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Abstract: The genesis of a 40-cm-thick buried Holocene humic soil horizon in a 6-m-high sequence near Towada volcano, Japan, was examined by dating stable, plant-derived humin particles by AMS-based radiocarbon (14C), and by analyzing stable carbon isotope ratios (δ13C), phytolith composition, and soil chemical properties. The AMS dating yielded calibrated ages ranging from 7570–7679 to 6180−6313calyr BP. We obtained a strong correlation (r=0.99, ***p<0.001) between sample depth and the mean age. The (now buried) humic soil was formed by the incremental accumulation of tephric loess and aeolian dust at a constant rate of ~30mm per century for at least 1200years. Whilst the soil surface was slowly rising, graminaceous vegetation was supplied at a constant rate so that developmental upbuilding pedogenesis ensued. The soil was buried and isolated by the fall of the Towada-Chuseri tephra about 6200calyr BP. Thus the tephra-soil sequence near Towada volcano represents both developmental and retardant upbuilding pedogenesis. [Copyright &y& Elsevier]

Spiraea thunbergii Sieb. was found to contain 1-O-cis-cinnamoyl-β-d-glucopyranose and 6-O-(4′-hydroxy-2′-methylene-butyroyl)-1-O-cis-cinnamoyl-β-d-glucopyranose as major plant growth inhibitory constituents along with related compounds of lower phytotoxicity including 6-O-(trans-cinnamoyl)-1-O-(4″-hydroxy-3″-methyl-furan-2″-one)-β-d-glucopyranose, 6-O-(4′-hydroxy-2′-methylene-butyroyl)-1-O-trans-cinnamoyl-β-d-glucopyranose, and 1-O-trans-cinnamoyl-β-d-glucopyranose. The former three compounds were cinnamoyl glucosides. [Copyright &y& Elsevier]

Abstract: At 12,900aBP, the eruption of the Laacher See volcano generated a new parent material for Holocene soil formation in parts of Western Germany. Weathering of these ashes commonly includes the formation of poorly crystalline minerals such as allophane, imogolite and ferrihydrite. Detection of these minerals in soil is difficult, yet an important task, because they may govern soil functions and processes, e.g., stabilisation of organic matter and nutrient availability. Therefore, we characterised three forested Andosols by a combination of wet-chemical and spectroscopic techniques including infrared and (27Al, 29Si) nuclear magnetic resonance (NMR) spectroscopy together with X-ray diffractometry. Deconvoluting the 29Si-NMR spectra revealed that 1.6 to 10.4% of total Si was present as allophanic compounds, which coincided with the amounts of oxalate-extractable Si. Since extraction methods are not completely selective, we observed a slight overestimation of allophanic Si estimated from oxalate extraction. Although the sites under study are located close to each other in similar relief positions and with similar vegetation, the combination of our results revealed varying amounts of loess in the parent materials and varying weathering intensity. High weathering intensities correlate with the amounts of allophane. [Copyright &y& Elsevier]

Plant growth inhibitory alkaloids were isolated from the extract of mesquite [Prosopis juliflora (Sw.) DC.] leaves. Their chemical structures were established by ESI-MS, 1H and 13C NMR spectra analysis. The I50 value (concentration required for 50% inhibition of control) for root growth of cress (Lepidium sativum L.) seedlings was 400 μM for 3⁗-oxo-juliprosopine, 500 μM for secojuliprosopinal, and 100 μM for a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine, respectively. On the other hand, the minimum concentration exhibiting inhibitory effect on shoot growth of cress seedlings was 10 μM for 3⁗-oxo-juliprosopine, 100 μM for secojuliprosopinal, and 1 μM for a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine, respectively. Among these compounds, a (1:1) mixture of 3-oxo-juliprosine and 3′-oxo-juliprosine exhibited the strongest inhibitory effect on the growth of cress seedlings. [Copyright &y& Elsevier]

The absolute configurations of 2-methoxy-2-(1-naphthyl)propionic acid and 2-methoxy-2-(2-naphthyl)propionic acid were reconfirmed by NMR analyses of phenylglycine methyl ester (PGME) derivatives. Their absolute configurations determined by the PGME method are consistent with those obtained by the 1H NMR anisotropy method and X-ray crystallography. [Copyright &y& Elsevier]

