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We investigated the influences of humic acid on the removal of Al tridecamer ([Al.sub.13]) from a bydroxyahiminum (HyA) solution at various humic acid/Al ratios. The Al species contained in the solution were analyzed by using a liquid-state [sup.27]Al-NMR and an atomic absorption spectrometer and fractionated into three Al species: (i) [Al.sub.13], (ii) Al monomer and dimer ([Al.sub.SYM]), and (iii) other undefined species including aggregated/precipitated Al ([Al.sub.NON]). By the addition of humic acid to the HyA solution, the concentration of [Al.sub.13] was rapidly decreased within 0.007 d (10 min). The decrease in [Al.sub.13] and the increase in [Al.sub.NON] were more pronounced at a higher humic acid/Al ratio. When the molar ratio of humic acid carboxylic groups to Al exceeded 0.8, [Al.sub.13] was undetected from solution within 0.007 d. The formation of [Al.sub.13]-humic acid complexes and the aggregation/precipitation of those complexes were a predominant mechanism in removing aqueous [Al.sub.13] at the early stage of the reaction. Approximately 10 mol of carboxylic groups in humic acid were required to remove 1 moi of [Al.sub.13] from the HyA solution. Aqueous [Al.sub.13] had greater preference in precipitating with humic acid than [Al.sub.SYM]. After 5 to 570 d of aging, the concentration of [Al.sub.13] and [Al.sub.NON] also decreased and increased, respectively, both in the presence and absence of humic acid. In conclusion, aqueous [Al.sub.13] would not exist in soil solution under a high humic acid condition.

The article discusses the use of biochar, a carbonated biomass generated through pyrolysis, for improving agricultural productivity and carbon sequestration. The benefits of biochar have been observed in regions such as East and Southeast Asia, where there is a long history of biochar utilization. The article highlights the importance of sharing information on biochar in order to effectively use it in other countries. The special section in the journal Soil Science & Plant Nutrition serves as a starting point for research on biochar utilization for soil sustainability from Asian agronomical and ecological perspectives. [Extracted from the article]

Aluminum (Al) accumulators are widely distributed in the plant kingdom but phylogenetic implications of internal Al detoxification mechanisms are not well understood. We investigated differences in the characteristics of Al accumulation (i.e., accumulation potential, chemical form, and localization) in three woody Al accumulators, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi (Symplocaceae, Ericales), Melastoma malabathricum L., and Tibouchina urvilleana Cogn. (both Melastomataceae, Myrtales). The order of Al accumulation potential under hydroponic conditions was S. chinensis ≅ M. malabathricum > T. urvilleana. Oxalate was at least partly involved in the internal Al detoxification mechanisms in leaves of all three Al accumulators, based on a correlation analysis between Al and organic acid in water and 0.02 mol x [L.sup.-1] HCl extracts and the 27Al nuclear magnetic resonance spectra of intact leaves. However, the Al forms in the leaves were not simple Al-ligand complexes in a specific cell structure. Al localization in leaf sections differed among the three species. Extremely high levels of Al were found in trichomes of the lower epidermis in leaves of T. urvilleana. These data illustrate that woody Al-accumulating angiosperms have independently developed various internal Al-tolerance mechanisms in which oxalate plays a significant role. Key words: aluminum accumulators, Melastoma malabathricum L., oxalate, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi, Tibouchina urvilleana Cogn., trichomes. Les accumulateurs d'aluminium (Al) sont largement distribues dans le domaine vegetal, mais les implications phylogenetiques des mecanismes de detoxication d'Al interne ne sont pas bien comprises. Nous avons examine les differences des caracteristiques d'accumulation d'Al (p.e. potentiel d'accumulation, forme chimique et localisation) chez trois accumulateurs ligneux d'Al, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi (Symplocaceae, Ericales), Melastoma malabathricum L. et Tibouchina urvilleana Cogn. (tous deux Melastomataceae, Myrtales). Sur le plan du potentiel d'accumulation d'Al en conditions hydroponiques se trouvaient, dans l'ordre, S. chinensis ≅ M. malabathricum > T. urvilleana. L'oxalate etait implique, du moins partiellement, dans la detoxication d'Al interne dans les feuilles des trois accumulateurs, selon une analyse de correlation entre l'Al et les acides organiques dans l'eau et les extraits dans 0.02 mol x [L.sup.-1] HCl et le spectre du (27) Al en resonance magnetique nucleaire des feuilles intactes. Cependant, les formes d'Al dans les feuilles ne consistaient pas en simples complexes Al-ligand dans une structure cellulaire specifique. La localisation de l'Al dans des sections de feuilles differait selon les trois especes. Des niveaux extremement eleves d'Al etaient trouves dans les trichomes de l'epiderme secondaire des feuilles de T. urvilleana. Ces donnees illustrent que les angiospermes ligneuses qui accumulent l'Al ont developpe de maniere independante differents mecanismes de tolerance a l'Al interne dans lesquels l'oxalate joue un role significatif. [Traduit par la Redaction] Mots-cles: accumulateurs d'aluminium, Melastoma malabathricum L., oxalate, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi, Tibouchina urvilleana Cogn., trichomes., Introduction Acid soils occupy approximately 30% of the world's ice-free land area (von Uexkull and Mutert 1995). Owing to the toxic effects of aluminum (Al), acid soils with high levels [...]

