Ultramafic Substrates Research Articles

Gynochthodes leonardii: a novel species of Morindeae-Rubiaceae from Palawan, Philippines

Gynochthodes leonardii, a new taxon from vegetations on ultramafic substrates in the northern and central regions of Palawan province, Philippines is described and illustrated. It is superficially similar to G. bartlingii but is readily recognized by the induments on its vegetative and reproductive structures, sulcate and lenticeled branches, scarious and deciduous stipules, 3–9 capitula in an inflorescence, and shorter corolla tubes.

Specialization to ultramafic substrates and narrow endemism of Cyclophyllum (Rubiaceae) in New Caledonia: contribution of novel species to the understanding of these singular patterns

New Caledonia, listed as a biodiversity hotspot, is ecologically unique because of the abundance on the main island of ultramafic soils. The Pacific genus Cyclophyllum Hook.f. (Rubiaceae) that belongs to the tribe Vanguerieae has its centre of diversity in New Caledonia, with 13 species described so far. The present taxonomic treatment describes seven species new to science: Cyclophyllum guillauminianum Baum.-Bod. ex Mouly & Jeanson, Cyclophyllum letocartiorum Mouly, Cyclophyllum macphersonii Mouly, Cyclophyllum memaoyaense Mouly, Cyclophyllum pindaiense Mouly, Cyclophyllum tieaense Mouly and Cyclophyllum tiebaghiense Mouly & Jeanson. These new species, all endemic to New Caledonia add to species already described for the genus. A determination key and few synonymies are provided here. These species present a very interesting pattern of narrow endemism probably resulting from adaptation(s) to ultramafic substrates. Indeed, 14 species out of 19 are restricted to constraining soils and 12 species are narrow endemics to diverse areas of the main island. The category of threat was evaluated for the new species and as a result several of the described species should be considered for conservation.

<I>Nepenthes</I> (<I>Nepenthaceae</I>) of Halmahera, Indonesia

Two new paniculate species of Nepenthes, N. halmahera and N. weda, both allied to N. danseri Jebb & Cheek, are described respectively from lowland and lower montane forest on ultramafic substrate. Nepenthes weda appears to be unique in the genus due to the adaxial tepal surfaces which in the distal portion are hairy and lack nectar glands. This species is also unique among paniculate members of the genus in its forward-facing, concave subapical lid appendage. Both species are currently only known from the Weda Bay Nickel Project concession area in Halmahera, Indonesia, and are assessed as Critically Endangered using the 2012 IUCN standard. Two character states are formally described and named for the first time in Nepenthes: nanophyll rosettes and multiseriate fringed pitcher wings. Stage-related heteromorphy in lid appendages is documented for the first time in the genus. Keys to the species of Nepenthes of Halmahera, and to the paniculate species of SE Asia are presented.

A preliminary survey of the diversity of soil algae and cyanoprokaryotes on mafic and ultramafic substrates in South Africa

Despite a large body of work on the serpentine-substrate effect on vascular plants, little work has been undertaken to describe algal communities found on serpentine soils derived from peridotite and other ultramafic rocks. We report a preliminary study describing the occurrence of algae and cyanoprokaryotes on mafic and ultramafic substrates from South Africa. Results suggest that slope and aspect play a key role in species diversity and community composition and, although low pH, nutrients and metal content do not reduce species richness, these edaphic features also influence species composition. Further, typical soil genera such as Leptolyngbya, Microcoleus, Phormidium, Chlamydomonas, Chlorococcum and Hantzschia were found at most sites. Chroococcus sp., Scytonema ocellatum, Nostoc linckia, Chlorotetraedron sp., Hormotilopsis gelatinosa, Klebsormidium flaccidium, Pleurococcus sp. and Tetracystis elliptica were unique to one serpentine site. The preliminary survey provides directions for future research on the serpentine-substrate effect on algal and cyanoprokaryote diversity in South Africa.