Highlights: [•] Conformationally constrained cis-cinnamic acid analogues were designed, in which the aromatic ring and the cis-olefin are connected by a carbon bridge. [•] Their inhibitory activities on elongation of lettuce roots was evaluated with inhibitory activities of five- and six-membered bridged compounds being enhanced. [•] The cis-analogue having a five-membered ring exhibited bioactivity ten times higher than cis-cinnamic acid. [Copyright &y& Elsevier]

Highlights: [•] cis-Cinnamic acid analogues was synthesized having substituents on the aromatic ring, and their inhibitory activities on the elongation of lettuce roots were evaluated. [•] Para- and ortho-substitution decreased potency. [•] meta-Substituted cis-cinnamic acid analogues were more likely to be potent. [•] m-Iodo, m-methoxy and m-trifluoromethyl substituents induced higher potency. [Copyright &y& Elsevier]

Highlights: [•] The citrate content in the roots was increased with Al treatments. [•] The activities of aconitase and NADP+-ICDH were decreased with Al treatments. [•] The activity of citrate synthase was not affected by Al. [•] Al–citrate complexes were a major chemical form in the cell sap of root tips. [Copyright &y& Elsevier]

Abstract: 1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C–C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C–C double bond were also investigated. [Copyright &y& Elsevier]

Abstract: To quantitatively clarify the organic carbon accumulation processes on the forest floor during an early stage of humification (3 years), solid-state 13C cross polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) signals were monitored for phased–humified beech and oak litters and soil surface horizons in the northern Kanto District, Japan. The mass loss rate of the carbon components during the humification for both litters was in the following order: O-alkyl > aromatic > aliphatic > carbonyl carbons. This result indicates that the labile O-alkyl carbons, probably dominated by holocellulose were selectively degraded compared to the other components. 44% of O-alkyl carbon mass for beech and 38% for oak lost throughout 3 years of incubation. Inversely, the mass of aliphatic carbons, which is mainly composed of saturated hydrocarbons, decreased quite slowly from 20 to 10% with humification, probably because a large proportion of the aliphatic carbons are secondary products of microorganisms. The aromatic carbon mass, which would be derived from lignin/tannin and their metabolites, also decreased gradually from 17 to 6% over 3 years. While, the carbonyl carbon mass was quite stable at around 2% throughout the incubation period, probably because the hydrolysis reactions of organic carbon would contribute to the formation of the carbonyl carbons. According to an exponential model, the total carbon stocks on the forest floor converged at 4.2 Mg C ha−1 for the first few years at the studying site. The carbon compositions converged to intermediate levels between those of the F and A 1 horizons. The simulation in the present study is able to represent the carbon accumulation process on the forest floor including a part of the mineral. [Copyright &y& Elsevier]

Abstract: Cyanamide (NH2CN) has recently been proven to be a natural product, although it has been synthesized for over 100 years for agricultural and industrial purposes. The distribution of natural cyanamide appears to be limited, as indicated by our previous investigation of 101 weed species. In the present study, to investigate the distribution of natural cyanamide in Vicia species, we monitored the cyanamide contents in V. villosa subsp. varia, V. cracca, and V. amoena during their pre-flowering and flowering seasons. It was confirmed that V. cracca was superior to V. villosa subsp. varia in accumulating natural cyanamide, and that V. amoena was unable to biosynthesize this compound under laboratory condition examined. The localization of cyanamide in the leaves of V. villosa subsp. varia seedlings was also clarified. In a screening study to find cyanamide-biosynthesizing plants, only Robinia pseudo-acacia was found to contain cyanamide among 452 species of higher plants. We have investigated 553 species to date, but have so far found the ability to biosynthesize cyanamide in only three species, V. villosa subsp. varia, V. cracca and R. pseudo-acacia. [Copyright &y& Elsevier]

