Floristics of forests across low nutrient soils in Sulawesi,Indonesia

The island of Sulawesi formed from the joining of proto-islands roughly three million years ago. Regions of zoological endemism, corresponding to the proto-islands, have been reported. Sulawesi's tree communities, however, remain poorly documented. In better-studied tropical regions, soil types similar to those found in Sulawesi often have distinctive tree communities. To gather data on Sulawesi's tree communities, we established ten (0.25 ha) plots on four soil types across three regions. We documented diversity, endemism, dominance, and species composition. Linear models of species composition showed greater influence of geographic distance rather than soil, and no relationship with climate. This suggests that the legacy of Sulawesi's formation may have influenced tree communities more so than the soil types we sampled. Most of our plots were on stressful soil types making it difficult to conclude on the importance of edaphic specialization in the Sulawesi tree flora. The lack of climatic effects reflects Sulawesi's position within the wet tropics where the small climatic differences are unlikely to have large influence on tree communities.     

The role of elevation and soil chemistry in the distribution and ion accumulation of floral morphs of Streptanthus polygaloides Gray (Brassicaceae), a Californian nickel hyperaccumulator

Background: The flora of serpentine/ultramafic soils provides an excellent model system for the study of natural selection in plant populations. Streptanthus polygaloides is a nickel hyperaccumulator that is endemic to serpentine soils in the Sierra Nevada of California, and has four floral morphs (yellow, purple, yellow-to-purple and undulate).

Aims: We investigate three hypotheses: (1) the purple morph occurs in colder, wetter climates than the yellow morph; (2) tissue–soil ionic relationships differ among morphs; and (3) morphs occur on soils with differing elemental concentrations.

Methods: We queried herbarium records to investigate patterns of occurrence among the yellow and purple floral morphs, and analysed soil and tissue samples from wild populations of all four morphs.

Results: The purple morph inhabited serpentine outcrops with colder temperatures and greater precipitation levels than the yellow morph. Concentrations of elements in leaf tissue and rhizosphere soil differed little among populations of the morphs, but showed substantial within-site variation.

Conclusions: Our results suggest that a climatic gradient may be responsible for divergence in floral colour among populations of S. polygaloides. Because of the large within-site variation in soil and tissue elemental concentrations, plants appear to have a varied physiological response to edaphic factors, regardless of morph membership.     

Diversity and biogeography of Ni‐hyperaccumulators of Alyssum section Odontarrhena (Brassicaceae) in the central western Mediterranean: evidence from karyology,morphology and DNA sequence data

The diversity of Alyssum section Odontarrhena in the central–western Mediterranean region was investigated to elucidate relationships and biogeography of Ni‐hyperaccumulators in the group. Karyological, morphometric and molecular phylogenetic analyses were performed on accessions of Ni‐hyperaccumulators from serpentine outcrops and non‐hyperaccumulators from calcareous–dolomitic soils in the region. Alpine and Apennine populations of A. argenteum, Sardinian A. tavolarae and some Tuscan A. bertolonii had a tetraploid chromosome complement and larger silicles, seeds and seed wings than diploid accessions. DNA sequences from the plastid rpoC1 locus corroborated the monophyly of section Odontarrhena but species relationships were poorly resolved. Bayesian analysis of combined ITS‐rpoC1 sequences retrieved three main lineages including hyperaccumulators and non‐hyperaccumulators of contrasting geographical origin. One lineage was mainly continental and included alpine and northern Apennine populations of A. argenteum, the Balkan complex of A. murale and the Iberian group of A. serpyllifolium, sister to Corsican A. robertianum as suggested by their similar diploid karyotype. In this clade no divergence was found between typical A. serpyllifolium and related Ni‐hyperaccumulator races from the Iberian peninsula, supporting their conspecific status. A second lineage was prevalently Mediterranean and included the sister species A. bertolonii and A. tavolarae, and other endemics from Sicily, the southern Balkans and Turkey from dolomite and serpentine habitats. The present data suggest new model systems consisting of hyperaccumulators and non‐hyperaccumulators of proven phylogenetic affinity for further research on the molecular mechanisms of Ni‐hyperaccumulation and serpentine tolerance at the diploid and tetraploid level. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 269–289.     

Serpentinite and the dawn of life

Submarine hydrothermal vents above serpentinite produce chemical potential gradients of aqueous and ionic hydrogen, thus providing a very attractive venue for the origin of life. This environment was most favourable before Earth's massive CO(2) atmosphere was subducted into the mantle, which occurred tens to approximately 100 Myr after the moon-forming impact; thermophile to clement conditions persisted for several million years while atmospheric pCO(2) dropped from approximately 25 bar to below 1 bar. The ocean was weakly acid (pH ～ 6), and a large pH gradient existed for nascent life with pH 9-11 fluids venting from serpentinite on the seafloor. Total CO(2) in water was significant so the vent environment was not carbon limited. Biologically important phosphate and Fe(II) were somewhat soluble during this period, which occurred well before the earliest record of preserved surface rocks approximately 3.8 billion years ago (Ga) when photosynthetic life teemed on the Earth and the oceanic pH was the modern value of approximately 8. Serpentinite existed by 3.9 Ga, but older rocks that might retain evidence of its presence have not been found. Earth's sequesters extensive evidence of Archaean and younger subducted biological material, but has yet to be exploited for the Hadean record.     