A unique diamondiferous peridotite xenolith from the Udachnaya kimberlite pipe, Yakutia: role of subduction in diamond formation

A unique xenolith of diamond-bearing pyrope peridotite has been studied, which consists of enstatite (Al2O3 = 0.39-0.43 wt.%; Cr2O3 = 0.20-0.23 wt.%; FeO = 4.81-5.1 wt.%; average Mg# = 92.7) and pyrope (0^3 = 4.43-5.11 wt.%; CaO = 4.15-4.8 wt.%; Mg# = 83.6-84.1). The xenolith is small (10.5 g) but contains more than 30,000 diamond microcrystals (10-700 qm). High-resolution 2D and 3D X-ray tomographic images show the volume ratios of rock-forming minerals and an uneven distribution of diamonds in the xenolith (enstatite— 38 vol.%; pyrope—35 vol.%; diamond—9.5 vol.%; sulfides—4 vol.%; and the remainder being mainly alteration products), with diamonds and sulfides being localized in the same zone. The sulfides are pentlandite and djerfisherite. Isotope and FTIR spectroscopic studies showed an extremely light carbon isotope composition (513Cav = -22.9%c) of the diamonds and minor nitrogen impurities (<15 ppm) in them. Nitrogen is present mainly in aggregated form. The phase composition of nanoinclusions in the diamonds was investigated by transmission electron microscopy (TEM), including electron diffraction and analytical electron microscopy (AEM). It has been shown that all nanoinclusions are polyphase structures consisting of Mg-Al-silicate-enriched phases, Ca-carbonate, graphite, and fluid. The fluid phase has high concentrations of K, Cl, and O. The mineral inclusions in the diamonds are identified as high-Mg olivine. The data obtained indicate that the formation of diamonds in the studied xenolith was a one-act process and that the fluid/melt metasomatizing ultramafic substrate was of crustal origin. This testifies to the crucial role of deep metasomatic processes in the formation of the Udachnaya kimberlite pipe.

Metals and secondary metabolites in saxicolous lichen communities on ultramafic and non-ultramafic rocks of the Western Italian Alps

There is a long history of studies on lichens found in ultramafic habitats, but comparisons between lichen communities on different ultramafic lithologies are scant, and potential metabolic adaptations to the multiple edaphic stresses of ultramafic substrates have been widely neglected. The present work is the first to characterise differences in the abundance and structure of saxicolous lichen communities on different ultramafic lithologies (dunite, lherzolite, and serpentinite), analysed in two areas of the Western Alps (NW Italy). Differences between communities on various ultramafic lithologies were observed, including differences between a mafic control (Mg-Al metagabbro); however, factors other than the substrate were observed to drive more remarkable differences between lichen communities on ultramafics of alpine and pre-alpine areas. XRF analyses demonstrated that the mineral composition of different lithologies is reflected by metal contents in crustose lichens, with weathering processes accounting for relative shifts in elemental abundances between rocks and thalli. A thin layer cromatography screening of lichen secondary metabolites (LSMs), which are thought to regulate metal and pH homeostasis in thalli, revealed lithological vicariance among dominant lichen species with different LSM patterns and intraspecific variability in LSM production associated with differences in lithology and location. In particular, the presence or absence of norstictic acid in species or lineages/individuals on the different lithologies, in relationship to concentrations of Fe, Mg, and Ni in lichen thalli, was recognised as a metabolic adaptation to metal stress. Pull-up tests revealed that physical factors such as a differential surface disaggregation may contribute more towards differences observed in lichen abundance on the different lithologies investigated.

Wildfire risk for main vegetation units in a biodiversity hotspot: modeling approach in New Caledonia, South Pacific.

Wildfire has been recognized as one of the most ubiquitous disturbance agents to impact on natural environments. In this study, our main objective was to propose a modeling approach to investigate the potential impact of wildfire on biodiversity. The method is illustrated with an application example in New Caledonia where conservation and sustainable biodiversity management represent an important challenge. Firstly, a biodiversity loss index, including the diversity and the vulnerability indexes, was calculated for every vegetation unit in New Caledonia and mapped according to its distribution over the New Caledonian mainland. Then, based on spatially explicit fire behavior simulations (using the FLAMMAP software) and fire ignition probabilities, two original fire risk assessment approaches were proposed: a one-off event model and a multi-event burn probability model. The spatial distribution of fire risk across New Caledonia was similar for both indices with very small localized spots having high risk. The patterns relating to highest risk are all located around the remaining sclerophyll forest fragments and are representing 0.012% of the mainland surface. A small part of maquis and areas adjacent to dense humid forest on ultramafic substrates should also be monitored. Vegetation interfaces between secondary and primary units displayed high risk and should represent priority zones for fire effects mitigation. Low fire ignition probability in anthropogenic-free areas decreases drastically the risk. A one-off event associated risk allowed localizing of the most likely ignition areas with potential for extensive damage. Emergency actions could aim limiting specific fire spread known to have high impact or consist of on targeting high risk areas to limit one-off fire ignitions. Spatially explicit information on burning probability is necessary for setting strategic fire and fuel management planning. Both risk indices provide clues to preserve New Caledonia hot spot of biodiversity facing wildfires.