Abstract: To determine the mechanism of aluminum (Al) detoxification in the roots of tea plants (Camellia sinensis (L.) Kuntze), the amounts of Al and Al-chelating compounds (fluoride (F), organic acids and catechins) were measured and the chemical forms of Al in root cell extracts were identified by the application of 27Al-nuclear magnetic resonance (NMR) spectroscopy. Tea plants were cultivated in nutrient solutions containing 0, 4, 1.0 and 4.0mM of Al at pH 4.2 for approximately 10 weeks. The levels of soluble Al, water-soluble oxalate and citrate, but not F, malate or catechins in young roots increased with an increase in the concentration of Al in the treatment solution. The 27Al NMR spectra of root tips and cell sap extracted from root tips that had been treated with Al were almost identical and had four signals, with two (11 and 16ppm) apparently corresponding to the known chemical shifts of Al–oxalate complexes. In the spectra of cell sap, the resonances at 11 and 16ppm increased with an increase in the Al contents. These results suggest that the levels of Al–oxalate complexes increased in response to an increase in the Al level, implying that oxalate is a key Al-chelating compound in the mechanism of Al detoxification in the tea root. [Copyright &y& Elsevier]

• Hydrophilic fulvic acid fractions had received much biological transformations. • Humic acid fractions had formed at early stage of soil formation with less biological transformation. • Fire event could be a possible formation mechanism of HA fractions. • Mobility of soil organic carbon fractions was limited to <4 mm per century. • The thick humic horizon reflects the successive up-building accumulation of soil particles containing soil organic carbon. A buried humic horizon (14C age between 5.4 and 6.8 kyr BP) of a volcanic ash soil in Aomori, Japan, which was collected from the depth between 147 and 187 cm at 5 cm-interval (total eight sub-horizon samples), was investigated to clarify the degree of biological transformation and mobility of soil organic carbon (SOC) fractions. The SOC fractions were prepared from each sub-horizon sample by extraction and precipitation procedures with controlling pH of the extracted solution, resulting in humin, humic acid (HA), and four fulvic acid (FA) fractions (two hydrophilic FA fractions: FA 1 and FA 2 , and two hydrophobic FA fractions: FA 3 and FA IHSS). The prepared SOC fractions were characterized by 14C age and stable isotopic ratios of 13C (δ13C) and 15N (δ15N). The hydrophilic FA fractions showed the highest δ13C and δ15N values, indicating that these SOC fractions had been most enriched with 13C and 15N by biological metabolic processes. On the other hand, the HA fraction showed the lowest δ13C and δ15N values, therefore this fraction would have been less-metabolized, although HA fraction has been regarded as well-processed in general. The 14C age of the HA fraction was almost same as the deposition age of the corresponding sub-horizon, indicating that the C in the HA fraction would have been fixed in situ right after photosynthesis by plants at the early stage of soil formation and chemically stabilized at soil surface, by fire event, etc. The average rates of vertical translocation of the SOC fractions were low (humin and HA fractions: <1 mm per century, FA fractions: 1–4 mm per century), implying that the vertical translocation of SOC would not be the main mechanisms for forming thick humic horizons. The present study showed strong evidence of the in situ formation of SOC on soil surface, and successive up-building accumulation of soil particles containing SOC would contribute to the formation of the thick humic horizons. [ABSTRACT FROM AUTHOR]

• We simulated the eradication of invasive goats and rats on an oceanic island. • Simultaneous eradication both goats and rats was favorable for ecosystem restoration. • The simultaneous eradication made the ecosystem be bi-stable. • In rare cases, the ecosystem was crashed after the eradication. The decline of the natural ecosystem on the Ogasawara Islands caused by invasive species has been an important environmental problem and projects for eradicating invasive species are currently underway. Some invasive species have proliferated in the host environment and are affecting the material cycle in the ecosystem. If the invasive species were removed from the environment, the material cycle of the ecosystem may be altered and native species that should be protected may be negatively affected. After the introduction of invasive alien species, namely goats and rats, the vegetation declined on Nakoudojima Island, an island that belongs to the Ogasawara Islands. Therefore, in this study, a mathematical model was developed to simulate and analyze the ecosystem changes that occurred following the eradication of goats and rats. When only rats were eradicated, the island's vegetation changed to grassland but revegetation was delayed and the biomass of the native animal species did not recover significantly. When only goats were eradicated, the vegetation recovered and the biomass of the native animal species increased; however, the island became forested and many native herbaceous plant species became extinct. When goats and rats were eradicated simultaneously, the vegetation recovered and the biomass of the native animal species increased; however, the ecosystem became very unstable and two extreme results were obtained – the vegetation of the entire island changed to either forest or grassland. The results of this study suggest that instead of simply eradicating invasive species, it is necessary to monitor post-eradication changes in the ecosystem and take adaptive measures as required. [ABSTRACT FROM AUTHOR]