The mineralization rate of black soil carbon in the deep layers of Japanese volcanic ash soil may be easily accelerated by labile carbon supply

ABSTRACT

The stability of black soil carbon in the deep layers of Japanese volcanic ash soil (i.e., buried A horizons) is often explained by its unique chemical (molecular structure) and physical (associated with short-range-order minerals) recalcitrance. However, the stability of black soil C in buried A horizons may be changed by labile C supply for soil microbes. Here, we hypothesized that the mineralization of black soil C in buried A horizons of Japanese volcanic ash soil could be easily accelerated by a supply of labile C (i.e., a priming effect; PE). To test our hypothesis, we investigated the direction and magnitude of the PE with a buried A horizon in Japan using ¹³C-labeled glucose (2.188 atom %) in a short-term (21 days) incubation study. We also investigated the effect of mineral nitrogen (N), which could contribute to microbial activity in this incubation study. We found that a positive PE occurred by glucose supply with (182%) or without (181%) mineral N input over the 21-day incubation, and its values were very similar to the PE ratios previously reported in other deep soils. The estimated mean residence time (MRT) of black soil C considering PE was clearly accelerated by glucose supply, regardless of mineral N input, compared with the initial soil MRT. These results strongly support our hypothesis that the mineralization rate of black soil C in buried A horizons is easily accelerated by a labile C supply, and it also demonstrates important implications for the effects of global warming on buried A horizons (e.g., increased root exudation, fine root biomass supply, and N deposition) in Japanese volcanic ash soils.     

Etiology of the resinous stem canker ofChamaecyparis obtusa: Cistella japonica as the causal agent

In order to confirm the pathogenicity ofCistella japonica, inoculation experiments were conducted onto several coniferous trees. Resinous lesions similar to those of the resinous stem canker developed by the inoculation withCi. japonica only onChamaecyparis obtusa. Chamaecyparis trees were heavily affected when inoculated with the fungus in November, but slightly in May and August. Resin flows occurred when inocula ofCi. japonica were put into the holes made on stem barks and on pruning scars. Isolates ofCi. japonica varied greatly in the pathogenicity. On the lesions caused by the fungus, resinous and necrotic areas expanded in fusiform or oblong shape, and resin cysts were formed in inner barks. Beneath some necrotic inner barks, sapwood was suppressed in growth for the damages in cambial cells and stained.Ci. japonica was reisolated from the inoculated lesion tissues, though isolation frequency of the fungus became lower in some lesions two or more years after the inoculation. The results of these inoculations proved thatCi. japonica was the causal agent of the resinous stem canker ofCh. obtusa.     

Amino acid composition of proteins as a product of molecular evolution

The average amino acid composition of proteins is determined by the genetic code and by random base changes in evolution. Small but significant deviations from expected composition can be explained by selective constraint on amino acid substitutions. In particular, the deficiency of arginine in proteins has been caused by constraint, during evolution, on fixation of mutations substituting arginine for other amino acids.     

The electrical conductivity of post-perovskite in Earth's D' layer

Recent discovery of a phase transition from perovskite to post-perovskite suggests that the physical properties of Earth's lowermost mantle, called the D' layer, may be different from those of the overlying mantle. We report that the electrical conductivity of (Mg0.9Fe0.1)SiO3 post-perovskite is >10(2) siemens per meter and does not vary greatly with temperature at the conditions of the D' layer. A post-perovskite layer above the core-mantle boundary would, by electromagnetic coupling, enhance the exchange of angular momentum between the fluid core and the solid mantle, which can explain the observed changes in the length of a day on decadal time scales. Heterogeneity in the conductivity of the lowermost mantle is likely to depend on changes in chemistry of the boundary region, not fluctuations in temperature.     

Gigantic photoresponse in 1/4-filled-band organic salt (EDO-TTF)2PF6

We report that the organic salt (EDO-TTF)2PF6 with 3/4-filled-band (1/4-filled in terms of holes), which forms an organic metal with strong electron and lattice correlation, shows a highly sensitive response to photoexcitation. An ultrafast, photoinduced phase transition from the insulator phase to the metal phase can be induced with very weak excitation intensity at near room temperature. This response makes the material attractive for applications in switching devices with room-temperature operation. The observed photo-induced spectroscopic change shows that this photoinduced phase transition process is caused by the cooperative melting of charge ordering assisted by coherent phonon generation.     