Riccardia elisabethae, a new species of Aneuraceae (Marchantiophyta) from New Caledonia.

A new species of Riccardia, R. elisabethae, is described from ultramafic substrate in mountain scrubland of New Caledonia. The new species is a member of the subgen. Thornoneura and differs from other species of this group by the rigid, unwinged thallus made up of large epidermal cells surrounding smaller medullary cells with thick porose walls and huge trigones.

Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge

The Kairei hydrothermal field was the first confirmed active submarine hydrothermal system on the Central Indian Ridge. It has been suggested to be related to mafic as well as ultramafic host rocks based on vent fluid composition and the presence of ultramafic rocks in its vicinity. In this study, detailed geochemical and mineralogical analyses have been carried out on the hydrothermal precipitates from the Kairei vent field in order to investigate the possible presence of indications for an ultramafic substrate at this vent site. The studied samples included fragments of sulfide chimneys, massive sulfides and talc-bearing and silicified breccias. Three mineralization stages were identified: (1) a high-temperature stage consisting largely of chalcopyrite, isocubanite, and pyrite; (2) a medium to low temperature stage characterized by the mineral assemblages of sphalerite and pyrite; and (3) a weathering stage characterized by secondary Cu-sulfides (bornite, digenite, covellite and idaite), Fe-oxihydroxides, Opal-A, and Cu-chloride (paratacamite and atacamite). The sulfide geochemistry is characterized by high concentrations of Cu and Zn (Cu + Zn up to 29.3 wt.%, n = 17) and Au (mean 5.28 ppm, n = 17), which is comparable to results from seafloor massive sulfides collected from ultramafic-hosted sites in the Atlantic Ocean, but differs from those of typical mafic-hosted deposits. The high concentrations of Cu and Au at the Kairei hydrothermal field could be an indication for the involvement of ultramafic rocks in the subseafloor. Ultramafic-hosted, Au-rich sulfide deposits may not be restricted to the Atlantic Ocean and may be common along all slow- and intermediate-spreading ridges.

Ardisia silamensis, a new ultramafic species from Borneo; studies in Malaysian Myrsinaceae II

A new species of Ardisia (Myrsinaceae) is described from the Malaysian state of Sabah in northern Borneo. Ardisia silamensis is a member of subgenus Pimelandra, and has been confused with the Peninsular Malaysian species A. solida, but differs in the indumentum type and distribution on the vegetative and especially on the floral parts, and the inflorescence bracts. The species is currently only known from ultramafic substrates on Mt Silam, and is assessed as Critically Endangered according to the IUCN criteria.

Cryptic adaptive radiation in tropical forest trees inNewCaledonia

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.

Ectomycorrhizal Pisolithus albus inoculation of Acacia spirorbis and Eucalyptus globulus grown in ultramafic topsoil enhances plant growth and mineral nutrition while limits metal uptake

Ectomycorrhizal fungi (ECM) isolates of Pisolithus albus (Cooke and Massee) from nickel-rich ultramafic topsoils in New Caledonia were inoculated onto Acacia spirorbis Labill. (an endemic Fabaceae) and Eucalyptus globulus Labill. (used as a Myrtaceae plant host model). The aim of the study was to analyze the growth of symbiotic ECM plants growing on the ultramafic substrate that is characterized by high and toxic metal concentrations i.e. Co, Cr, Fe, Mn and Ni, deficient concentrations of plant essential nutrients such as N, P, K, and that presents an unbalanced Ca/Mg ratio (1/19). ECM inoculation was successful with a plant level of root mycorrhization up to 6.7%. ECM symbiosis enhanced plant growth as indicated by significant increases in shoot and root biomass. Presence of ECM enhanced uptake of major elements that are deficient in ultramafic substrates; in particular P, K and Ca. On the contrary, the ECM symbioses strongly reduced transfer to plants of element in excess in soils; in particular all metals. ECM-inoculated plants released metal complexing molecules as free thiols and oxalic acid mostly at lower concentrations than in controls. Data showed that ECM symbiosis helped plant growth by supplying uptake of deficient elements while acting as a protective barrier to toxic metals, in particular for plants growing on ultramafic substrate with extreme soil conditions. Isolation of indigenous and stress-adapted beneficial ECM fungi could serve as a potential tool for inoculation of ECM endemic plants for the successful restoration of ultramafic ecosystems degraded by mining activities.