Soil erosion after vegetation degradation induced by disturbance by feral goats, an invasive mammal, can lead to loss or accumulation of soil at a local scale and can alter soil chemical properties. This alteration of soil properties can in turn affect the establishment of plant species. We evaluated relationships among the extent of soil erosion, soil chemical properties, and the distribution of plant species in grassland ecosystems after goat eradication on Nakodo‐jima Island in the northwestern Pacific. In 105 1 × 1–m quadrats, changes were measured in the position of topsoil over 2 years. Surface soils were sampled for analysis of chemical properties, and plant species in the quadrat were recorded. Changes in the position of topsoil were related to the area of bare ground. Soil loss occurred at sites where areas of bare ground were extremely large. Significantly higher values of soil exchange acidity and smaller amounts of available phosphorus, total carbon, and total nitrogen were detected in soils at sites with large soil losses. Most of the 11 dominant plant species were absent from sites with large losses of soil. The presence of eight species was significantly negatively related to soil exchange acidity, and three species were significantly positively related to available phosphorus. Our results indicated that exposure of subsoils at the soil surface after vegetation degradation can increase soil loss, which can alter soil chemical properties, and this alteration can continue to limit the establishment of plant species, even long after goat eradication. [ABSTRACT FROM AUTHOR]

Effective conservation of global species diversity requires a clear understanding of spatial scales that support overall diversity across broad scales. Abandonment of semi-natural grasslands has increased their fragmentation and decreased their areal extent. We quantified diversity patterns of plant communities in Japan across hierarchical scales to facilitate the development of an effective nationwide strategy for conserving species diversity in remnant semi-natural grasslands. We applied additive partitioning of plant species diversity, using a nested hierarchical design at three spatial scales (quadrat, grassland, and western and eastern regions of Japan) for three groups of plant species (all species, grassland species and national Red Listed species). We consistently found lower proportions of among-quadrats diversity, and higher proportions of among-grasslands diversity and between-regions diversity in the overall diversity of the entire species complement than would be expected by chance. The high contribution of among-grasslands diversity to overall diversity suggests that each grassland had a unique species content. The second-ranking contributor to overall diversity differed between grassland species and Red Listed species: the second-ranking contributor for grassland species was diversity at the among-quadrats scale but the second-ranking contributor for all species and for Red Listed species was diversity at the between-regions scale. Thus, effective conservation of diversity of the entire species complement in remnant semi-natural grasslands requires preservation of beta diversity in individual grasslands. Our findings highlight the importance of strengthening local preservation and restoration activities within each grassland, and of nationwide strategies for conserving Red Listed species in remnant semi-natural grassland communities. [ABSTRACT FROM AUTHOR]

Soil organic phosphorus (P) is an important P source for biota especially in P-limited forests. Organic P has various chemical formations which differ in bioavailability and these organic P can be degraded by phosphatase enzymes. Here, we report soil P fractions inferred from solution 31P-NMR spectroscopy and soil phosphatase activities of two tropical rain forests on contrasting parent materials; sedimentary and ultramafic igneous (serpentinite) rocks. Compared to the sedimentary soils　and previous studies, P fractions of the serpentinite soils have distinctly high proportions of pyrophosphate and scyllo-inositol hexakisphosphate (scyllo-IP6). The accumulation of pyrophosphate and scyllo-IP6 may be related to strong sorptive capacity of iron oxides present in the serpentinite soils, which implies a consequent low P availability in the serpentinite soils. Mean value of soil phosphatase activities was higher in the serpentinite soils than in the sedimentary soils, suggesting that biota in these serpentinite forests depend more on soil organic P as a P source. [ABSTRACT FROM AUTHOR]