Estimation of culm volume reduction factors in five bamboo species(Phyllostachys spp.)

The hollow cylindrical culm is one of the most remarkable morphological characters of most bamboo species.In relation to its hollow structure,there are two different attributes of the culm volume in bamboo:the apparent culm volume(va:the total culm volume including the hollow portion)and the woody culm volume(vw:the volume of the woody walls of the culm).The ratio of vw to va is defined as the reduction factor for culm volume(fv).The quantity fv is useful to quantify the biomass resources of bamboo culms as well as to evaluate the carbon stock of bamboo forests.However,the direct measurement of fv requires destructive sampling,which consumes time and labor.Hence,an alternative method for obtaining fv is desired.In this study,we examined fv in five species of the genus Phyllostachys and proposed alternative methods to estimate fv.Our data showed that fv varied by species,some of which exhibited a dependency of fv on culm sizes.These findings indicate that the intraspecific and interspecific variation in fv should be considered carefully when converting va into vw by fv.Based on our results,we propose here six approaches for predicting fv and we discuss their advantages and disadvantages.Our results are intended to facilitate evaluation of the carbon sequestration capacity of bamboo forests and the commercial utilization of bamboo culms.

Survey of Annual and Seasonal Fungal Communities in Japanese <i>Prunus mume</i>Orchard Soil by Next-Generation Sequencing

Fungi play a vital role in the management of soil environment. Although various fungal communities are found in soil, it is difficult to determine the fungal community structure in soil. In this study, we conducted a comprehensive survey of fungal communities in Japanese Prunus mume orchard soil from 2010 to 2012 growing seasons using next-generation sequencing technology. Fungal DNA was directly extracted from the soil samples and the internal transcribed spacer 1 region was amplified by PCR and sequenced. We identified 34,826 fungal clone sequences from the soil samples. The fungal clones were sorted into 2132 operational taxonomic units and a majority of the discriminated clone sequences were classified as Ascomycota and Basidiomycota. The number of fungal species belonging to Ascomycota showed increases in June in the three growing seasons. That belonging to Glomeromycota showed increases in August in the three growing seasons. As Ascomycota fungi are wood decomposers and saprotrophs, the results suggested that the number of plant pathogenic fungi increased in Japanese P. mume orchard soil in June. These findings show for the first time the annual and seasonal fungal community structures in Japanese P. mume orchard soil, and are expected to provide valuable clues for improvement when planting new P. mume trees in Japanese orchards.

Hard-to-Soft Transition in Radial Buckling of Multi-Concentric Nanocylinders

We investigate the cross-sectional buckling of multi-concentric tubular nanomaterials, which are called multiwalled carbon nanotubes (MWNTs), using an analysis based on thin-shell theory. MWNTs under hydrostatic pressure experience radial buckling. As a result of this, different buckling modes are obtained depending on the inter-tube separation d as well as the number of constituent tubes N and the innermost tube diameter. All of the buckling modes are classified into two deformation phases. In the first phase, which corresponds to an elliptic deformation, the radial stiffness increases rapidly with increasing N. In contrast, the second phase yields wavy, corrugated structures along the circumference for which the radial stiffness declines with increasing N. The hard-to-soft phase transition in radial buckling is a direct consequence of the core-shell structure of MWNTs. Special attention is devoted to how the variation in d affects the critical tube number Nc, which separates the two deformation phases observed in N -walled nanotubes, i.e., the elliptic phase for N Nc. We demonstrate that a larger d tends to result in a smaller Nc, which is attributed to the primary role of the interatomic forces between concentric tubes in the hard-to-soft transition during the radial buckling of MWNTs.