Structural and floristic diversity of mixed tropical rain forest in New Caledonia: new data from the New Caledonian Plant Inventory and Permanent Plot Network (NC‐PIPPN)

AbstractAimsTo describe the structural and floristic diversity of New Caledonian mixed tropical rain forest and investigate its environmental determinants.LocationNew Caledonia (SW Pacific), a biodiversity hotspot.MethodsStructural (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).ResultsA 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 &lt;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 &gt;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.ConclusionsNC‐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.

Small genomes dominate in plants growing on serpentine soils in West Balkans, an exhaustive study of 8 habitats covering 308 taxa

Habitats on ultramafic substrate present a hostile environment for plant development. We aimed to determine whether any particular range of genome size is favoured in such habitats. Genome sizes of natural serpentinophyte populations were estimated using propidium iodide cytometry and compared with published data by phylogeny paired t-tests with plants from other substrata. The panel included 308 taxa belonging to 213 genera, with new values for 28 genera and 93 species. Using Leitch’s criteria, 56 % taxa belong to the group very small genomes (1C ≤ 1.4 pg), 22 % to small (1.4–3.5 pg), 19 % to intermediary (3.5–14 pg), 3 % to large (14–35 pg) and 0.31 % to very large (1C ≥ 35 pg). The majority of species were either indifferent for substrate (56 %) or facultative serpentinophytes (33 %). Most obligate serpentinophytes possessed very small genomes, and none exceeded 5 pg (1C). On average, plants growing on serpentine exhibited lower Cx-values than the same taxa growing on other soil types. About 4 % of species were annuals and 88 % perennials. Hemicryptophytes were dominant. Presence of at least two ploidy levels was recorded for 10 species. Water stress, high temperatures and presence of heavy metals in serpentine habitats impose a high selective pressure and favour perennial species with very small genomes.

Réhabilitation d'Oxera pancheriDubard (Lamiaceae), espèce menacée de la Nouvelle-Calédonie

ABSTRACT Rehabilitation of Oxera pancheri Dubard (Lamiaceae), a threatened species from New Caledonia. Oxera pancheri Dubard, a name placed in synonymy under Oxera sulfurea Dubard in the revision of the genus in 1999 and 2004, is rehabilitated. Newly collected specimens, especially the first material ever with fruits, supports the recognition of this species, first described in 1906. Morphologically, O. pancheri differs from O. sulfurea by its racemiform inflorescences, its stamens and style slightly exserted and its velutinous fruits. Oxera pancheri seems morphologically closer (based on inflorescence type, shape and characteristics of the mericarps, juvenile foliage) to O. microcalyx Guillaumin than to O. sulfurea. Oxera pancheri is endemic to the southern part of New Caledonia's main island “Grande-Terre”, growing on ultramafic substrates. The limited geographic distribution of this species and the threats to its remaining populations lead us to assign a provisional conservation status of Endangered us...

Rhizosphere bacteria ofCostulariaspp. from ultramafic soils in New Caledonia: diversity, tolerance to extreme edaphic conditions, and role in plant growth and mineral nutrition

Rhizosphere bacteria were isolated from Costularia spp., pioneer sedges from ultramafic soils in New Caledonia, which is a hotspot of biodiversity in the South Pacific. Genus identification, ability to tolerate edaphic constraints, and plant-growth-promoting (PGP) properties were analysed. We found that 10(5) colony-forming units per gram of root were dominated by Proteobacteria (69%) and comprised 21 genera, including Burkholderia (28%), Curtobacterium (15%), Bradyrhizobium (9%), Sphingomonas (8%), Rhizobium (7%), and Bacillus (5%). High proportions of bacteria tolerated many elements of the extreme edaphic conditions: 82% tolerated 100 μmol·L(-1) chromium, 70% 1 mmol·L(-1) nickel, 63% 10 mmol·L(-1) manganese, 24% 1 mmol·L(-1) cobalt, and 42% an unbalanced calcium/magnesium ratio (1/16). These strains also exhibited multiple PGP properties, including the ability to produce ammonia (65%), indole-3-acetic acid (60%), siderophores (52%), and 1-aminocyclopropane-1-carboxylate (ACC) deaminase (39%); as well as the capacity to solubilize phosphates (19%). The best-performing strains were inoculated with Sorghum sp. grown on ultramafic substrate. Three strains significantly enhanced the shoot biomass by up to 33%. The most successful strains influenced plant nutrition through the mobilization of metals in roots and a reduction of metal transfer to shoots. These results suggest a key role of these bacteria in plant growth, nutrition, and adaptation to the ultramafic constraints.

