannas and thickets have quite the same number of species (424 and 410), but this flora in the dry forest covers less than 300 km2 with an endemicity rate of 55%, when the endemicity rate of the flora in the savannas and thickets spread on more than 6000 km2 is only 11%. The results of the study show how important are the influence of the extent of the forest, the diversity of the environmental conditions, the consequences in the vegetation change after disturbance (depending on the nature of the substrates), on the flora diversity of many a vegetation units. The whole floras on ultramafic rocks as well as the one in the dense humid forests on acidic rocks make most of the floristic diversity of New Caledonia.

ABSTRACT The taxonomic reference base Florical and characteristics of the native vascular flora of New Caledonia. The floristic inventory presented here comprises the evolving computerised database Florical (http://www.botanique.nc/herbier/florical). As of the date of publication, it lists all native vascular plant species (as well as infraspecific taxa) present in the territory of New Caledonia, whether validly published or in press, along with their basionym, organised according to the most recent classifications systems (APG III 2009 for the angiosperms, Smith et al. [2006] for the ferns and lycophytes, and Mabberley [2009] for the gymnosperms), accompanied by their status (native or endemic) and the various vegetation types in which they occur. After a brief historical review of our knowledge of New Caledonian botany, the characteristics (richness, composition and endemism) of the different taxonomic groups (ferns and lycophytes, gymnosperms and then angiosperms -mono- and dicotyledons) are analyzed, followed by an assessment of the distribution of these groups among the vegetation types. The vascular flora of New Caledonia is characterised by its high level of richness (3371 species, including 3099 for the flowering plants alone), despite the absence or under-representation of some taxa that are abundantly represented elsewhere in the tropics, and especially by its remarkable distinctiveness (with endemism at the species level reaching 74,7%, and 77.8% for the flowering plants). The flora stands out by the presence of several relictual taxa and a high level of speciation among certain groups, despite the fact that the island was re-colonised relatively recently following the total submersion of its much older basement during the Paleocene and the Oligocene. Details of the measures taken to conserve this extraordinary natural heritage show that only 3.4% of the territory's total surface area is effectively protected. Despite the undeniable progress made in recent years by the authorities concerned, significant work remains to be done, especially in the northern Province.

We describe the floristic composition of dry forest relicts on the west coast of New Caledonia. Using multivariate techniques, four floristic groups were defined from 71 floristic samples. The large proportion of species with rain forest affinities in all floristic groups shows similarities with the ?dry? rainforest of Australia. The two more open and disturbed groups have the highest proportion of species associated with dry areas, the strongest level of endemism and more ?most threatened? species. The two more closed groups have the highest proportion of rain forest species, but are slightly less original and have fewer threatened species. This raises the question of the exact relation of the dry forest still present in the study area to mesic forest, which has not yet been studied separately from dense humid forest in New Caledonia. The influence of the local micro-climatic conditions on the distribution of floristic groups appears critical. A good knowledge of these conditions is necessary for a sound delimitation of new protected areas, and for the implementation of protective and restorative measures appropriate to each vegetation category.

For a long time, Ni-hyperaccumulating plants have been considered to be non-mycorrhizal species. However, two recent publications have reported arbuscular mycorrhizal fungi ( AMF) colonisation in Ni-hyperaccumulators. In this work, 9 endemic Ni-accumulators of unknown mycorrhizal status, from New Caledonia, were studied. All were mycorrhizal, but some were poorly colonised by the symbiots. Only AMF were observed. We analysed the relationships between Ni-hyperaccumulation ability and AMF colonisation of the plants. The roots of the three strongest hyperaccumulators, namely Sebertiaacuminata, Psychotria douarrei and Phyllanthus favieri, were characterised by a lower mycorrhizal colonisation than the others. Mycorrhizal density varied with the level of Ni concentration in soil and plant. Root-colonisation by AMF was negatively correlated with leaf Ni content and with extractable-Ni concentration in soil. The roots of Ni-hyperaccumulators and the soils collected under these plants clearly inhibited germination of AMF spores. Hence, it appears that mycorrhizal colonisation is inhibited above a certain threshold of Ni concentration in soil and plant and becomes either absent or very low. However AMF isolated from the roots of strong Ni-hyperaccumulators have developed a very high level of Ni-tolerance and are then able to colonize at least parts of their roots.

ABSTRACT Bradyrhizobium strains, isolated in New Caledonia from nodules of the endemic legume Serianthes calycina growing in nickel-rich soils, were able to grow in the presence of 15 mM NiCl 2 . The genomes of these strains harbored two Ni resistance determinants, the cnr and nre operons. By constructing a cnrA mutant, we demonstrated that the cnr operon determines the high nickel resistance in Bradyrhizobium strains.

Cantharellus garnierii sp. nov. est decrit a partir de sept recoltes provenant des maquis miniers nickeliferes de Nouvelle-Caledonie. Il est signale comme associe a Acacia spirorbis, Casuarina coltina et Nothofagus balancae au sein d'un cortege assez classique et diversifie de champignons ectomycorhiziens comprenant, entre autres, les genres Russula, Lactarius, Inocybe, Suillus, Boletus, Cantharellus... Ce taxon est caracterise par la taille moyenne de ses carpophores, qui sont d'un jaune a jaune orange uniforme, sa croissance le plus souvent fasciculee, sur des sols nickeliferes ultrabasiques, ses spores de taille moyenne, son mediostrate relativement differencie, et enfin ses hyphes bouclees a paroi distinctement epaissie au niveau de l'epicutis. Aucune autre espece decrite au niveau mondial ne se rapproche de C. garnierii. (Resume d'auteur)

In New Caledonia, nickel mining activities have drastic impacts on a rich but particularly fragile environment. Mining companies are more and more concerned with the need to restore the degraded sites, in adverse edaphic conditions. Symbioses, both nitrogen-fixing and mycorrhizal, are known to play key roles in these processes in allowing the plant nutrition with major elements like N and P, in facilitating access and use of water, in stabilizing the soils through hyphal mats and possibly buffering metal toxicity. Over 30 years of field trials, a range of plants species have been identified as good candidates for revegetalisation and ecological restoration. About 38 genera, from 20 botanical families have thus been identified by Jaffre and Pelletier (1992). To optimise the use of these plants in ecological restoration, we explored their mycorrhizal status within their natural ecosystems and characterized their fungal partners. The aim of this work is to present the particular potential of some of the candidate plants in early revegetation steps, in compatibility with their natural environmental conditions. Among the 20 botanical families, almost half (9) have been reported as including ectomycorrhizal species, which is a quite huge rate compared to the rate of ectomycorrhization among plants. For 3 families, no reports have been found on their mycorrhizal status. Arbuscular associations have been reported for 17 families, of which 2 exhibits myconodules. The characteristics of these differents associations will be presented. (Texte integral)

This paper describes a study undertaken in the dry sclerophyll forest in the Tiea Botanical Conservation Area (Pouembout). Together with low-altitude, ultramafic shrubland (maquis), dry sclerophyll forest is the most endangered habitat in New Caledonia. Phytosociologic and floristic analysis reveal two highly-modified, secondary vegetation types comprised primarily of introduced herbaceous (mainly Gramineae) or locally abundant indigenous ligneous species, and three primary forest types which — although modified to a greater or lesser extent — still contain the species characteristic of dry forest, albeit often in reduced populations. Due to their rarity, 19 of these species are included on the IUCN list of endangered plants. These threatened plants must now be propagated so they can be re-established in the most damaged parts of the Conservation Area, and methods to reduce the effects of competition on them by introduced species have to be developed.