Functional ecology of ecotypic differentiation in the Californian serpentine sunflower (Helianthus exilis)

* Here, we examined phenotypic differences between locally adapted serpentine and riparian populations of the serpentine sunflower Helianthus exilis from northern California, USA. * Within a common environment, plants from serpentine and riparian sites were grown in regular potting soil or serpentine soil. Physiology, morphology, phenology and fitness-related traits were measured. * Overall, riparian plants grew more rapidly, attained a larger final size, produced larger leaves, and smaller flowering heads. Riparian plants also invested less in root biomass and were more water-use-efficient than the serpentine plants. Serpentine and riparian plants also differed in leaf concentrations of boron, magnesium, sodium and molybdenum. * These ecotypic differences suggest contrasting adaptive strategies to cope with either edaphic stress in serpentine sites or intense above-ground competition at riparian sites. There was a significant population origin x soil type crossing interaction in one fitness trait (average dry weight) that mirrored local adaptation previously documented for these riparian and serpentine ecotypes. However, because all other fitness traits did not exhibit this crossing interaction in our common garden study, it is possible that phenotypic differences underlying local adaptation may be amplified in the field as a result of biotic and abiotic interactions.     

Mineral Carbonation as the Core of an Industrial Symbiosis for Energy‐Intensive Minerals Conversion

The longer term sustainability of the minerals sector may hinge, in large part, on finding innovative solutions to the challenges of energy intensity and carbon dioxide (CO₂) management. This article outlines the need for large‐scale “carbon solutions” that might be shared by several colocated energy‐intensive and carbon‐intensive industries. In particular, it explores the potential for situating a mineral carbonation plant as a carbon sink at the heart of a minerals and energy complex to form an industrial symbiosis. Several resource‐intensive industries can be integrated synergistically in this way, to enable a complex that produces energy and mineral products with low net CO₂ emissions. An illustrative hypothetical case study of such a system within New South Wales, Australia, has been constructed, on the basis of material and energy flows derived from Aspen modeling of a serpentine carbonation process. The synergies and added value created have the potential to significantly offset the energy and emission penalties and direct costs of CO₂ capture and storage. This suggests that greenfield minerals beneficiation and metals refining plants should consider closer integration with the power production and energy provision plants on which they depend, together with a carbon solution, such as mineral carbonation, as a critical element of such integration. Other sustainability considerations are highlighted.     

Congeneric Serpentine and Nonserpentine Shrubs Differ More in Leaf Ca:Mg than in Tolerance of Low N, Low P, or Heavy Metals

Serpentine soils limit plant growth by NPK deficiencies, low Ca availability, excess Mg, and high heavy metal levels. In this study, three congeneric serpentine and nonserpentine evergreen shrub species pairs were grown in metalliferous serpentine soil with or without NPKCa fertilizer to test which soil factors most limit biomass production and mineral nutrition responses. Fertilization increased biomass production and allocation to leaves while decreasing allocation to roots in both serpentine and nonserpentine species. Simultaneous increases in biomass and leaf N:P ratios in fertilized plants of all six species suggest that N is more limiting than P in this serpentine soil. Neither N nor P concentrations, however, nor root to shoot translocation of these nutrients, differed significantly between serpentine and nonserpentine congeners. All six species growing in unfertilized serpentine soil translocated proportionately more P to leaves compared to fertilized plants, thus maintaining foliar P. Leaf Ca:Mg molar ratios of the nonserpentine species were generally equal to that of the soil. The serpentine species, however, maintained significantly higher leaf Ca:Mg than both their nonserpentine counterparts and the soil. Elevated leaf Ca:Mg in the serpentine species was achieved by selective Ca transport and/or Mg exclusion operating at the root-to-shoot translocation level, as root Ca and Mg concentrations did not differ between serpentine and nonserpentine congeners. All six species avoided shoot toxicity of heavy metals by root sequestration. The comparative data on nutrient deficiencies, leaf Ca:Mg, and heavy metal sequestration suggest that the ability to maintain high leaf Ca:Mg is a key evolutionary change needed for survival on serpentine soil and represents the physiological feature distinguishing the serpentine shrub species from their nonserpentine congeners. The results also suggest that high leaf Ca:Mg is achieved in these serpentine species by selective translocation of Ca and/or inhibited transport of Mg from roots, rather than by uptake/exclusion at root surfaces.     

Metal Tolerance and Accumulation Ability of the Ni Hyperaccumulator Streptanthus polygaloides Gray (Brassicaceae)

High concentrations of metals occur in some plant species (termed hyperaccumulators), such as the Ni hyperaccumulator Streptanthus polygaloides. We determined the tolerance of S. polygaloides to, and its accumulation abilities for, six metals (Ni, Zn, Cu, Co, Mn, and Pb). Potting mix concentrations used for all metals ranged from 0 to 1200 μg/g dry weight. For Ni, a treatment of 1600 μg/g was included. For Mn, treatments of 1600, 2000, and 2500 μg/g also were used, and for Pb these concentrations plus 3500 μg/g were included. Germination, plant number per pot, and size at days 30 and 39, number of plants at the end of the experiment (day 49), flower production, and metal concentration in the aboveground biomass were documented. Lead and Ni showed no consistent effects on plant performance, but yielded increased tissue metal concentrations. Streptanthus polygaloides was more sensitive to Co, Cu, and Zn, as ≥ 400 mg/g significantly suppressed plant growth, survival, and flower production. Tissue metal concentrations also were increased to maxima of 1500 μg Co/g, 120 μg Cu/g, and 6000 μg Zn/g. Manganese affected S. polygaloides less markedly, as ≥ 800 mg/kg decreased growth, survival, and flower production. Maximum tissue Mn concentration was 2900 μg/g. We concluded that S. polygaloides would be an appropriate phytoextractor for soils contaminated with Ni or low levels of Co but would not be useful for Cu, Zn, Mn, and Pb.