Une nouvelle espèce micro-endémique deScaevolaL. (Goodeniaceae) de Nouvelle-Calédonie en danger critique d'extinction

ABSTRACT A new narrow endemic endangered species of Scaevola (Goodeniaceae) from New Caledonia. A new endemic species of the pantropical genus Scaevola L., S. barrierei A.S. Wulff & Munzinger, sp. nov. is described from New Caledonia. It grows in open shrub land on ultramafic substrate. It is characterized by its coriaceous and pubescent leafs on the abaxial side and its raised yellow flowers, pubescent on the exterior. This species is preliminarily assigned as “critically endangered” (CR) following IUCN Red List Categories and Criteria.

Further new endemic taxa of Cunoniaceae from New Caledonia

A description, illustration, distribution map and conservation assessment are given for each of three new species of Cunoniaceae from New Caledonia and plants endemic to the same localities from other genera are mentioned. Cunonia bopopensis Pillon & H. C. Hopkins is known from forest on ultramafic soils at high elevation on Mt Tchingou. This massif offers ecological conditions markedly different from those of its surroundings, which may explain the occurrence of several micro-endemics on this mountain. Some specimens of C. bopopensis were previously identified as C. bernieri Guillaumin but the type of the latter is probably a hybrid and this name is now considered doubtful. Geissois belema Pillon & H. C. Hopkins is endemic to Ile Art in the Belep archipelago, where it occurs in forest on ultramafic soils; it is the only species of Geissois known from Ile Art. Pancheria xaragurensis H. C. Hopkins & Pillon is found largely on the little-explored Forgotten Coast (“Cote Oubliee”) of south-eastern Grande Terre, generally in maquis along streams and in river beds at low elevation on ultramafic substrate. Morphological and ecological variation in the widespread taxa Geissois pruinosa Brongn. & Gris and Weinmannia dichotoma Brongn. & Gris are discussed and the combinations G. pruinosa var. intermedia (Vieill. ex Pamp.) H. C. Hopkins & Pillon and W. dichotoma var. monticola (Daniker) H. C. Hopkins & Pillon are published to accommodate some of this variability.

Holocene forest development and maintenance on different substrates in the Klamath Mountains, northern California, USA

The influence of substrate on long-term vegetation dynamics has received little attention, and yet nutrient-limited ecosystems have some of the highest levels of endemism in the world. The diverse geology of the Klamath Mountains of northern California (USA) allows examination of the long-term influence of edaphic constraints in subalpine forests through a comparison of vegetation histories between nutrient-limited ultramafic substrates and terrain that is more fertile. Pollen and charcoal records spanning up to 15000 years from ultramafic settings reveal a distinctly different vegetation history compared to other soil types. In non-ultramafic settings, the dominant trees and shrubs shifted in elevation in response to Holocene climate variations resulting in compositional and structural changes, whereas on ultramafic substrates changes were primarily structural, not compositional. Fire activity was similar through most of the Holocene with the exception of declines over the last 4000 years on ultramafic substrates, likely due to the reduction of understory fuels and cooler wetter conditions than in the middle Holocene. These results suggest that the tree and shrub distributions were more responsive to past climate changes on non-ultramafic substrates compared to those on ultramafic substrates. The combination of these dynamics may help explain high levels of plant diversity in the Klamath Mountains and provide insights for managing these complex ecosystems.

Large-scale habitat selection by parrots in New Caledonia

Habitat studies are important for conservation, particularly for parrots, as many are threatened and their ecological requirements are often poorly known. Our aim was to contribute to the conservation of parrots in New Caledonia by examining their selection of habitat at a large scale. From 2002 to 2010, we documented 1,357 encounters with New Caledonian Parakeets (Cyanoramphus saisseti), Horned Parakeets (Eunymphicus cornutus), and New Caledonian Rainbow Lorikeets (Trichoglossus haematodus deplanchii) throughout mainland New Caledonia. We used GIS to infer habitat selection in relation to vegetation, forest cover, forest size, altitude, rainfall, and soil. New Caledonian Parakeets selected forested areas with oligotrophic soils, particularly those from ultramafic substrates. Horned Parakeets selected habitats with a high proportion of rainforest, as well as oligotrophic soils on metamorphic substrates, yet soil fertility was less important for them. Both parakeet species favoured large forests, and appeared to avoid areas with low forest cover. Altitude had a relatively minor influence upon habitat selection by parakeets. Rainbow Lorikeets favoured areas at low altitudes with minimal rainfall and mesotrophic soils, although they were not influenced by soil fertility to the same degree as the parakeets. We consider rainforests on oligotrophic soils at intermediate altitudes (200–800 m) to be most important for parrot conservation in New Caledonia, as these habitats are likely to support significant parakeet populations.