Teratogenic effects of isolated and combined short‐term hypercapnia and hypoxia on red sea bream (Pagrus major) embryos

Some vertebral anomalies in cultured fish arise from unusual environmental conditions during embryogenesis. We investigated the individual and combined teratogenic effects of short‐term hypercapnia and hypoxia on embryos of red sea bream (RSB), Pagrus major. Ten‐somite stage embryos were exposed to hypercapnia (60 and 120 mg/L dissolved carbon dioxide: DCD) and hypoxia (0%, 10%, 25%, 50%, and 75% dissolved oxygen: DO) independently and concomitantly for seven different periods (0, 30, 60, 90, 120, 150 and 180 min) to examine somitic disturbances at hatching, which are prodromal symptoms of centrum defects. Another experiment examined vertebral anomalies in juveniles raised from eggs exposed to hypercapnia (120 mg/L DCD) and hypoxia (10% DO) independently and concomitantly. Short‐time exposures (30–180 min) to hypercapnia (60 and 120 mg/L) and hypoxia (10% DO or less) independently and additively caused larval somitic disturbances and juvenile centrum defects. The results indicate that short‐term hypercapnia and hypoxia generally have the same teratogenic effect on embryos, although there were some differences in the locations of the somitic disturbances and centrum defects, with additive teratogenicity when the conditions were combined. These results suggest the necessity of maintaining appropriate DCD and DO concentrations during egg incubation and transport and during reproduction in recirculating aquaculture.     

Smallholder reforestation and livelihoods in the humid tropics: a systematic mapping study

Systematic mapping studies provide a snapshot of the literature based on systematic literature searches. In this systematic mapping study, the original research that links reforestation and livelihoods in the tropics was mapped and analysed to identify the trends, biases and gaps in the literature. In total, 339 papers from 92 journals were identified. Agroforestry Systems was the journal in which articles were most frequently published, and Cameroon and Indonesia the most frequently studied countries. The greatest number of authors came from the USA, and authors were most commonly affiliated with ICRAF. A limited collaboration between research groups in the tropical regions was identified. Anthropology and Social Sciences were the most frequent areas of research, especially in Africa. Latin America had more technical studies and more publications discussing payment for environmental services than the other regions. Based on the temporal analysis of the main terms in abstracts of the publications included, it was found that agriculture-related terms and terms related to the human component in the landscape were consistently prevalent in the literature relating reforestation and livelihoods throughout time. Agroforestry systems were especially important in small-scale reforestation and livelihoods. Trends, biases and gaps were discussed. Broader cooperation between tropical regions and between clusters of authors would be beneficial for research and practice.     

The potential global distribution of <Emphasis Type="Italic">Chilo partellus</Emphasis>, including consideration of irrigation and cropping patterns

Chilo partellus is a major crop pest in Asia and Africa, and has recently spread to the Mediterranean region. Knowledge of its potential distribution can inform biosecurity policies aimed at limiting its further spread and efforts to reduce its impact in areas that are already invaded. Three models of the potential distribution of this insect have been published, each with significant shortcomings. We re-parameterized an existing CLIMEX model to address some parameter inconsistencies and to improve the fit to the known distribution of C. partellus. The resulting model fits the known distribution better than previous models, highlights additional risks in equatorial regions and reduces modelled risks in wet and extremely dry regions. We bring new insights into the role of irrigation in the potential spread of this invasive insect and compare its potential distribution with the present known distribution of its hosts. We also distinguish regions that are suitable for supporting persistent populations from those that may be at risk from ephemeral populations during favourable seasons. We present one of the first demonstrations of a new capability in CLIMEX to automatically estimate parameter sensitivity and model uncertainty. Our CLIMEX model highlights the substantial invasion risk posed by C. partellus to cropping regions in the Americas, Australia, China, Europe, New Zealand and West Africa. Its broad host range and reported impacts suggest that it should be a pest of significant concern to biosecurity agencies in these presently uninvaded regions.